Patent GB-195397-A (GB)
Title: Improvements in automatic electric control systems
IPC: H02H1/00
Filed: 1923-03-23
Abstract: 195,397. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Moss, C. M., and Peterson, A. J. A.). March 23, 1922, [Convention date]. Systems depending on the use of static transformers; switching systems.-An electric supply system, comprising main sources of supply and an auxiliary source of supply, is provided with an automatic control system adapted to connect all the bus-bar sections to a predetermined source of supply when the load is below a predetermined value, and to connect the other sources to individual bus-bar sections in a predetermined order as the load increases, the sources being disconnected as the load falls off. The auxiliary source may replace a faulty main source either during the connection of the main source or when an attempt is made to correct it. To connect the line A to the system an underload relay 100, connected in the circuit of current transformers 12 operates to energize a relay 96 which closes a contactor 99 to energize relays 24 associated vith bus-bar interrupters 70, 80. The energization of the operating magnets 14 of the interrupters 70, 80 causes these interrupters to be closed and latched in the closed positions, and contactors 16 associated with the interrupters close the circuits of the coils 35 of relavs 25 to open the circuits of the relays 24 at the contactors 39. Under this condition the bus-bars AA, BB, CC are connected through the interrupters 70, 80. If now the supply line A becomes energized a phase and voltage relay 27 associated with this line opens its switch 27a to deenergize the relay 71 to close the contactor 72 in the circuit of a relay 24 associated with the highpotential interrupter 10 of the line A thereby energizing the relay 24 over the contactors 20 of interrupters 70, 80 contactor 72 and switches 39 of relays 25 and 26. The closure of interrupter 10 closes a contactor 16 to energize the winding 35 of the relay 25 thereby opening the circuit of the relay 24 at the switch 39, the interrupter 10 being latched in its operated position. The contactor 16 also closes the circuit of the relay 24<a> of the low-potential interrupter 11 the circuit of the relay 24<a> being broken in a similar manner to that of the relay 24 after the interrupter 11 has been closed. The line A is now connected to the bus-bars A A and BB. When the load on the bus-bars A A1 BB exceeds a predetermined value an overload relay 90 operates to close the circuit of a relav 91 the contactor 95 of which completes the circuit of a relay 75 thereby ener gizing the relay 44 of the high-potential interrupter 30 in line B over the contactor 82 of relay 81, which is de-energized by the opening of the relay 47 connected to line B, and over the contactors 39 of relays 45 and 46. The closure of the interrupter 30 energizes the winding 35 of the relay 45 over the contactor 16, and the circuit of the relay 44 is opened at contactor 39 of relay 45. The low-tension interrupter 31 is now closed. To disconnect the bus-bars A A and B B under this condition the underload relay 100 operates to open the circuit of a relay 96 thereby closing a contactor 98 to close the operating circuit of the trip coil 15 of the interrupter 70 over the contactors 20, 20<a> of interrupters 30, 31 and the contactors 18<a>, 18 of interrupters 11, 10. 'The circuit of the trip coil 15 of the interrupter 80 is similarly closed in order that the lines A and B are connected to their respective bus-bars AA, BB. When the load decreases below a predetermined value the overload relay 90 opens its switch and the underload relay 100 closes its switch to energize the relay 96, the contactor 99 of which closes the circuits of the relays 24 associated with the bus-bar interrupters 70, 80 and these interrupters are closed'. The trip coil 15 of the interrupter 30 is now closed over contactors 19 of interrupters 80, 70, contactors 21a, 21 of interrupters 11, 10, contactor 93 of relay 91, trip coil 15 and contactor 17 of interrupter 30. The closure of the contactor 22 of interrupter 30 closes the circuit of the trip coil 15a of interrupter 31. To replace line A by line C, when both lines A and B are connected up and when line A becomes faulty due to phase reversal or failure or to low voltage, a relay 27 closes its contacts 27a to energize a relay 71 the contactor 73 of which closes the circuit of the trip coil 15 of the interrupter 10 the circuit being completed over the contactor 17 of this interrupter. A contactor 22 on the interrupter 10 closes the circuit of the trip coil 15<a> of the interrupter 11. Contactors 22 and 22a close the circuits of the resetting coils 38 and 38a of the relays 25 and 25a in order that the contactors 39 and 39<a> of these relays may prepare the circuits of the relays 24 and 24a for future energization. The diminished load causes the underload relay 100 to energize the relay 96 the contactor 99 of which completes the circuits of the relays 24 associated with the interrupters 70 and 80 and the bus-bars A A and B B are conr.ected to the. line B. The underload relay 100 opens its contactor and the overload relay 90 is energized to complete the circuit of the relay 91. A relay 85 is thereby energized over the contactor 95 of relay 91, contactors 23 and 23<a> of interrupters 10 and 11, contactor 97 of relay 96. The relay 85 operates to energize the relay 64 of the interrupter 50 over the contact 67<b> of relay 67 and the contactors 39 of relays 65 and 66. The low-potential interrupter 51 is then closed to connect line C to bus-bars C C. The trip coil 15 of the interrupter 80 is energized to disconnect bus-bars C C from bus-bars B B leaving line C - connected to bus-bars A and line B connected to bus-bars BB. If the line B becomes faultv the line C is similarly connected up to the busbars B B. If under the conditions of line A being connected to bus-bars A A and line C being connected to bus-bars B B, the line A becomes faulty the relay 27 operates to control the disconnection of line A and the underload relay 100 operates to control the closing of interrupter 70 thereby connecting line C to bus-bars A A and BB. Line C is disconnected upon the occurrance of abnormal conditions on that line by the operation of relay 67. When line C is connected to bus-bars A A and B B and the conditions of line A become normal the relay 27 is operated to de-energize the relay 71, and contactor 72 closes the circuit of the relay 24 of the interrupter 10 over the contactors 20 of the interrupters 80 and 70 and line A is finally connected to bus-bars A A. Since the load is less than the overload capacity of line A relay 90 will be opened allowing contactor 92 of relay 91 to be closed. The circuit of the trip coil 15 of the interrupter 50 is then closed over the contactors 18 of interrupters 80, 70, contactors 19<a>, 19 of interrupters 11, 10, contactor 92 of relay 91, trip coil 15 and contactor 17 of interrupter 50. The interrupter 50 is thereby opened and finally the low-potential interrupter 51 is opened. To disconnect the line A from the bus-bars A A, BB, when the line A becomes faulty and to replace this line by line B the relay 75 is energized either by the operation of the relay 27 or the operation of a relay 76 controlled by a lock-out relay 26 which is in turn controlled by a thermal relay 28. The relay 75 controls the circuit of the relay 44 associated with the interrupter 30 and the line B is finally connected to the system. If the line B be faulty either the relay 81 or the relay 86 will be energized so that the operation of the relay 75 cannot initiate the connection of the line B. When under this condition and if line C is normal this line is connected to replace faulty line A. If when the line B has been switched in to replace the faulty line A and the load is increased beyond the capacity of this line the relay 85 is energized over the contactor relay 75 or the contactor 95 of the overload relay 91, the contactors 23, 23a of interrupters 10, 11 and the contactor 97 of relay 96. The line C is thereby connected to bus-bars A A through bus-bars C C and the interrupter 80 is opened. When normal conditions are established in line A this line is connected up, the interrupter 70 is opened, and the line C is disconnected.