What is MPCB? Requirement and Characteristics of MPCB
MPCB is used to protect the motor. In this article on What Is MPCB?, we will know in detail, in which what is MPCB? How does it work? For what capacity can it run? You will find the answer to such questions in it. Hope this will be helpful for you.
MPCB – Motor Protection Circuit Breaker
What is MPCB?
The full form of MPCB is Motor Protection Circuit Breaker. Well, its meaning is hidden in its name itself. A motor is needed to run any device. The device that protects that motor is called MPCB - Motor Protection Circuit Breaker.
The most important thing in this is that there is no need for an overload relay and MCB. Motor Protection Circuit Breaker does the work of both.
Requirement of Motor Protection Circuit Breaker
By the way, there are other types of switches in the electrical protection switchgear such as, MCB, RCCB, MCCB, ELCB which are designed to protect according to different requirements in different situations.
But here we talk specifically about MPCB, then it is a device designed for motor protection only. That is why MPCB is effective only in terms of the reliability of motor protection.
Usually, the starter is there to start the motor. It has an MCB or SFU for incoming power, a contactor, and an overload relay for protection. Here instead of MCB and overload relay, only MPCB can be used to drive the motor.
MPCB Working Principle, Function and Protection
Overload protection
Normally bimetal overload relay is used for motor protection which is called a thermal-magnetic circuit breaker. MPCB gives protection of overload on this principle.
In which two different metal T strips expand and shrink according to their properties due to increasing current. If the contact is opened, the circuit trips. Which protects us from the damage caused by overloading the motor.
Short Circuit Protection by MPCB
If there is a short circuit or a fault in the line, the magnetic protection will work and immediately cut off the power to the circuit.
In magnetic protection, there is a coil inside the switch, in which a magnetic field is generated due to the passage of too much current at the time of fault such as a short circuit. One who pulls a plunger.
The plunger connection rests with the tripping coil. Which immediately disconnects the circuit from power during any problem and provides protection to the motor.
Unbalance Load
Motor protection circuit breakers are mostly used in three-phase motors. The voltage should also be balanced as the winding resistance of a three-phase motor is, only then the load that ls current balance will remain.
The current of all three phases should also be balanced. If it is unbalanced due to any reason then it is not good for the motor. In such a situation the motor protection circuit breaker will trip and isolate the power supply to protect the motor.
Single Phasing
SPP This protection is very important. For efficient output lane of motor, it should get balance voltage in all three phases. Single phasing means that there is no voltage in any one phase, that is, due to some reason, the voltage in one of the three phases becomes zero.
In such a situation, the possibility of burning the windings of the motor is very high. But motor protection circuit breaker has single facing protection. Due to which the motor gets tripped before any damage occurs. and disconnects it from the supply.
Features of Motor Protection Circuit Breaker
MPCB does not have the same reliability as using SFU- Switch Fuse Unit and MCB in the motor starter.
MPCBs are available in different ranges from 1 Ampere to 100 Ampere. And according to the rating current of the motor, you can set it to the perfect setting.
Available in voltage ratings up to 230VAC, 380VAC, 415VAC, 440VAC, 500VAC, and 660VAC. Which should be selected according to our motor rating voltage.
The frequency of our electricity is 50Hz. But the specialty of motor protection circuit breakers is that they can run up to 60 Hz.
For the protection of the motor, there is no need for a separate protection device. Motor protection circuit breaker acts as a protective device.
The specialty of Motor Protection Circuit Breaker
There is also an indicator on the MPCB, which can be detected if the motor has tripped.
Motor protection circuit breaker has 'NO' 'NC' axillary contact. Which we can use for trip indication, trip alarm, or any other interlock.
There is a Test button in MPCB, by pressing which if the switch is correct then it trips. Which we get to know whether Motor Protection Circuit Breaker is working properly or not.
Cool downtime in a motor protection circuit breaker that's it which is very important for motor protection. Once the motor is tripped under overload, the auto-restart will not happen immediately. There will be some time for motor cooling, later the motor will start. Which is very good for the life of the motor.
The starting current in a three-phase motor is three to five times the rated current. The starting kick of the motor is not affected due to the overload protection thermal-magnetic in the motor protection circuit breaker. And the motor gets started easily.
Motor Protection Circuit Breaker – Available in three different sizes according to the ampere capacity.
It can be used in motors ranging from 0.37 KW to 37KW.
So in this article on what is MPCB, I have tried to cover all the related topics here.
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