Patent GB-413723-A (GB)
Title: Improvements in or relating to electric relay arrangements
IPC: H02J3/42
Filed: 1933-01-13
Abstract: 413,723. Synchronizing. REYROLLE & CO., Ltd., A., Hebburn - on - Tyne, and LEBEN, H., 212, Wingrove Road, Newcastleon-Tyne. Jan. 13, 1933, No. 1198. [Class 38 (iv).] An electric relay arrangement responsive to the phase relationship between corresponding voltages of two three-phase systems involves a mechanically balanced relay having a contact member differentially controlled by two coils respectively energized in accordance with two voltages whose magnitudes are dependent on such phase relationship. As shown in Fig. 1, a network A<1>-A<3> is adapted to be connected by a circuit-breaker D to a feeder B<1>-B<3> fed through a power transformer C, the circuit of the circuit-breaker closing coil D being controlled at contacts J<1> of a time lag relay J. The operation of the relay J is dependent upon the operation of relays E-H, the relay E being a balanced voltage relay, F and G synchronizing relays and H being a " leading phase " relay arranged according to the present invention. The operating and restraining coils H<2> and H<3> of the leading phase relay H are connected respectively between a phase of the feeder, say B<2>, and the corresponding lagging phase A<3> of the network and the phase B<2> of the feeder and the corresponding leading phase A<1> of the network. Thus the voltages L<2>, L<3> (Fig. 3) impressed upon these coils vary with the phase angle between corresponding phase voltages of the feeder and the network and the relay will close its contacts H<4> when the feeder voltage leads the corresponding phase voltage of the network by an angle not greater than a few degrees more than 180‹ or when the feeder voltage lags behind the corresponding phase voltage of the network by a few degrees. The synchronizing relays F, G are under-voltage relays connected between corresponding phases of network and feeder and close when the voltages between these phases fall below a predetermined value, i.e. when the voltages are approximately in phase and differ by small amounts only. The relay E has its operating and restraining coils E<2>, E3 fed by corresponding phase-to-phase voltages of network and feeder and closes its contacts E<4> when the feeder voltage exceeds the network voltage. Thus the closing of the circuit breaker takes place only when a power flow from the feeder circuit to the network will take place. A relay K provides an alternative closing circuit for the circuit breaker when the feeder is dead. The arrangement of relays described may be made operative with unbalanced loading by the provision of a second leading phase relay connected across different sets of phases so that at least one of the two relays will hold its contact open when the conditions are unsatisfactory for closing the circuit-breaker D. If the system is to be protected against reversal of power when the circuit-breaker is closed, the number of relays may be reduced by using the differential relays E and H as reverse-power relays, the connections of the coils being changed over for this purpose, either by auxiliary contacts on the circuit-breaker itself or by auxiliary contacts on the time-lag relay J. The connections are then as shown in Fig. 7, in which the operating coil N normally carries opposing currents proportional to the phase current and voltage between phases and the restraining coil N<1> normally carries these currents in the same direction. On reversal of power tripping contacts N<3> are operated. Further modifications employing relays with combined functions are described.