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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