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SIX MONTHS INDUSTRIAL TRAINING AT HAVELLSINDIA LTD.
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COMPANY PROFILEHavells India Limited is one of the largest electrical and
power distribution equipment Company in the country,manufacturing products as under:
Industrial and domestic switchgear Power cables Energy meters Fans Luminaries
Bath fitting Modular switches. It is countrys largest manufacturer of miniature circuit
breaker and is among the top ten internationalmanufacturers.
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GENERAL LAYOUT OF HAVELLS INDIA
LIMITED BADDI (H.P)
The plant has the following three manufacturing divisions:
Domestic unit
Export Oriented Unit (EOU)
Industrial Products/ Crabtree ( Switches, fuse,
changeover, etc)
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STUDY OF MCBMiniature Circuit Breaker - electromagnetic device
used to feed electricity to houses, industries, railways,etc.
Provides protection against short circuit and overloadconditions.
Switching Mechanism
Contact MechanismArc Extinguishing device
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WORKING PRIN
CIPLE OF SOLENOID TOPROVIDE PROTECTION FROM SHORT
CIRCUITFaradays law - when current is passed through asolenoid (coil shaped thing) f lux is produced aroundthe coil, due to this the medium inside the coilbecomes magnetized & there is a force of attractionbetween the 2 parts (Anchor assembly & coil rivet)
only if it is a magnetic material.By this the plunger trips the mechanism.
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WORKING PRINCIPLE OF BIMETAL FOR
PROTECTION FROM OVERLOAD
Cantilevers principle - The different elements havedifferent thermal expansions. When 2 differentelements were bonded together physically withdifferent thermal expansions & exposed to hightemperatures it turns into curvature.
When we fix one end of the bimetalthen all the deflection happens at the free end, this iscalled cantilever principle.
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MAIN COMPONENTS USED
Bimetal
Pointer
Bimetal carrier
Anchor spring
Plastic latch
Anchor assemblyAluminium bush
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uCONTINUEDCoil rivet
Coil washer
Arc runnerOuter yoke
Latching fork & u latch
Operating fork
D.T. Spring & s.T. Spring
Knob & knob link
M.S. Pin
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INTERNAL VIEWOF MCB
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VARIOUS STAGES TO MANUFACTURE AMCB
Spot welding
Mechanism assemblyCalibration and testing
Verification
Packaging
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TESTING AND VERIFICATION
In this unit MCBs are tested whether they are tripping withinthe required time limit or not. This process comprises offour cycles:
At T1 Current passesAt T2- Screw sets
At T3- Angle sets (Angle is determined between bimetaland carrier)
At T4- Tripping occursThere are various types of indicators:
Red- If theres no fault
Yellow- If fault occurs
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STUDY OF RCCB (RESIDUALCURRENT
CIRCUIT BREAKER)Residual current circuit breaker - also called ELCB (earth leakage
circuit breaker) or RCD (residual circuit device)Function
Breaks the circuit automatically when it senses fraction of anampere leakage current flowing to earth in excess topredetermined amount.
RCCB provides high degree of effective protection againstelectric shock or death due to direct or indirect contact to livepart by human being.
Prevents fire hazards by sensing less than 1 amp leakage currentflowing to earth. Stops the unused leakage current flow as low as 30 mA and saves
electric charges.
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PRINCIPLE INVOLVED IN RCCB TRIPPING
Current balance principle- Kirchoffs Current Law
In a healthy circuit the current in phase is equal to
current in neutral and vector sum of the current iszero.
During earth leakage the vector sum of current is notzero. This imbalance induces a current on the
secondary winding of the current transformer, whichin turn trips the RCCB mechanism.
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STUDY OF RCBO
Residual Current Circuit Breaker with overloadand short circuit conditions - single composite
device which provides protection against over currentsand earth leakage faults in the same width and profileas that of a standard MCB.
RANGE
6A, 10A, 16A, 20A, 25A, 32A & 40ASENSITIVITY
30mA, 100mA, 300mA
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WORK TO BE DONE
Manufacturing of ACCL(Automatic Changeover
Current Limiter)
Work to be done in Export unit
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THANK YOU