What the 25 A rating means for your motor branch circuit
That 25 A figure is the thermal continuous rating — the breaker will carry that current indefinitely in a 40 °C ambient without nuisance tripping, which is the baseline for sizing it to a motor's full-load amps. The magnetic trip is set at 150...350 A, so it handles motor inrush (typically 6–8× FLA) without dropping out, but clears a bolted fault fast. The utilisation category is AC-3 per IEC 60947-4-1, meaning it is tested for switching squirrel-cage motors — starting, stopping, and plugging. Category A per IEC 60947-2 covers general distribution faults. The combination means this single device serves both motor control and branch-circuit protection in one enclosure, which is the point of a motor circuit breaker over a separate contactor plus MCCB.
The GV4L25B delivers 50 kA Icu at 220...240 V AC, 25 kA at 380...415 V, 20 kA at 440 V, and 10 kA at 500 V. These are the ultimate short-circuit breaking capacities — the breaker can clear one fault at these levels and still be serviceable afterward. The standards are EN/IEC 60947-2 (circuit-breaker performance) and EN/IEC 60947-4-1 (contactor/motor-starter coordination). That dual certification is what lets a single device serve both as a disconnecting means and as motor overload protection — it is listed for both roles, not just one.
Motor power coverage across common voltages
The GV4L25B covers a range of motor power ratings depending on supply voltage: 5.5 kW at 400...415 V, 7.5 kW at 500 V, and up to 18.5 kW at 660...690 V. That spread reflects the fact that at higher voltages the same 25 A carries more power. For a 400 V line, the 5.5 kW rating is the one to use for BOM matching; for a 690 V mining or marine installation, it reaches 18.5 kW.
Termination and environmental fit
Terminals are EverLink BTR screw type — top accepts 1.5...70 mm² solid or 1.5...50 mm² flexible; bottom accepts 2.5...95 mm² solid or 2.5...70 mm² flexible. Tightening torque is 9 N·m for the larger cables (16...95 mm²) and 5 N·m for smaller ones (1.5...10 mm²). The EverLink design uses a clamping plate that maintains contact pressure over temperature cycles, which reduces the need for retorquing during commissioning. Operating altitude up to 5000 m without derating — useful for high-altitude installations where air density affects arc extinction.
Mechanical durability is rated at 40,000 cycles, electrical durability at 40,000 cycles for AC-3 at 440 V at half rated current (In/2), and 20,000 cycles at full rated current (In). That is typical for a motor circuit breaker in this class — the electrical endurance at full load is half the mechanical figure, which is the number to use when calculating maintenance intervals on a frequently cycled load like a conveyor or a compressor.