Circuit Breakers

Our offering includes the Motor Protection Circuit Breakers (MPCBs), the electromechanical devices that perform three important functions upstream of your electric motors. They provide isolation, motor protection against overload and short circuit and control (on/off) of the motor.

Top-quality motor protection circuit breakers are available to you from the renown manufacturer:

• Benedict.

The motor protection circuit breakers automatically disconnect electrical circuit in the event of overcurrent and short circuit that may damage the motor. Some of them also protect against phase loss.

MPCBs have internal contacts connect the power supply line to the load. Short-circuit currents (high or very high current values) and overcurrents (current values slightly higher than the nominal value) are detected by the internal coil and a heat-sensitive element welded on the bimetal, respectively. In the event of overcurrents, either the coil or the bimetal determines the opening of the contacts.

When choosing the MPCB you should pay attention to the motor rated current and the MCBS’ breaking capacity.

Overloading overheats the motor, causing it to draw a higher than nominal current. That may occur for several reasons: the resistant torque is too high for the motor in question, or the rotor jams, or the motor is starting too frequently, or one of the three power phases is lacking, or the starting time is too long.

When choosing the MPCB you should ensure that it is sized based on the motor rated current. You need to pay attention to the minimum motor start-up times against which it is necessary to identify one of the intervention classes identified by the IEC standard i.e., 2 – 3 – 5 – 10 – 10A – 20 – 30 – 40. The most common intervention classes are 10 – 10A, which corresponds to an intervention within 10 s for an overcurrent equal to 7.2 In.

Short circuit is a dangerous fault that can cause serious damage, fire, and even small-scale explosions. It can occur for a number of reasons: due to faulty insulation or loose connections, an abnormal build-up of electrical currents within electrical wiring system, old or malfunctioning appliances with damaged plugs or power cords, deterioration of the wire casing due to punctures, wire-liquid encounter, etc.

When choosing the MPCB you should check its breaking capacity i.e., the maximum current that the device is able to “open” (or interrupt). The breaking capacity of the MPCB should be greater than the maximum short-circuit current calculated in that point of the system. This current does not depend on the motor nominal current, but on the characteristics of the upstream network.

To increase the level of their reliability, some motor protection circuit breakers also implement the function of protection against phase loss. This function puts the motor safe from dangerous overheating of the windings or even the burning of them.

You can use circuit breakers in various applications. Warehouses, factories, and large industries all have the motor protection circuit breakers integrated within their electrical systems.