In any industry, if you have a generator, load bank testing is an important part of adjusting, calibrating and verifying the proper function of the generator. You need to be able to rely on your equipment, and load bank testing is part of the process that ensures you can.
Everything from small backup generators for retail to large generators for expansive mining operations should be load tested. When, how, and how well you test your generator matters too. Every facility and organization should have a specific process of testing all of their electrical equipment, especially backup generators, in order to ensure they will function properly when you need them to.
What is a Load Bank Test for a Generator?A load bank is a specialized piece of equipment that simulates the effects of an electrical load on a generator or, sometimes, another piece of equipment. By simulating the load, we can look at the generator performance without actually risking damage to the equipment that relies on them, or without actually switching over the power of a facility to a backup generator. That’s because the load is not actually real, although it makes the generator respond as if it is real. The advantage of load bank testing is that repairs, maintenance, and other issues can be addressed without worrying that a potentially underperforming generator may impact your facility or your operation when the need arises. Load bank tests are also useful for manufacturers and companies that rent out generators to help ensure their product is performing properly for your use. A load bank test requires running the generator to be tested with the load bank at the maximum capacity of the generator for a specific period of time. As the test goes on, professionals will assess the performance of the generator. It should be able to work at progressively higher kW loads, should achieve its maximum load, and should be able to operate at this level for a certain period of time. Load banks are sometimes outfitted with accessories to give read-outs on different aspects of the generator’s performance.
Why Test Generators with a Load Bank?There are many advantages of load testing generators and many scenarios where you should perform a test. New generators should be load tested to ensure that they will handle the load they need to. This should be done before the generator comes into use. Then, once the generator is installed and in use, it should be tested regularly to ensure it will work as efficiently as possible. The load bank may ensure the generator is properly using fuel (with diesel-powered generators). There are several different applications for load banks, including:
- Testing turbines and engine diesel generators
- Reducing wet stacking issues in diesel engines that are over-powered for their current use
- Ground power testing
- Use of standby generators to prevent issues from idleness
- Engine cell testing
- Testing hydro, aircraft, and wind generators
How Does a Load Bank Work?There are a few different kinds of load banks, which work differently.
- Resistive load banks: This is the most common type of load bank. It converts electrical energy with resistors and must dissipate the heat that this creates. Then, for each kilowatt of power the load bank applies to the generator, the generator applies an equal amount to the prime mover. Usually, this is accomplished through wise resistance or a saltwater rheostat.
- Inductive load banks: Inductive loads instead use an iron-core reactive element to create the load on generators. They can better simulate the load from mixed commercial use, which might include motors and transformers but also lighting and heating.
- Capacitive load banks: If instead, you need to replicate the loads created by telecommunications, fluorescent lighting, computer or UPS loads, then you may be best choosing a capacitive load bank. These are like modified versions of resistive load banks, but they create reactive power from the loads to the system.
- Resistive reactive load banks: These are also called combined load banks. They use resistors and inductors at once, or you can turn one or the other off in order to test a generator with just one type of load. This is typically the best kind of load bank for those who need to test equipment driven by motors, transformers or capacitors.
- Electronic load banks: These load banks are intended to test circuits. They are precision testing and not useful for generators per se, but still useful to know about.
Load Bank Testing RequirementsWhat are your requirements for load bank testing equipment? How often and for how long should you test it? This depends on your needs and your specific equipment. However, there are guidelines and regulations that you can lean on to make your decision. For example, for backup generators for critical infrastructures, such as at hospitals, you may want to test your backup generators at a full load for at least 30 minutes every month. Unsure when and for long you should test? Contact our experts at VCM Solutions today; they would be happy to give you general guidelines and advice for load banking testing for your specific industry.
Generator Load Bank Testing RequirementsWhat do you need in order to test your generator? It’s not just about your load bank. You also need professional guidance or someone within the company to understand the detailed specifics of how to run the test and assess the results of your generator.
Generator Load Bank Testing FrequencyMonthly testing is usually recommended for most kinds of generators. However, others may need only yearly testing. What about the length of the test? While many generators need to be tested for long periods of time, particularly those that typically operate at a low load and for which wet stacking is a risk, others may need to be tested for 30 minutes or less. Some generators cannot function until their water and oil levels have stabilized, so to keep them operational for longer, limiting their testing time makes sense. You should discuss the load bank testing needs for your equipment with a specialist to be sure that you are getting the right testing for your specific needs. For example, when testing a generator to prevent wet stacking, you may need to test for longer periods of time to burn off the build-up that occurs when a generator operates beneath its full capacity.
Generator Load Bank ChecklistTo perform a load bank test for your specific equipment, you should refer to professionals for an exact procedure that will work for your specific equipment. However, you can use this checklist as a starting point for your test. Just be sure to add in your own metrics and extra steps that your equipment may provide.
- Check the generator fuel tank is full.
- Check that the oil level is appropriate.
- Check that the radiator or coolant is full.
- Check all other fluid levels in the generator.
- Start the generator and wait for it to reach normal temperature.
- Listen for potential noises from the generator.
- Stay aware of any potential issues with the generator.
- Connect the loads from the load bank as required for your testing.
- Add each load slowly, and do not exceed 50% of the maximum load on any one leg.
- Check the amperage of each leg with an ammeter.
- Check the voltage of each leg for potential drops (which may indicate failure).
- Monitor the generator and shut it down if problems develop.
- Know how long you should be testing your generator.
- After the test, remove loads from the generator gradually.