SCHNEIDER A9R74425 Residual Current Circuit Breaker (RCCB) Type AC 4P 25A 300mA

SCHNEIDER A9R74425 RCD Circuit Breaker, Residual Current Device RCCB Type AC 4P 25A 300mA
The Schneider A9R74425 circuit breaker is a residual current circuit breaker (RCCB) in the Acti 9 iID family, crucial for electrical system safety. Designed for 3-phase (4P) systems, it has a maximum rated operating current of 25A. Its key feature is a 300 mA (milliampere) earth leakage detection sensitivity and Type AC classification, meaning it can instantaneously detect pure sinusoidal alternating leakage currents (AC). With this 300 mA sensitivity, the A9R74425 is categorized as a device focused on fire protection caused by deteriorated cable insulation and high-level earth leakage currents, as well as protecting personnel from indirect contact at a safe level. This device operates voltage-independently, meaning it can trip the circuit even in cases of low or fluctuating system voltage, ensuring the system disconnects when leakage currents occur to protect both assets and the continuity of the electrical installation.

Specifications
- Fire protection and indirect contact electric shock protection
- With 300 mA sensitivity, this device is configured to trip when high leakage current occurs, a level that helps prevent risks of overheating in wiring which leads to electrical fires.
- Suitable for installation as an earth leakage protection device in the main panel (Main Distribution Board) or sections requiring comprehensive 3-phase protection.
- Capable of detecting pure sinusoidal AC leakage currents, which are common in standard electrical appliances
- The tripping mechanism operates independently of the supply voltage (voltage-independent, no electronic circuits), ensuring that the device trips immediately for safety upon an earth leakage current, even during low voltage or fluctuations

Applications & Usage
- Commercial buildings/small factories: Used as a main earth leakage protector (Main RCD) for MDBs supplying 3-phase power to the building, installed upstream of 3-phase machine or motor control units to prevent major earth leakage caused by internal motor insulation degradation.
- Cascaded / Selective installation: Install the A9R74425 300 mA upstream of sub-panels; if a 30 mA leakage occurs on a branch circuit, the 30 mA device trips first, cutting off only that specific circuit while the A9R74425 serves as backup and overall fire protection.
- Server rooms, hospitals (in specific areas), or facilities where a complete power outage is critical: Using 300 mA upstream ensures the device avoids nuisance tripping from cumulative minor leakage currents caused by numerous devices operating simultaneously, tripping only in severe hazardous conditions.