Definitions and Glossary of Common Charging Systems Terms

ALTERNATORAn alternating current electrical generator with a direct current output. After the aircraft engine begins running, it supplies all required system electrical current and charges the battery.
GENERATORAn electromechanical device that converts mechanical energy into electrical energy. Aircraft generators produce direct current for all system electrical current needs.
VOLTAGE REGULATORA device that keeps the output voltage of an alternator or generator fairly constant regardless of changes in speed, temperature, or electrical load conditions by controlling the field current.
FIELD CURRENTThe electrical charge flowing from the voltage regulator through the field winding of an alternator or generator. It excites the alternator or generator to produce higher current.
CURRENT SENSORA device that monitors the current going into or out of a system for current limiting or over-current protection or warning purposes. One such sensor is the CURRENT LIMITER: A circuit that limits the amount of electrical current produced by a generator or alternator. REVERSE CURRENT PROTECTION device or electrical circuit that senses when current is coming into a generator instead of flowing out of it and prevents the battery current from flowing into the generator.
OVER-VOLTAGE PROTECTIONThe disconnection of the over-excited alternator or generator from the aircraft electrical system because of its over-voltage condition. OVER-VOLTAGE is a condition in which alternator or generator puts out excessive voltage. A direct short between the bus or ground and the field of the alternator or generator may cause this condition. An OVER-VOLTAGE RELAY or circuit removes the field current or aircraft's electrical system from a generator or alternator that is producing excessive voltage.
LOW-VOLTAGE SENSING / INDICATIONA sensor that monitors and warns of a system or bus voltage that is at or below the battery voltage due to alternator or generator failure.
REMOTE VOLTAGE SENSORProvides for better voltage regulation by sensing the aircraft system voltage right at the output of the alternator or generator.
ALTERNATOR OUT SENSORSenses the auxiliary or stator terminal of the alternator to determine if it is off-line (i.e. not supplying current to the aircraft electrical system) and turns on the Alternator Out (off) light.
PARALLELING RELAY or EQUALIZER CIRCUITSenses the difference in voltage or current outputs of two alternators or generators, ties them together, and equalizes their outputs.
GROUND FAULT PROTECTIONA circuit that turns off a device (e.g. voltage regulator, ACU, GCU, etc.) that is connected to it when there is a ground fault condition on the protected output like the field. GROUND FAULT is a condition caused by a device’s input or output shorting to ground. FIELD-TO-GROUND SHORT PROTECTION is the protection of the ACU or GCU against field winding, wiring, or brushes short to ground.
ALTERNATOR or GENERATOR CONTROLLERCombines or more of these parts: a Voltage Regulator, OVER-VOLTAGE RELAY, LOW-VOLTAGE SENSOR, CURRENT SENSOR, PARALLELING RELAY, LINE CONTACTOR CONTROL etc. in one box. This box controls most of the alternator or generator functions.
FAULT / FUNCTION INDICATOR LIGHT(A SELF & SYSTEM DIAGNOSTIC FEATURE) - A light mounted on a voltage regulator, alternator controller, etc. to indicate the working conditions of the particular unit and system. It indicates good or defective voltage regulator or ACU, no power to voltage regulator, defective alternator switch, or circuit breaker, open or grounded alternator field, and open remote sensing wire