Application - GE IACS3A Instructions Manual

Ti me ove r c ur r e n t r e lays
of uti li ty and
ove r load ba ckup
ti me - c ur r e n t chara c te r i s ti c
a pplic a tion i n
d e pendent ma i n ly upon the locati on of the fault r e lati ve to the relay
a nd on ly s l i g h tly upon the s y s tem generating s e tup at the ti me of the
fault. Use of rela y s havi ng the ve r y - i n ve r s e chara c te r i s ti c
s i tua t i on wi ll us ua lly
i n ve r s e r e lay we r e us ed.
The gene r a l pr a c ti ce
i n te r phase fa ults
s i ng le -pha s e -to-g r ound
a ppli cati on are
i s a d va n tag e ous be c a us e i t can be adjusted to prov i d e more s e n s i t i ve
pr ote c ti on on g r ound f a ults .
In the a pplic a ti on
devi c e s , the r e s e t ti me s h ould be c on s i d e r ed .
IAC 53 a nd IAC54 re la y s c ove r ed by the s e in s tr uc tion s i s a pproxima tely
60 s e c ond s , fr om the
s e t a t the n umbe r 10 time d i a l.
Whe n s e tti ng the s e r e lays to c oor d i na te wi th " d own s tr ea m"
a c oord i na ti on
a llowed, d e pend i ng
Th e s e c oor d i na tion
ti me , 0. 1 0 s e c ond
fac tor . For exa mple ,
c y c le s ) , the c oor d i nati on
ti me i s s e t by
f a c tor may be r e duced
.10
overtravel of
c y c le s (0. 08 s e c onds )
coor d i nati on.
induction
The
3
Fi g ur e s a nd 4 s h ow the inducti on un i t mounted
un i ts a re of the
a c tuated by a c urre n t-ope r a ti ng
d i s k s ha ft ca r r i e s
tr i p c i r c ui t whe n i t touches the s tati ona r y c on ta c t or c on ta c ts .
d i s k s haft i s
c on ta c t-closing
ma g n e t a c t i ng on the d i s k to g i ve the c or r ec t time d e la y .
Th e r e is a
left of the shaft of the ti me-ove r c ur r e n t un it.
its c oi l i n s e r i e s a nd i ts contacts i n pa r a l l el wi th the c on ta c ts of
the ti me - ove r cur r en t un i t,
c los e ,
the s e a l- i n un i t pi c ks up and seals i n.
GEK-34054

APPLICATION

a r e
i nd us tr ia l d i str i buti on
pr otecti on a t oth e r
makes
loc a t i on s whe re
r e s ult· i n
is to us e a
a nd a s e pa r a te
fa ults .
sh own i n Figure
of th ese
f ully clos ed
t i me of f r om 0. 25
on the c lea r ing
ti me s i nclude ,
for r e lay ove r tr a vel
i f the br eake r -clea r i ng time
ti me would be
te s t at the c ur r e n t
f r om 0. 1 7
second, if the
a min i mum
CONSTRUCTION
unit the
is
i nduction-d i s k-c ons truc ti on
the movi ng
r e s tra i ned by a
c urre n t, and its
ta rg e t a nd sea l-i n un i t mounted o n the
s uch tha t whe n the i nd ucti on -un i t c on ta c ts
us ed e xte n s ively
s y s te ms ,
loca ti on s .
th e s e re la y s
the fault-c urre n t
fa s te r clea r ing
set of two or
r e la y , r e s i d ua lly
Ty pi c a l c on n ec ti on s
1 5. Us e of a s e pa ra te g round
re lays wi th
The re s e t t i me of a ll
to the f ully
t o . 040 sec on d s
ti me of the
i n add i ti on
and 0. 17
0. 40 s e c on d .
le vel i n
to 0. 07 s e c ond.
"do wnstream"
0.25 seconds c ould be allowed f or
of
basic unit in all
in
type .
c oi l on a lami n a ted
c on ta c t tha t c omplete s
s p i ra l s pri ng
moti on i s r e ta r de d
Wh e n the s ea l- i n un i t
4
for the prote c t i on
and freque n tly
The i r ve r y - i n ve rs e
we ll s ui te d
ma g n itude
i n this
ti me s tha n if
thr e e r elay s
c on n e c te d ,
for s uc h
re la y
a utoma t i c re c los in g
ope n pos i ti on ,
re la y s ,
i s g e n e r a lly
bre a ke r i nvolve d .
t o bre a ke r- c le a ring
s ec ond f or s a f e ty
i s 0. 1 3 s e c ond
If the re lay
que s ti on , the s a f e ty
The n , wi th relay
breaker time is
r e lays.
Type IAC
the c radle . The s e
The disk
U-mag n e t.
the a la r m
to g i ve the prope r
by a perma n e n t
fr ont, t o the
The s e a l- i n un i t h a s
for
for
i s
the
f or
f or
a n
whe n
(8
5
i s
The
or
The