ABSTRACT
Auxiliary power supplies can be provided from the generator terminals, from the switchgear connected to the generator, from the high-voltage supply in the switchyard or from an auxiliary transformer directly connected to the low voltage terminals of the main transformer. For voltages of 33 kV and below, an auxiliary transformer in the switchyard connected to the HV system is a simple and satisfactory solution but for higher voltages the transformer becomes expensive and difficult to manufacture.
