Selective residual current device

摘要

A selective residual current device has an electronic trip circuit (16), with a bridge rectifier circuit (24), between a summing current transformer (20) and the excitation winding (14) of a release. A zener diode (44), a storage capacitor (46) and an RC element (48) with a delay capacitor (50) are connected to the output of the bridge rectifier circuit (24), the voltage on which delay capacitor (50), which rises in a delayed manner, drives an electronic valve (30) via CMOS logic (60), by means of which electronic valve (30) the energy in the storage capacitor (46) is released to the excitation winding (14). The residual current device according to the invention is cheap to manufacture, operates accurately and enables very precise conformity with the tolerance limits for the tripping time. <IMAGE>