Motorised drive e.g. for electric multiple-contact or stepping switch

摘要

The present invention relates to a motor drive for a selective switch, a change-over switch or a moving coil, exhibiting a running-time monitoring function by means of additional mechanical contacts. Two additional monitoring contacts are provided in order to verify at different time intervals if the motor protection and the stepping relay are working in an orderly manner during a shift sequence when switching occurs as malfunction of said components could otherwise cause the motor drive to move into an undesired final position. The motor drive is shut down if monitoring reveals that one of the said components is not operating correctly.