RAPID PRESSURE RISE CIRCUIT

摘要

A circuit is provided to protect a liquid-filled electrical power transformer (10) from damage due to an internal fault which causes a rapid rise in pressure. A pressure transmitter assembly (12) converts the internal pressure of the transformer tank to an electrical current signal and transmits this signal to the receiver circuit (16) of the power/control assembly (14). The receiver circuit (16) converts the transmitted pressure signal to a proportional voltage V(p) on conductor (18). The voltage V(p) enters a differentiator circuit (20) whose ouput Vdp/dt (22) is a voltage proportional to the rate of change of pressure. The discrimination between external and internal faults is provided by using field adjustable time delay (24) and threshold (30) circuits and signals. When the delay circuit output (26) momentarily exceeds the threshold value the comparator (28) activates a latch (32) which in turn operates relays (36) which activate transformer control relays (38) to remove power from the transformer (10).