MPCB vs MCCB: What's The Difference?

MPCB is a particularly built electrical protection and safety device for electrical motors. MCCB is a specially designed electrical protection and safety device for electrical motors. MCCB, on the other hand, is an electrical protection device developed for electrical power circuits that transport a lot of currents. This article will learn about the fundamental distinctions between MCCB and MPCB and their construction, operating principles, and features. MPCB is for Motor Protection Circuit Breaker, and MCCB stands for Moulded Case Circuit Breaker.

Table of Contents

What is MPCB

A Motor Protection Circuit Breaker is a basic electromechanical device that protects a single electric motor from overload, input current variations, and unplanned main circuit interruptions. This includes line faults, phase loss, and imbalance in three-phase motors.

A Motor Protection Circuit Breaker saves space and money by offering fuseless protection that promptly shuts down motors to prevent damage. In a short circuit, it will also disconnect the current safely. It will most likely have a thermal delay to allow the motor to cool down and automatic reconnection after it has.

The motor protection circuit breaker is a variant of the thermal-magnetic circuit breaker, but it has extra features developed specifically to safeguard electric motors. The basic operation is comparable to that of all other circuit breakers.

The motor protection circuit breaker is a variant of the thermal-magnetic circuit breaker, but it has extra capabilities designed specifically to safeguard electric motors. The basic operation concept is the same as for all other circuit breakers.

Overload prevention is provided by thermal protection for electric motors. It’s based on an expanding and contracting contact that disconnects the motor if it detects too much current. It’s critical to understand that thermal protection has a delayed response time to allow for large inrush currents when a motor starts. The thermal protection will react to the extended inrush current if the engine cannot start.

When a short circuit, line fault, or other high current electric fault occurs, magnetic protection is activated. Magnetic protection, unlike thermal protection, is instantaneous, allowing harmful fault currents to be disconnected quickly.

The MPCB distinguishes itself from other circuit breakers by being able to defend against phase unbalance and phase loss. Three live conductors with balanced voltages are required for three-phase circuit motors to function properly. The motor’s service life will be shortened if the unbalance is greater than 2%.

The effect is significantly more destructive if one of the phase voltages is suddenly lost because the motor will continue to run with only two phases. The motor protection circuit breaker can detect these conditions by sensing phase voltage differences and promptly disconnecting the motor if they occur. Phase current unbalance is typical in three-phase systems that power independent single-phase loads, but it is inappropriate when the three-phase circuit powers an electric motor.

PCBs also have a manual interruption mechanism that allows electric motors to be disconnected for replacement or repair.

Motor safety circuit breakers come in various current ratings, and many versions allow the current rating to be modified, which is one of its best features. As a result, the same MCPB can be used to safeguard motors of various capacities.

MPCB Functions and Features

MPCB is a type of circuit board that is used in electric motors. The MPCB’s principal function is to trip when the motor draws more current than the set limit. An overcurrent flow triggered an MCB or MCCB; however, they did not have an adjustable current set limit. We can manually set the current limit in MPCB.

MPCB also has an important purpose in that it can automatically reconnect the motor to the power supply after the problem has been eliminated.
MPCB can also protect you from phase unbalance. The motor will not work properly if phase unbalances occur; it will take an unbalanced current and become overheated. As a result, the motor will be instantly disconnected if phase unbalances develop when MPCB is applied.
MPCBs also protect Line to Line and Line to Ground faults. When a line-to-line or ground fault occurs, the MPCB automatically disconnects the motor.
MPCB provides overload and Short Circuit protection. MPCBs, like MCBs, has two methods for thermal overload and short circuit protection: bi-metallic strips for thermal overload and a magnetic coil for short circuit protection.

What is MCCB

The Moulded Case Circuit Breaker (MCCB) is a circuit breaker with a molded case. When customizable tripping is required, the MCCB is used. It’s mostly utilized for high-current applications and comes with a manually actuated circuit breaker. It’s mostly employed in the industrial sector for low and high breaking capacities. The electric device in question is an electrical protection device that protects an electric circuit from excessive current, which might cause an overload or short circuit.

