what is trip on generator

My generator keeps tripping(It’s Causes & Ways to Fix it)

Tripping is basically the word used to describe abrupt disconnection of any electric device when the circuit breaks. Every electric device contains circuit breakers. These help to switch the device off whenever there is a surge in electricity or any other issue that might harm the device or other devices connected to it. 

Just like main electric supplies, generators also trip at times unexpectedly. It can be really frustrating when there is no electricity and the generator also trips. In this article, you will learn different reasons why a generator might trip, what you can do to fix it and how to prevent it from happening. 

Main Reasons for Tripping 

Generally, a generator trips due to either the circuit breaker disrupting the supply or a problem with the Ground Fault Circuit Interrupter (GFCI) receptacles .

Both the circuit breaker and GCFI are used to protect devices from damage, however, they serve slightly different purposes. 

All generators contain circuit breakers (and fuses) that trip or disconnect electric supply whenever there is a potential threat for the connected devices. Mostly they are used to deal with the unexpected electric surges and only trip when the electric supply is higher than needed.  

In contrast to the circuit breakers, the GFCI receptacles are used to detect any potential leakage of electricity from the device . In other words, they indicate that the electric current is being lost in some unwanted direction instead of following the desired path to the ground. 

There can be different causes of electric leakages; these include torn wires, worn insulation, water or moisture, a defective electrical appliance and even contact with the human skin . A GFCI is very important and life-saving equipment that abruptly shuts down the generator to prevent any possibility of electric shock or electrocution. If the GFCI does not work properly, there is a possibility of a fire breaking out. 

While both circuit breakers and GFCIs are extremely important, there are times when they start malfunctioning and keep turning the generator off without any valid reason . When that happens, then you will have to check each of them to see where the problem lies. 

• Read Surge protector vs GFCI

Quick Ways To Fix It

Finding the fault.

Since there are two main possible causes of a generator tripping, it is important to find out the exact cause and narrow down the problem. It should be noted that all generators do not have GFCI receptacles so the first thing you should do is to find out if your generator has them. 

Sometimes, it is possible that both the circuit breaker and GFCI trip at the same time . If it is only the former, then you may need to ensure that you are not putting load beyond the generator’s capacity. However, if i t is only the GFCI that is tripping, then it is a most likely leakage of electric current. 

• Read What happens when you run a generator without load

Checking the GFCI Receptacle 

In order to check whether the GFCI receptacle is causing the trip or not , you will have to turn off the generator and disconnect all the devices from your generator . After doing so, you have to restart the generator and reset the GFCI receptacle. This is done by simply pressing the “Reset” button. See if the button remains depressed afterwards – if not, then that is an indication that your generator’s GFCI receptacle has stopped functioning and needs to be replaced. 

If you find no potential issue with the GFCI receptacle, then you can try connecting a small electrical load, such as a bulb, directly without using any extension cord . Wait for at least 15 seconds to see whether it trips or not. If it does not, then that further suggests that there is nothing wrong with the GCFI receptacle and there might be some other cause of the problem. 

Even in the case the bulb trips, do not jump to conclusions before repeating the procedure with a different bulb or some other small load . If every device that you are connecting keeps tripping, then you may need to seek professional help. 

Check the Cords 

If you use an extension cord to connect your devices, then once you have checked or fixed the GFCI receptacles, you must also examine your cord using the same process . Connect all cords to your generator one by one and also check if there is any dirt or moisture affecting any of them. If the generator trips with any of the cords, then that cord needs to be replaced . 

If there is no problem with the GFCI receptacles or the cords, then you may have to check your circuit breaker and get it replaced . In some situations, the generator works for some time and then then the automatic air switch trips a few minutes later, releasing a burning odour. 

This is usually the result of insufficient spring pressure or poorly contacted air switch. This increases the contact resistance in the main circuit and hence heats the switch, causing it to trip . To fix this, you should properly clean the switch and get rid of any moisture or dust. Make sure the switch is properly in place. 

In some cases, the generator will trip as soon as you connect the load to it. This is usually because either the load is too heavy or there is an external short circuit. For this, you might need professional support to find exactly where that external short circuit is and get it fixed. 

Checking the Capacitor

Checking your capacitor is an even more complicated task than checking the GFCI receptacles. Many circuit breakers have a built-in indicator to show that there is an overload and the device has tripped . However, there are times when either there is no indication or the breaker stops working and hence the indicator cannot be trusted. 

To confirm that whether it is actually the faulty breaker or something else, you may have to try the same steps and connect different appliances . You can also use a multi-meter to measure the resistance on the lead wire connections that are present inside the panel. 

Usually, any readings suggest that the breaker is functioning and the problem is somewhere else. If the reading shows ‘OL’ (overload) or Infinity despite having no appliances connected, then that is an indication that the circuit breaker is malfunctioning and must be replaced. 

Check the Wires 

Wiring is also very crucial and sometimes damaged wires can also cause the circuit breaker to react and trip the generator. It is better to check on the wires every few days. 

Choosing the Right Circuit Breaker

While there is no way, you can control the power surges and unwanted tripping that will happen unexpectedly at times, choosing the right kind of capacitor can make it easy . Here are some things to keep in mind when buying a capacitor. 

High Voltage Rating

All capacitors come with a specific voltage rating . A good capacitor is the one which has enough voltage capacity to run the appliances and will not heat up easily. The higher the rating, the better it is. 

• Read Why Is My Generator Output Voltage Too Low

Must-Have a High Maximum Interrupting Capacity

Interrupting capacity of a capacitor is basically its potential to deal with the electric surges without getting damaged. T he interrupting capacity of a capacitor should always be high so that it does not stop working when power fluctuates. 

Should Deal with High Temperature

A good capacitor should always have the potential to deal with high temperatures whenever a device heats up. Always find out if the capacitor you are buying is recalibrated to the environment you are going to use it in.

Prevent from Corrosion and Moisture

It was mentioned earlier as well that often dust and moisture can result in tripping of the generator . There are some capacitors in the market that are designed to deal with the moisture. When buying a capacitor, keep these properties in mind. 

Conclusion 

In this article, we have highlighted different issues that might cause the generator to trip. We have also discussed how to check where the problem lies so it can be fixed accordingly.

Moreover, we have also explored some of the qualities that we should seek in a capacitor to prevent everyday problems. The information provided in this article can help people understand why their generator trips. Those who understand electric circuits can benefit from this and use it to fix their generators.  

While having knowledge of things is good, it is always better to seek the help of experts in every field. Unless there is an emergency, it is always better to call a professional electrician to deal with these problems.

Sometimes, tripping might indicate a deeper problem that can even be life-threatening at times. 

If you smell a burning odour, a spark or severely heated up wires, then it is important to seek professional support at the earliest. Ignoring these signs or not getting proper help can often result in the outbreak of fire. Sometimes, there are certain things that only an expert can understand.

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Traffic Impact Study Improvements: Part 5 – When is a Trip Not a Trip?

By   Mike Spack

October 27, 2015

Guest Post by Bryant Ficek, PE, PTOE, Vice President at Spack Consulting

Earlier this year, I detailed how our standard process for a Traffic Impact Study has several points of assumptions at best or guesses at worst. This post continues that discussion.  Check out the “ Top 6 Ways to Pick Apart a Traffic Study ” for more on the general topic and expect more posts to follow on this subject.

Trip generation is the process of estimating the amount of traffic a proposed development will have once it is built and operating. Trip distribution is the process by which we take the raw projected traffic for a development (trip generation) and add it to the existing volumes on the transportation network. The step in-between is determining whether all the trip generation will be new to the roadway.

To start with, there are several types of trips as follows (with definition summarized from the Institute of Transportation Engineers or ITE). The figure below illustrates the different types of trips.

• Primary or New.  Traffic with the specific purpose of visiting the site being studied.
• Pass-By.  Traffic already on the way from an origin to a primary trip destination that will make an intermediate stop at the site being studied without a route diversion.
• Diverted. Traffic attracted to the site being studied from adjacent facilities without direct access to the site. A diverted trip example is a through trip on a freeway that diverts to an exit and a development, adding traffic to the local road but removing traffic from the freeway.
• Internal.  Traffic associated with multi-use developments where trips among various land uses can be made on the site being studied without using the major street system. These trips can be made either by walking or by vehicles using internal roadways.

These different trip generation options, combined with so many different types of land uses, leads to virtually limitless possibilities for the amount and type of traffic a particular site could generate on the roadway system. As with our trip distribution column, we initially thought about testing multiple scenarios, which would be relatively easy with today’s software. At least, theoretically. To restate our collective conclusion – While interesting on a pure research level, a thicker actual traffic impact study report covering multiple results leads us down a path no one wants to go.

