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Inspection & Preventive maintenance of breakers PowerPoint PPT Presentation


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Inspection & Preventive maintenance of breakers . Why and what has to be maintained on breakers ?. Case Mechanism Arc chute Main contacts Control unit Connection systems Auxiliary Devices Communication system. Maintenance of case. Function of case :

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Inspection & Preventive maintenance of breakers

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Inspection preventive maintenance of breakers l.jpg

Inspection & Preventive maintenanceof breakers


Why and what has to be maintained on breakers l.jpg

Why and what has to be maintained on breakers ?

  • Case

  • Mechanism

  • Arc chute

  • Main contacts

  • Control unit

  • Connection systems

  • Auxiliary Devices

  • Communication system


Maintenance of case l.jpg

Maintenance of case

  • Function of case :

    • isolate the main contacts and protect from arcing effects

    • support the mechanism, tripping device, auxiliary devices, terminals

    • Must withstand the stresses during short circuit

  • Damaged case is the consequence of :

    • shocks,

    • moisture,

    • high short circuit,

    • overheating ( loose connection)

  • Preventive maintenance includes :

    • visual inspection of dust, dirt, grease, moisture, cracks, soot,

    • cleaning, ( dust, dirt, soot,) with dry cloth, brush or vacuum cleaner

    • replacement in case of cracks


Maintenance of the mechanism l.jpg

Maintenance of the mechanism

  • Breaker mechanism

    • Spring energy on Masterpact

    • Tumbler on Compact NS

    • operate the contacts to establish and interrupt the circuit

  • Chassis mechanism

    • to rack in and out the breaker, test the breaker

  • Jammed mechanism is the consequence of :

    • dust :

    • shocks : bending of mechanical part

    • corrosive atmosphere : rust and corrosion of metallic part

    • No operation for a long time

  • Preventive maintenance includes :

    • dust removal : vacuum cleaner recommended

    • cleaning : dry cloth, brush, solvent prohibited

    • greasing : only Schneider recommended greases, in small quantity

    • operation of breaker / chassis : to give the spring charged energy and the mechanism their original characteristics


Maintenance of the arc chute power breaker only l.jpg

Maintenance of the arc chute (Power breaker only)

  • Function of arc chute :

    • splitters : extinguish the arc and absorb the energy under normal condition and electric fault

    • filter : blow the pressured gas out , cool down the gas

  • Arc chute deteriorates

    • under In : the insulation material of the arc chamber can perforate

    • under Icc : the metal part is vaporised

  • Arc chute in bad condition may result in a non interruption of the arc, decrease of the isolating function and ultimately destruction in case of high short circuit current.

  • Filters : avoid compound (made of dust + grease) covering the filter

  • Preventive maintenance includes :

    • periodic inspection after a fault : splitters should not present holes and be too thin, plastic part should not have holes ( decrease of insulation level)

    • replacement

    • cleaning of filter


Maintenance of main contacts power breaker only l.jpg

Maintenance of main contacts (Power breaker only)

  • Function of main contacts :

    • To make or break the circuit under normal ( In) or fault conditions (overload and Short-circuit )

  • Contacts get worn during each mechanical and electrical open / close operation and after short circuit ( maxi 2 cycles at Icu)

  • Worn contacts will result in :

    • over heating of the breaker ( increase of contact resistance)

    • decrease of life expectancy

  • Preventive maintenance includes :

    • periodic visual check, control of the mechanical contact wear indicator and electronic wear indicator on Micrologic P & H

    • measurement of individual pole resistance

    • replacement


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Maintenance of electronic control unit

  • Function of control unit :

    • permanently analyse the phase current compare it to the protection set and in case of fault trips the breaker

  • Control unit is sensitive to :

    • environment : ambient temperature, humidity, corrosive atmosphere,

    • operating conditions : vibration, electro-magnetic field,

  • A malfunctioning of the trip unit will result in :

    • a non interruption of the fault current

    • damage of equipment and breaker

  • Preventive maintenance includes :

    • periodic push to trip test or trip test

    • control of the complete tripping channel

    • curve adjustment

    • saving of log event, settings ( Micrologic P & H)


Maintenance of thermal magnetic trip unit l.jpg

Maintenance of thermal-magnetic trip unit

  • Function of thermal-magnetic trip unit :

    • Connected permanently in series with the phase currents

    • based on the bending of a bimetal for overload and the movement of a magnet in a strong magnetic field

  • Thermal -magnetic trip unit is sensitive to :

    • ambient temperature, corrosive atmosphere

  • A malfunctioning of the trip unit will result in :

    • a non interruption of the fault current

    • damage of equipment and breaker

  • Preventive maintenance includes :

    • primary injection test to trip the breaker


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Maintenance of connection systems

  • Function of connection systems :

    • Link together various types of devices by mean of electrical distribution systems (bus bars, cables, auxiliary wires, ).

  • Bad connection ( too tight or too loose) will result in :

    • Thermal effect leading to destruction of devices

    • short circuit or fire

  • Preventive maintenance includes :

    • For fixed connectors : No need of control if done with Schneider recommendation . otherwise : check temperature rise, if loose, dismantle and tighten with new screws, bolts & washers

    • For sliding connectors : (mainly chassis)

      • periodic cleaning and greasing with Schneider recommended grease

      • if corrosive atmosphere ( SO2 / H2S) : clean with special solution ( Thiourée) and re grease

    • Wires : check tightening and the insulation material


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Maintenance of auxiliary devices

  • Function of auxiliary devices :

    • Shunt trip release, under voltage release, OF contacts, SD/SDE alarm contacts , electrical motor MCH

  • Malfunctioning of the auxiliary device will result in a wrong operation of the breaker

  • the consequences can be :

    • no safety operation ( emergency)

    • wrong operation in the circuit

  • Preventive maintenance includes :

    • functional test of auxiliary device at nominal voltage

    • replacement


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Maintenance of communication systems

  • Function of communication systems :

    • allow the dialogue with control unit ( read, write)

    • allow the remote control of breaker ( open close)

  • Bad communication will result in :

    • loss of information (status, monitoring, maintenance, production)

    • loss of control of breaker

  • Preventive maintenance includes :

    • testing of reading network parameters

    • testing of reading setting and changing setting

    • testing of remote control


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