Westhomes WCM6E Series 100A 250A 400A 600A Electric Moulded Case MCCB Circuit Breaker

The WCM6E is Westhomes' series of moulded case circuit breakers (MCCBs) designed for low-voltage distribution, motor protection, and general industrial switching. It uses a moulded insulating case housing a thermal-magnetic or electronic trip unit, operating mechanism, and arc chute. The "E" typically denotes an enhanced frame/electronic-trip variant within the product family.

The WCM6E series is offered in frame sizes of 100 A, 250 A, 400 A, and 600 A, covering the common medium-current industrial band. Each frame size can carry several plug-in or interchangeable trip ratings within it, so the same case can be configured to protect different loads. Selecting the correct frame and trip setting depends on the full-load current, starting conditions, and fault level of the circuit.

Yes. The thermal (long-time) and, on electronic-trip variants, the magnetic (instantaneous) thresholds are field-adjustable via dials or screws on the trip unit. This lets the electrician set the long-time trip current (Ir) and time delay to match the load, and the instantaneous threshold (Ii) to coordinate with downstream protection. Adjustable settings are a key reason engineers choose MCCBs over fixed MCBs.

The thermal element uses a bimetal whose deflection — and therefore the trip time — depends on both the magnitude and duration of the overcurrent, producing an inverse-time curve. The magnetic element trips instantaneously when the current crosses a set multiple of rated current. Adjusting the thermal dial changes the current at which overload protection begins; adjusting the magnetic dial changes the short-circuit pick-up level. This allows selectivity grading with other breakers in the same installation.

It is typically available in 3-pole and 4-pole versions for three-phase systems, with smaller frames (100 A) sometimes also offered in 1- or 2-pole for single-phase loads. Three-pole breakers switch L1, L2, and L3; four-pole versions additionally switch the neutral conductor, used where neutral isolation is required or where upstream/downstream neutral switching must be coordinated.

Breaking capacity (Icu) is offered in several ratings within the series — commonly from around 25 kA up to 50 kA or more at 415 V, depending on frame size and variant. The correct breaking capacity must be chosen so that it is at least equal to the maximum prospective short-circuit current at the installation point. A higher Icu is selected when the supply transformer is large or the breaker is near the transformer secondary.

It is panel- or DIN-rail-mounted inside a distribution board or MCC, with line and load cables/barrels connected to the terminals to the manufacturer's torque. The breaker must be mounted in its intended upright orientation with the operating handle accessible. Busbar or cable lug kits are used for the 400 A and 600 A frames, which carry heavier conductors. Adequate creepage and clearance distances must be maintained per the enclosure design.

Westhomes supplies the WCM6E series with international type-testing certification such as CB Scheme and CE marking for the relevant markets. Certification documentation, test reports, and certificates should be requested at quotation to confirm the specific rating, pole configuration, and breaking capacity covered. Certification is a prerequisite for tender, export, and project acceptance.

It is designed to IEC 60947-2, the standard for low-voltage AC and DC circuit breakers. This standard defines rated current, rated voltage, impulse withstand, breaking capacity (Icu/Ics), utilization categories, and the type-test sequence including overload and short-circuit tests. Compliance is declared on the nameplate and in the technical datasheet.

The 100–600 A frames are commonly used as sub-main breakers in distribution boards, motor-protective circuit breakers for medium-sized motors, feeder protection, generator and UPS output switching, and capacitor bank protection. Their adjustable trip curves support selective coordination between the main incoming breaker and downstream MCBs/MCCBs, reducing the area affected by a fault.