Furthermore, sub-dividing the raw trip generation into parts is not something that can be quantified into a “one-size fits all” equation. Given the possibilities and the limits of our collective traffic research to date, ITE provides the best procedure to follow. So this article is dedicated to reviewing that procedure, which is spelled out in ITE’s Trip Generation Handbook and Trip Generation Manual, Volume 1 . That step-by-step process is as follows:

• Raw Trip Generation.  Using ITE or other land use information (try tripgeneration.org !), calculate the raw trip generation for the site.
• Pass-By and Diverted Number of Trips. Use either local data or ITE data to determine a percentage of the reduced trip generation that is pass-by or diverted. Similar to the ITE Trip Generation data, both pass-by and diverted trip percentages are available by average rate or an equation for many land uses. Use this percentage to calculate the total pass-by and diverted trips for the site.
• Pass-By and Diverted Trip Patterns. Use the existing traffic to determine how the pass-by and diverted trips will access the site.
• Pass-By and Diverted Trip Volume Adjustment. Apply the existing traffic patterns to the pass-by and diverted trips to establish the impact on the roadway system for these trips.
• Remaining Primary/New trips. Determine the remaining trip generation after reducing for internal trips and then removing the pass-by and diverted trips.
• Primary/New Trip Pattern. We discussed factors to consider for the primary/new trip distribution in Part 4 of this series.
• Primary/New Trip Volume Adjustment . Apply the trip distribution to the primary/new trips to determine the impact on the roadway system for these trips.
• Final Volumes. Combine the pass-by, diverted, and primary/new trips at each study intersection to determine the final impact of the site being studied.

We can demonstrate this process on a theoretical study site with the following characteristics:

• 17,000 square feet of office, 3,000 square feet of fast food with a drive-thru, and 10 vehicle fueling positions at a gas station with convenience market
• One driveway accesses the site off a busy road (1,000 vehicles in the p.m. peak hour)
• A highway interchange with the busy road is located just east of the site
• Trip Generation (PM Peak)
• General Office, Land Use 710 – 98 raw trips
• Fast Food with Drive Thru, Land Use 934 – 98 raw trips
• Gas Station with Convenience Market, Land Use 945 – 136 raw trips
• Internal Trips

4. Pass-By and Diverted Patterns (per the theoretical roadway data)

6. Remaining Primary/New trips:

• Office – (98 raw – 5 internal – 0 pass-by – 0 diverted) = 93 primary/new trips
• Fast Food – (98 raw – 21 internal – 43 pass-by – 23 diverted) = 11 primary/new trips
• Gas Station – (136 raw – 22 internal – 57 pass-by – 26 diverted) = 31 primary/new trips

7.  Primary/New Trip Pattern (per knowledge of theoretical area)

8.  Primary/New Trip Volume Adjustment

9.  Final Volumes (add the pass-by, diverted, and primary/new trips together)

We don’t include all of the above example graphs in our reports. Instead, our short-hand method is a trip generation table that looks like this:

As a final note, the internal, pass-by, diverted, and new percentages are often adjusted from the base ITE information. ITE itself notes the limited amount of data available and the inherent variability in surveyed sites. The best approach, if possible, is to discuss the percentages with the governing agency to achieve agreement and buy-in before you get too far down the path in your analysis.

Did you miss the other installments of the  Traffic Impact Study Improvements series? Here are the links to the other articles:

• Part 1 – Traffic Counts
• Part 2 – Would Multiple Results Help Us?
• Part 3 – All Trips are Equal, But Some Trips are More Equal Than Others

At what point would you apply a reduction for non-SOV trips such as transit? It looks like ITE would have you apply internal capture, transit and then pass-by.

very precious and informative post…thanks so much..I had found the answer of one of my question in another post of yours..thanks for sharing your experiences

Sometimes I drive right by a coffee shop and then think, hmm, I could really use a good cup of black coffee and then I turn around and go back. Is this a pass-by trip or a diverted trip (or both?). What about a cappuccino?

If the need for java hit as you approached the site, and you turned right in, this would be a standard diversion. But since you passed the driveway and turned around, ….you need to take public transit and stop burning up our resources.

Hey Mike, After you do trip gen. calcs (let’s say for a built-up year 2029) but you want to consider design year (typical 20 years) and you want to design/improve nearby roads for the design year 2049 (2029 + 20 years); do you apply same growth rate on trip generated as you would do for existing traffic? or you apply the growth rate on existing traffic, and use trip gen numbers without applying a growth rate?

No – the growth rate is not applied to the trip generation. For instance, the trips generated by a single family home isn’t going to keep growing over time. They’re assumed to be static.

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Trip Generation - Yarger Engineering, Inc.    317-475-1100    Email Us

What is trip generation.

One of the first steps in a traffic impact study is trip generation where traffic to and from the proposed development, or a nearby off-site development, is forecasted. Normally it will be based on the land use type and development size, number of employees, or dwelling units depending on the land use type. The primary source of the trip generation information comes from the Institute of Transportation Engineers Trip Generation Manual . It contains instructions and about 2,000 pages of data from small studies at various developments to establish equations that associate an independent variable with the trips counted at the site. The independent variable should be the cause of the variation in trips from a site and easily measured or forecasted, like the number of homes in a subdivision. Many of the land uses have more than one independent variable to choose from, such as office where the square foot or the number of employees can be used. Trips can be estimated on a daily or hourly basis for the street peak and generator peaks and are one-way. A round trip is counted as two one-way trips. Of course, there are separate equations for weekdays, Saturdays and Sundays. The street peak is when the traffic on the adjacent street is highest, typically between 7:00 AM and 9:00 AM and 4:00 and 6:00 PM. The generator peak may or may not occur at the same time. For example, fast-food restaurants peak around lunch time.

Once the total number of trips in and out of a development is forecasted for a particular time, the next step is estimate the number of internal trips if there is more than one land use that can be accessed without going back on to the street system. This is very typical in mixed use developments that may have retail, office and residential uses. Internal trips can be tricky to estimate, but generally reduce the impact of the development on the public roads when a motorist can visit a restaurant, bank, grocery store and dry cleaner without going back on the public roads. They can park and walk or drive between the land uses as long as they don’t use public roads to do so. The ITE Handbook has a method that can be used to estimate internal trips, and it can be supplemented with data from NCHRP Report 684 . In some studies that include the site’s internal road network, it may be necessary to assign the internal trips rather than just subtracting them from the external trips.

After reducing the total trips by the number of internal trips, the next step is to divide the remaining trips into primary, pass-by and diverted link trips.

Primary trips are those where the motorist only goal in getting the vehicle was to come to the development and then return to where they came from. These are estimated by forecasting the pass-by trips and the diverted link trips, and then subtracting them from the total trip minus the internal trips.

Pass-by trips are those trips already on the roadways immediately adjacent to the site, but altering their path at the driveway to visit the site. Pass-by trips differ from diverted link trips in that the diverted link trips would be on nearby streets whereas pass-by trips would be on the adjacent streets with driveways. Pass-by trips require a development driveway on the street where the motorist would have been driving on anyway. See the red line above.

Diverted link trips are those that would have been on the roadway network anyway, but alter their path to visit the site. For example, for a gas station at an interchange, diverted link trips are those that would come off the freeway and then go back to the freeway in their initial direction. See the blue line above. They are not pass-by trips since the site doesn’t have a driveway to freeway.

Occasionally mass transit, walking, biking or even horse and buggies can come into the mix as well, but for most traffic impact studies in Indiana and Kentucky, the assumption is that the data in the ITE Trip Generation Manual reflects the same conditions as the proposed development. In some cases, the trips need to be assigned to the road network before determining the mass transit percentages since they may vary by location due to the availability of mass transit. Distance also needs to be considered for walking and biking.

Yarger Engineering offers free initial consultations, and we would be glad to discuss your situation. Call us at 317-475-1100 or email us !

(317)831-8677

200 Robert Curry Dr. Martinsville Indiana 46151

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Why Does My Generator Circuit Breaker Keep Tripping?

A big storm is heading for your neighborhood. Local authorities have advised you to expect prolonged power outages. Fortunately, you’re prepared because your home has a whole-house backup generator. 

As predicted, the storm rolls in, and you lose power; your generator kicks on only to trip a few seconds later. You run to reset the breaker, and the same thing happens again!

While this issue can be frustrating and even potentially dangerous, it’s not uncommon. There are many possible causes for a generator’s circuit breaker to trip, or in some cases, fail without tripping. Fortunately, there are various simple steps that you can take to restore power to your home during a blackout.

What Causes a Circuit Breaker to Trip?

Many homeowners don’t realize that their home generator may come with two different types of circuit breakers. Standard breakers and Ground Fault Circuit Interrupter (GFCI) breakers.

Standard circuit breakers are automatically operated overcurrent protection devices fitted to a generator, designed to trip (cut power) when the unit is drawing in more amps than the circuit can manage.

When too many appliances are connected to a generator, more electricity is flowing through the circuit than it can handle, causing it to overload and trip the breaker to protect your devices. 

GCFI breakers , on the other hand, are designed to detect and handle “power leaks” that occur when an electrical current tries to ground itself using a different path than the one provided for the generator.

Power leaks can be caused by a combination of moisture, dust, or worn-out wires. When the GCFI detects a difference in the electrical input and output, the breaker will trip, preventing potential fires or electrocution.

How To Fix a Tripping Generator

The most important thing to remember is that your generator is tripping for a reason. The breakers are doing their job to protect you and your connected devices from harm. If it continuously happens, you’re going to need to address an underlying issue. Here are a few things you can do to fix your tripping breaker:

• Identify which breaker is tripping – If your generator has both standard circuit breakers and GFCI’s, the first thing you need to do is find out which one is tripping to help you narrow down the possible issues. 
• Disconnect non-essential appliances during blackouts – Overloading your generator circuit devices is a sure-fire way to trip the breaker. Depending on the size of your generator, you may want to consider limiting your power usage to necessary appliances such as HVAC systems, refrigerators, and garage door openers.
• Avoid “daisy-chaining” power strips – Plugging a power strip into an extension cord or even another power strip is not only an easy way to overload the circuit but, according to the National Fire Protection Agency (NFPA) , is one of the leading causes of home electrical fires.

