SWITCHBOARD PROTECTIVE MODULE FOR TELEPHONE COMMUNICATION SYSTEMS

摘要

FIELD: break-contact overcurrent and surge-voltage protective gear for telephone communication systems. SUBSTANCE: universal module that functions to eliminate voltage surges either by their discharge through station general ground circuit or by opening user-to-station circuit has thermistors inserted in overcurrent protective circuits which incorporate provision for stepped transition to high-resistance state when operating current rises to critical value of 1.1-100 of rated value and its surge-voltage protective circuits constitute three-electrode arrester whose central electrode leads contact ground bus on one end and state indicator on other end. Two spring-loaded releases inserted in circuit open the latter in case of too long surge current pulse, break its contact with bonding ring on arrester, and ground or short out the circuit; indicator released from holding member protrudes beyond arrester body. Reclosure is effected by re- soldering mentioned spring-loaded release to bonding ring on arrester body and turning indicator through 360 deg./h to place central electrode lead in new thrust slot on indicator. EFFECT: improved reliability, facilitated reclosure upon operation of protective gear. 6 cl, 3 dwg