Operating Principles - GE SBC23A Instructions Manual

Static breaker backup relays

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cur ren t exceeds

i ts

sta t i s t i cal bas i s, d epe nd i n g on what i n s ta nt i n t h e curre n t cycl e t h e DC vol ta ge i s

appl i ed. I n order to l i mi t th i s v a r i at i on, i t i s recommended tha t the i nput cur rent

to the re l ay be sel ected i n t h e ra nge of 5 to 10 t i mes the p i ckup s e tt i n g.

for s e tt i n g th i s t i me r i t i s sugge s ted t h a t s i n g l e -pha s e cur ren t be fed i n to the

g round c i rcui t w i th the g round p i ckup s e tt i n g on the m i n i mum po s s i bl e s e tt i n g.

i nput cur ren t s houl d then be s e l ected to be about 5 to 10 t i me s t h e RMS v a l ue

re qui red to get a co n t i nuous output from t h e curre n t d e tecto r.

w i l l l i mi t t h e s ta t i st i ca l v a r i a t i on t o some fract i o n o f a mi l l i s econd.

a nd

the

i n s t ruct i on s

ACCEPTANCE TESTS.

It s houl d be n o ted that w i th t h e above s e tt i n g s t h e re l ay w i l l , fo r seve re faul ts,

ope rate i n the se t t i me.

s l owe r, wh i ch i s i n the d i rect i on t o prov i d e s l i g h t l y mo re ma r g i n fo r these faul ts

whe re s tabi l i ty and damage con s i d e ra t i on s a re con s i de rabl y l e ss o n e rous.

The second a ry ( B/0) t i me d e l ay i s s e t w i th t h e AND2 l i nk i n t h e OUT pos i t i o n a nd

w i th no i nput cur re n t.

t i me a s t h e powe r suppl y.

sw i tched t o +DC fo r i n i t i a t i on o f t h e B /0 t i mer.

Aft e r s e tt i ng the t i me d e l ay, t h e p i ckup s e tt i n g s o n p h a se a nd ground curre n t s

shoul d

b e

ma de,

co n s i d e ra t i on s re l a ted to the actua l s e tt i n g s to s e l ect have bee n d i scussed i n the

s ect i o n under

APPLICATION.

INTRODUCTION

The ope ra t i n g s e que nce o f l o g i c s i g n a l s for each o f t h e S B Cs can be fo l l owe d wi th

the a i d o f the proper i n te rn a l co n n ect i on s d i a g ram, as s hown bel ow:

RELAY TYPE

S B C 2 3 A

SBC23B

S B C2 3 C

Al l the S B C s con ta i n funct i o n a l e l eme n ts as de scr i be d be l ow:

+10.2 V,

-10.2 V

( P r i n te d C i rcu i t Ca rd i d ent i fi ed a s 11 Y 11 )

B )

Powe r

suppl y l ev e l - s e n s i n g ci rcu i t,

g round ed

C )

A C ci rcu i t surge suppre s s i o n ( Cl t h rough C8)

Tr i pl e ra nge p r i ma ry tapped tra nsacto rs a nd tap bl ocks fo r Phase A , Phases,

Ph a s ec, 3Io cur rent ci rcu i ts ( TRA, TRB, TRC, T RD; TBl, TB2 , TB3, TB4 )

s e n s i t i v i ty,

the re can be

make

these

For l ow-current faul ts, i t may ge t a few mi l l i s econ d s

The co n tact con ve rter ( CCI ) must be energ i zed a t the same

Te rm i nal s 9 a nd 17 can be co n n ected to g e t h e r a nd t h e n

a s

i nd i ca ted

i n