Contact the Generator Pros

If, even after your best efforts to find a solution, your generator circuit breaker keeps tripping, it’s time to contact the pros. At Midwest Generator Solutions, we care about the safety of your family and your home. For years, our team of expert technicians has provided top-notch generator installation, repair, and maintenance service to the residents of central Indiana. 

Don’t get caught in the dark! Contact us today to schedule a consultation.

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3.4: Trip Generation

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• Page ID 47326

• David Levinson et al.
• Associate Professor (Engineering) via Wikipedia

Trip Generation is the first step in the conventional four-step transportation forecasting process (followed by Destination Choice, Mode Choice, and Route Choice), widely used for forecasting travel demands. It predicts the number of trips originating in or destined for a particular traffic analysis zone.

Every trip has two ends, and we need to know where both of them are. The first part is determining how many trips originate in a zone and the second part is how many trips are destined for a zone. Because land use can be divided into two broad category (residential and non-residential) we have models that are household based and non-household based (e.g. a function of number of jobs or retail activity).

For the residential side of things, trip generation is thought of as a function of the social and economic attributes of households (households and housing units are very similar measures, but sometimes housing units have no households, and sometimes they contain multiple households, clearly housing units are easier to measure, and those are often used instead for models, it is important to be clear which assumption you are using).

At the level of the traffic analysis zone, the language is that of land uses "producing" or attracting trips, where by assumption trips are "produced" by households and "attracted" to non-households. Production and attractions differ from origins and destinations. Trips are produced by households even when they are returning home (that is, when the household is a destination). Again it is important to be clear what assumptions you are using.

People engage in activities, these activities are the "purpose" of the trip. Major activities are home, work, shop, school, eating out, socializing, recreating, and serving passengers (picking up and dropping off). There are numerous other activities that people engage on a less than daily or even weekly basis, such as going to the doctor, banking, etc. Often less frequent categories are dropped and lumped into the catchall "Other".

Every trip has two ends, an origin and a destination. Trips are categorized by purposes , the activity undertaken at a destination location.

Observed trip making from the Twin Cities (2000-2001) Travel Behavior Inventory by Gender

Some observations:

• Men and women behave differently on average, splitting responsibilities within households, and engaging in different activities,
• Most trips are not work trips, though work trips are important because of their peaked nature (and because they tend to be longer in both distance and travel time),
• The vast majority of trips are not people going to (or from) work.

People engage in activities in sequence, and may chain their trips. In the Figure below, the trip-maker is traveling from home to work to shop to eating out and then returning home.

Specifying Models

How do we predict how many trips will be generated by a zone? The number of trips originating from or destined to a purpose in a zone are described by trip rates (a cross-classification by age or demographics is often used) or equations. First, we need to identify what we think the relevant variables are.

The total number of trips leaving or returning to homes in a zone may be described as a function of:

\[T_h = f(housing \text{ }units, household \text{ }size, age, income, accessibility, vehicle \text{ }ownership)\]

Home-End Trips are sometimes functions of:

• Housing Units
• Household Size
• Accessibility
• Vehicle Ownership
• Other Home-Based Elements

At the work-end of work trips, the number of trips generated might be a function as below:

\[T_w=f(jobs(area \text{ }of \text{ } space \text{ } by \text{ } type, occupancy \text{ } rate\]

Work-End Trips are sometimes functions of:

• Area of Workspace
• Occupancy Rate
• Other Job-Related Elements

Similarly shopping trips depend on a number of factors:

\[T_s = f(number \text{ }of \text{ }retail \text{ }workers, type \text{ }of \text{ }retail, area, location, competition)\]

Shop-End Trips are sometimes functions of:

• Number of Retail Workers
• Type of Retail Available
• Area of Retail Available
• Competition
• Other Retail-Related Elements

A forecasting activity conducted by planners or economists, such as one based on the concept of economic base analysis, provides aggregate measures of population and activity growth. Land use forecasting distributes forecast changes in activities across traffic zones.

Estimating Models

Which is more accurate: the data or the average? The problem with averages (or aggregates) is that every individual’s trip-making pattern is different.

To estimate trip generation at the home end, a cross-classification model can be used. This is basically constructing a table where the rows and columns have different attributes, and each cell in the table shows a predicted number of trips, this is generally derived directly from data.

In the example cross-classification model: The dependent variable is trips per person. The independent variables are dwelling type (single or multiple family), household size (1, 2, 3, 4, or 5+ persons per household), and person age.

The figure below shows a typical example of how trips vary by age in both single-family and multi-family residence types.

The figure below shows a moving average.

Non-home-end

The trip generation rates for both “work” and “other” trip ends can be developed using Ordinary Least Squares (OLS) regression (a statistical technique for fitting curves to minimize the sum of squared errors (the difference between predicted and actual value) relating trips to employment by type and population characteristics.

The variables used in estimating trip rates for the work-end are Employment in Offices (\(E_{off}\)), Retail (\(E_{ret}\)), and Other (\(E_{oth}\))

A typical form of the equation can be expressed as:

\[T_{D,k}=a_1E_{off,k}+a_2E_{oth,k}+a_3E_{ret,k}\]

• \(T_{D,k}\) - Person trips attracted per worker in Zone k
• \(E_{off,i}\) - office employment in the ith zone
• \(E_{oth,i}\) - other employment in the ith zone
• \(E_{ret,i}\)- retail employment in the ith zone
• \(a_1,a_2,a_3\) - model coefficients

Normalization

For each trip purpose (e.g. home to work trips), the number of trips originating at home must equal the number of trips destined for work. Two distinct models may give two results. There are several techniques for dealing with this problem. One can either assume one model is correct and adjust the other, or split the difference.

It is necessary to ensure that the total number of trip origins equals the total number of trip destinations, since each trip interchange by definition must have two trip ends.

The rates developed for the home end are assumed to be most accurate,

The basic equation for normalization:

\[T'_{D,j}=T_{D,j} \dfrac{ \displaystyle \sum{i=1}^I T_{O,i}}{\displaystyle \sum{j=1}^J T_{TD,j}}\]

Sample Problems

Planners have estimated the following models for the AM Peak Hour

\(T_{O,i}=1.5*H_i\)

\(T_{D,j}=(1.5*E_{off,j})+(1*E_{oth,j})+(0.5*E_{ret,j})\)

\(T_{O,i}\) = Person Trips Originating in Zone \(i\)

\(T_{D,j}\) = Person Trips Destined for Zone \(j\)

\(H_i\) = Number of Households in Zone \(i\)

You are also given the following data

A. What are the number of person trips originating in and destined for each city?

B. Normalize the number of person trips so that the number of person trip origins = the number of person trip destinations. Assume the model for person trip origins is more accurate.

Solution to Trip Generation Problem Part A

\[T'_{D,j}=T_{D,j} \dfrac{ \displaystyle \sum{i=1}^I T_{O,i}}{\displaystyle \sum{j=1}^J T_{TD,j}}=>T_{D,j} \dfrac{37500}{36750}=T_{D,j}*1.0204\]

Solution to Trip Generation Problem Part B

Modelers have estimated that the number of trips leaving Rivertown (\(T_O\)) is a function of the number of households (H) and the number of jobs (J), and the number of trips arriving in Marcytown (\(T_D\)) is also a function of the number of households and number of jobs.

\(T_O=1H+0.1J;R^2=0.9\)

\(T_D=0.1H+1J;R^2=0.5\)

Assuming all trips originate in Rivertown and are destined for Marcytown and:

Rivertown: 30000 H, 5000 J

Marcytown: 6000 H, 29000 J

Determine the number of trips originating in Rivertown and the number destined for Marcytown according to the model.

Which number of origins or destinations is more accurate? Why?

T_Rivertown =T_O ; T_O= 1(30000) + 0.1(5000) = 30500 trips

T_(MarcyTown)=T_D ; T_D= 0.1(6000) + 1(29000) = 29600 trips

Origins(T_{Rivertown}) because of the goodness of fit measure of the Statistical model (R^2=0.9).

Modelers have estimated that in the AM peak hour, the number of trip origins (T_O) is a function of the number of households (H) and the number of jobs (J), and the number of trip destinations (T_D) is also a function of the number of households and number of jobs.

\(T_O=1.0H+0.1J;R^2=0.9\)

Suburbia: 30000 H, 5000 J

Urbia: 6000 H, 29000 J

1) Determine the number of trips originating in and destined for Suburbia and for Urbia according to the model.

2) Does this result make sense? Normalize the result to improve its accuracy and sensibility?