The MCCB has two configurations, one for over-temperature and the other for over-current. It has a bimetallic contact that expands and contracts when the temperature changes. The bimetallic contact permits electricity to flow through the circuit under typical operating conditions freely. However, if the current exceeds the upper predetermined limit, the bimetallic contact will warm up and expand until it opens. As a result, the circuit is separated from the main supply, preventing harm to the equipment.

Working Principle of MCCB

A circuit is protected from fault current by an MCCB. To break those fault currents, it employs thermal and magnetic methods. Overload protection is provided by the thermal mechanism, whereas the magnetic mechanism provides short circuit protection.

Overload Protection

When a current exceeds a limit over an extended period, it is called overload. To defend against overload, MCCB incorporates a thermal mechanism with a bimetallic contact. A bimetallic strip comprises two distinct metals with varying thermal expansion rates—the strip bends or contracts as the temperature changes.

The bimetallic strip carries the main current. The contacts heat up and expand when the current surpasses a particular limit. The strip bends and trips the circuit due to various expansion rates.

The current in electrical equipment might overload for short periods; this is normal and should not be mistaken for fault current. As a result, the MCCB has a time delay, allowing the overload current to flow for a short time before tripping the circuit.

Short Circuit Protection

MCCB protects against a short circuit using a solenoid that produces electromagnetic force. The main current flows through the solenoid that attracts and repels a plunger responsible for tripping the breaker.

If the current remains below the threshold, the solenoid produces a weak magnetic force that cannot attract the plunger. In short circuit conditions, a very high current flows through the solenoid that generates a very strong magnetic force. It attracts the plunger that trips the circuit.

MPCB vs MCCB: What’s The Difference?

Low voltage AC circuit breakers, such as motor protection circuit breakers and molded case circuit breakers, are both low voltage AC circuit breakers. It’s used to manually open and close the circuit and interrupt it when faults occur. Overload and short circuit protection are provided by both MPCB and MCCB. If you have any questions about this topic, please leave a comment below, and if you have any opinions on it, please let me know in the comments section.

MPCB Vs. MCCB

MPCB stands for motor protection circuit breaker, and MCCB stands for molded case circuit breaker.
MPCBs are used to turn on and off electric motors manually and protect them against various types of motor problems. In contrast, MCCBs are utilized in power distribution, low voltage distribution circuits, and motor loads.
MPCBs are built specifically for motor protection, whereas MCCBs are developed for general-purpose circuit protection.
MPCB protects the motor against overloads, short circuits, phase loss, and under-voltage faults, whereas MCCB protects the motor from overloads and short circuits. This circuit makes under-voltage, earth faults, and phase failure faults possible, but they require additional accessories.
Circuit breakers are divided into two types: molded case circuit breakers (MCCB) and motor protection circuit breakers (MPCB).
MPCBs are used to manually turn on and off electric motors while also protecting them from various defects in motors. In contrast, MCCBs are utilized in power distribution, low voltage distribution circuits, and motor loads.
MPCBs are built specifically for motor protection, whereas MCCBs are developed for general-purpose circuit protection.
MPCB protects the motor against overloads, short circuits, phase loss, and under-voltage faults, whereas MCCB protects the motor from overloads and short circuits. This circuit makes under-voltage, earth faults, and phase failure faults possible, but they require additional accessories.
Overload protection is provided by an adjustable bimetallic strip on the MPCB. This strip can be set between two different values, although the MCCB overload value can range from 40% to 100% of its rated value.
MPCB can protect a motor from overload and short circuits, but MCCB can only guard against short circuits when used in a motor protection circuit. As a result, an additional overload relay and contactor are required.
A motor can be turned on and off manually using an MPCB; the contactor is optional in these circumstances, but with MCCB, contractors are required.
Some MPCBs have auto-resetting functions that allow motors to restart operating after a brief period following an overload trip, but this capability is not accessible in MCCBs.
Overload relay is unnecessary for motor circuits with MPCB backup, but it is required for motor circuits with MCCB backup.
While some MPCBs have an auto-resetting capability that allows motors to continue running after a brief period following an overload trip, this feature is not accessible in MCCBs.

Conclusion

Low voltage AC circuit protection devices such as MPCBs and MCCBs are used. The former is a motor protection device (Asynchronous/Induction motors), whereas the latter is a general-purpose protection device. The right selection of these devices, on the other hand, is the only way to ensure reliable protection.

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