A combined load bank usually consists of both resistive elements and inductors that can be used to provide load testing at non-unity PF (lagging) including the capability to test the generator set fully at 100% nameplate kVA rating. Combined load banks incorporate resistors and inductors all in a single construction which can be independently switched to allow resistive only, inductive only, or varying lagging power factor testing. Combined load banks are rated in kilovolt-amperes (kVA). It’s worth noting that combined load banks can consist of resistive, inductive, and capacitive (RLC) also.

Typically, facilities require motor-driven devices, transformers and capacitors. If this is the case, then the load banks used for testing require reactive power compensation. The ideal solution is a combination of both resistive and reactive elements in one load bank package.

Resistive/reactive loads are able to mimic motor loads and electromagnetic devices within a power system, as well as provide purely resistive loads.

Many backup generators and turbines need to be commissioned at nameplate capacity using a combination of resistive and reactive load to fully qualify their operating capability. Using a resistive/reactive load bank enables comprehensive testing from a single unit. A range of resistive/reactive load banks are available to simulate these types of loads on a power source and the transformers, relays and switches which will distribute the power throughout the facility.

Resistive/reactive load banks may be used for testing turbines, switchgear, rotary UPS, generators and UPS systems. They can also be used for integrated system testing of utility substation protection systems, particularly for more complex relays like distance, directional overcurrent, power directional and others. A resistive/reactive inductive and/or capacitive load is often required to test solar inverters to ensure solar panels can be stopped from producing electricity in the event of a power outage. The resistive/reactive combination load banks are used to test the engine generator set at its rated power factor. In most cases this is 0.8 power factor.