Earth connection current or fault determination - in AC systems uses current transformer and current measuring instrument

摘要

Faulty or earth connection current determination in AC systems uses current transformer and current measuring instrument. A resistance system dependent on voltage is arranged between the current transformer (1) and current measuring instrument. It consists of a rectifier bridge (2), a Zener diode (3), a limiting resistor (RB) and a smoothing circuit. The secondary voltage of the transformer (1) is across the first terminals (A, B). If the secondary voltage is caused by a low primary current after rectification in the rectifier bridge (2), voltage lower than the Zener voltage of the diode is across the second terminals (C, D). A voltage approx. proportional to the secondary voltage is connected across the third terminals (E, F).