CURRENT PROTECTIVE GEAR-TESTER Russian patent published in 1997 - IPC

FIELD: electrical engineering; testing electromagnetic overcurrent relays, thermal relays, or circuit breaker overcurrent releases; measuring current and operating time of such device. SUBSTANCE: tester is, essentially, automatic-control system closed by negative feedback for controlled variable (test current). Entire test-current measurement range is covered by varying thyristor control angle. Introducing correcting device and properly selecting current regulator structure and parameters provide for transient overshoot of test current not to exceed 10-20% of its steady state value and for setting transient process within one or two cycles of ac current of power supply. Practically sinusoidal of test current is attained by introducing power filter which enables tester to suppress higher harmonics caused by supply voltage distortions. EFFECT: reduced mass of power transformer, facilitated procedure, enlarged functional capabilities of tester. 3 cl, 1 dwg