• \(T_{O,i}\) - Person trips originating in Zone i
• \(T_{D,j}\) - Person Trips destined for Zone j
• \(T_{O,i'}\) - Normalized Person trips originating in Zone i
• \(T_{D,j'}\) - Normalized Person Trips destined for Zone j
• \(T_h\) - Person trips generated at home end (typically morning origins, afternoon destinations)
• \(T_w\) - Person trips generated at work end (typically afternoon origins, morning destinations)
• \(T_s\) - Person trips generated at shop end
• \(H_i\) - Number of Households in Zone i
• \(E_{off,k}\) - office employment in Zone k
• \(E_{ret,k}\) - retail employment in Zone k
• \(E_{oth,k}\) - other employment in Zone k
• \(B_n\) - model coefficients

Abbreviations

• H2W - Home to work
• W2H - Work to home
• W2O - Work to other
• O2W - Other to work
• H2O - Home to other
• O2H - Other to home
• O2O - Other to other
• HBO - Home based other (includes H2O, O2H)
• HBW - Home based work (H2W, W2H)
• NHB - Non-home based (O2W, W2O, O2O)

External Exercises

Use the ADAM software at the STREET website and try Assignment #1 to learn how changes in analysis zone characteristics generate additional trips on the network.

Additional Problems

• the start and end time (to the nearest minute)
• start and end location of each trip,
• primary mode you took (drive alone, car driver with passenger, car passenger, bus, LRT, walk, bike, motorcycle, taxi, Zipcar, other). (use the codes provided)
• purpose (to work, return home, work related business, shopping, family/personal business, school, church, medical/dental, vacation, visit friends or relatives, other social recreational, other) (use the codes provided)
• if you traveled with anyone else, and if so whether they lived in your household or not.

Bonus: Email your professor at the end of everyday with a detailed log of your travel diary. (+5 points on the first exam)

• Are number of destinations always less than origins?
• Pose 5 hypotheses about factors that affect work, non-work trips? How do these factors affect accuracy, and thus normalization?
• What is the acceptable level of error?
• Describe one variable used in trip generation and how it affects the model.
• What is the basic equation for normalization?
• Which of these models (home-end, work-end) are assumed to be more accurate? Why is it important to normalize trip generation models
• What are the different trip purposes/types trip generation?
• Why is it difficult to know who is traveling when?
• What share of trips during peak afternoon peak periods are work to home (>50%, <50%?), why?
• What does ORIO abbreviate?
• What types of employees (ORIO) are more likely to travel from work to home in the evening peak
• What does the trip rate tell us about various parts of the population?
• What does the “T-statistic” value tell us about the trip rate estimation?
• Why might afternoon work to home trips be more or less than morning home to work trips? Why might the percent of trips be different?
• Define frequency.
• Why do individuals > 65 years of age make fewer work to home trips?
• Solve the following problem. You have the following trip generation model:

\[Trips=B_1Off+B_2Ind+B_3Ret\]

And you are given the following coefficients derived from a regression model.

If there are 600 office employees, 300 industrial employees, and 200 retail employees, how many trips are going from work to home?

Trip generation

What is trip generation .

A trip is usually defined in transport modeling as a single journey made by an individual between two points by a specified mode of travel and for a defined purpose. Trips are often considered as productions of a particular land-use and attracted to other specified land-uses. The number of trips arises in unit time, usually for a specified zonal land use , is called the trip generation rate.

How to estimate trip generation ?

Trip generation is estimated in three ways:

(i) traditionally by linear and multiple regression

(ii) by aggregating the trip generating capability of a household or car and aggregating the total according to the distribution of each selected category in the zones, and

(iii) by household classification method through a catalogue of the characteristic mean trip rates for specific types of household.

The attraction points are identified as trip generated by work, and other purpose visits. By assigning suitable values to the independent variables of the regression equations forecasts can be made of the future trip ends for zones by either method.

Trip distribution :Trip generation estimates the number and types of trips originating and terminating in zones. Trip distribution is the process of computing the number of trips between one zone and all other. A trip matrix is drawn up with the sums of rows indicating the total number of trips originating in zone i and the sums of columns the total number of destinations  attracted to zone j.

Each cell in the matrix indicates the number of trips that go from each origin zone to each destination zone. The trips on the diagonal are intra-zonal trips, trips that originate and end in the same zone. The balancing equation is implemented in a series of steps that include modeling the number of trips originating in each cases, adding in trips originating from outside the study area(external trips), and statistically balancing the origins and destinations.

This is done in the trip generation stage. But, it is essential that the step should have been completed for the trip distribution to be implemented. Two trip distribution matrices need to be distinguished. The first is the observed distribution. This is the actual number of trips that are observed traveling between each origin zone and each destination zone. It is calculated by simply enumerating the number of trips by each origin-destination combination. It is also called trip-link. The second distribution is a model of the trip distribution matrix, called the predicted distribution.

Generally trips should be distributed over the area proportionally to the attractiveness of activities and inversely proportional to the travel resistances between areas. It is assumed that the trips between zones will be by the most direct or cheapest routes and, taking each zone in turn, a minimum path is traced out to all other zones to form a minimum path tree. The trip distribution is a model of travel between zones-trips or links. The modeled trip distribution can then be compared to the actual distribution to see whether the model produces a reasonable approximation.

Read about:  Zoning of Land for OD Survey , Traffic Volume Count , Origin Destination Survey Methods

About The Author

• View Record

TRID the TRIS and ITRD database

Trip Generation Manual, 11th Edition

This new edition of the Trip Generation Manual enhances the 10th edition’s modernized content, data set, and contemporary delivery - making it an invaluable resource. The 11th edition features: (1) All the latest multimodal trip generation data for urban, suburban and rural applications, (2) Reclassified land uses to better meet user needs, (3) Integrated digital copies of all land use definitions, plots and supporting materials, and (4) Full ability to filter the data to match local conditions (in digital versions only).

• Record URL: https://ecommerce.ite.org/IMIS/ItemDetail?iProductCode=TG11-C
• Record URL: https://ecommerce.ite.org/IMIS/ItemDetail?iProductCode=TG11-D
• Record URL: https://ecommerce.ite.org/IMIS/ItemDetail?iProductCode=IR-016L
• Summary URL: https://www.ite.org/technical-resources/topics/trip-and-parking-generation/
• Find a library where document is available. Order URL: http://worldcat.org/isbn/9781734507874
• Abstract reprinted with permission from the Institute of Transportation Engineers.

Institute of Transportation Engineers (ITE)

• Publication Date: 2021-9
• Media Type: Digital/other

Subject/Index Terms

• TRT Terms: Land use ; Multimodal transportation ; Trip generation
• Subject Areas: Highways; Planning and Forecasting;

Filing Info

• Accession Number: 01787570
• Record Type: Publication
• ISBN: 9781734507874
• Files: TRIS
• Created Date: Nov 10 2021 1:54PM

Why Does My Generator Keep Tripping?

Generators are a valuable tool to have, particularly during power outages or when you’re outdoors camping or sailing. However, it can be frustrating when your generator’s circuit breaker keeps tripping, leaving you without power. In many cases, the cause of the tripping is an overload or a power leak/ ground fault . It is imperative to understand the reasons behind these issues and how to resolve them. This article will delve into the common causes of generator circuit breaker tripping, including faulty breakers and loose connections, and provide practical steps to troubleshoot and fix them. So if you’re wondering, “Why does my generator circuit breaker keep tripping?” read on to find out.

What Causes Generator Tripping?

One of the major causes of a generator circuit breaker tripping repeatedly is overload. Every generator has a maximal load capacity, and going over that limit can cause the circuit breaker for that generator to trip. To prevent overloading your generator, it is essential to understand load capability.

Reducing The Load To Avoid Tripping

By unplugging some electronics or appliances, you can lessen the burden on your generator and prevent overload trips. Turn off any additional devices you added to the circuit to reduce the load. You should be aware of load capacities and carefully monitor them if you frequently use your generator outside.

Importance Of Monitoring Load Capacity

Monitoring the load capability is crucial to prevent overusing and endangering the generator. Overloading occasionally can harm the engine beyond repair. Studying the generator’s manual and comprehending its load capacity before using it is crucial.

GFCI Breakers

GFCI ( Ground Fault Circuit Interrupter ) breakers protect people from electrical shocks, which sense ground faults and trip the circuit to turn off the power. They keep track of the electrical current moving through the circuit and contrast it with the current traveling back toward the source. If there is a difference, it indicates that some of the circuit’s electricity is leaking out and moving through something else, like a person’s body. When it’s raining, this can be dangerous.

Power Leaks And Ground Faults

GFCI breakers typically activate due to power leaks and ground faults. This is known as a power leak when energy enters a machine or appliance, even when it is off. A malfunctioning gadget or faulty wiring may cause this. Electricity flowing from the circuit to the earth results in a ground fault. A flawed cabling system, an improperly grounded device, or someone touching an electrically charged surface can cause this.

Moisture and Its Impact On GFCI Breakers

GFCI devices can be significantly impacted by moisture as well. Even without a ground fault or power leak, moisture in or around the breaker can cause the circuit to trigger. Therefore, the circuit breaker will not trip, and an error will not be detected. Water can make a path for electricity to flow through that is less resistant. For GFCI breakers to avoid accidentally tripping, they must be kept dry and clear of moisture.

Faulty Breakers

A faulty breaker is a possible culprit when dealing with a generator circuit breaker that keeps tripping. Signs of a bad breaker include:

• The breaker trips without a load.
• The breaker is short-circuiting.
• There are signs of damage to the breaker, such as blackened spots or a smoky smell.

Importance of replacing a faulty breaker

Replacing your generator’s circuit breaker when you detect a problem is critical. In addition to making your generator fail, a broken breaker risks your safety. You can only use your generator with a circuit breaker.

Replacing a circuit breaker with the proper tools and a little knowledge is a reasonably simple task. It’s always ideal to seek the assistance of a certified electrician if you feel uncomfortable doing it yourself.

