The Principle of Condenser Discharge Applied to Central Station Control Problems

The paper describes the principle of a resistor coupled condenser discharge circuit as a means for indicating the rate of change of an electrical potential. The application of this circuit to an impulse relay which may be used in connection with quick response excitation regulating equipment is outlined. The principle of operation of an electronic voltage regulator is referred to, and an oscillogram is given indicating the definite anti-hunting action which can be obtained with the condenser discharge circuit as an anti-hunting means. A thermionic type automatic synchronizer, which requires only 5 voltamperes per potential transformer, is described in detail. The paper treats the method by which, for any frequency difference within limits of present operating practise, the synchronizer will cause the closing coil of the circuit breaker to be energized in advance of synchronism by a time equal to that required to close the breaker, so that, assuming the frequency difference between the two systems remains constant during the short time required to close the breaker, the breaker contacts will always be closed at the instant of zero voltage phase displacement. A formula has been derived whereby the synchronizer ``advance'' may be calculated for various frequency differences when the constants of the thermionic circuits are known, and the results obtained with the thermionic type automatic synchronizer in a generating station with propeller type water wheels are described.