estandar iec 60947-2.pdf

International standardIEC 60947-2Low voltage switchgearPart 2: Circuit-breakers

DBTP83-Fr-03/99

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Standard IEC 60947-2 Contents

n I. General 3

n 2. Definitions 8

n 3. Circuit-breaker characteristics 10

n 4. Constructional requirements 14

n 5. Specific points (appendices) 21

n 6. Tests 27

n 7. Conclusion 34

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Standard IEC 60947-2

Standard IEC 60947-2n Came into force in 1989n Takes into account the circuit-breaker main technological upgradesStandard IEC 60947-2n Is internationally recognized and approved

and is applied in the majority of countries (> 100)

General

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IEC

IEC

UL

CSAIEC

JIS/IEC

IEC

IEC

IEC

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Standard IEC 60947-2 Generalconstitution

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IEC60947

IEC60947-1

IEC60 947-2

IEC 60947-3

IEC 60947-4-1

IEC 60947-4-2

IEC 60947-6-2

IEC 60947-7-1 … ...

or

or or or

or or

Standard IEC 60947-2 is part of a set of 7 standards characterizinglow voltage switchgear

Generalrules

Circuit-breakers

SwitchesContactorsand starters

Dimmersand starters

Control andconnectiondevices

Terminalblock

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Standard IEC 60947-2 GeneralThe scope

« Standard IEC 60947-2 applies to circuit-breakers, the main contactsof which are intended to be connected to circuits, the rated voltage ofwhich does not in exceed 1000 V AC or 1500 DC; … »

The standard applies to circuit-breakers intended for use byexperienced operators.

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Standard IEC 60947-2 GeneralThe scope

Standard IEC 60947-2 contains additional specifications for:n Circuit-breakers suitable for isolationn Residual current devices (appendix B)n Circuit-breakers with electronic protection (appendices J and F)n Circuit-breakers for IT systems (appendix H)

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Standard IEC 60947-2 General

Standard IEC 60947-2 definesn The circuit-breaker classificationo according to utilization category A or Bo according to design type

air circuit-breaker, moulded case circuit-breaker

n The circuit-breaker mechanical and electrical data:size, trip unit, etc.

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Standard IEC 60947-2 DefinitionsCircuit-breaker classification

Utilization category A Utilization category BCircuit-breaker not specifically intended Circuit-breaker specifically intendedfor discrimination for discrimination:n Without an intentional short-time delay n With intentional short-time delay

(adjustable)n Without short time withstand current n With short time withstand current

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Extract from appendix K of standard IEC 60947-2Characteristics Ue Rated operational voltagevoltage Ui Rated insulation voltage

Uimp Rated impulse withstand voltagecurrent In Rated current

Ith Conventional free-air thermal currentIthe Conventional enclosed thermal currentIcm Rated short-circuit making capacity

short-circuit Icu Rated ultimate short-circuit breaking capacityIcs Rated service short-circuit breaking capacityIcw Rated short-time withstand currentIr Adjustable overload setting current1.05 x Ir Conventional non-tripping current

trip unit 1.30 x Ir Conventional tripping currentIsd Short time delay tripping setting currentIi Instantaneous tripping setting current

DefinitionsTerminology / Vocabulary

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Standard IEC 60947-2 Circuit-breaker characteristicsOverload withstand

In (in A rms) = rated currentn Maximum uninterrupted current withstood at ambient temperature, given without abnormal temperature rise

Ir (in A rms) = adjustableoverload setting currentn Ir depends on Inn Ir characterizes the

overload protection

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Standard IEC 60947-2 Circuit-breaker characteristicsShort-circuit withstand

Icu (kA rms) = rated ultimateshort-circuit breaking capacityn This performance expresses

the maximum value of theshort-circuit current that canbe broken by the circuit-breaker

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Standard IEC 60947-2 introduces anew important performance

Ics (as a % of Icu) = rated serviceshort-circuit breaking capacityn This performance expresses

the suitability of a circuit-breaker toensure fully normal service afterbreaking this current 3 times

n Normal ratio between Ics and Icu

Utilization category A Utilization category B % of Icu % of Icu 25 50 50 75 75 100 100

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Standard IEC 60947-2 introduces anew performance forcategory B circuit-breakers

Icw (in kA rms) = rated short-timewithstand current

n Icw is the maximum short-circuitcurrent that a circuit-breaker canwithstand for a short duration∆t without deterioration ofthese characteristics

n ICW must be at least equal to12 In or 5 kA for In ≤ 2500 A30 kA for In > 2500 A

n The standardized delay time ∆t is: 0.05 - 0.1 - 0.25 - 0.5 - or 1s

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Standard IEC 60947-2 Constructional requirementsIsolation co-ordination

