AC VOLTAGE REGULATOR
The automatic voltage regulation uses a controlled dc current through the generator's exciter field. There are various methods used on different aircraft, we will only discuss the transistorized method. With the earlier designed systems the voltage regulation is adjustable in situ; this normally applies to a carbon pile type voltage regulator which does tend to drift during service. In the later type of transistor controlled voltage regulator, in situ adjustment is not allowed. Voltage adjustment is a workshop function only. With the larger type of aircraft there is a long distance between the generator and the distribution point which can lead to a small volts drop under heavy loads. As we require a controlled voltage at the busbar, the point of regulation is chosen as near to the distribution busbar as possible but on the generator side of the GCB. Some systems control the generators maximum overload current. This is achieved, within the voltage regulation section of the GCU, by monitoring the load current and reducing the generator's output voltage when the load current limit is reached.
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