| 摘要 |
PURPOSE:To eliminate the need for correction operation, and further permit good searching of high resistance faults even in sections where commercial frequency current is flowing by providing a temp. compensation function of an amplifier and a malfunction eliminating function by commercial frequency current to a receiver. CONSTITUTION:The 1st gate 9 is opened to allow the passage of the output of an amplifier 8 for the time which is integer times of one period of a commercial frequency and is longer than the pulse width of high voltage pulses from the point of the time when a signal is received. Next, it is passed through a subtractor 16 having a subtraction function of (the 1st gate output)-(the 2nd gate output) and is integrated twice by the 1st integrator 10 and the 2nd integrator 11. Next, the integration is ceased for one period of the commercial frequency or a time (about 10mus) extremely shorter than one period from the point of the time when the gate 9 is closed so that the contents of the integrator 10 are returned to the initial state. Next, a gate 15 is opened for the same time as that for the gate 9, and the output of the amplifier 8 is inverted of polarities by the subtractor 16 and is integrated twice. Next, a display gate 12 is opened for the time shorter than the pulse application time and the contents of the integrator 11 are indicated by a meter 13. |
