Co-ordination of LV Protection Devices DBTP107PRE-En-07/00

Contents Operator needs Availability of electrical energy 3 Co-ordination of LV protection devices 8 Co-ordination techniques 12 o The IEC 60947-2 standard 12 o Discrimination techniques 16 o Limitation 21 o Cascading 23 Schneider solutions 24 o Masterpact and the incoming end of the installation 25 o Compact NS and power distribution 30 o Multi 9 circuit-breaker and final distribution 33 o Discrimination rules for 1 to 6300 A 34 Conclusion 35

From one application to another operator needs are the same 61343 60803 Commentaires : 85293 …The availability of electrical energy...

The availability of electrical energy Savings for the operator through: o the continuity of electrical supply o the optimised cost of his installation …A source of profit for the operator... 63647-7 62242 61485 Commentaires : 60632

Availability of electrical energy and the LV protection plan Structure of LV Distribution Level 1 General LV = incomer Switchboard Level 2 = MSB feeders Distribution Level 3 Switchboard = power or distribution motor control Level 4 Final = final distribution switchboards distribution Loads Commentaires : E62649

Availability of electrical energy and the LV protection plan Structure of LV Distribution Installation design o priority / non priority feeders Protection of LV distribution o level 1 and 2: using Air Circuit-Breaker (ACB) or Moulded Case Circuit-Breaker (MCCB) with high rating 800 to 6300 A o level 3: using LV industrial Fuse or Moulded Case Circuit-Breaker (MCCB) 63 to 1250 A o level 4: using Miniature Circuit-Breaker (MCB) 1 to 100 A Commentaires :

Availability of electrical energy and the LV protection plan Continuity of electrical energy supply Cost of the electrical installation Customer needs Co-ordination of protection devices: discrimination, cascading & constraint limitation Protection Plan

LV co-ordination techniques Optimising LV electrical distribution through 3 actions at the Protection Plan Level 1) discrimination to guarantee continuity of supply 2) limitation to reduce constraints 3) cascading to optimise performances Commentaires :

Co-ordination of protection devices 1) discrimination Whatever the fault: o overload o short-circuit o insulation fault only the circuit-breaker located just upstream from the fault trips 4 types of discrimination o current o time o energy o logic E41139 Commentaires :

Co-ordination of protection devices 2) limitation Technique that allow for the harmful effects of short-circuit currents to be diminished Limitation reduces effects of the following type: o electromagnetic: reduction in EMC disturbances o mechanical: reduction of deformation and/or breaks o thermal: rise in the life span of trunkings Isc presumed transient peak steady peak Isc limited peak Isc 10 % Â tsc t 100 % t A2 I2sc Presumed energy 100 % Limited energy < 1 % 1 % 100 % Commentaires : E62650 E62651

Co-ordination of protection devices 3) cascading The limiting upstream circuit-breaker helps the downstream circuit-breakers to open Technique that allows for the cost of LV electrical distribution to be optimised Non priority feeder Commentaires : E62667

The IEC 60947-2 standard and co-ordination of protection devices Recognises the 2 co-ordination elements (appendix A) o discrimination o cascading Defines testing to guarantee this co-ordination Characterises the circuit-breakers capable of time discrimination o utilisation category B Commentaires : E55229

The IEC 60947-2 standard appendix A discrimination Definition of the discrimination limit Is Tests to be conducted Commentaires : E62653 E62654

The IEC 60947-2 standard appendix A cascading Definition of the current IB and of the reinforced breaking capacity IcuD2+D1 Tests to be conducted Commentaires : E62680 E62681

The IEC 60947-2 standard category B circuit-breakers They ensure time discrimination that is characterised by Icw during Dt o Icw must be at least equal to 12 In or 5 kA for In £ 2500 A 30 kA for In > 2500 A o Dt - standardised delay - of: 0.05 - 0.1 - 0.25 - 0.5 - or 1 s They are subjected to additional testing Commentaires : E62652

LV discrimination techniques Quality of discrimination Comparison of the discrimination limit Is to the presumed short-circuit current Isc determines the quality of discrimination o total discrimination: Is > Isc o partial discrimination: Is < Isc o if the discrimination limit is equal to the Icu of the upstream circuit-breaker discrimination is total E62682 Commentaires : only D2 trips D1 and D2 trip

Current discrimination Linked to the natural staging of Long Delay curves of the association o discrimination limit Is = Isd1 discrimination technique generally used in Final Distribution Commentaires : E62655

Time discrimination Time delay Dt of the upstream circuit-breaker’s Short Delay CR tripping o extension of current safety o discrimination limit Is = Ii1 (= Icw1) o discrimination technique generally used on the incoming end of the installation the upstream circuit-breaker is from category B with a high EDW (Icw1 = Icu1) Commentaires : E62683

Energy discrimination Comparison of energy curves (tripping D downstream/non tripping ND upstream) allows for the discrimination limit Is to be determined Only the manufacturer can guarantee the quality of discrimination of the energy type D Tripping ND Non tripping Commentaires : E62656 E68104

Logic discrimination (ZSI) Circuit-breakers fitted out with electronic trip units o a pilot wire between upstream / downstream circuit-breakers o no threshold rules This technique o is easily implemented o reduces to a minimum constraints from delayed tripping of time discrimination E62659 Commentaires :

