Many standby diesel generators that run rarely or lightly loaded can build up fuel deposits in parts of the engine over time, which may compromise the generator performance. A generator load test raises a generator's operating temperature, which burns off excess fuel buildup and tests the system's ability to handle high loads. Conducting a load back testing is an important part of regular generator maintenance. Read on and learn about the important role of load bank testing in diesel generator set.

What is the load bank testing of a diesel generator?

Diesel generator load bank testing is an essential part of a comprehensive preventative generator maintenance routine. This task involves using a load bank to put artificial loads on the generator to test the Uninterruptible Power Supply (UPS) and generator under load conditions. During the test, all parameters are monitored and documented and the information about the specific generator tested will be showed in the load bank test report. With the report, you will see a clear picture of the overall health of the emergency stand-by power system.

With a proper load bank testing, you can verify the generator’s ability to deliver the power you need during a power outage and ensure efficient operation of a genset.

What is a load bank? A load bank is a device with kilowatt rated sizes and battery type cables, which is designed to provide electrical loads for testing power sources and UPS. It can be used to test the system’s ability to generate power and maintain voltage and current levels within specified limits. Load banks can help test and improve the health of generator and its components. During load bank testing, all the data, such as PSI, time, volts, Amps, Hertz, oil, kW, water temperature and exhaust temperature, can be recorded that offers a more thorough look into the overall health of the gen set.

There are four primary types of load banks: resistive, reactive, resistive-reactive and inductive. Each of them works differently, you need to choose the right kind of load bank for your generator set and application.

Benefits of performing a load bank testing

Performing load bank testing in conjunction with periodic maintenance is recommended by the National Fire Protection Association (NFPA). There are many benefits of conducting a diesel generator load bank test:

Verify the reliability of generator: The failure of diesel generator set during an emergency situation could result in catastrophic conditions. By conducting a generator load bank testing, you can ensure the generator is capable of reaching its rating during an actual emergency. The test verifies the genset's capabilities opposed to just routinely starting it up. You can also discover potential genset problems in a controlled situation and take remedial actions. The test helps to determine if your generator functions properly and efficiently at any critical point in time. 

Prevent wet-stacking: If your diesel engine generator set is not used frequently or only runs on light loads, it can be prone to experience unburned fuel and soot buildup in the exhaust system. This is called wet-stacking. When wet-stacking occurs, you may find back smoke during generator operation or excessive build-up of carbon and oil around the engine turbo. Your generator is likely to perform poorly or even fail to work. During a load bank testing, your machine is run at full operating power and temperature, which can burn off the residue and build-up and reduce wet stacking issues.

Increase your generator’s lifespan: As your generator ages, it’s likely to experience increasing problems over time. In addition to eliminating wet-stacking, the load bank testing can spot and minimize potential weaknesses in a diesel generator system. Regular load bank testing increases the lifespan of your generator by regularly running the exhaust valves and turbo-chargers and reducing the risk of internal damage .

Reduce costs: Diesel generator load bank tests can reveal generator issues before they become serious problems. Problems discovered early can be significantly less expensive. Preventing future mechanical failures reduces costs in the long term.

How to perform a diesel generator load bank test?

To conduct a generator load bank testing, you can follow the steps below:

Connect the load bank to the generator using the attached cables.
Inspect the fluid levels and make sure your generator has sufficient fuel, oil and coolant to operate.
Start and run the generator and allow it to reach its standard operating temperature.
Begin applying loads in descending voltages until the load carried reaches 50% of the generator’s maximum continuous rated load.
Check the voltage and amperage within each leg with an ammeter.
Monitor the generator for signs of overheating and any abnormal noises.
When the test is gradually wound down, remove the loads methodically, allowing the generator to run under progressively lighter loads for about an hour.
Once all loads are removed, allow the generator to cool down before completely shutting the unit down.

The load bank test will provide timely identification of problems with the generator and you can take corrective actions if any problem is found.

A well-maintained diesel generator set can operate as designed during power outages. Generator load bank testing is an important aspect of preventative maintenance. Unsure when and for long you should test? Contact Dingbo Power today.