Withdrawable circuit breaker with Sentinel trip unit 55 kA 1250 A 4P HW1M412DB

Withdrawable air circuit breaker with Sentinel trip unit

This device is a four‑pole air circuit breaker with a rated current of 1250 A, designed for use in industrial and commercial installations where high making capacity and the ability to replace the breaker quickly without disconnecting cables are required. It is engineered as a draw‑out unit—allowing safe removal and replacement without disconnecting the main power conductors, which reduces service time and minimizes the risk of installation errors.

The built‑in trip indication system (indicator) provides immediate visual information on the device’s status—whether it is closed or tripped. This is especially useful for fault diagnosis or when inspecting installations in dark or hard‑to‑reach locations.

A making capacity of 55 kA at 400 V means the breaker can safely interrupt very large short‑circuit currents—typical for large central switchgear or transformer power supplies. It does not include built‑in ground‑fault protection or an over‑voltage trip; its operation depends on an external Sentinel trip unit, which must be installed separately. This offers flexibility: the installer can select the appropriate type of trip unit (current, time‑delay, selective) according to the circuit characteristics.

The main terminals are not mounted directly to the enclosure—they require a separate enclosure part (the so‑called “separate terminal”), which eases installation in confined spaces and facilitates integration with busbars or larger‑diameter cables. It cannot be mounted on a DIN rail—it is a stationary device intended for distribution panels with suitable construction.

IP2X protection provides basic protection against accidental contact with live parts—while it does not protect against dust or water, it meets the requirements for indoor installations in controlled environments. Built‑in auxiliary contacts (4 changeover) allow control of signaling, interlocking, or automation logic—e.g., indicating “closed” or “tripped” status to a SCADA system.

An optional motorized drive (for installation) enables remote opening/closing—ideal for automation systems or where physical access to the breaker is difficult. However, there is no integrated drive—it must be added as an accessory.

Internal resistance (50 µΩ) and power loss (187.4 W at Iu) indicate low thermal losses—resulting in reduced panel cooling load and longer contact life. Mechanical endurance of 25 000 cycles and electrical endurance of 6 000 cycles guarantee long‑term reliability even with frequent manual operations.

This is not a self‑protecting device—it operates only in conjunction with an external Sentinel trip unit. It is not a “plug‑in” solution; it is a system module that requires planning and compatible integration.