| 摘要 |
945,071. Control of motors. GENERAL ELECTRIC CO. Ltd. Oct. 10, 1962 [Oct. 18, 1961], No. 37369/61. Heading H2J. A control system for selecting between high voltage and low voltage operating states of an electric traction equipment in dependence upon the magnitude of the voltage supplied thereto is arranged so that the equipment can be set to a low voltage operating state only as a change from a high voltage operating state and when the magnitude of the supply voltage is appropriate to the low voltage state. On operating a pantograph " up " push-button, contact 24 is closed and coil 5 is energized so that the equipment is set in the high voltage operating state, interlock contacts 7, 8, closing upon completion of this operation. In a neutral section of the supply line, no further action occurs. If the supply voltage is in a low range, however, relay R3 closes contacts R31 to establish another circuit for the coil 5 and opens contacts R32 to prevent selection of the low voltage state of the traction equipment. Contacts R33 close to energize relay R1 and its slave relay SR1. This causes resistors 16, 17 to be inserted in series with relay R3 and permits relays R2A, R2B to pick up on sufficient supply voltage. Contact SR14 opens to remove one connection to coil 5, and contact SR13 closes to permit subsequent selection of the low voltage state. The existence of a low voltage supply is confirmed by the inability of relay R3 to remain closed when in series with resistors 16, 17. Consequently, contacts R33, R31, open to de-energize coil 5 and contact R32 closes to energize coil 6 and select the low voltage state. Control lead 3 is then energized to close a main circuit-breaker. Subsequent transfer to a neutral section causes relay R1 to drop out, the selection circuit reverting to the high voltage state set by energization of coil 5 through contact SR14 and interlock 30. If the supply voltage is within a medium range, a sequence of operations as for low voltage supply occurs, but in addition relays R2A, R2B, prevent energization of coil 6, and relay R4 is energized and retained, thus blocking the equipment from the low voltage state. On encountering a high voltage supply, the relay R3 will not drop out, so confirming the high voltage selection. On high voltage operation, false low voltage state selection is prevented by opening of contact R41 of relay R4 in the medium and high supply voltage ranges. The contacts of relay R2A are duplicated by relay R2B, and these relays are fed from different rectifier bridges. A ballast resistor 27 is connected across supply transformer 14 to produce such a change in the total circuit impedance that the operation of relay R3 is consolidated when there is a change to a high voltage supply. A modification of the circuit is used in a frequency selecting system, the various relays being frequency-responsive. |
