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Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

alternator-rectifier exciter
a source of field current of a synchronous machine derived from the rectified output voltage of an alternator. The components of the exciter consist of the alternator and the power rectifier (including possible gate circuitry), exclusive of all input control elements. The rectifier circuits may be stationary, or rotate with the alternator, which may be driven by a motor, prime mover, or by the shaft of the synchronous machine.
compound-rectifier exciter
a source of field current of a synchronous machine derived from the phase voltages and currents of the machine. The phase voltages and currents of the machine are fed through transformers, then rectified in order to provide DC quantities to the field winding. The components of the exciter are the transformers (voltage and current), rectifiers (including possible gate-circuitry), and power reactors; exclusive of all input control elements.
diode rectifier
a circuit in which the output voltage is fixed by the circuit parameters and the load. The direction of power flow is not reversible. An example of a single-phase diode-bridge rectifier with a capacitor filter is shown. Note that the diodes are on only for a short duration, while the rectified line voltage is greater than the capacitor voltage.
full-wave rectifier
a device that passes positive polarity portions of a signal and reverses negative polarity portions of an AC signal. Ideally, for a sinusoidal input vi(t) = Vm cos(ωt), the output of an ideal full-wave rectifier is vo(t) = |Vm cos(ωt)|.
half-wave rectifier
a device that passes positive polarity portions of a signal and blocks negative polarity portions of an AC signal. Ideally, for a sinusoidal input vi.t) = Vm cos.!t/, the output equals the input while the input is positive and is zero while the input is negative.
potential source rectifier exciter
a source of energy for the field winding of a synchronous machine obtained from a rectified stationary AC potential source. The AC potential can be obtained from the machine phase voltages, or from an auxiliary source. The components of the exciter are the potential source transformer and the rectifiers (including possible gate-circuitry).
rotating-rectifier exciter
an AC generator, with rotating armature and stationary field, whose output is rectified by a solid-state device located on the same shaft to supply excitation to a larger electrical machine, also connected to the same shaft.
single-phase rectifier
a rectifier with a single-phase AC voltage input. See also half-wave rectifier and full-wave rectifier.
three-phase rectifier
a rectifier with a three-phase AC voltage input.
thyristor rectifier
a rectifier where the switches are thyristors. Thyristors are turned on by a gate trigger signal, and turned off by natural commutation. The output voltage is controllable by adjusting the firing angle of the trigger signal. The direction of the power flow is reversible when an inductive load is used. When the average power flow is from DC to AC, the rectifier is said to be operating in the line-commutated inverter mode.
rectifier
a circuit that changes an AC voltage to DC. Switching elements or diodes are used to create the DC voltage. Diode rectifiers
and thyristor rectifiers are the two most commonly used rectifiers.