| 摘要 |
1,206,696. Arcing preventing in switches. LA TELEMECANIQUE ELECTRIQUE. 14 Aug., 1968 [16 Aug., 1967], No. 38859/68. Heading H1N. A "hybrid contactor" comprises an electromagnetic contactor B, P, a shunt thyristor Th1 connected across the contacts P, a second thyristor Th2 to discharge a blocking capacitor C through the thyristor Th1, and an arrangement for controlling the thyristors so as to prevent or minimize arcing at the contacts, this arrangement including a differentiating circuit A1 to derive a signal for triggering the thyristor Th1 from the leading edge of the voltage pulse arising across the contacts P when opened. This signal is applied through a monostable vibrator A2 and amplifier A3 to the control electrode G1 of the thyristor Th1 to cause the thyristor Th1 to conduct. The signal from A3 is also applied to a second differentiating circuit A4 which differentiates the trailing edge of the signal to produce an output, which through an inverter A5, a gate A6, and an amplifier A7 triggers the thyristor Th2 after a delay imposed by a resistance capacity circuit C4, R13 in the inverter A5. The thyristor Th2 conducts to permit the capacitor C to discharge through and block thyristor Th1. If however the opening of the contacts P was due to contact bounce, the control switch I for the coil B being closed, then an inverter A10 applies a blocking signal to the gate A6 to prevent the operation of the blocking circuit Th2, C, the thyristor Th1 ceasing to conduct when the contacts reclose. A differentiating circuit All, an amplifier A12 and a pulse transformer A13 control a third thyristor Th3, through which the capacitor C is charged. The supply for the transistors in the various circuit elements is provided by a capacitor Cl which is charged from the contactor coil supply through switch I and discharged by a thrystor Th4 which is triggered on at the end of an opening operation by the signal from amplifier A7. |
