초록 ▼

In a relay protective system a method of providing volts per Hz, loss of field, ground differential, phase distance and over voltage protective relay functions. In addition, the inventive method provides an improved method to selectively block any of the above functions in response to input contacts

In a relay protective system a method of providing volts per Hz, loss of field, ground differential, phase distance and over voltage protective relay functions. In addition, the inventive method provides an improved method to selectively block any of the above functions in response to input contacts and selectively activate output contacts in response to operation of the above functions using programmable inputs and outputs.

대표청구항 ▼

A method of providing a loss of field protection of a synchronous generator connected in an alternating current and voltage electrical power system, said method consisting of the steps of, a) charting the characteristics of an impedance relay having a defined positive sequence impedance on a rectang

A method of providing a loss of field protection of a synchronous generator connected in an alternating current and voltage electrical power system, said method consisting of the steps of, a) charting the characteristics of an impedance relay having a defined positive sequence impedance on a rectangular coordinate graph (having an abscissa, an ordinate, an origin and four quadrants) to obtain two circles which are offset from the origin for identifying the operate to trip portion of said impedance relay, b) positioning said circles to include said origin within a circle to coordinate the impedance values depicted by said circles to the minimum excitation limits and capabilities of the generator; c) providing a directional trip limiting element extending on said graph from the fourth quadrant, through the origin, through the second quadrant, and through at least one of said circles to effectively prevent tripping of said relay in the first quadrant and limited portions of the second and fourth quadrants; d) comparing said relay characteristics with the sensed impedance of said generator to determine whether the positive sequence impedance of said generator is within the operate to trip portion of said circles; and e) setting a generator trip time delay to effect tripping when said generator impedance is within said operate to trip portion, whereby mis-operation during frequency excursions, power swings and fault conditions are prevented.