Device for measuring grounding resistance

Abstract

PURPOSE: To improve the reliability of the device for measuring the grounding resistance by causing a level comparator to operate by the induction voltage of a feedback coil when the engagement of a transformer for injection becomes deteriorated thereby to actuate an indicator. CONSTITUTION: After the induction voltage e 2 of a feedback coil NF provided in a transformer CT 1 for injection has been rectified in a rectifying and amplifying circuit RE 2 , it is added to an indicator DS through a level comparator LV. Accordingly, if the threshold voltage of the level comparator LV is set, for example, at a value in the vicinity of the limit value of the control of a feedback loop, when the engagement of the transformer CT 1 is deteriorated and the size of the air gap exceeds the limit value of the control of the feedback loop and the voltage e 2 exceeds the threshold value of the level comparator LV, the level comparator LV operates, whereby the indicator DS operates. The output of the indicator DS becomes an alarm signal. COPYRIGHT: (C)1980,JPO&Japio

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