03- Non dir Overcurrent time protection.pdf

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Overcurrent timeProtection



Overcurrent-time Protection functions

Definite-time overcurrent-time protection

Criteria for fault: overcurrent

Criteria for selectivity: time



t

t

t

t

I>>

I>

TRIP

IE>>

IE>

IL1

IL2

IL3

IE

Valid for 7SJ602, 7SJ511, 7SJ512, 7SJ531, 7SJ61, 7SJ62(all devices are with 4 CT inputs)

TRIP

Overcurrent-time protection functions



IL1

IL2

IL3

(IE)

TRIP

I>> t

I> t

Valid for 7SJ600, suitable for all kinds of neutral-point treatment

I>>

I>

I>>

I>

IL1

IL2

IL3

IE

IE will be calculated,(min. 0,1 x IN)and with timer holded.




Valid for 7SJ600

I>> t

I> t TRIP

TRIP

t

t


L2 will be calculated

I>>

I>

I>>

I>

IL1

IL2

IL3

IE

IL2

IL1

IL3

(IE)



t [sec]

0.5

1.0

1.5

2.0

x IN0.5 1.0 1.5 2.0 2.5I> I>>

Tripping area

Tripping characteristic of a two-staged overcurrent-time protection device(definite time)

Overcurrent-time Protection, Characteristic



x IN0.5 1.0 1.5 2.0 2.5

t [sec]

0.5

1.0

1.5

2.0

Tripping characterictic of a overcurrent-time protection device (inverse time)

Characteristics:?IEC?ANSI?British Standard

Overcurrent-time Protection, Characteristic



-

Power supply with stations DC voltage

Protection device

=

=

+

-

+

Circuit-breaker

Converter

Power supply for overcurrent-time protection device



Power supply by current transformer and tripping auxillary-transformer (one phase representation)

Currenttransformer?30VAby seriestripping


Protection device

Circuit-breaker

?

=

Internal powersupply

Tripping auxillary-transformer

Measurement



Power supply by current transformer (one phase representation)Tripping with pulse tripping device (energy-weak tripping device)


Protection device

Circuit-breaker with energy-weaktripping device

?

=Internal power supply

Measurement



Used as:

Line protectionSelectivityby time-grading

1x

O/C

x

O/C

1

x

M

O/C

2x

O/C

3

Main protection

Application Overcurrent-time Protection

2 Motor protectionwith short circuit- and overload protection

3 Transformer protectionfor Network transformerswith short circuit- and overload protection



Application Overcurrent-time protection

Main protection as Line protection

x x x x

O/C O/C O/C O/C

t = 0mst = 300mst = 600mst = 900ms

Advantage: simple device, only current transformers are necessary

Disadvantage: near infeed higher tripping time



Protection of distribution transformers

x

O/C

x

> 1600kVA

Short circuit and overload protection

I t2

x

< 1600kVA

Short circuit and overload protection

HV-fuseTyp: GTr

O/C

> 1600kVA

Short circuit

xx



x

I

1

x

I

O/C

O/C

x

O/C

x

I

2

Used for:

Line differential-protection

1

Back-up protection

Application Overcurrent-time protection

2 Transformer-differential protection



x

UMZ

x

I

Back-up protection of transformers

Settings:

I>> > IN[A], t = 0

uk = short-circuit voltage of transformerIN = nominal current from high-voltage side

With that respondes I>> only on high-voltage side faults of transformer

I>: Exitation value for faults from the low-voltage side. The value must be higher as the summof all nominal currents of all feeders, converted of the high-voltage side.t = 300ms + biggest time in the outputs.

100[%]uk[%]



Overcurrent-time Protection, SIPROTEC-V3

7SJ600 Overcurrent-time protection, Motor protection, 3 CT inputs, Ground fault protection,RS485-system-interface, width 1/6 of19‘‘

7SJ601 Overcurrent-time protection (only 10 Parameter),simplified version of the 7SJ600, 3 CT inputs, Ground fault protection, width 1/6 of 19‘‘

7SJ602 Overcurrent-time protection,Motor protection,4 CT inputs, Ground fault protection, DIGSI-front interface,system interface fibre-optic and electrical,width1/6 of 19‘‘

7SJ511 Overcurrent-time protection,Motor protection,4 CT inputs, Ground fault protectionIntermittent ground fault protection,DIGSI-front interface, system interface fibre-optic, width 1/3 from 19‘‘

7SJ512 Overcurrent-time protection, Motor protection, Ground fault protection, Sensitive directional ground fault protection, Automatic reclosure, Intermittent ground fault protection, 5 CT inputs, up to 4 VT/PT inputs, DIGSI-front interface, system interface fibre-optic, directional O/C protection (optional), width 1/3 of 19‘‘

7SJ531 Overcurrent-time protection, Motor protection, Ground fault protection Control forone switching device, big Display, Sensitive directional ground fault protection, Automatic reclosure, Intermittent ground fault protection, 5 CT inputs, up to 4 VT/PT inputs, front interface, system interface fibre-optic, width 1/3 from 19‘‘



7SJ61 Overcurrent-time protection, Motor protection, Ground fault protection,automatic re-closure, Control, Automatisation function, 4-line Display, 4 CT inputs, different system interface possible, width 1/3 of 19‘‘ (successor of 7SJ511)

7SJ62 Overcurrent-time protection, Motor protection, Directional O/C protection, Ground fault protection, Sensitive directional ground fault protection, automatic reclosure, Control, Automatisation function, 4-line Display, 4 CT inputs, 3 VT/PT inputs, different system interface possible, width 1/3 of 19‘‘ (successor of 7SJ512)

7SJ63 Overcurrent-time protection, Motor protection, Directional O/C protection, Ground faultprotection, Sensitive directional ground fault protection, automatic reclosure, Control,key-switch, Automatisation function, big graphical display, feeder mimic diagram, 4 CT inputs, 3 VT/PT inputs, different system interface possible, width 1/2 of 19‘‘(successor of 7SJ531)

Overcurrent-time Protection, SIPROTEC 4

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03- Non dir Overcurrent time protection.pdf