MINIATURE CIRCUIT BREAKER(MCB)

byS. Santhosh Kumar

14125A0231

Objective

To understand the components, working principle of Miniature Circuit Breaker (MCB), and its

advantages over traditional fuse.

Contents

• Introduction: history and its use

• Function

• Construction of MCB

• Working Principle

• Advantages

• Application

• Comparison : Fuse Vs MCB

• Conclusion

Introduction

• Thomas Edison developed the idea for a circuit breaker in 1879.

• Granville Woods improved upon the design and invented the automatic circuit breaker in 1900.

• Cutter Manufacturing Company manufactured the first circuit breakers in Philadelphia in 1904.

Functions

• Switching Function: On/Off

• Protection Function: Overloads/Short Circuits

CONSTRUCTIONOF

MINIATURE CIRCUIT BREAKER

Cross-Sectional View

Main Parts of MCB

THERMAL UNIT MAGNETIC UNIT

Parts of MCB

ARC-CHUTES KNOB

Parts of MCB

INCOMING AND OUT GOING TERMINAL INSIDE OF MAGNETIC UNIT

WORKING PRINCIPLEOF

MINIATURE CIRCUIT BREAKER

On/Off Positions

Arc Formation

Arc-Chute

Comparison: MCB Vs fuse

MCB(Miniature Circuit Breakers)

FUSE

1 MCB trips off in case of excessive load.

Fuse melts/fuses in case of excessive load.

2 MCB is to be just put-on after correcting the fault in wiring.

Fuse needs to be replaced with a new one.

3 Since we do not change the MCB, there is no risk of putting on the MCB/switch even if the fault is not correctly repaired.

There is a risk of putting on the switch in case; due to ignorance higher capacity fuse-wire is positioned.

4 Compact, small equipment. Porcelain base and top. Not attractive.

5 Works on Bi-metal expansion or induced magnetism.

Works on melting/fusing due to high temperature.

6 Relatively costlier than fuse. Relatively cheaper than MCB.

Advantages over fuse

• Easily identify the faulty zone of electrical circuit

• Simple to resume supply

• Better Interface: knob

• Electrically safer

• More sensitive to current than fuse

• Reusable

• Less maintenance and replacement cost.

Applications

• Home Electrical Panels

• Ground Fault Trip Mechanism

• Lights

• Industrial Applications

• Heaters

Conclusion

Miniature Circuit Breakers are more effective than traditional fuse.

Thank You