Faulty Wires and Loose Connections

The circuit breaker for the generator can also trip due to faulty cables and loose connections. It can still happen, even though it is less frequent than other problems. The breaker can detect a problem with the wiring and trip to stop further harm or danger. The same problem can also be brought on by loose connections, which can prevent the passage of electricity and make the breaker trip unnecessarily.

You can look at the screws holding the wires in position to check for loose connections. The problem is frequently resolved by slightly tightening them. Handling the cables carefully and ensuring they are securely fastened is crucial to avoid any possible risks. It is best to consult a qualified electrician to help identify and resolve the issue if you anticipate faulty wiring. Failure to do so may result in additional damage and endanger you or those near the generator.

Short Circuit

When a wire’s insulation in the generator’s electrical system wears away and the exposed wire comes into contact with other wires or metal parts, a short circuit may result. Bypassing the intended course establishes a direct route for the electricity to flow, which can result in a surge of electricity that trips the generator.

Using a multimeter, you can examine the resistance of the wires in the electrical system to find a short circuit. A short circuit is probably present if there is no resistance. You might have to swap out the electrical system’s harmed parts or wires to resolve a short circuit.

Low Oil Pressure

Oil is necessary for generators to lubricate the internal parts and avoid overheating. The generator may trip due to low oil pressure as a safeguard against harm to the motor.

It’s crucial to routinely check and maintain the oil levels in the generator to avoid low oil pressure. Before every use, you should verify the oil level and change the oil per the manufacturer’s recommendations.

Overheating

Overheating may happen when the generator is used in a place with poor ventilation or an issue with the cooling system. It could result in harm and the generator tripping if the internal parts get too hot.

It is crucial to give the generator the appropriate ventilation by situating it in a well-ventilated area to prevent overheating. Additionally, it’s critical to routinely check the cooling system and remove any obstructions to the airflow.

Fuel Issues

When the generator doesn’t get enough fuel or the fuel is tainted, problems with the power can happen. The generator might fail or operate inefficiently as a result of this.

You can check for clogs in the fuel filter or change the fuel if it is contaminated to solve fuel-related problems. Additionally, it’s crucial to check that the fuel lines are not kinked or damaged and that the fuel tank is correctly vented. Maintenance of the fuel system regularly can stop problems with the gasoline from tripping the generator.

Quick Ways to Fix It

Finding the fault.

A generator circuit breaker problem can be solved by finding the source of the issue. Inspect the generator’s parts for overloads, power leaks, defective breakers, and loose links.

Checking The GFCI Receptacle

Check the GFCI outlet to see if a ground malfunction caused the tripping. See if resetting it fixes the issue. If it keeps tripping, the circuit might have a power loss.

Checking The Cords

Look for indications of deterioration in the generator’s cords, such as frayed wires or cracked insulation. Any damaged wires should be replaced because they could be to blame for the trip.

Checking The Capacitor

The battery handles the generator’s start-up. If it is broken, the circuit breaker might fail. If required, examine the capacitor and replace it.

Checking The Fuel

The circuit breaker may occasionally trip due to issues with the gasoline, such as contamination or old fuel. If required, check the fuel and replace it.

Reducing The Load

If an overload is to blame for the tripping, use a smaller generator or unplug some appliances to lessen the burden on the generator.

Tightening Connections

Verify the tightness of all connections, including cables and screws. Loose links can set off the circuit breaker. For a solution, tighten any open links.

Seeking Professional Help

Contact a qualified electrician or generator expert if you need help resolving the issue. They’ll be able to identify the problem and fix it for you.

How to Know Which Circuit Has Tripped

It can be challenging to identify which circuit is at fault when a circuit breaks. Finding the circuit that tripped to correct the issue and prevent it from occurring again is crucial. The procedures to take to determine which course has been faulty are as follows:

• Check the GFCI breaker : On the GFCI breaker, look for a reset button that has come out. The circuit may have been tripped as a result of this.
• Check the circuit breaker: Look for a tripped circuit switch in the house’s fuse box or electrical panel. Typically, a broken breaker is in the “off” position.
• If the home has a fuse box rather than a circuit breaker switch, check for blown fuses. Look for a dark or metallic blue on the tube containing the explosive.
• Check the electrical panel switches: If off, it could indicate a tripped circuit.

Once you have identified the tripped circuit, reset it by turning off all the connected appliances and flipping the circuit breaker back on. If the circuit trips again immediately, there could be a more severe problem, and you should seek professional assistance. Remember, tripping circuits are a safety feature that protects your appliances from damage, so it is essential to address the underlying issue promptly.

Why does my generator keep tripping?

Numerous factors, such as overloads, short circuits, ground faults, and faulty cabling, can cause generators to trip. Short circuits happen when two wires with opposite polarities contact, creating an electrical imbalance, while overloads happen when the generator is given more power than it can handle. Faulty wiring can occur due to wear and tear, while ground faults happen when electricity seeps through the insulation of the generator.

How can I prevent my generator from tripping?

You can stop your generator from tripping by being careful not to overload it, keeping it in good condition, and routinely inspecting its cabling. Additionally, when connecting items to the generator, use the proper extension cords and outlet adapters.

How can I determine which circuit is tripping my generator?

Examine the GFCI receptacles and the circuit breaker to find out which circuit is causing your generator to trip. On the GFCI outlets, check for a reset button that has popped out, and on the circuit breaker, look for any broken fuses. If everything appears in order, check the outlets to see if they trip with a tiny electrical load, such as a portable radio. If so, there may be a leak or other issue with the exit.

Can a generator trip if it’s not overloaded?

Even if a generator is manageable, it may trip. Even when the power consumption is within capacity, a ground fault or short circuit could cause the generator to shut off.

What should I do if my generator keeps tripping?

Try to determine the root of the problem by using the methods above if your generator continues tripping. It is best to seek expert assistance from an electrician or generator repair technician if you cannot identify the cause. Using a defective generator longer than necessary can be risky and harm your appliances.

How often should I perform maintenance on my generator to prevent it from tripping?

A minimum of once a year, or after 100 hours of use, is advised for generator upkeep. This entails inspecting the spark plug, verifying the oil level, and cleaning the air filter. Regular maintenance can help avoid problems that could trip your generator.

Can the weather affect my generator and cause it to trip?

Yes, extreme weather conditions can influence your generator and trip it, such as high temperatures or heavy rain. To avoid this, ensure your generator is adequately shielded from the elements and ventilated.

Can overloading my generator cause it to trip?

Overloading your generator can indeed make it crash. Every generator has a maximum power production; if you go over it, the circuit breaker on the generator trips. Ensure to operate only a few appliances or devices simultaneously to avoid overloading.

Can faulty wiring in my home cause my generator to trip?

The answer is yes, faulty wiring in your house can trip your generator. Your home’s electrical wiring may trip your generator’s circuit breaker if damaged or improperly fitted. You should call an electrician if the wiring requires repairs.

Can a malfunctioning GFCI outlet cause my generator to trip?

Indeed, your generator may trip due to a damaged GFCI (Ground Fault Circuit Interrupter) outlet. A GFCI outlet is made to recognize electrical leakage and limit power to stop electrocution from occurring. Your generator may trip if the GFCI outlet is broken or malfunctioning. To fix the problem, you might have to replace the GFCI receptacle.

A generator trip is a safety measure to guard your equipment against harm from overloads or power faults. Your generator must receive routine maintenance to guarantee proper operation and prevent frequent tripping when your generator trips, the first thing to do is to determine which circuit—a circuit breaker or a GFCI—has broken. To find the source of the issue, you can then test the GFCI outlets and look for electrical leaks in the cables. It is advised to obtain professional help if the problem continues. Keep in mind to always follow safety protocols when using generators and electricity.

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If you follow these articles closely, you know that Merts Heating & Air Conditioning is a big believer in the value of a backup generator . A whole-house generator by Briggs & Stratton is the best way to keep life normal when power outages hit Illinois or Northwest Indiana. That doesn’t mean the system always operates flawlessly.

A GENERATOR CAN TRIP

Sometimes frustration will set in because a generator starts tripping, meaning it shuts down. Just like your home’s electrical system, a generator is protected by one or more circuit breakers. These will switch the generator off whenever an electrical overload or surge is detected. This prevents damage to the generator and the appliances it is powering. That doesn’t make it any less frustrating for the homeowner who’s depending on the generator to keep the lights on during an outage.

WAYS IT CAN HAPPEN

Most of the time this “tripping” scenario can be prevented when a generator is properly installed and receives regular maintenance. Let’s take a closer look at some reasons your generator might trip and steps to correct the problem.

• OVERLOADS— When a whole-house generator is professionally installed it should be able to meet the electrical demands for all the household circuits it’s linked to. If new appliances are added to a circuit, or an appliance is malfunctioning, the electrical load can exceed the generator’s capability. 
• RESETTING THE BREAKER— Many times a circuit breaker trips because of a one-time event. Try resetting the breaker and see if the generator will operate normally. If it does trip again you need to call for professional help to find out why.
• GFCI OUTLET(S) TRIPPING— This can happen with portable generators designed to power just a few household appliances and maybe some lights. They are often equipped with GFCI outlets which will shut down if any short circuits are detected.
• CHECK YOUR EXTENSION CORDS— If you have a portable generator chances are good that you’re using extension cords to power things like refrigerators, freezers, TVs, and computers. A faulty extension cord can cause a GFCI outlet to trip. Try checking the cords by plugging them in one at a time to determine which one is causing the problem. Again, if the problem continues the only safe thing to do is get professional help.

