4. INTRODUCTION
• Thomas Edison developed the idea for 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.
7. • Mcb is meant for two type of overcurrent situation overload and short
circuit.
• It contain of magnetic and thermal trip unit.
• Both units acts independently and mechanically with breaker’s trips
mechanism to open breaker’s contact.
• The magnetic trip unit protect against a short circuit.
• The thermal trip unit protects against continuous overload
8. HOW IT WORK?
• There are two arrangement 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
bio metallic strip whenever continuous over current flow through
mcb,the bimetallic strip is heated and deflects by bending.
9. APPLICATION
• A mcb is used in new construction instead of the older type of fuse.
• Circuit breaker are small device used to control and protect the
electrical panel and the other device from overflowing of electrical
power.
• Mcb are much safer than the typical fuse because they can be reset
manually and because they handle much larger amounts of power
hence they are used in home application.
12. INTRODUCTION
• An elcb is a safety device used in electrical insallation with high earth
impedence to prevent shock.
• It detects small stray voltage on the metal enclosure of electrical
equipment and interrupts the circuit if a dangerous voltage is detected.
• It basic function is to detect a fault condition and then must be
replaced,circuit breaker can be rest to resume normal operation.
13. FUNCTION
• An elcb is special type of latching relay that has a bulding,incoming
mains power connected through it switching contact so that the elcb
disconnected the power in an art leakage condition.
• The elcb detects fault current from live to the earth wire within the
insallalization it protects.
• If sufficiently volage aapears across the elcb sence coil,it will switch
off the power ,and remain off until manullay reset.
15. WORKING OF ELCB
• When the fault occurs, the leakage current start flowing through
conductor so there will be non zero flux set up in current transformer
core.
• The metal housing of the induction of the induction motor is always
connected to earth.
• If user standing on earth touch the live point the protection against
such current is essential and it is provide by device called elcb
16.
17. ADVANTAGE
• They are less sensitive to fault condition therefore have less nuisance
strips.
• They can be aarnnged to protect against cable damage only.
• And not strip on faults in down line installations.
