inspection Preventive Maintenance of Breakers
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Transcript of inspection Preventive Maintenance of Breakers
Inspection & Preventive maintenanceof breakers
DDI - Department - Name - Date 2
Developments - Industry
Why and what has to be maintained on breakers ? Case
Mechanism
Arc chute
Main contacts
Control unit
Connection systems
Auxiliary Devices
Communication system
DDI - Department - Name - Date 3
Developments - Industry
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
DDI - Department - Name - Date 4
Developments - Industry
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
DDI - Department - Name - Date 5
Developments - Industry
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
DDI - Department - Name - Date 6
Developments - Industry
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
DDI - Department - Name - Date 7
Developments - Industry
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)
DDI - Department - Name - Date 8
Developments - Industry
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
DDI - Department - Name - Date 9
Developments - Industry
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
DDI - Department - Name - Date 10
Developments - Industry
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
DDI - Department - Name - Date 11
Developments - Industry
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