AN OUNCE OF PREVENTION

Regular maintenance is the best way to make sure your generator is ready to operate flawlessly when the power does go out in Steger, IL or Crown Point, IN. Problems that could cause your generator to start tripping off can be identified and fixed by the expert technicians from Merts Heating & Air Conditioning. Be sure to like and follow us on Facebook and Twitter for more great information like this.

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Class-A, Class-B and Class-C Tripping Classification of Generator

Class-A, Class-B, and Class-C Tripping Classification of Generator are done according to types of the fault in the generator and its associated circuits. In this post, we will discuss the trip classes of generators in detail.

Basis of Tripping Classification

In the case of a fault in the electrical network, the generator needs to isolate from the supply system as well as from the turbine side to protect the generator. There are various protection schemes for the generator in use. We can classify the generator tripping classes on the basis of the nature of the fault.

Some faults, such as differential protection and stator earth fault, need to clear by tripping of generator breaker immediately. On the other hand, some faults do not need immediate action for generator breaker tripping. Thus, depending on the type of fault, the generator breaker tripping is accomplished automatically to safeguard the generator.

There are three classes of generator tripping. They are;

Now, we will have a discussion on each tripping class of the generator.

The stator earth fault and the differential fault in a generator are the faults that show problems in the generator winding. If the generator remains connected to the grid, in this case, severe damage happens to the generator as well as to the electrical system. In such a case, the generator breaker needs to be isolated immediately. In such a situation, the protection scheme is called Class-A tripping of the generator. There are two ways of connecting the generator circuit breaker to the Grid supply.

The single line diagram synchronization scheme where the generator circuit breaker synchronizes. ( Synchronization with GCB Scheme)

The single line diagram synchronization scheme where the Grid circuit breaker synchronizes. ( Synchronization without GCB Scheme)

Class-A Trip

The class-A tripping can be further bifurcated into two categories.

Class-A1 Trip

Class-A1 comprises the faults that need immediate isolation of the generator. The list of the faults is as follows.

1. Generator Differential Protection(87G)

This protection operates when there is a fault in the stator of the generator winding. The relay sense and measure the incoming and outgoing current in the stator winding and shows the fault if there is a difference between the incoming and outgoing current in the winding. This difference between currents happens only when there is some fault in the winding.

2. Generator Over Voltage Protection(59)

Overvoltage in a generator occurs due to increased grid synchronized voltage, sudden load throw-off, lightning strike, transients, AVR malfunctioning, and turbine over speed. The overvoltage may cause insulation failure of the generator’s winding, and to protect the generator the protection relay must trip the generator breaker.

Overvoltage occurs due to sudden load through off, elevated grid synchronized voltage, AVR malfunctioning, power transformer taps changer failure, a lightning strike on the transmission line, turbine over speed, etc.

3. 100% Stator Earth Fault Protection(64G2)

The neutral grounding resistor (NGR) installed between the neutral point of the generator and the ground provides the earth fault protection for 95% of the stator winding. The balance 5% stator winding remains unprotected in this protection scheme. A different protection scheme is used to protect the balance 5 % winding to achieve 100 % stator earth fault protection.

4. Dead Machine Protection

The generator stator breaker must not be energized in standstill condition. This causes a generator to function as a motor. Consequently, it may cause damage to the generator. The dead machine protection ensures no energization of the generator in its standstill state.

Dead Machine Protection in a Generator is provided to ensure that Generator is not energized accidentally in standstill condition. or when the Generator is on Turning Gear.

5. 95% Stator Earth Fault Protection (64G1)

The neural point of the generator is connected to one end of the neutral ground resistor(NGR) and the other end of NGR is connected to the ground. This scheme is called resistance earthing. This scheme is used for generators to detect the fault in 95% of the stator winding. The protection relay trips the generator breaker in the event of an earth fault.

6. Starting Over Current Protection

The overcurrent protection ensures the tripping of the generator breaker in the case the current is above the full load current (FLC) of the generator.

On actuation of Class-A1 protection, the tripping of the following happen.

• Tripping the generator circuit breaker
• Tripping the generator’s field circuit breaker
• Turbine Tripping

Class-A2 Trip

Faults in the generator transformer(GT), isolated phase bus duct(IPBT), and unit transformer(UT) may cause damage to the generator and its associated circuits if the equipment does not isolate from the grid supply. All these faults are grouped in the class-A2 trip.

The following protection relays of the generator, grid transformer, and unit transformer provide the class A-2 trip.

• Over fluxing Protection of Generator
• Back up Impedance Protection of Generator
• Differential Protection of GT
• Buchholz Relay of GT
• Trip from OTI & WTI of GT
• Fire protection of GT
• Differential Protection of UT
• Buchcholz Relay & PRD of Main Tank of UT
• Trip from OTI & WTI of UT
• Fire protection of UT

In the event of initiation of the above-mentioned protection the following equipment is isolated from the supply system.

• Tripping of Generator Circuit Breaker
• Tripping of Field Circuit Breaker
• Tripping of Generator Transformer Circuit Breakers
• Tripping of Unit Transformer LV Circuit Breakers
• Tripping of Turbine

Class-B Trip

Some of the protections for the fault that do not need quick isolation are grouped in the Class-B trip. The following protection fault comes in the category of Class-B.

• The problem in the turbine or in the steam process
• Loss of generator Excitation(40G)
• Rotor Earth fault (64F)

In the case of a problem in the steam process, the turbine trips first. The generator is allowed to run to utilize the trapped steam in the system. When the power delivery of the generator reached below the forward power setting of the relay, the low forward power relay (32F) trips the generator circuit breaker.

Class-C Trip

The generator that runs in synchronization with the Grid needs protection in the case of a fault in the Grid. The protection for the Grid faults that needs disconnection of synchronizing circuit breaker falls into Class- C trip.

The synchronizing breaker trips when there is a fault in the grid. The generator now operates in islanding mode, continuously delivering power to the connected load.

The following protections come under the Class-C trip.

• Under Frequency (81G)
• Over frequency(81G))
• Negative Phase Sequence or Unbalance(46)
• Back up Impedance Protection(21)
• Phase Fault Protection
• EMF Equation of Alternator and AC Generator
• What is the Insulation Class of Transformer oil?
• Thermoelectric Power Generators or Seebeck Power Generation
• What is Through Fault?

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Explainer: power station ‘trips’ are normal, but blackouts are not

Honorary Associate Professor, Centre for Climate Economics and Policy, Australian National University

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Hugh Saddler writes a monthly newsletter on electricity policy issues, published by the Australia Institute

Australian National University provides funding as a member of The Conversation AU.

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Tens of thousands of Victorians were left without power over the long weekend as the distribution network struggled with blistering temperatures, reigniting fears about the stability of our energy system.

It comes on the heels of a summer of “trips” , when power stations temporarily shut down for a variety of reasons. This variability has also been used to attack renewable energy such as wind and solar, which naturally fluctuate depending on weather conditions.

The reality is that blackouts, trips and intermittency are three very different issues, which should not be conflated. As most of Australia returns to school and work in February, and summer temperatures continue to rise, the risk of further blackouts make it essential to understand the cause of the blackouts, what a power station “trip” really is, and how intermittent renewable energy can be integrated into a national system.

Read more: A month in, Tesla's SA battery is surpassing expectations

Initial reports indicate recent blackouts in Victoria were caused by multiple small failures in the electricity distribution system across the state, affecting all but one of the five separately owned and managed systems that supply Victorians.

Across the whole of mainland Australia, very hot weather causes peak levels of electricity consumption. Unfortunately, for reasons of basic physics, electricity distribution systems do not work well when it is very hot, so the combination of extreme heat and high demand is very challenging. It appears that significant parts of the Victorian electricity distribution system were unable to meet the challenge, leading to uncontrolled blackouts.

Parenthetically, electricity distribution systems are vulnerable to other types of uncontrollable extreme environmental events, including high winds, lightning, and bushfires. Sometimes blackouts last only a few seconds, sometimes for days, depending on the nature and extent of the damage to the system.

Read more: What caused South Australia's state-wide blackout?

These blackouts are very different from those caused by power station “trips”, although they have the same effect on consumers. When electricity is insufficient to meet demand, certain sections of the grid have to be startegically blacked out to restore the balance (this is known as “load shedding”).

It is the possibility of blackouts of this second type which has excited so much commentary in recent months, and has been linked to power station “trips”.

What is a ‘trip’ and how significant is it?

“Trip” simply means disconnect; it is used to describe the ultra-fast operation of the circuit breakers used as switching devices in high-voltage electricity transmission systems. When a generator trips, it means that it is suddenly, and usually unexpectedly, disconnected from the transmission network, and thus stops supplying electricity to consumers.

The key words here are suddenly and unexpectedly . Consider what happened in Victoria on January 18 this year. It was a very hot day and all three brown coal power stations in the state were generating at near full capacity, supplying in total about 4,200 megawatts towards the end of the afternoon, as total state demand climbed rapidly past 8,000MW (excluding rooftop solar generation).

