Editing Dynamometer (section)

===Electric motor/generator dynamometer===
[[Electric motor]]/[[electric generator|generator]] dynamometers are a specialized type of [[adjustable-speed drive]]. The absorption/driver unit can be either an [[alternating current]] (AC) motor or a [[direct current]] (DC) motor. Either an AC motor or a DC motor can operate as a generator that is driven by the unit under test or a motor that drives the unit under test. When equipped with appropriate control units, electric motor/generator dynamometers can be configured as universal dynamometers. The control unit for an AC motor is a [[variable-frequency drive]], while the control unit for a DC motor is a [[Adjustable-speed drive#DC drives|DC drive]]. In both cases, regenerative control units can transfer power from the unit under test to the electric utility. Where permitted, the operator of the dynamometer can receive payment (or credit) from the utility for the returned power via [[net metering]].

In engine testing, universal dynamometers can not only absorb the power of the engine, but can also drive the engine for measuring friction, pumping losses, and other factors.

Electric motor/generator dynamometers are generally more costly and complex than other types of dynamometers.