Limitation Technique consists in using the arc voltage to limit short-circuit currents 3 criteria to be considered o early o fast o high Technique that has multiple advantages o limitation of constraints on the installation o better discrimination o circuit-breaker cascading I asymetric peak Isc IL early fast high E68105 E62660 Commentaires :

Improving discrimination through limitation The use of a limiting downstream circuit-breaker extends current and/or time discrimination with the upstream circuit-breaker The downstream circuit-breaker by limiting the fault current Id increases the discrimination limit Is Isc in D2 D2 non limiting D2 limiting Is Commentaires : E62657 D2 non limiting Is Is D2 limiting Isc (D2) presumed

Cascading The use of a limiting upstream circuit-breaker “increases” the breaking capacity of the downstream circuit-breaker Technique that allows for the installation of a limiting circuit-breaker downstream from circuit-breakers with optimised Breaking Capacities E62661 E62662 Commentaires :

Totally co-ordonated Schneider protection devices Schneider solutions Continuity of electrical energy supply Cost of the electrical installation Customer needs Totally co-ordonated Schneider protection devices Constraint Limitation Discrimination as a standard in the circuit-breaker ranges Economical association of circuit-breakers through Cascading

Masterpact power circuit-breakers Discrimination upstream: setting the long delay (LR) slope (IDMTL) allows for better discrimination Discrimination downstream: o better time discrimination thanks to higher Icw o on very high Isc (up to 150 kA), maintains a high level of discrimination Limitation of very high constraints Masterpact offers unequalled performances as a standard for all applications E62663 Commentaires :

Improving MV/LV discrimination thanks to IDMTL curves 5 suggested slopes: o DT: definite time o SIT: inverse standard time o VIT: very inverse time o EIT: extremely inverse time o HVF: HV compatible fuse HVF curve tr = 2 s MV Fuse 80 A brought to LV I2t curve tr = 12 s Short delay threshold = 4 Ir E62664 Commentaires :

Ensuring total time discrimination as a standard Time discrimination with very high Icw (up to 85 kA 1s) thanks to: o a globally reinforced mechanism, enclosure, copper parts o the use of air CTs for measurement 63047-7 Accuracy zone of the instantaneous tripping threshold (± 10 %) E62675 Commentaires : Maximum time discrimination NW H2 E62676 Icw = thermal withstand = self-protection DIN threshold

Increasing the breaking capacity without sacrificing discrimination Conciliate high breaking capacity (150 kA) and high Icw (65 kA -1s) Disengagement Half moon actvating the pole shaft Effort sensor 61343 Kinematic chain Commentaires : E62665 E68106

Limiting as much as possible the constraints on the incoming end of the installation Limitation o using disengagement for very fast breaking o modification of the fixed pole to increase the repulsion force Time discrimination up to 37 kA Unequalled performances for a limiting circuit-breaker Breaking chamber Presumed short-circuit current E68106 Magnetic U Limited current Total breaking time U-shaped current loop Commentaires : E62666 Intervention time E62678

Compact NS power distribution Arc New breaking technology o roto-active breaking o pressure (“reflex” tripping) n o E62670 E62669 Fixed contact Breaking enclosure Breaking chamber Mobile contact Piston Short-circuit current Breaking chamber Short-circuit current Provides an exceptional limiting capacity n Fixed contact Breaking enclosure Mobile contact E62670 E62669 Piston New breaking technology o roto-active breaking E62669 E62670 n o Fixed contact Breaking enclosure Breaking chamber Mobile contact Piston Short-circuit current 053100 Commentaires :

Natural discrimination Compact NS circuit-breakers have natural discrimination performances o current and/or time tripping curves o natural discrimination energy curves 053100 Commentaires : E62672 E62671

Simultaneous discrimination and cascading Compact NS circuit-breakers have natural Cascading performances reflex tripping (piston) Reinforced Breaking Capacity without loss of Discrimination D1 053100 D2 Commentaires : E62673

Final distribution Multi 9 circuit-breakers Technology with magnetic actuator Guaranteed performances o ultra rapid breaking o exceptional limitation o total discrimination with circuit-breakers located upstream 031887 E62674 Commentaires :

Schneider discrimination rules Masterpact total discrimination with Compact NS (<630 A) circuit-breakers located downstream Compact NS total discrimination as soon as the ratio between ratings is greater than 2.5 Note: it is necessary to conserve current and time threshold staging The Schneider solution ensures total natural discrimination from 1 to 6300 A Commentaires :

The Schneider solution: mastering the technique Continuity of supply thanks to total discrimination CA Recording box production Compact NS 1 to 160 A Commentaires : Factory assembly line E62679

The Schneider solution: mastering the financial aspect Upon installation During operation Thanks to the quality of limitation of these circuit-breaker ranges Commentaires : E43480 E43481

The Schneider solution: mastering services Simple and high-performance tools o software: Ecodial 3 o catalogue: Exhaustive choice table E43478 E43477 E43476 LV Catalogue Commentaires :

“No one in the world does more with electricity” Schneider offers circuit-breaker ranges from 1 to 6300 A with unequalled performances Standards are respected Performance of co-ordinations: o discrimination as a standard o highly economical cascading Simple and high-performance catalogues and software Schneider guarantees a safe and high- performance electrical installation for mastering the LV protection plan CT150fi E68107 056409 053100 031887 Commentaires : E62677