Improvements in devices for automatically synchronising two alternating current networks

摘要

551,791. Electricity supply. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET., and EGER, L. Aug. 6, 1941, No. 9982. [Class 38 (iv)] Synchronizing.-Two, relays 13, 14 are selectively operated according to the order in which relays 7, 8 operate during the synchronizing of two circuits. 1, 2. The'relays 7, 8 close their contacts 7a, 8a when insufficiently energized, and are subject respectively to rectified beat currents between transformers 4, 5, and 4, 6 which beats change their relative timing as synchronism is passed through. The mutually interlocked relays 13, 14 respectively energize self-locking relays 15, 16 which release only when the order of operation of relays 7, 8 changes. Each energizes'respectively relays 17, 18 which control contactors 27, 28 starting a speed adjusting motor or motors 30 in the appropriate direction. The relays 13, 14 also energize a relay 19 which maintains the relays 17, 18 and the motor in operation for a fixed period determined by a timing relay 20 which it energizes on closing. The relay 19 also operates a timing relay 21 which determines the period of closure of relay 20 and renders relays 17, 19 temporarily unresponsive to relays 7, 8. The intervals between operations of the motor depend upon the'time between de-energization of relay 22 and the succeeding impulse due to relay 7 or 8 and increase with the beat period ; when these intervals exceed a given value relay 23 closes resulting in operation of a time relay 25 which causes periodic operation of the motor for fixed periods at fixed intervals.