MCB & Earth Leakage Circuit

BreakerPresented By:

Navinkumar PatleSuraj Poul

Madhu PrasadPiyush Saudagare &

Kirti SaindaneGCOEJDEPARTMENT OF

ELECTRICAL ENGINEERING

• WHAT IS CIRCUIT BREAKER ? • TYPES OF CIRCUIT BREAKER .• MCB• MCB COSTRUCTION .• HOW MCB WORK ? • USES OF MCB .• ELCB • WHY WE USE ELCB ?• CONSTRUCTION OF ELCB .• OPERATION

Content

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and current flow. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.

An air circuit breaker for low-voltage (less than 1,000 volt) power distribution switchgear

What are Circuit Breakers?

Low Voltage Circuit Breaker (e.g. MCB)

Magnetic Circuit Breaker

Thermal Magnetic Circuit Breaker

Common Trip Breaker

Medium-Voltage Circuit Breaker

High-Voltage Circuit Breaker

Disconnecting Circuit Breaker

Types Of Circuit

Breaker

A Miniature circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow. It comes under Low Voltage Circuit breaker

MCB

MCB-Miniature Circuit Breaker

MCB is meant for two type of overcurrent situation overload and short circuit

It consist of magnetic and thermal trip unit Both units act independently and

mechanically with breaker’s trip mechanism to open breaker’s contact.

Magnetic trip unit (Short circuit protection): The magnetic trip unit protects against a short circuit. The magnetic trip unit is comprised of an electromagnet and armature.

Thermal trip unit (Overload protection)The thermal trip unit

protects against continuous overload. The thermal unit is comprised of bimetal element located behind the circuit breaker trip bar and is part of the breaker’s current carrying path.

Construction

A: contact D: thermal overloadB: latch mechanism E cable clampC: magnetic trip F: tension Spring

• There are two arrangements of operation of miniature circuit breaker.• One due to thermal effect and

other due to electromagnetic effect of over current.• The thermal operation of miniature

circuit breaker is achieved with a bimetallic strip whenever continuous over current flows through MCB, the bimetallic strip is heated and deflects by bending

HOW MCB Works?

• A miniature circuit breaker is used in new constructions instead of the older types of fuses. Circuit breakers are small devices used o control and protect the electrical panel and the other devices from overflowing of electrical power.

• Home Electrical PanelsMCB are much safer than the typical fuses, because they can be reset manually and because they handle much larger amounts of power hence they are used in home appliances. MCB as a Home Appliance

Uses

• Ground Fault Trip MechanismIn some cases, you can use a miniature circuit breaker with ground

fault, or arc fault mechanisms, because the breakers consist of a system that opens the contacts if a line to ground fault occurs.• Lights

Using miniature circuit breakers in the lighting system of the house, because they can deal with the amount of power needed to light a house, especially if using specific types of lamps, such as fluorescent lights. • Industrial Applications

There are many small scale industrial buildings that use the miniature circuit breakers instead of the old fuses. These installations require up to 30 kA capacity, therefore the miniature breakers are ideal for this type of applications and devices. Same with commercial installations and applications. Some industrial applications that use miniature breakers are large stoves, and appliances used in restaurants, bakeries and food commercial stores.

An earth leakage circuit breaker (ELCB) is a safety device used in electrical installations with high earth impedance to prevent shock. It detects small stray voltages on the metal enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is detected. Once widely used, more recent installations instead use residual current circuit breakers which instead detect leakage current directly.

ELCB-Earth leakage circuit Breaker

The main purpose of earth leakage protectors is to prevent injury to humans and animals due to electric shock

Why we Use ELCB?

Construction

Operation• An ELCB is a specialised type of latching relay that has a

building's incoming mains power connected through its switching contacts so that the ELCB disconnects the power in an earth leakage (unsafe) condition.• The ELCB detects fault currents from live to the earth

(ground) wire within the installation it protects. If sufficient voltage appears across the ELCB's sense coil, it will switch off the power, and remain off until manually reset. A voltage-sensing ELCB does not sense fault currents from live to any other earthed body.

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