Suddenly, at 4:35pm, one of the two 500MW units at Loy Yang B, Victoria’s newest (or, more precisely, least old) coal-fired power station tripped. At the time this unit was supplying 490MW, equal to about 6% of total state demand.

The system, under the operational control of the Australia Energy Market Operator (AEMO), responded just as it was meant to. There was considerable spare gas generation capacity, some of which was immediately made available, as was some of the more limited spare hydro capacity. There was also a large increase in imports from New South Wales, and a smaller reduction in net exports to South Australia.

By the time Loy Yang B Unit 1 was fully back on line, three hours later, Victoria had passed its highest daily peak demand for nearly two years. There was no load shedding: all electricity consumers were supplied with as much electricity as they required. However, spot wholesale prices for electricity reached very high levels during the three hours, and it appears that some large consumers, whose supply contracts exposed them to wholesale prices, made short-term reductions in discretionary demand.

Read more: A high price for policy failure: the ten-year story of spiralling electricity bills

This (relatively) happy outcome on January 18 was made possible by the application of the system reliability rules and procedures, specified in the National Electricity Rules.

These require AEMO to ensure that at all times, in each of the five state regions of the NEM, available spare generation capacity exceeds the combined capacity of the two largest units operating at any time.

In other words, spare capacity must be sufficient to allow demand to continue to be reliably supplied if both of the two largest units generating should suddenly disconnect.

Forecasting

AEMO forecasts energy demand, and issues market notices alerting generators about reliability, demand and potential supply issues. On a busy day, like January 18, market notices may be issued at a rate of several per hour.

These forecasts allowed generators to respond to the loss of Loy Yang B without causing regional blackouts.

What is not publicly known, and may never be known, is why Loy Yang Unit B1 tripped. AEMO examines and reports in detail on what are called “ unusual power system events ”, which in practice means major disruptions, such as blackouts. There are usually only a few of these each year, whereas generator trips that don’t cause blackouts are much more frequent (as are similar transmission line trips).

It has been widely speculated that, as Australia’s coal fired generators age, they are becoming less reliable, but that could only be confirmed by a systematic and detailed examination of all such events.

Managing variable generation

Finally, and most importantly, the events described above bear almost no relationship to the challenges to reliable system operation presented by the growth of wind and solar generation.

With traditional thermal generation, the problems are caused by unpredictability of sudden failures, and the large unit size, especially of coal generators, which means that a single failure can challenge total system reliability. Individual wind generators may fail unpredictably, but each machine is so small that the loss of one or two has a negligible effect on reliability.

The challenge with wind and solar is not reliability but the variability of their output, caused by variations in weather. This challenge is being addressed by continuous improvement of short term wind forecasting. As day-ahead and hour-ahead forecasts get better, the market advice AEMO provides will give a more accurate estimate of how much other generation will be needed to meet demand at all times.

Read more: 100% renewable by 2050: the technology already exists to make it happen

Of course, AEMO, and the generation industry, do still get caught out by sudden and unexpected drops in wind speed, but even the fastest drop in wind speed takes much longer than the milliseconds needed for a circuit breaker in a power station switchyard to trip out.

At the same time, as the share of variable renewable generation grows, the complementary need for a greater share of fast response generators and energy storage technologies will also grow, while the value to the system of large, inflexible coal-fired generators will shrink.

• Renewable energy
• Solar power
• Energy policy
• National Electricity Market
• South Australia blackout

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Parking Occupancy - Independent Variables

For a new land use being surveyed, one or more appropriate independent variables need to be identified, measured, and analyzed. When identifying a potential independent variable, the following points should be considered:

• The data for the independent variable should be readily available.
• Variables for similar sites should be provided directly and not be merely estimated from a different variable. For example, the number of employees at a site may appear to be a valid independent variable, but it should not be used if the value is typically derived by factoring in another independent variable, such as gross square footage of the development site.

Data Collection

• Site Selection
• Permissions
• Background Data
• Existing Data
• New Surveys

Independent Variables

Data Submission

• Excel Spreadsheet

Variable Definitions

Employees: Unless otherwise stated in the land use description, the number of employees refers to the total number of persons employed at the survey site, including all shift workers.

Gross Floor Area (GFA) [i] : The sum (in square feet) of the area of each floor level in the building, including cellars, basements, mezzanines, penthouses, corridors, lobbies, stores and offices, that are within the principal outside faces of exterior walls, not including architectural setbacks or projections. Included are all areas that have floor surfaces with clear standing head room (6 feet, 6 inches minimum) regardless of their use. If a ground-level area, or part thereof, within the principal outside faces of the exterior walls is not enclosed, this GFA is considered part of the overall square footage of the building. However, unroofed areas and unenclosed roofed-over spaces, except those contained within the principle outside faces of exterior walls, should be excluded from the area calculations. For purposes of trip generation and parking generation calculations, the GFA of any parking garages within the building should not be included within the GFA of the entire building. The unit of measurement for office buildings is currently GFA; however, it may be desirable to also obtain data related to gross rentable area and net rentable area. With the exception of buildings containing enclosed malls or atriums, gross floor area is equal to gross leasable area and gross rentable area.

Gross Leasable Area (GLA) [ii] : The total floor area designed for tenant occupancy and exclusive use, including any basements, mezzanines, or upper floors, expressed in square feet and measured from the centerline of joint partitions and from outside wall faces. For purposes of trip generation and parking generation calculations, the floor area of any parking garages within the building should not be included within the GLA of the entire building. GLA is the area for which tenants pay rent; it is the area that produces income. In the retail business, GLA lends itself readily to measurement and comparison; thus, it has been adopted by the shopping center industry as its standard for statistical comparison. Accordingly, GLA is used in this report for shopping centers. For strip centers, discount stores and freestanding retail facilities, GLA usually equals GFA. 

Gross Rentable Area (GRA) [iii] : The area computed in square feet by measuring the inside finish of permanent outer building walls or from the glass line where at least 50 percent of the outer building wall is glass. GRA includes all the area within outside building walls excluding stairs, elevator shafts, flues, pipe shafts, vertical ducts, balconies, and air conditioning rooms. 

Independent Variable: A physical, measurable, or predictable unit describing the study site or generator that can be used to predict the value of the dependent variable. Some examples of independent variables used in this book are GFA, employees, seats, and dwelling units.

Net Rentable Area (NRA) [iv] : Computed in square feet by measuring inside the finish of permanent outer building walls or from the glass line where at least 50 percent of the outer building wall is glass. NRA includes all the area within outside building walls excluding stairs, elevator shafts, flues, pipe shafts, vertical ducts, balconies, air-conditioning rooms, janitorial closets, electrical closets, washrooms, public corridors, and other such rooms not actually available to tenants for their furnishings or to personnel and their enclosing walls. No deductions should be made for columns and projections necessary to the building. Typically, the NRA for office buildings is approximately equal to 85 to 90 percent of the GFA.

Servicing Position: The number of vehicles that can be serviced simultaneously at a quick lubrication vehicle shop or other vehicle repair shop. That is, if a quick lubrication vehicle shop has one service bay that can service two vehicles at the same time, the number of serving positions would be two.

Vehicle Fueling Position (VFP): The number of vehicles that can be fueled simultaneously at a service station. For example, if a service station has two product dispensers with three hoses and grades of gasoline on each side, where only one vehicle can be serviced at a time on each side, the number of vehicle fueling positions would be four.

[i] Institute of Real Estate Management of the National Association of Realtors. Income/Expert Analysis, Office Buildings, Downtown and Suburban , 1985, p. 236.

[ii] Urban Land Institute. Dollars and Cents of Shopping Centers , 1984.

[iii] Institute of Real Estate Management of the National Association of Realtors. Income/Expert Analysis, Office Buildings, Downtown and Suburban , 1985, p. 236.

If you have any questions, do not hesitate to contact Lisa Fontana Tierney .

Electrical Concepts

Tricky but Easy Electrical Engineering!

Reverse Power Protection of Generator

The  consequences  of  generator  motoring  and  the  level  of  power  drawn  from  the  power system will be dependent on the type of prime mover as under this condition prime mover acts as a load for synchronous Motor. For steam turbines, the motoring power is around 0.5-3 % of rated power of Generator. Under the failure of prime mover, due to motoring of turbine windage loss will be more in turbine blades as there is no steam to cool it down. Thus it will lead to damage of turbine.

Reverse Power element of Numerical Relay calculates the three phase active power using its current and voltage input based on the following formula,

P = V a I a Cos Ø a + V b I b Cos Ø b + V c IcCos Ø c

The Numerical Relay is connected with the convention that the forward current is the current flowing from the generator to the busbar. This corresponds to positive values of the active power flowing in the forward direction. When a generator is operating in the motoring mode, the machine is consuming active power from the power system and if this active power crosses the set value, then after the set time delay the relay will operate to trip the Breaker.

You may like to read,

Introduction and Architecture of Numerical Relay

Programmable Scheme Logic (PSL) in Numerical Relays

As discussed earlier, one cause of reverse power flow in a generator is failure of prime mover. Now failure of prime mover may be because of failure of Governor or failure of Governor Valve or maloperation of Boiler Pressure Control System.

Another cause of reverse power flow occurs during synchronization of Generator. Let us assume that Generator is to be synchronized with the Grid. The general practice for synchronizing a Generator is to close the breaker when the needle on the synchroscope is moving clockwise and crossing 11 O’clock position as shown in figure below.

