What Is MCB?
MCB (miniature circuit breaker) is an electromagnetic device that embodies the entire enclosure in a molded insulating material. Main function of MCB is to open the circuit automatically when current passes through it exceeding the value for which MCB is set. MCB can be manually switched ‘On’ and ‘Off’ just like normal switches if necessary.
The device starts its operation for protection whenever overload occurs long enough to create danger to circuit. MCB does not respond to the transient loads like motor starting currents and switching surges. Usually, they are designed to work at less than 2.5 milliseconds during the short circuit fault and 2 seconds to 2 minutes when overload occurs.
Miniature circuit breakers are manufactured in varied pole versions like single, double, triple and four pole structures with distinct fault levels of current.
Working Principle Of MCB
The tripping operation of MCB is achieved with bimetallic strip when continuous over current passes through the device; bimetallic strip gets heated and deflects by bending. Deflection of the strip releases mechanical latch. The latch is attached with the operating mechanism, which allows MCB contacts to open. But during short circuit, sudden rise of current causes electromechanical displacement of plunger that is associated with solenoid of MCB or tripping coil. The plunger strikes trip lever resulting release of latch mechanism as a result circuit breaker contacts open.
Meaning Of RCCB (also called ELCB)
RCCB (residual current circuit breaker) is a type of circuit breaker, which is a current sensing electrical device utilized to protect low voltage circuit if fault occurs. The switch in it turns off whenever fault occurs in circuit.
The device is aimed at guarding individual from risks of electrocution, electrical shocks and fires, which are occurred because of earth or wiring faults. It is useful in the situations when there is sudden earth fault occurs in circuit. Example, an individual comes in contact with open live wire. In such kind of condition, if there is an absence of RCCB in circuit, the individual is at risk of receiving electrical shock.
However, in case the circuit is protected with RCCB, it will trip circuit immediately thus protecting the person from electric shock.
Working Principle of RCCB
Principle behind device operation, in ideal situations, current flows into the circuit via live wire should be similar as returning current from neutral. In case of earth fault, current finds passage to the earth through accidental mode (like accidental contact with open wire etc.). As a result, returning current from the neutral is reduced. Difference in current is too known as ‘Residual Current’.
RCCB is made in a way that it continuously compares for differences in the current values between neutral wires and live wires. Any small change in current value would trigger RCCB to trip off circuit.
According to studies, an individual is capable to sustain electric shock only to magnitude of 30mA. RCCBs are created in a way; they will trip off circuit even for a small change in residual current of up to 30mA. Response time is around 40 millisecond to make sure that the individual is completely protected from electric shocks.
Browse PROTECTION DEVICES > MCB and PROTECTION DEVICES > RCCB to buy MCB and RCCB online respectively.
