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Title:

Inspection

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Communication system. DDI - Department - Name - Date. 3. Developments - Industry ... greasing : only Schneider recommended greases, in small quantity ... – PowerPoint PPT presentation

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Title: Inspection


1
Inspection Preventive maintenanceof breakers
2
Why and what has to be maintained on breakers ?
  • Case
  • Mechanism
  • Arc chute
  • Main contacts
  • Control unit
  • Connection systems
  • Auxiliary Devices
  • Communication system

3
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

4
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

5
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

6
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

7
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)

8
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

9
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

10
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

11
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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