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Presentation Is-limiter

byVolker Schmidt

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� Influencing on short-circuit current

� FCL

� Function of IS-limiter

� IS-limiter and circuit breaker compared

� Structure of IS-limiter

� Application examples

� Reliability

� Calculation of tripping and setting values

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� FCL

� Function of IS-limiter

� IS-limiter and circuit breaker compared

� Structure of IS-limiter

� Application examples

� Reliability

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� Impedance of transformer and generator

� Splitting of busbars

� HVDC - converter

� Fault Current Limiter (FCL)

� Topology of the net


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Fault current limiter - type 2 (without current interruption)

Fault current limiter - type 1 (with current interruption)

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A. Devices which are commercially available :

� Current limiting reactor (type 2)

� Fuse (type 1)

� Is-limiter (type 1)

B. Devices which are still in a stage of research:

� Superconducting Fault Current Limiter (SCFCL)

� Semiconductor Fault Current Limiter

� Hybrid Fault Current Limiter


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� Overview: Commercially available

Rated current

Power losses

Voltage drop

Current interruption

<= 4000A high high No (type 2)

Current limiting reactor

<= 200A very low zero Yes (type 1)

Fuse

<= 4000A very low zero Yes (type 1)IS-limiter

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� Technical data Is-limiter

RatedVoltage0,75 kV

12,00 kV17,50 kV24,00 kV36,00 kV40,50 kV

For higher rated currents IS-limiters can be connected in parallel

RatedCurrent

. . . . . 5000 A

. . . . . 4000 A

. . . . . 4000 A

. . . . . 3000 A

. . . . . 2500 A

. . . . . 2500 A

SwitchingCapability

. . .140 kA RMS. . . 210 kA RMS. . . 210 kA RMS. . . 140 kA RMS. . . 140 kA RMS. . . 140 kA RMS

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� 3000 IS-limiters in service in 78 countriesCustomers:

Industry

Town‘s utilitiesUtilities

Test-laboratories

� Paper mills� Refineries� Chemical industries� Car industries� Power stations� Steel-, Aluminium mills� On-Off-shore platforms� Ships / Vessels

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� Comparison: IS-limiter – Circuit Breaker

t

i

Total operatingtime of theIS-limiter: T = 5 - 10 ms

T

T2T0 T1 T3

T1 : Operating time of the protection relais: 30 - 40 ms

T2 : Operating time of the circuit breaker: 40 - 80 ms

T3 : Arc duration: 10 - 20 ms

T0 : Response time of the protection relais: 10 - 20 ms

90 - 160 ms

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� Breaking of a short-circuit current with IS-limiter

Current curve at the short-circuit location

i1

i = i1 + i2without IS-limiter

i2

i = i1 + i2with IS-limiter

160 kA

80 kA31,5kA x � x 2

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� IS-limiter components

A,B,C: three phase-separatedsystems

A: Insert holder with pulse transformer and insert

A

B: Measuring and trippingunit

B

C: Current transformerC

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� IS-limiter insert holder and insert

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� Section of an IS-limiter switchgear panel17.5 kV, 1250 A – 4000 A24 kV, 1250 A – 3000 A

A Busbar compartmentB IS-limiter compartmentC CT / PT compartmentD IS-limiter measuring and

tripping device

A B D

C

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� IS-limiter in a switchgear- truck mounted -

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� Reliability

Self monitoringRedundancy (for each phase one independent system)

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1 phase fault

2 phase fault

� Redundancy IS-limiter

Is-limiter

L1

L2

L3

CB

G

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� Reliability

Self monitoringRedundancy (for each phase one independent system)

Protection against EMI- special current transformators

(low impedance shield between primary and secondary winding)

- filters for incoming / outgoing wires

- special tripping and measuring wires(each pair tightly twisted and protected by steel conduit)

Test equipment(quick, complete and easy test by user)

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IS-limiter insert holder with test insert

Test equipment

� Test set for IS-limiter

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� Safety related reliability of IS-limiter

1-phase 3-phase

Safety Integrity Level (SIL)

- Average Probability of Failure on demand 4,9E-5 1,02E-4

- Hardware Failure Tolerance 0 1

- Safe Failure Fraction 96,1 96,1

- % of SIL 3 4,9 10,2

- MTTF: 196 years

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� Detection of the Short-circuit current

didt( )3

3didt( )2

i

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ilimit

2

1

1 Short-circuit currentwithout IS-limiter

2 Short-circuit current– IS-limiter tripped –

3 Over current– IS-limiter not tripped –

ilimit ^ (di/dt)^ = logical „and“

4 4 Peak value of service current

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� Schedule for tripping

T1T2

T0: Reaching time for tripping criteria (instantaneous value and di/dt).

T4T0t

i

T3

.