The circuit-breaker, as a safety device, must be able to withstand

n Network overvoltagesthis suitability is characterized by the withstand to the conventionaldielectric test at 2 Ui + 1000 - 1 min at power frequency

n Impulse voltages ( «lightning stroke» simulation)this suitability is characterized by the withstand to the1.2/ 50 µs impulse voltage test of value Uimp

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Uimp (kV peak) = rated impulse withstand voltage

Characterization of Uimp

n Depends on the LV network voltage

n Depends on the position of the circuit-breaker in the LV network

n Depends on altitude: Uimp must be valid up to 2000 mtests carried out at +23 % of value

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Characterization of Uimp

Nominal Applications installation voltage

at the origin of the on the distribution and at loadinstallation/MSB final circuits level

230/400 V 6 4 2.5 400/690 V 8 6 4

Constructional requirementsIsolation co-ordination

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Industrial circuit-breaker Uimp = 8 kVn Tests to be consideredo Uimp + 23 % = 9.8 kV

o standard industrial circuit-breakers and those suitable for isolation

Application of Impulse voltage value impulse voltage Breakers Disconnector BreakersPhase-to-phase 9.8 kV 9.8 kVUp-to-downstream 12.3 kV (*)contacts openPhase-to-earth 9.8 kV 9.8 kV

(*) 14.7 kV for front face class II circuit-breaker as per IEC 61 140

Test between upstreamand downstream

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Standard IEC 60947-2 Constructional requirementsCircuit-breaker suitable for isolation

Test of isolation suitability

n 3 tests designed to ensure users that a device«suitable for isolation» is not dangerous

o in open position... - even after having eliminated a short-circuit up to Icu - even in the event of overvoltage on the network ... or in closed position

o cannot be declared «open» and/or « padlockable »

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Standard IEC 60947-2 Constructional requirementsCircuit-breaker suitable for isolation

Leakage current measurement testat 110 % of maximum utilization voltage Uen New device, leakage current < 0.5 mA per pole,n After breaking at Ics, leakage current < 2 mA per pole,n After durability tests, leakage current < 2 mA per pole,n After breaking at Icu, leakage current < 6 mA per pole

Impulse voltage withstandn Uimp = 12 kV (instead of 9.8 kV) between the inlet and the outlet of the

open device(*) 14.7 kV for front face class II circuit-breaker as per IEC 61 140

Mechanical ruggedness test

n Circuit-breaker with a pole held in closed position must not be indicated«open» and/or «lockable» by padlock.

Padlockable in « open » position

Class llenclosure

Class llfront face

Front face class ll

Mechanical ruggedness

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Standard IEC 60947-2 Constructional requirementsCircuit-breaker/isolator

Marking

n A circuit-breaker that is «suitable for isolation» will display the circuit-breaker/isolator symbol on its front face

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Standard IEC 60947-2 Specific points (appendix A)

n Cascading n Discrimination

Standard IEC 60947-2 recognizes and defines circuit-breakerco-ordination

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Standard IEC 60947-2 Specific points (appendix B)Residual current device

Standard IEC 60947-2 appendix B defines

n The characteristics of the residual current devices

n The tests and verifications that must be performed on a residual currentdevice

o in order to guarantee the safety of the residual current function

o in order to guarantee the quality of the residual current function(malfunctioning)

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Tests and verifications

n Safety of the residual current function

o after breaking at Icu and Ics, no deterioration of the earth leakage protection units,

o correct operation of the function:- in harsh environmental conditions

(damp heat 28-day cycle)14h30 duration(h)

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Tests and verifications

n Quality of the residual current function

o no nuisance tripping in the event of:- single-phase overcurrent (standardized tests)- current waves generated by impulse voltage- network capacitance load- in event of an insulation fault with a DC component

(class A),

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Standard IEC 60947-2 Specific points (appendix F)Circuit-breaker with electronic trip unit

Standard IEC 60947-2 appendices F definesn The additional specifications

for circuit-breakers withelectronic trip unit

n The tests required to guaranteetheir correct operation inrestrictive industrialenvironments

o EMC tests: immunity todisturbances,

o EMC tests: verification ofradiated emission level,

o (very harsh) environmentaltests, dry and damp heat,temperature variationsAfter each test,verification of propertrip unit operation

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Standard IEC 60947-2 Specific points (appendix H)

Circuit-breaker suitable for ITStandard IEC 60947-2n Defines this breaking type

(with a single pole at phase-to-phase voltage)n Stipulates a specific testo the devices not suitable for use with the IT system are marked

with the symbol IT

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Standard IEC 60947-2 Tests

Standard IEC 60947-2 makes provision for complete device testing

Cumulative tests grouped into sequencesn One sample undergoes all the sequence tests

5 Test Sequences + 1 Combined test sequencen All the functions and characteristics are tested

Specific testsn Circuit-breaker suitable for isolationn Residual current device,n Circuit-breaker with electronic trip unit,EMC Testsn etc.

