The Schneider Electric EZ9R03263 is an Easy9 range residual current circuit breaker (RCCB) — a 2-pole, Type AC device rated for 63 A continuous load with 30 mA earth leakage sensitivity.
The 63 A rated current (In) and 30 mA leakage sensitivity are the two numbers that decide whether this RCCB fits your distribution board. Type AC means it detects sinusoidal AC earth faults only; if your load includes pulsed DC (e.g., VFDs, UPS, EV chargers), you need a Type A or B device instead. Mechanical durability is 5000 cycles; electrical durability is 2000 cycles at rated load. That is typical for a residual current device — it is not a switching device for frequent operation, but a protective device meant to trip only on fault. The instantaneous trip (no intentional time delay) means it clears earth faults without waiting, which is the right behaviour for personal protection.
Where it goes in the panel
This RCCB is an outgoer device — it sits downstream of the main switch or incoming breaker, protecting a subcircuit or a group of MCBs. The neutral is on the left, and the connection pitch between phases is 18 mm. Terminal tunnels accept 1…35 mm² rigid or 1…25 mm² flexible cable; tighten to 3.5 N·m. Strip 16 mm of insulation. The IP20 finger-safe terminals are fine inside a closed panel but not for wet or dusty locations.