| 摘要 |
PURPOSE:To operate a unit correctly even if the electric resistance of a signal line is changed or the power source voltage is fluctuated a little and prevent an excessive current from being flowed even if the signal line is short-circuited by an accident, by using a constant-current element in stead of a protection resistance. CONSTITUTION:A control unit consists of power source units 1-4 which can invert the polarity of a DC current and transmit the DC current, constant-current element 7 which limits the current above to a fixed value, relays 5 and 6 which are operated by this limited current, relay 9 which is operated by voltage drop of constant-current element 7, Zener diode 8 which is connected to relay 9 to limit the operation range, and indicator lamps 10-12 which are lit by operations of respective relays. A controlled unit is constituted by relays 14 and 16 which are operated according to the current transmitted from the control unit, diodes 13 and 15 which discriminate the direction of the current, and relays 22 and 23 which have contacts to short-circuit diodes 13 and 15. Then, the controlled unit providing with relay 15 which intermits signal line C by a fault is connected to the control unit by signal line C, thus controlling arbitrarily normal rotation, reverse rotation, stop, etc., of motor M, etc. |
