GB1059566A - Improvements in or relating to circuit breaker closure means - Google Patents

Abstract

1,059,566. Synchronizing. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Nov. 15, 1963 [Nov. 23, 1962], No. 44457/62. Heading H2H. An automatic synchronizing system comprises a circuit breaker having an operating winding which is controlled by phase matching means sensitive to the alternating voltages on either side of the breaker, means being provided whereby closure of the circuit breaker is initiated at a given time period before the voltages attain synchronism such that actual closure of the circuit breaker occurs when the voltages reach synchronism. With the circuit breaker 17 open the alternator 3 is run up by a turbine 1 to approximately full speed and the automatic synchronizing apparatus switched on. A speed matching unit IV is then effective by way of a connection D to a change-over unit VI, a motor controller 33 and a speeder motor 11, to adjust the setting of the governor 9 of the turbine to adjust the alternator speed to about 1% above the synchronous speed of the alternating supply grid 31A, 31B. Before this operation is completed however, the voltage matching unit VII operates to reduce the voltage difference across the circuit breaker 17 to less than a prescribed percentage of the grid voltage by way of a setting unit 35 which adjusts the setting of an automatic voltage regulator 15 for the alternator 3. Once the voltage difference is within the prescribed limits the speed matching unit IV applies pulses, by way of a connection E, to a pulse unit V to cause a relay RL2 to close each time the alternator and grid voltages beat thus effecting, through the speeder motor 11, a small reduction in the turbine and alternator speed. When the alternator speed is within permissible limits for synchronizing the speed matching unit IV provides a signal, by way of a connection C, to an AND gate 39. When the phase difference between the alternator voltage and the grid voltage is such that it is proper to initiate closure of the circuit breaker 17 the phase matching unit VIII provides a further signal, by a connection K, to the AND gate 39. If at this instant the protective unit XIII has operated and the phase, voltage, slip speed and overspeed check units IX to XII respectively are providing signals to the AND gate 39 the operating winding 19 is energized to close the circuit breaker 17. In order to allow for the finite time between initiation by the phase matching unit VIII of closure of the circuit breaker 17 and the actual closure thereof means are incorporated in the phase matching unit to derive from the grid voltage a delayed voltage, the magnitude of the delay being proportional to the slip speed between the grid voltage and the alternator voltage. Thus the alternator voltage will coincide with the delayed grid voltage its coincidence with the actual grid voltage, closure of the circuit breaker 17 being initiated at the instant of coincidence of the alternator voltage and the delayed grid voltage thereby allowing the circuit breaker a given time period for closure before coincidence of the alternator and actual grid voltages. Specifications 1,059,564 and 1,059,565 relate to other aspects of the disclosures herein.