| 摘要 |
1,151,336. Control of motors. ENGLISH ELECTRIC CO. Ltd. 7 March, 1967 [3 May, 1966], No. 19407/66. Heading H2J. In a system in which current is collected by a sliding contact 14 from an A.C. line 13 and supplied to at least one D.C. or A.C. motor 15 via an automatic voltage regulator 16, a switching circuit is provided responsive to loss of contact of the collector. The voltage control comprises unspecified thyristor circuits 16 and the switching circuit has transistors 24 28 and Zener diode 26 arranged so that a voltage on line 32 disappears when the output of a transformer 17 is zero, and this suppresses the thyrister triggering pulses. A delay 31 prevents suppresion at zero points in the A.C. waveform. When contact is restored the triggering pulses are released and advanced to restore normal operation. A tap-changing transformer 10 provides coarse control and the system is normally operated to maintain constant tractive effort. The switching circuit may also operate an indicator. |
