Protection circuit for testing electrical equipment - has monitoring unit and switching system with earthed connection at input detector resistance

摘要

The safety protection system for electrical equipment being tested, has one pole which carries the operating or measured voltage connected to earth through a detector resistance (D) (RD). This resistance is at the control input of a monitoring unit (US) incorporated in the testing unit, and forms the input to the latter. The monitoring unit is a cut-out switch (AE) operated with a switching characteristic which gives a reduced switch off time as the detector current increases. This characteristic is determined by a capacitor at the input of the monitoring unit.