The OFPM 4P is a high-performance four-pole (4P) modular Residual Current Operated Circuit Breaker (RCCB) strictly designed in accordance with industrial standards. This product is specifically designed for three-phase four-wire low-voltage AC power distribution systems. Featuring an integrated, robust white housing, its core function is to provide high-reliability, high-sensitivity residual current (earth leakage) monitoring and protection for main power distribution or critical branch circuits. By continuously comparing the vector sum of currents between the three-phase conductors and the neutral line, it can synchronously interrupt all poles within an extremely short time when a ground fault or insulation leakage occurs in the system, achieving complete electrical isolation of the faulty circuit. It is a core protective component for preventing electrical fires and safeguarding system and personnel safety.