Differences Between Reactive & Resistive Load Bank Testing

There are many differences between reactive and resistive load bank testing. It is crucial to understand these prior to scheduling generator load bank service. When testing is performed, it is essential that they adhere to NFPA Code 110 and any applicable requirements set forth by the manufacturer. Regular testing is essential because generators can sit idle for long periods of time, and it is uncommon for them to regularly carry heavy loads.

Resistive Load Bank Testing

Resistive load bank testing determines whether the generator is capable of producing 100% power at a power factor of 1.0. These tests gradually increase load on the generator during the testing period. The test determines electricity production at the unit’s full power rating and whether it is correctly releasing exhaust gases and heat from the engine via the engine cooling system. Further, resistive testing confirms that the generator will operate at full load without overheating or sudden failure. Finally, the testing includes examination of critical systems including oil, fuel, and other essential components. This helps identify potential problem areas under strictly controlled conditions.

Resistive load bank testing is of limited use for emergency applications. The tests leave facilities exposed if a single component within the system falters. Should something falter, it can lead to complete failure of the generator that a resistive test can’t predict.

Reactive Load Bank Testing

Reactive load bank testing simulates real-world scenarios that your generator can expect to encounter. It is more complex and requires more time to complete than a resistive load bank test. Reactive load bank testing can simulate inductive or capacitive loads and examine alternator function, KVAR sharing, and transient responses. Reactive testing is ideal for use when the generator supplies power for motor-driven equipment, transformers, and capacitors. During the test, the load converts the current into a magnetic field that can be measured. The load resists the voltage change which in turn causes the circuit current to lead voltage.

The Best of Both

There are advantages and disadvantages of both types of testing. That is why many facility managers opt to use a resistive/reactive load bank testing, especially when the system is a parralleling system. These tests allow you to determine whether the generator can deliver the rated power factor and whether there are any pending failures that need to be addressed and repaired. More comprehensive than reactive or resistive testing alone, these tests provide the clearest picture possible of generator function and capability.

Gen-Tech offers reliable generator load bank service you can depend on. We encourage you to contact us at (800) 625-8324 to discuss your testing needs with our skilled technicians. It is our pleasure to help you schedule and perform your next load bank test.

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