GB888475A - Improvements in or relating to polyphase alternating current systems - Google Patents

Abstract

888,475. Synchronizing. ALLIS-CHALMERS MANUFACTURING CO. Nov. 25, 1958 [Nov. 26, 1957], No. 37985/58. Class 38 (4). A circuit arrangement wherein all the components are static components with no moving members, ensures the closing of a circuitbreaker between the incoming source and the existing source only when the phase relationship of, and the magnitudes of, the incoming and existing voltages have predetermined values. An incoming transformer having bus-bars 1, 2, 3 is connected to existing bus-bars 4, 5, 6 by a circuit-breaker 15, the operating coil of which can only be energized when the magnitude and phase relationships of the transformer and supply voltages have the requisite values. Each phase is provided with a circuit arrangement including two transistors 93, 100. The transistor 93 is controlled by the part of the circuit arrangement which includes transformers 31- 34, the transformers being supplied with voltages such that the output of the secondary windings when rectified will render the transistor 93 conductive only when the incoming transformer voltage and the existing supply voltage have the required phase relationship with each other. The transistor 100 is controlled by the part of the circuit arrangement which includes transformers 55-58, the transformers being supplied with voltages such that the output of the secondary windings when rectified will render the transistor 100 conductive only when the incoming transformer voltage and. the existing supply voltage have the required magnitudes relative to one another. When the two transistors 93, 100 are conducting the circuit-breaker closing control coil is energized from a transformer 88 to close the circuit breaker 15. As shown in Fig. 1, the outputs of the three circuits associated with phases A, B, C are serially connected to the breaker closing control coil; they may, if desired, be parallelly connected. Varistors are used in certain parts of the circuits as voltage limiters.