PROGRAMMED OVEREXCITATION PROTECTIVE RELAY AND METHOD OF OPERATING THE SAME

摘要

42 A programmed overexcitation protective relay with selectable time-overexcitation operation to govern the interruption of energy to a piece of power equipment, like a transformer, generator or the like. A programmed processor is included to derive an overexcitation time-to-trip in accordance with sampled measurement voltage values of at least one power line supplying energy to the power equipment being protected, and selected derivation constants stored in a memory look-up table. The derivation constants are selected from the look-up table based on derivation parameters which may be set and read by the programmed processor from time to time. The programmed processor utilizes the selected derivation constants to derive the time-to-trip over a number of predetermined time intervals during which the overexcitation condition persists.