| 摘要 |
PURPOSE:To prevent breakdown of power supply or load due to overvoltage on a line filter, upon throw-in of power supply, by starting power supply to the load only when the function of the line filter is effective. CONSTITUTION:A power switch 2, a short circuit switch 43, and a power supply switch 44 are all in open state before power is supplied. Upon throw-in of the power switch 2, a capacitor 32 in a line filter 3 is charged with current which is limited by the current limit resistor 41 in an overcurrent preventing circuit 4. Upon detection of the end of charging operation of the capacitor 32, charging operation monitoring circuit 42 in the overcurrent preventing circuit 4 closes the short circuit switch 43 to short-circuit the current limiting resistor 41 so as to enable the function of the capacitor 32 in the line filter 3. At the same time, the charging operation monitoring circuit 42 closes the power supply switch 44 and starts power supply to a load 5. By such arrangement, overcurrent due to the line filter can be prevented. |
