JPS6457176A - Electrostatic capacity measuring apparatus - Google Patents

Abstract

PURPOSE:To measure the electrostatic capacity of a smoothing capacitor in a mounting state on the basis of a load current and ripple voltage, by connecting dummy load to the smoothing capacitor. CONSTITUTION:AC voltage is applied to a converter 2 to be rectified and the DC voltage smoothed by a smoothing capacitor 3 is applied to dummy load 9. The load current I flowing to the load 9 by said DC voltage is detected by an ammeter 11 and the DC voltage applied to the load 9 is insulated by the insulating circuit 12 connected to the load 9 and dropped to 1/n to be sent to a ripple voltage detector 13. This DC voltage is applied to an upper and lower limit voltage detector 14 to detect upper and lower limit voltage values VU, VL and both voltage values are sent to an adder-subtractor 16 to calculate deviation and multiplied by the coefficient (n) calculated by the voltage drop due to the circuit 12 to obtain the P-P amplitude DELTAV of ripple voltage to sent the same to an operator 17. The operator 17 performs operation on the basis of the amplitude DELTAV, the current I and the charge period (t) determined by the characteristic of the converter 2 from an input means and electrostatic capacitor can be simply measured in such a state that the capacitor 3 is mounted on a rectifying circuit.