230V AC Digital RCD Tester with Fast Trip Test - 

Robin-Amprobe RCD tester ism a simple to use device designed to check for correct operation of RCD devices. Features Fast Trip Test for complete range of testing applications. 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).