SUDDEN PRESSURE RELAY SUPERVISORY APPARATUS

• Main Authors: WALTER ALCORN ELMORE, HUNG JEN LI
• Format: Patent
• Language: English
• Published: 24.09.1986
• Edition: 4
• Subjects: CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS; GENERATION

Apparatus for the supervision of a sudden pressure relay (SPR) system which protects a power system network transformer having a plurality of windings associated with each phase of the power system network. This apparatus overcomes the difficulties associated with previous overcurrent supervision of the SPR system for multiple-winding transformers. The apparatus utilizes a maximum restraint signal selection network which offers a discriminating differentiation between high and low current levels in all of the transformer windings and accomplishes this in one embodiment with a single measuring unit per phase of the power system network. For each phase, when the selected maximum restraint signal exceeds a predetermined level, the supervisory unit blocks the SPR from operating the breakers which isolate the power transformer from the power system network. This blocking condition is relieved after a predetermined time period from when the selected restraint signal falls below the predetermined level. The apparatus is further capable of detecting both an internal fault condition and an inrush energization condition of the power transformer and for inhibiting the blockage of the SPR from operating the breakers during either of these detected conditions.