local remote backup line protection

7/28/2019 Local Remote Backup Line Protection

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Basic Protective RelayingRemote-Local Backup

ProtectionEd Khan

April, 2013

Proprietary Mater ial-Do not reprodu ce witho ut permiss ion


2/19

Backup Protection

Back Up Protect ion are of three types:

Remote

Local

Beaker Failure



3/19

Backup ProtectionOverlapping Zon es of Protect ion



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Backup Protection

Overlapp ing Zones



5/19

Backup Protection

Zones of Protect ion Prov ide Remote Backup



6/19

Remote Backup ProtectionDRemote Backup is inherent when we overlap the zones.

D The tr ipp ing o ccurs at stat ion or s tations other than the one

that is respon sib le to provide pr imary protect ion

D The speed is slow

DA large part of sys tem has to b e tr ipped to iso late the faul tDSomet imes the remo te backup may n ot be sensi t ive enou gh

B

Zone 1

Zone 2

Zone 3

X

12

3

4


5

6

Breaker 5 opens co rrect ly

Breaker 3 fai ls to open

Remote protect ion at

Breakers 1 and 6 have to

open and isolate the faul t .

C


7/19

Remote Backup Protection

21

5

6

7

8

11

12

13 14

3 4

9 10

15 16

17

18

Supp ose breaker 8 fails to op en even though th e relaying may

have worked fine. In that case we cou ld rely on remo te back

at br eakers 14, 16 and 18.



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Backup Protection

21

5

6

7

8

11

12

13 14

15 16

3 4

9 10

17

18

We lose larger part of the sys tem using remote backup. Also ,

t r ipp ing is not assured under all operating con di t ions due to

Infeed effect, etc.



9/19

Remote Backup Protection

21

5

6

7

8

11

12

13 14

3 4

9 10

15 16

17

18

Remote backup is inherent ly there due to overlapp ing of

zones of pro tect ion.



10/19

Remote Backup ProtectionSubstat iontopo logy

affects tr ipp ing

requirements.

Less impact on

system wi th

Breaker and

a Half

arrangement

13 14X



11/19

Backup Protection


With the advent of EHV and increased concern for sys tem

rel iabi l ity a greater emph asis is being placed on local

backu p/breaker failure. Remote backup st i l l remains as a

secon d tier. Also , in som e instances, a faul t may have to be

cleared by a com binat ion of local and remote backup


12/19

Local Backup Protection


What does Lo cal Backup compr ise of :

D Redund ant pr imary and secondary re lays

D Primary and secon dary relays from dif ferent manu facturersD Different techno logies for pr imary and secondary relaying

D Redundant CTs

D Redundant battery sup pl ies

D Dual breaker tr ip

We do not u sual ly prov ide dual PTs


13/19

Local Backup Protection

21

5

6

7

8

11

12

13 14

15 16

3 4

9 10

17

18

Faul t between breakers 6 and 8 needs to cleared by these

breakers. If pr imary relaying at any of th ese breakers fai ls,

secon dary protect ion ( local backup ) at these breakers shou ld

operate.



14/19

Breaker Failure Protection


Even w ith all the redundanc ies, the local backup

is not complete ly adequate because of the

fai lure of a breaker to open when called upon todo so .

This is known as breaker fai lure.

This is a type of local backup


15/19


What is Breaker Failure

Breaker Fai ls to tr ip to clear a faul t due to :

Trip Coi l is defect ive

Contro l Wir ing Problem

Gas pressure low

Operat ing m echanism is jammed



16/19


Breaker Fai lure Relaying Funct ional Log ic

OR

L1

L2L3

Fault detectors

62

Aux relay

AND 62BF 86BF


Timer


17/19


Protect ion

Trip: 1Cy.

Operat ing

Time of CB : 2Cy.

Drop out t ime

Of current prot : 1 Cy.

Margin : 5 Cy.

Breaker fai l t imer t ime d elay : 8 Cy.

Breaker fail protection start



18/19


Operat ing

Time of CB : 2Cy.

Protect ion

Trip: 1Cy.

Drop out t imeOf current prot : 1 Cy.

Margin : 5 Cy.

Margin

7 Cy.

Operat ing

Time of CB : 2 Cy.Breaker fai l

Protect ion tr ip : 0.5 Cy

Breaker fai l t imer t im e delay : 8 Cy.

Breaker fail protect ion star t

Remote Zone 2 Back up protect ion op erat ion t ime :say 20 Cy.



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Any Quest ions ?

Thank You


local remote backup line protection

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