AC Generator Concepts and Waveform Terminology

Vocabulary flashcards defining key electrical terms, generator components, and AC waveform parameters.

Armature

The winding in a generator where an induced voltage is created.

Excitation current

The current supplied to the field of an AC generator, which creates the magnetic field that the armature cuts through.

Exciter

The DC magnetic field for a generator, whether spinning or stationary.

Frequency

The number of complete waveforms completed in $1$\,second, measuring how often the waveform is completed in relation to time, expressed in cycles per second.

Hertz (Hz)

The unit of measure for frequency, named after Heinrich Hertz, representing cycles per second.

Peak-to-peak value

The full value of the AC sine wave measured from the positive peak to the negative peak, also referred to as the P-to-P value.

Permanent magnet generator (PMG)

A type of generator in which the field is provided by a very strong permanent magnet.

Revolving armature AC generator

A generator that has the field windings on the stator and the armature windings on the rotor.

Revolving field generator

A generator that has the field windings on the rotor and the armature windings on the stator.

Root mean square (RMS)

The square root of the mean, or average, of all the instantaneous values squared of an AC waveform, providing the effective value that has the same heating effect as DC of the same value.

Slip rings

Continuous bands of metal installed around a shaft that are connected to the rotating windings and provide a path for the current to reach the brushes.

Synchronous speed

The exact speed of a rotating member to produce a desired frequency for a generator, or the speed produced by a specific frequency to make an induction motor run.

Instantaneous value

The magnitude of voltage or current of a sine wave at a specific point or given degree of rotation along its waveform.