Stationary air circuit breaker 1250A 4P HW1W412FS

Stationary air disconnect switch with locking mechanism and built‑in drive

This device is designed as a permanent main and safety disconnect for low‑voltage installations where reliable insulation and the possibility of manual or remote control are required. It is intended for mounting in distribution panels, and its construction allows for front‑central mounting as well as intermediate mounting – providing flexibility when integrating with existing systems.

It has four poles and operates in a voltage range of 440 to 690 V AC, with a maximum continuous current of 1250 A. Under AC-23 conditions (motor loads) it can safely carry a power current of 563 kW at 400 V – making it suitable for controlling large machines such as pumps, fans, or compressors.

Its short‑circuit withstand capability is 55 kA for 1 second, ensuring safety even in extreme fault conditions. The rated short‑time current complies with PN-EN-60947-3, and the insulation is designed for an impulse voltage of 12 kV and an insulation voltage of 1000 V.

Construction and additional functions

The device includes a built‑in motor drive – no external power source is needed to open or close it. An optional voltage release can be fitted, allowing automatic shutdown when voltage drops below safety thresholds. The locking mechanism prevents accidental closing during service – a critical feature for maintenance work.

It provides four auxiliary changeover contacts – there are no make‑or‑break contacts, so it does not indicate “on” or “off” in the traditional sense. Instead, the changeover contacts can be used to control auxiliary circuits or automation interfaces.

IP2X front‑panel protection offers basic protection against accidental contact with live parts – sufficient for enclosed panels. There is no 4‑hole panel mounting option – the unit must be permanently fixed using a busbar system.

Application and safety

Designed as a maintenance disconnect – a device that physically isolates the circuit before service work. Its fixed mounting design and lack of re‑closing capability mean it is not intended for frequent load switching. It serves as a safety device rather than an operational switch.

Operating temperature range: –25 °C to +70 °C – suitable for both climate‑controlled rooms and unheated industrial installations. Operating frequency: 50–60 Hz – standard for European and American networks.

It does not have an emergency trip function – it does not automatically react to overloads or short circuits. Over‑current protection must be provided by other devices (e.g., circuit breakers).