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Inspection & Preventive maintenance of breakers. DDI - Department - Name - Date 2 Developments - Industry Why and what has to be maintained on breakers.

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Presentation on theme: "Inspection & Preventive maintenance of breakers. DDI - Department - Name - Date 2 Developments - Industry Why and what has to be maintained on breakers."— Presentation transcript:

1 Inspection & Preventive maintenance of breakers

2 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

3 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

4 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

5 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

6 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

7 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)

8 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

9 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

10 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

11 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


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