Over-voltage on transmission systems due to dropping of load

H. W. Smith: The paper by Mr. Burnham is valuable in that it gives us actual tests on the over-voltages due to over-speeding of waterwheel generators. This problem has also been encountered by the Niagara Falls Power Company who have had lightning arresters fail due to the rise in voltage on dropping of load. Tests have shown that with load suddenly dropped, the generator voltage has increased from 12,000 to 21,000 volts. There was an instantaneous increase up to about 30 per cent above normal voltage. An over-voltage relay has been used to correct this difficulty, and the primary relay of the standard induction feeder regulator has been used as the voltage relay. This relay operates in about ten cycles of a 25-cycle system, and has been set to operate at 30 per cent above normal voltage.