Co-ordination of LV Protection Devices DBTP107PRE-En-07/00 E58640.

Co-ordination of LV Protection Devices

DBTP107PRE-En-07/00

E58640

DBTP107PRE-En-07/00 2

Contents

Operator needs Availability of electrical energy 3

Co-ordination of LV protection devices 8

Co-ordination techniques 12 The IEC 60947-2 standard 12 Discrimination techniques 16 Limitation 21 Cascading 23

Schneider solutions 24 Masterpact and the incoming end of the installation 25 Compact NS and power distribution 30 Multi 9 circuit-breaker and final distribution 33 Discrimination rules for 1 to 6300 A 34

Conclusion 35


From one application to anotheroperator needs are the same

…The availability of electrical energy...

60803

85293

61343


The availability of electrical energy

Savings for the operator through:

the continuity of electrical supply

the optimised cost of his installation

…A source of profit for the operator... 60632

63647-7

62242

61485


Availability of electrical energy and the LV protection plan

Structure of LV Distribution

Level 1 General LV= incomer Switchboard

Level 2= MSBfeeders

Distribution Level 3 Switchboard = power ordistribution motor

control

Level 4 Final = final distribution switchboards distribution

Loads

E62649


Availability of electrical energyand the LV protection plan

Structure of LV Distribution

Installation design

priority / non priority feeders

Protection of LV distribution

level 1 and 2: using Air Circuit-Breaker (ACB) or

Moulded Case Circuit-Breaker (MCCB) with high rating

800 to 6300 A

level 3: using LV industrial Fuse or Moulded Case Circuit-Breaker (MCCB)

63 to 1250 A

level 4: using Miniature Circuit-Breaker (MCB)

1 to 100 A


Customer needsContinuity ofelectrical energy supply

Cost of the electrical installation

Co-ordination of protection devices:

discrimination, cascading

& constraint limitation

Protection Plan

Availability of electrical energyand the LV 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


Co-ordination of protection devices1) discrimination

Whatever the fault:

overload

short-circuit

insulation fault

only the circuit-breaker located just upstream from the fault trips

4 types of discrimination

current

time

energy

logic

E41139

a

A

CB


Co-ordination of protection devices2) limitation

Technique that allow for the harmful effects of short-circuit currentsto be diminished

Limitation reduces effects of the following type: electromagnetic: reduction in EMC disturbances mechanical: reduction of deformation and/or breaks thermal: rise in the life span of trunkings

E62650

E62651

Isc presumed transient peak

Isc presumed steady peak

Isc limited peak

Isc

10 %

Â

tsc t

100 %

t

A2

I2sc

Presumedenergy 100 %

Limitedenergy< 1 %

1 %

100 %


Co-ordination of protection devices3) cascading The limiting upstream circuit-breaker helps the downstream

circuit-breakers to open

Technique that allows for the cost of LV electrical distributionto be optimised

E62667

Non priorityfeeder


The IEC 60947-2 standardand co-ordination of protection devices

Recognises the 2 co-ordination elements (appendix A) discrimination cascading

Defines testing to guarantee this co-ordination

Characterises the circuit-breakers capable of time discrimination utilisation category B

E55229


The IEC 60947-2 standard appendix Adiscrimination

Definition of the discrimination limit Is

Tests to be conducted

E62654

E62653


The IEC 60947-2 standard appendix Acascading

Definition of the current IB and of the reinforced breaking capacity IcuD2+D1 Tests to be conducted

E62680

E62681


The IEC 60947-2 standardcategory B circuit-breakers They ensure time discrimination that is characterised by Icw during t Icw must be at least equal to 12 In or 5 kA for In 2500 A

30 kA for In > 2500 A t - standardised delay - of: 0.05 - 0.1 - 0.25 - 0.5 - or 1 s They are subjected to additional testing

E62652


Quality of discrimination Comparison of the discrimination limit Is to the

presumed short-circuit current Isc determines the quality of discrimination

total discrimination: Is > Isc

partial discrimination: Is < Isc

if the discrimination limit is equal to the Icu of the upstream circuit-breakerdiscrimination is total

LV discrimination techniques

only D2 trips D1 and D2 trip

E62682


Current discrimination

Linked to the natural staging of Long Delay curves of the association

discrimination limit Is = Isd1

discrimination technique generally used in Final Distribution

E62655


Time delay t of the upstream circuit-breaker’s Short Delay CR tripping extension of current safety discrimination limit Is = Ii1 (= Icw1)

discrimination technique generally used on the incoming end of the installationthe upstream circuit-breaker is from category B with a high EDW (Icw1 = Icu1)

Time discrimination

E62683


Comparison of energy curves (tripping D downstream/nontripping ND upstream) allows for the discrimination limit Is to be determined

Only the manufacturer can guarantee the quality of discriminationof the energy type

Energy discrimination

E62656

E68104

DTripping

NDNontripping


Logic discrimination (ZSI)

Circuit-breakers fitted out with electronic trip units a pilot wire between upstream / downstream circuit-breakers no threshold rules

