The 7PG1903 electro-mechanical three phase circulating current protection is used to detect phase and earth faults. The relay is applied to busbars, connections, auto-transformers, reactors and motors. The relay is used in high impedance schemes in conjunction with external stabilizing resistors and non-linear Resistors (Metrosils) per phase. The 7PG1903 is fast operating, typically 17ms at 3x setting. Relays are housed in E6 cases.