T1: Response time of the electronic approx. 15 µs

T2: Time for opening the bursting bridge and for commutating the current to the fuse element approx. 85 µs

T3: Melting time of the fuse element approx. 500 µs

T4: Arc duration

iA: Tripping criteria are reached (instantaneous value and di/dt).

iB: Current at beginning of fuse element's melting

iC: Let-through current

iC

iB

iA

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L1

L2

L3

Circuit-breaker

Measuringand trippingdevice

Tripping-unitL1

L2L3

* further voltages on request

Alarms:- Is - limiter tripped- Is - limiter not ready- Supply voltage failure- Is - limiter blocked

Main supply-voltage

95 VAC - 250 VAC*

Auxiliary supply-voltage

95 VAC - 250 VAC*

DC supplyvoltage

24 VDC - 250 VDC*

Blocking

TrippingIndication

Power-supply

Self-monitoringIndication

ReadinessIndication

Power-unit Indication-unit

Tripping

Tripping ClosingInterlocking

� Interface of IS-limiter measuring and tripping device

Measurement Input

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� IS-limiter mounted in bus sectionAdvantages:

� Improving „powerquality“

� Increasing the relia-bility of the system

� Reduction of thenetwork-impedance

� Optimal load flow

� Existing busbarsystem has not to be changed

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� IS-limiter in generator feederAdvantages:

� Generator can be connected indepen-dent on the short-circuit capability of the system

� Existing busbarsystem has not to be changed

� No need of expensive generator breaker

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� IS-limiter in parallel to reactorAdvantages:

� Avoid copper losses of the reactor

� Avoid voltage drop of the reactor

� No electro-magnetical field of the reactor

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� Calculation of the lossesTechnical Data: Ur = 13.8 kV, Ir = 4000 AReduction: 50 kA to 40 kA

(L = 0.172 mH, P = 42.5 kW/phase)

Copper losses per year: 42.5 kW * 3 *24h *330T = 1.009.800 kWh (Iservice = 4000 A)

10.625 kW * 3 * 24h * 330dT = 252.450 kWh (Iservice = 2000 A)

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� IS-limiter versus reactorProblem:

� Reactor is not able to limit the short-circuit current to zero

� There is still a contribution to the peak value of the short-circuit current

G

Grid IndustrialSystem

10 kA �

1 MVA14 %

415 V

IK reactor''

1250 A

2,37 kA2,9 kA3,8 kA4,5 kA5,5 kACurrent Ik reactor''through reactor

uk = 40 %uk = 30 %uk = 20 %uk = 15 %uk = 10 %

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� Short-circuit contribution with reactor

Situation:

� 4 industrial generators behind reactors will fully load the grid in sight of short-circuit currents

Technical data of the Reactor:IR = 1250 AuK= 15 %

Technical data of generator:1 MVA, 14 %IK’’ = 10 kA

Grid Industrial System

0 kA(no contribution)

G1

4,5 kA

G2

4,5 kA

G3

4,5 kA

G4

4,5 kA

18 kA �

415 V

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� Connection of a generator to a network with current-direction comparison Advantages:

� Private / industrial generator feeder can be connected to the fully loaded grid

� Selective tripping of the IS-limiter (IS-limiter will operate only for short-circuit faults in the grid 1 ; will not operate in the grid 2 )

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� IS-limiter installations

- Chartered Semiconductor Mfg Ltd / Singapore- Shell - Windparks in Germany / Spain- Aluminium works in Australia- Oil/Gas platforms world-wide- Refineries world-wide- Utilities / Town-Utilities in Germany, Scandinavia, …- Los Alamos National Laboratories / USA- MIT / Bosten USA- Rolls Royce / Great Britain- Deutsche Bundesbank (German state bank)- …

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Solves short-circuit problems in new and extended systems

Optimum solution for interconnection of switchgear installations

Tried and tested in thousands of installations

Worldwide in service

The peak short-circuit current cannot be reached

� Conclusion

Reduces costs of switchgear installations

The short-circuit current is limited at the first current rise

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Advantage of IS-limiter

- Tripping criteria:

instantaneous current and di/dt of current

- Additional tripping criteria can be used

- No cooling time to replace tripped inserts

- Automatic connection of tripping wires to inserts

- Type tested enclosure

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IS-limiter insert holder with test insert

Test equipment

� Test set for IS-limiter

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A 4

Q 6 L 1 T 1 L 1 Q 6 L 2 T 1 L 2 Q 6 L 3 T 1 L 3

L1 L2 L3

Block diagram of the IS-limiter device Power unit

Tripping units

Anti-interference unit

Indication unit

Miniature circuit-breaker forsupply voltage

IS-limiter (insert holder and insert)

IS-limiter tripping transformer

Flag-type relay to monitorsupply voltage

Flag-type relay to monitorreadiness for operation

Flag-type relay to indicatetripping

G1:

A2:

A3:

A4:

F116:

Q6:

T1:

H106:

H116:

H1:

H106 H116IS-limiternot ready

H1L1Phase L1tripped

H1L2Phase L2tripped

H1L3Phase L3tripped

Anti-interference unit A3

F116

Powerunit

G1

Trippingunit

Phase L1A2L1

Trippingunit

Phase L2A2L2

Trippingunit

Phase L3A2L3

+ 150V

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Schematic diagram of a tripping unitof the tripping device type QR3S . . . / standard design

IS-limiter tripping transformerIntermediate transformer oftripping unitPulse transformerMeasuring inductanceSetting resistorsTripping capacitorDischarge resistorCharge

T1:T2:

T3:L1:R1...R6:C1:RS:RZ:

+ 150 V

C+ -

RZ

T3

T2

L1

U1 U2

T1

15

R5

R6

R3

R2

R1

R4

RS144

1

236

5

7

10

U3 U5

U4

Re

b1

Test socketconnector

Meteringelement 1

Trippingpulseemitter

Meteringelement 2

c1 h3 h6 high short circuit current in medium voltage ... · pdf fileinfluencing on...

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