As shown in figure, the position of needle is at 12 O’clock. Suppose the frequency of Generator is less than the frequency of Grid, in this case the needle of synchroscope won’t move in clockwise i.e. fast direction rather it will move anticlockwise direction i.e. toward slow direction. If we close Generator circuit breaker in such condition, then the Grid will try to take the Generator to synchronous speed by feeding power to the Generator and motoring of Generator will take place. Thus in such case also reverse power will flow.

12 thoughts on “Reverse Power Protection of Generator”

in the power plant which i work has provided reverse power protection with two different time delays, can you please specify the reason for having two different time delays for same protection

I need to check. I will post on this. Please check latter.

Often there will be different time delays for different levels of reverse power. The effect of reverse power while generating is overheating your generator: The more reverse power the faster it heats requiring a faster disconnection time to stop insulation burning.

my hydro power plant frequently tripped during about 70 percent loaded condition as well while starting time displaying reverse power protection. could you please suggest the reason behind it?? what is the causes of reverse power protection in hydro power plant??please suggest remedial action.

How much is the setting for reverse power protection?

the reason for setting two time delay are 1) If reverse power relay operates due to actual/ real fault in the generator 2) For shutdown of power plant, Basically the two timings will have different set values. Set 1 is used as low set operates for large value for power and set 2 is for shutdown.

@ Rajendra Prasad Kafle 1. Please check the delay setting reverse power relay, correct if it has been tampered by any technician and is different from the design setting. 2. During synchronisation, confirm whether the load is being increased immediately by DCS/SCADA engineer or not, Delay in increasing load may cause reverse power drawing from the grid and finally the reverse power protection acts. 3. For tripping at load of 70% , check the characteristics of the controller whether it is working properly in that zone or not, inability to feed the desired quantity of water to move the prime mover may also act the tripping on reverse power protection as the generator tend to maintain the frequency synchronous to that of the grid.

In a situation whereby the master generator is calling in the slave generator and after few seconds of trying to call in the slave its shutdown boths, what is the cause?

i have CAT 220kVA with woodward LSeries actuator and synchro panel intelicompact nt mint 5 engines in parallel. they start very ok but problem on synchronization part. before synchronizing genset operate ok, when synchronized they get load on each genset to much and the priority 4 gets 250A each phase and alternator heats up. voltage drop but freq and rpm stay within limits. how do i solve this?

Good day, I have 2 cat generators (1.5MVA) in parallel, whenever there is a power utility failure, the two gen start (gen1 has priority over gen2) and they are loaded, after few minutes the gen2 drop load and show reverse power trip alarm When I try to clear the alarm on gen2 and put it on auto to start in parallel with gen1, afer it sync (loads) with gen1 few minute its dropped load and popup reverse power alarm…..One thing I discovered was that when gen2 sync and load with gen1, I noticed Gen1 power start increasing instead of dropping since gen2 has sync and loaded, after gen2 popup alarm the gen1 goes back to its normal power value

PLEASE WHAT COULD BE THE CAUSE OF THIS………. Your answer will be appreciated

How to solve the problem of reverse power, unit gets synchronized but eventually the breaker trips showing the reverse power status? Plz I need some suggestions.

Please check relay setting if the mode is set Generating mode or Motor?

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Preferential Trip On Ship With Diagram

>> Your Comments are always appreciated... >> Discussion is an exchange of knowledge It Make the Mariner Perfect.... Please Discuss below...

Please include the alarm circuit also in the diagram

The preference trip light on my generator can not go off and the generator refused to take load while the preference trip light is on. If I start the other generator, it also can not go off . Why

How test will conducted by current injection

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South looks north, as solar storm brings auroras

Geoff Brumfiel

The solar flare as captured by NASA's Solar Dynamics Observatory on Thursday. The flare has triggered a severe geomagnetic storm watch for the first time in nearly 20 years. AP hide caption

The solar flare as captured by NASA's Solar Dynamics Observatory on Thursday. The flare has triggered a severe geomagnetic storm watch for the first time in nearly 20 years.

Planet Earth is getting rocked by the biggest solar storm in decades.

Late Friday, the National Oceanic and Atmospheric Administration declared that the Earth was experiencing a G5, or "Extreme," geomagnetic storm. This is the first G5 storm to hit the planet since 2003.

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Photos: see the northern lights from rare, solar storm, noaa issues first severe geomagnetic storm watch since 2005.

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NOAA warns several waves of flares will slam into the Earth over the next few hours and days, potentially disrupting communications and navigation, triggering power outages and damaging satellites. The 2003 event briefly knocked out power in part of Sweden and damaged electrical transformers in South Africa.

NOAA's Space Weather Prediction Center says that this latest storm may induce auroras visible as far south as Northern California and Alabama.

On social media, posters were putting up photos of bright auroras visible across Russia , Scandinavia , the U.K . and continental Europe . Some reported seeing the aurora as far south as Mallorca, Spain .

my cat just experienced the aurora borealis, one of the world's most radiant natural phenomena... and she doesn't care pic.twitter.com/Ee74FpWHFm — PJ (@kickthepj) May 10, 2024

The source of the solar storm is a cluster of sunspots on the sun's surface that is 17 times the diameter of the earth. The spots are filled with tangled magnetic fields that can act as slingshots, throwing huge quantities of charged particles towards our planet. These events, known as Coronal Mass Ejections, become more common during the peak of the Sun's 11-year solar cycle.

Usually, they miss the Earth, but this time, NOAA says several are headed directly towards our planet.

Extreme (G5) geomagnetic conditions have been observed! pic.twitter.com/qLsC8GbWus — NOAA Space Weather Prediction Center (@NWSSWPC) May 10, 2024

"We have high confidence that a series of coronal mass ejections ... are directed right towards Earth," says Shawn Dahl, service coordinator for the Space Weather Prediction Center told reaporters early Friday.

NOAA's GOES-16 satellite captured a flare erupting occurred around 2 p.m. EDT on May 9, 2024.

While they expect the storm to be large, there's still a lot of uncertainty about what the other effects could be, Dahl says.

"I wouldn't want to speculate on that," Dahl says.

Shocking problems

The most disruptive solar storm ever recorded came in 1859. Known as the "Carrington Event," it generated shimmering auroras that were visible as far south as Mexico and Hawaii. It also fried telegraph systems throughout Europe and North America.

While this geomagnetic storm will not be as strong, the world has grown more dependent on electronics and electrical systems. Depending on the orientation of the storm's magnetic field it could induce unexpected electrical currents in long-distance power lines — those currents could cause safety systems to flip, triggering temporary power outages in some areas.

Stronger activity on the sun could bring more displays of the northern lights in 2024

The storm is also likely to disrupt the ionosphere, a section of Earth's atmosphere filled with charged particles. Some long-distance radio transmissions use the ionosphere to "bounce" signals around the globe, and those signals will likely be disrupted. The particles may also refract and otherwise scramble signals from the global positioning system, according to Rob Steenburgh, a space scientist with NOAA. Those effects can linger for a few days after the storm.

What Causes The Northern Lights? Scientists Finally Know For Sure

Steenburgh says it's unclear just how bad the disruptions will be. While we are more dependent than ever on GPS, there are also more satellites in orbit. Moreover, the anomalies from the storm are constantly shifting through the ionosphere like ripples in a pool. "Outages, with any luck, should not be prolonged," Steenburgh says.

The radiation from the storm could have other undesirable effects. At high altitudes, it could damage satellites, while at low altitudes, it's likely to increase atmospheric drag, causing some satellites to sink toward the Earth.

The changes to orbits wreak havoc, warns Tuija Pulkkinen, chair of the department of climate and space sciences at the University of Michigan. Since the last solar maximum, companies such as SpaceX have launched thousands of satellites into low Earth orbit. Those satellites will now see their orbits unexpectedly changed.

"There's a lot of companies that haven't seen these kind of space weather effects before," she says.

The International Space Station lies within Earth's magnetosphere, so its astronauts should be mostly protected, Steenburgh says.

In a statement, NASA said that astronauts would not take additional measures to protect themselves: "NASA completed a thorough analysis of recent space weather activity and determined it posed no risk to the crew aboard the International Space Station and no additional precautionary measures are needed," the agency said late Friday.

People visit St Mary's lighthouse in Whitley Bay to see the aurora borealis on Friday in Whitley Bay, England. Ian Forsyth/Getty Images hide caption

People visit St Mary's lighthouse in Whitley Bay to see the aurora borealis on Friday in Whitley Bay, England.

While this storm will undoubtedly keep satellite operators and utilities busy over the next few days, individuals don't really need to do much to get ready.

"As far as what the general public should be doing, hopefully they're not having to do anything," says Dahl. The largest problem could be a brief blackout, so keep some flashlights and a radio handy, he says.

I took these photos near Ranfurly in Central Otago, New Zealand. Anyone can use them please spread far and wide. :-) https://t.co/NUWpLiqY2S — Dr Andrew Dickson reform/ACC (@AndrewDickson13) May 10, 2024

And don't forget to go outside and look up, adds Steenburgh. This event's aurora is visible much further south than usual.

A faint aurora can be detected by a modern cell phone camera, he adds, so even if you can't see it with your eyes, try taking a photo of the sky.

The aurora "is really the gift from space weather," he says.

• space weather
• solar flares
• solar storm