A residual-current device (RCD) disconnects a circuit whenever the electric current is not balanced between the energized and the neutral conductors. The imbalance indicates that there is a leakage current outside of the system sometimes caused by the person accidentally touching the energized part of the circuit, and sometimes by lack of sufficient insulation (excessive moisture or worn out, poor quality insulation materials).
RCDs are designed to disconnect quickly to mitigate the harm caused by such shocks and to avoid current leaks which may lead to fire and other dangerous situations. Robin-Amprobe RCD testers are simple to use devices designed to check for correct operation of RCD devices. They feature three levels of trip currents with either Fast Trip or Ramp Test for complete range of testing applications.