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Test sequencesCategory A Category B

Icw < Ics Icw = Ics Icw = Ics = IcuSequence 1General operating n n n ncharacteristicsSequence 2Service breaking n ncapacity IcsSequence 3Ultimate breaking n n ncapacity IcuSequence 4Rated short time nwithstand current IcwCombinedtest sequence n nExample NS100 to NS630 C801 to C1251 CM1251 Masterpact

+ Multi 9 Masterpact H2-L1 to 3200 N1-H1

Tests

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Examplen Sequence 1 and 2Test Circuit-breaker type Tests to be performed in turn Additional tests forsequences Cat. A Cat. B on the same circuit-breaker circuit-breakers declared

Icw Icw Icw suitable for isolation< Ics = Ics = Ics

= IcuSequence 1 1. Verification of tripping thresholds 1. DittoGeneral 2. Dielectric properties 2. Dielectric propertiesoperating 2.1 If an Uimp is declared by the Uimp withstand compulsory:characteristics Manufacturer: Uimp Test phase-to ditto opposite plus between

n phase, phase-to-earth Inlet and Outlet: Uimp + 25 %2.2 If no Uimp is declared and leakage current test

Dielectric test 50 Hz at 2Ui + 1000 (< 0.5 mA per pole at 110 % Ue)3. Mechanical durability 3. Ditto4. Electrical durability 4. Ditto5. Operation in overload at 6 In 5. Ditto6. Dielectric withstand at 2 Ue (min. 1000 V) 6. Ditto + leakage current test

(< 2 mA per pole at 110 % Ue)7. Temperature rise at In 7. Ditto8. Verification of non-drift of 8. Ditto

overload trip unitsSequence 2 1. Three successive current breakings Ics 1. DittoService as per cycle O - 3 mm - CO - 3 mm - CObreaking 2. Verification of suitability for 2. Dittocapacity Ics n operation, achievement of 5 %

of electrical durability3. Dielectric withstand at 2 Ue (50 Hz-1 mm) 3. Ditto + leakage test current

(≤ 2 mA per pole at 110 % Ue)4. Temperature rise at In 4. Ditto5. Verification of non-drift of 5. Ditto

overload trip units

Test sequences

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Standard IEC 60947-2 Tests

n Tripping curveso all the important points

on the tripping curveare tested

o essential features are tested in realand the hardest conditions

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In «sequence 3» of standardized testsO - t - CO test

Verificationsn Dielectric at 2 Ue (minimum 1000 V) for 1 minute,

NB: for circuit-breaker suitable for isolationtest of leakage I = < 6 mA at 110 % Ue

n Verification of overload trip units at 2 Ir

Standard IEC 60947-2 clarifies the definition of circuit-breakerbreaking capacityThe circuit-breaker must not be «dangerous » after 2 breakings at Icu

Tests Icu

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Standard IEC 60947-2 Tests Ics

In « sequence 2 » of standardized testsO - t - CO - t - CO test

Verificationsn Dielectric at 2 Ue (minimum 1000 V) for 1 minute,

NB: for circuit-breaker suitable for isolationtest of leakage I ≤ 2 mA at 110 % Ue

n Of suitability to break its nominal current by achieving 5% of electricaldurability

n Of temperature rise at In,n Verification of overload trip units at Ir

The circuit-breaker must be suitable for operation after a short circuitat Ics. This performance is guaranteed 3 times.

The Ics performance represents a « practical » breaking capacity.

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In « sequence 4 » of standardized testsCategory B circuit-breaker

Verificationsn Device withstand at Icw and ∆t indicated by the manufacturern Of temperature rise at In, after O - t - CO cycle

at Icw at maximum voltagen Dielectric at 2 U 1(minimum 1000 V) for 1 minute,n Overload trip units at 2 Ir

The circuit-breaker must be suitable for operation after a short-circuitat Icw

Tests Icw

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Standard IEC 60947-2 Conclusion


A standard that adheres to realitySimple, clear choice of circuit-breakersn In and Icu are sufficient to determine the circuit-breaker,

New recognized, defined and tested characteristics / functionsn Suitability for isolation,n Residual current device,n Circuit-breakers with electronic trip unit

Tests representative of the real stresses exerted on a circuit-breakern Ics, etc.n Cumulative tests in sequences,n Tests of all the design characteristics

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A standard that adheres to realityExamples

o probable Isc very close to o probable Isc less thanprospective Isc: Ics = 100 % Icu prospective Isc: Ics = 50 % IcuNS160N is optimized C60L is optimized

Conclusion

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1250 kVA

Isc = 29 kA

28 kA

160 A

MSB

Sub-distributionboard

18 kA

8.5 kA

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Standard IEC 60947-2 Conclusion

A circuit-breaker certified according to Standard IEC 60947-2guarantees a quality device with durable performance of all its safetyfunctions.

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estandar iec 60947-2.pdf

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