Molded Case Circuit Breakers (MCCB)

January 21, 20220

What Are MCCBs?

Molded Case Circuit Breaker (MCCB) is a type of low-voltage circuit breaker. MCCB is an automatic electrical device used to protect the electrical equipment from overload, short circuit, instantaneous over current and earth fault. It is an advanced version of MCB (Miniature circuit breaker). It is used in a wide range from 16 Amps to 1600 Amps.

Because MCCBs have wide current ratings and high breaking capacity, they can be used in industrial applications. Also they can be used for protection of capacitor bank, generator protection and main electric feeder distribution. It can be used for higher current rating and fault level even in home applications.

Schneider MCCB, NSX160F 3P 160A

How Do They Work?

The MCCB uses a temperature sensitive device (the thermal element) with a current sensitive electromagnetic device (the magnetic element) to provide the trip mechanism for protection and isolation purposes.

This enables the MCCB to provide:

  • Overload protection,
  • Electrical fault protection in case of short circuit currents,
  • Electrical switch for disconnection.

How Are They Selected ?

MCCBs in an electrical circuit should be selected according to the circuit’s expected nominal operating current and possible short circuit fault currents. The three main criteria while selecting MCCBs are shown below:

  • The rated operating voltage of the MCCB should be same with system voltage.
  • The trip value of the MCCB should be set according to applications.
  • The breaking capacity of the MCCB should be higher than the theoretical possible maximum short circuit fault currents.
Eaton MCCB, NZMB2 3P 160A

What Are the Accessories of an MCCB?

There are some accessories which are used with MCCB to provide extra function or indicate control voltage. these are shown in below.

  • Rotary Handle (Extended/Direct)
  • Motorized Operation
  • Manual/Auto Operation
  • Mechanical Interlocking
  • Shunt Trip
  • Alarm Contact
  • Under Voltage Trip
  • Auxilliary Contact

VEKMAR supplies all these range of MCCBs in stock quantities as official distributor of Schneider Electric, Eaton and LS Electric. We will be glad to assist you with your project related to MCCB equipment. You can contact our expert engineering team when you need.

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