Portable instrument for resistance to earth measurement - has voltage divider whose output voltage is rectified and compared with voltage derived from network

摘要

The resistance is measured in networks provided with fault current protective switches, using a voltage divider connected by a push-button switch, with the divider tapping connected to the protective conductor. Voltage divider resistors (Rs, Rp) have resistance values which are based on a voltage lower than the permissible shock voltage, and a resistance lower than the permissible resistance to earth. The divider resistor (Rs) is connected through a conductor (N) to a rectifier (4), in turn connected to a comparator (5) to the input of which a reference voltage can be applied through a switch (T).