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Difference between MPCB and MCCB
An electrical device that is designed for switching and protection of an electrical circuit is called circuit breaker. A circuit breaker may operate manually as well as automatically to stop the flow of current through the circuit. There are several types of circuit breakers available such as MCB, MCCB, MCPB, RCCB, ACB, OCB, VCB, etc.
In this article, we will highlight the differences between MPCB and MCCB by considering various parameters such as basic definition, type of protection provided, application, etc. Let's start with the basics of MPCB and MCCB.
What is MPCB?
MPCB stands for Motor Protection Circuit Breaker. The MPCB are the specially designed circuit breakers for protecting the electric motors against overload, short circuit, under voltage, phase loss, etc.
Basically, the motor protection circuit breaker (MPCB) is a type of thermal-magnetic circuit breaker that protects the motor against the faults. The MPCBs are available for different voltage levels, typical range of voltages is around 230 V to 660 V.
In practice, the selection of MPCB for a particular electric motor is based on the full load current of the motor and the maximum possible short circuit current. A unique feature of MPCB is that it can withstand the starting (inrush) currents without interrupting the circuit.
What is MCCB?
MCCB stands for Molded Case Circuit Breaker. An MCCB is also an electrical protection device that protects the electrical circuit from excessive current caused by short circuit or overload.
For protection and disconnection, the MCCB uses a bimetallic strip (thermal element) with a current sensitive electromagnetic device. Thus, the MCCB can provide protection against overload, short circuit currents, and it can also be used as electrical switch for ON/OFF of the circuit. The MCCB can be used in a wide range of voltages with a current rating of up to 3200 A.
The MCCBs are extensively used in heavy duty applications like for protection of capacitor banks, protection of welding machines, protection of electrical feeders, protection of motors, etc.
Difference between MPCB and MCCB
Both MPCB and MCCB are electrical protection devices used in low-voltage AC circuits. Both perform the same function of switching of circuit and interruption of circuit automatically on the occurrence of faults in the circuit. However, there are several differences between MPCB and MCCB that are highlighted in the following table −
| Basis of Difference | MPCB | MCCB |
|---|---|---|
| Full Form | MPCB stands for Motor Protection Circuit Breaker. | MCCB stands for Molded Case Circuit Breaker. |
| Used for | MPCB is used to manually turn ON/OFF an electric motor and to provide protection to the motor in case of fault. | MCCB is used for switching and protection of distribution circuits and electric motors. |
| Design purpose | MPCB is mainly designed to protect an electric motor from faults. | MCCB is a designed to provide protection to the general purpose circuits such as wiring systems, distribution systems, etc. |
| Protection provided | MPCB provides protection to the electric motors against short circuit current, overload current, under voltage fault and phase loss. | MCCB protects the circuit or motor against overload and short circuit currents only. |
| Base of setting of parameters | In case of MPCB, the maximum load current is set based on the full-load current drawn by the motor. | The parameters such as overload current, short circuit current and trip delay time are set based on the type of application for which the MCCB is used. |
| Selection criteria | MPCB is selected based on the full-load current of the motor and the maximum possible value of short circuit current. | MCCB is selected on basis of maximum load current and maximum short circuit current that it must interrupt safely. |
| Function in motor circuit | MPCB protects a motor against both overload and short circuit. | MCCB protects a motor against short circuit only. |
| Need of overload protection relay | There is no need of an overload protection relay in the motor circuit with the MPCB, as it has inbuilt overload protection feature. | It is required to connect an overload protection relay in the circuit with MCCB. |
| Auto – resetting feature | Modern MPCBs are designed to have auto-resetting feature so that the motor can resume its operation after a short period from occurrence of an overload trip. | The auto-resetting is not available in MCCBs. |
| Response to starting currents | MPCB can withstand the starting inrush currents of the motor without disconnecting the circuit. | MCCB must be selected based on the starting current of the motor, otherwise it may cause false tripping. |
| Need of contactor | In case of MPCB, the contactor is optional, i.e. the MPCB can be used itself for turning ON and OFF the motor manually. | For switching purpose, a contactor is necessarily required in case of MCCB. |
Conclusion
The most significant difference between an MPCB and an MCCB is that the MPCB is most suitable for protecting electric motors from short circuit, overload, under voltage fault and phase loss fault, while the MCCB is a general-purpose circuit protection device that protects a circuit from short circuit and overload faults.
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