Resistive load bank testing for generator

suggests that you should factor in the .8 power factor into the equation, as this is the power factor of the loads that will be loading the generator.
  • #1
Ok, so here's my scenario/question. I am a technician that works on generators and does load bank testing on them. I'm having a debate with my boss about power factor and IF I'm wrong--I would like to understand why.
Today I load banked a generator that was rated at 25kVA and could run at 120/240 single phase, 120/208 3 phase, or 277/480 3 phase. I was running the generator on the 480 setting and, according to the data plate, the max amps at 480 is 30.1. The power factor on the data plate says .8, however the load bank is purely resistive and has a pf of 1.0. So, I put 30.1 amps on it and the generator couldn't take it. My boss told me that I was overloading the generator and that i need to factor in the .8 power factor, but my thinking is--the load is a 1.0 so i need to forego the pf and run it at what the data plate says. Who is right and who is wrong? a little explanation of pf would be helpful. thanks.

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  • #2
He is right. Generally in generators we face the two group limitation, mechanical and electrical limitation. In your description you just concentrate to machine electrical characteristics whereas you should check the mechanical performance of machine too.
Seemingly, the active power capacity of your machine is 25/0.8 = 20 KW, if it is right, you can drive a resistive load with maximum current of 24 A (20000/1.73*480) not 30.1 A.

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  • #3
Resistive load bank for testing generators

We have developed a resistive load bank 30 KWatts in our setup based on readings we have taken on different loads with different generators and maximum current rating observed was 36 Amperes at 0.8 Pwr Factor. Therefore, we designed our load bank catering to the maximum current being drawn by the load and developed our load bank with a capacity of 45 Amperes (which is 20 % over and above the observed current).

Now, the user is objecting on our design on the premise that we have designed our load bank as purely resistive bank of loads without appreciating the fact that our developed load bank design is already catering the maximum current rating.

Kindly offer your comments whether there are going to be any parameters which will remain un-checked if our load bank is connected to a generator having same specifications (i.e 30 KVA).

Best regards


1. What is resistive load bank testing?

Resistive load bank testing is a method of evaluating the performance and capacity of a generator by applying a resistive load to simulate real-world operating conditions.

2. Why is resistive load bank testing important?

Resistive load bank testing is important because it helps ensure that a generator is functioning properly and can handle the expected load during a power outage. It also helps identify any potential issues or weaknesses in the generator.

3. How is resistive load bank testing performed?

During resistive load bank testing, a load bank is connected to the generator and a resistive load is applied. The load bank is equipped with instruments to measure the generator's performance, including voltage, frequency, and power output. The generator is then run at different load levels to simulate various operating conditions.

4. When should resistive load bank testing be performed?

Resistive load bank testing should be performed during commissioning of a new generator, as well as on a periodic basis (typically every 2-3 years) to ensure the generator is still functioning correctly. It should also be performed after any major repairs or modifications to the generator.

5. Are there any safety precautions to take during resistive load bank testing?

Yes, it is important to follow all safety protocols and procedures when performing resistive load bank testing. This includes wearing appropriate personal protective equipment, ensuring proper ventilation, and following manufacturer's instructions for the load bank and generator. It is also important to have a qualified technician conduct the testing.

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