| 摘要 |
PURPOSE:To prevent the mulfunctioning in sequential load changeover operation otherwise caused by a stepping relay by means of a circuit for discriminating the on/off action of the power source due to power failure from the normal switch operation. CONSTITUTION:A load control circuit 2 is connected in series to the power source 3 to detect the on/off operation of a switch with a switch operation discrimination circuit in the circuit 2. A stepping relay is excited each time detection is made to perform changeover in the connection of loads 6a to 5d to the power in sequence. For example, the charge or discharge of capacitors is employed for the switch operation discrimination circuit to determine whether the power suspension is short (in the case of power switch operation) or long in duration (in the case of power failure. A resistance 7 can be connected in parallel to the switch 1 to make discrimination as mentioned above, utilizing the difference of the voltage applied on the load control circuit 2 between the on/off operation of the switch and the power failure. |