This technique is easily implemented reduces to a minimum constraints from delayed tripping of time discrimination

E62659


Technique consists in using the arc voltage to limit short-circuit currents

3 criteria to be considered

early fast high

Technique that has multiple advantages limitation of constraints on the installation better discrimination circuit-breaker cascading

Limitation

I asymetricpeak

Isc

IL

E62660

early fast high

E68105


The use of a limiting downstream circuit-breaker extends currentand/or time discrimination with the upstream circuit-breaker

The downstream circuit-breaker by limiting the fault current Id increasesthe discrimination limit Is

Improving discrimination through limitation

E62657

D2non limiting

D2limiting

Iscin D2

Isc (D2)presumed

Is

IsD2 limitingD2 non limiting

Is


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

Cascading

E62661

E62662


Schneider solutions

Customer needs Continuity of electrical energy supply

Cost of the electrical installation

Discrimination as a standard in the circuit-breaker ranges

Economical association of circuit-breakers through Cascading

Totally co-ordonated Schneider protection

devices

Constraint Limitation


Discrimination upstream: setting the long delay (LR) slope (IDMTL) allows for better discrimination

Discrimination downstream: better time discrimination

thanks to higher Icw on very high Isc (up to 150 kA),

maintains a high levelof discrimination

Limitation of very high constraints

Masterpact offers unequalled performances as a standard for all applications

Masterpact power circuit-breakers

E62663


Improving MV/LV discrimination thanks to IDMTL curves

5 suggested slopes:

DT: definite time

SIT: inverse standard time

VIT: very inverse time

EIT: extremely inverse time

HVF: HV compatible fuse

E62664

HVF curvetr = 2 s

MV Fuse 80 Abrought to LV

I2t curvetr = 12 s

Short delaythreshold = 4 Ir


Ensuring total time discrimination as a standard

Time discrimination with very high Icw (up to 85 kA 1s) thanks to:

a globally reinforced mechanism, enclosure, copper parts

the use of air CTs for measurement

Accuracy zone of the instantaneous tripping threshold(± 10 %)

Maximum time discrimination

Icw = thermal withstand = self-protection DIN threshold

E62675

E62676

NW H2

63047-7


Increasing the breaking capacity without sacrificing discrimination

Conciliate high breaking capacity (150 kA) and high Icw (65 kA -1s) Disengagement

E62665

Kinematic chain

Half moon actvating the pole shaft

Effort sensor

E68106

61343


Limiting as much as possible the constraints on the incoming end of the installation

Limitation using disengagement for very fast breaking 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

Magnetic U

U-shaped current loop

E62666

E68106

E62678

Total breaking time

Presumed short-circuitcurrent

Limited current

Intervention time


New breaking technology roto-active breaking

Compact NS power distribution

053100

E62669

E62670

Fixed contact

Breakingenclosure

Breakingchamber

Breakingchamber

Mobile contact

Fixed contact

Piston

Short-circuit current

Breaking chamber

Arc

Arc

New breaking technology roto-active breaking pressure (“reflex” tripping)

E62670

E62669

Fixed contact

Breakingenclosure

Breakingchamber

Breakingchamber

Mobile contact

Fixed contact

Piston


Breaking chamberBreaking chamber


Provides an exceptional limiting capacity

Fixed contact

Breakingenclosure

Breakingchamber

Breakingchamber

Mobile contact

Fixed contact

E62670

E62669

Piston


Natural discrimination

Compact NS circuit-breakers have natural discrimination performances

current and/or time tripping curves

natural discrimination energy curvesE62671

E62672

053100


Compact NS circuit-breakers have natural Cascading performances

reflex tripping (piston)

Reinforced Breaking Capacity without loss of Discrimination

Simultaneous discrimination and cascading

E62673

053100

D1

D2


Final distribution Multi 9 circuit-breakers

Technology with magnetic actuator

Guaranteed performances

ultra rapid breaking

exceptional limitation

total discrimination with circuit-breakers located upstream

E62674

031887


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

Schneider discrimination rules


The Schneider solution: mastering the technique

Continuity of supply thanks to total discrimination

E62679

Compact NS1 to 160 A

CA

production

Recordingbox

Factory assembly line


The Schneider solution: mastering the financial aspect Upon installation During operation

Thanks to the quality of limitation of these circuit-breaker ranges

E43481

E43480


The Schneider solution: mastering services

Simple and high-performance tools

software: Ecodial 3

catalogue: Exhaustive choice table

E43477

E43478

E43476

LV Catalogue


Schneider offers circuit-breaker ranges from 1 to 6300 A with unequalled performances

Standards are respected

Performance of co-ordinations: discrimination as a standard highly economical cascading

Simple and high-performance cataloguesand software

Schneider guarantees a safe and high-performance electrical installation for mastering the LV protection plan

“No one in the world does more with electricity”

CT150fi

E62677

056409

031887

053100E68107

Co-ordination of LV Protection Devices DBTP107PRE-En-07/00 E58640.

Documents

Transcript of Co-ordination of LV Protection Devices DBTP107PRE-En-07/00 E58640.