Circuit breaker Icu=50kA 4P C 20A HMX420

Circuit breaker with high breaking capacity

The HMX420 circuit breaker provides effective protection of three‑phase circuits against overload and short circuit, especially where large inrush currents occur – e.g., motors, pumps or compressors. The C‑characteristic allows it to withstand short‑duration current flows when starting inductive loads without false tripping, which increases system reliability.

It is designed for surface mounting on a DIN rail and occupies 6 modules (106 mm width). Its construction enables safe connection of single‑core wires with cross‑section from 1 to 70 mm² and multicore wires up to 50 mm². The terminals are aligned both at the top and bottom, facilitating compact installation in distribution boards and eliminating the need for additional aligning components.

A short‑circuit rating of 50 kA at 400 V means the breaker can safely interrupt even extremely high fault currents – making it suitable for modern industrial and commercial installations where fault levels may be high. Insulation voltage 500 V and impulse voltage 6 kV provide an extra safety layer in degree‑3 polluted environments – i.e., where dust, moisture or other external factors are present.

Operating temperature from –25 °C to +70 °C allows use both in cold technical rooms and hot machine spaces. Protection class IP20 protects against contact with live parts but is not intended for outdoor installation.

Optional accessories (e.g., lockout devices, undervoltage releases) give flexibility in system design – it can be easily expanded with monitoring or safety‑lock functions. The terminal tightening torque (3.6–5 Nm) is precisely specified – a regular screwdriver with a torque limiter is sufficient to avoid damaging the terminals.

Electrical power loss is 7.75 W at rated current – indicating low heat loss and stable operation even under prolonged load. Mechanical endurance of 20 000 cycles and electrical endurance of 4 000 cycles guarantee long‑term reliability – without the need for frequent replacement.