Draw-out circuit breaker with Sentinel trip unit, 66 kA, 400 A, 3P HW1E304DB

Air circuit breaker with Sentinel trip unit, 400 A, 3P, 66 kA

This device is a withdrawable air circuit breaker with an electronic Sentinel trip unit, designed for stable and safe protection of installations in low‑voltage systems. It is intended for mounting in distribution boards of type Unimes, Univers or Quadro, where a high breaking capacity at large fault currents is required.

The Sentinel trip unit operates as an independent control module – it does not have built‑in protection against earth‑fault or over‑voltage, but offers precise settings for overload and short‑circuit protection (L, S, I). An LCD display with a black background and coloured indicators (green – ready, orange – alarm, red – trip) allows quick diagnosis of the device status without opening the enclosure. The trip indicator shows the cause of the opening – whether overload, short circuit or system fault.

Rated current 400 A at a voltage up to 690 V enables its use in medium and large industrial circuits. The breaking capacity of 66 kA at 400 V AC means the device can cope with extreme fault conditions – e.g., transformer failure or a short circuit on busbars. This rating is tested and certified according to PN-EN 60947-2.

Installation is performed via separate enclosure parts – the connections are not mounted directly to the breaker itself, which facilitates replacement or service without disconnecting cables. The withdrawable cassette allows safe disconnection of the device from the live network – after moving to the “test” or “off” position you can work on the terminals without risk of electric shock. All control functions (buttons “O”, “1”, RESET) are accessible on the front of the device.

An advantage is the possibility to add an optional motor drive – although it is not built in, its installation does not require modification of the enclosure. Auxiliary changeover contacts (4 pcs) can be used to signal the breaker status (e.g., on/off) in a SCADA system or control panel. The absence of make‑and‑break and auxiliary closing contacts means the configuration focuses on status signalling rather than external circuit control.

IP2X protection rating provides basic protection against accidental contact with live parts – sufficient for installations in distribution cabinets. The device operates from –25 °C to 70 °C and withstands impulse voltage up to 12 kV. Total power loss at full load is only 19 W – indicating low heat generation and reduced cooling system load.

No DIN‑rail mounting is required – the construction is dedicated to mounting in special distribution frames. It also does not include Bluetooth communication or active energy measurement functions – this is a base device focused on solid protection and reliability.