T Y P E CO CIRC U I T O P E N I NG R E LAY
CO RELAY
(FRONT 'f l EW)
\TIMER STOPS
I
(:��:YA��Hacr l
(OPENS
I
TO
(TIMER
(WHEN SWI[CH
START
( "S "
CLOSES
I
!�!TCH
V'OL.TS
SUB. 1
l83A21L
Fig. 10. D i agram of Test Connections for the Circ uit
Opening CO Relay in the Type FT2 1 Case.
SETT I NGS
CO UNIT
Th e overc urrent unit settings can be d efined
either by tap setting and time dial position or by tap
setting and a specific time of operation at some c ur
rent multiple of the tap s etting ( e . g .
4
tap s etti n g ,
2
time d ial position or
4
tap settin g ,
0 .6
seconds at
6
times tap value c urrent).
To provide selective c ircuit breaker operation, a
minimum coordinating time of
0 . 3
seconds plus c ir
c uit breaker time is recommended between the relay
being set and the
re lays with which coordination is to
be effected .
Th e c o n n e c tor s c rew on the terminal p l a t e a bove
the t i m e d ia l m ak E� s connec tions t o various turns o n
t l1P orwrating c oi l . By p l a c i n g th1s screw in the
van ous termin a l plate h o l es ,
th e
r e l ay will res pond to
m u l tipl E's of tap val u c c urrents in a c c ord a n c e with
tlw \·a n ous ty p1c a l tim(?-c urrent c urvc s .
CAUTION
Since the tap block connector screw carrie s oper
ating current , be sure that the screw is turned tight.
In order to
a void
opening the current transform er cir
cuits when changing taps under load , connect th e
spare connector screw in th e desired tap position
before removing the other tap screw from the original
1
2
3
51-1
DEV I C E NUM�ER CHART
5 1
•
DVERCURRENT RELAY, TYPE CD
5 1
Sl
}
P H .
I
}
PK. 2
}
PH. 3
CS - DE- I ON COHTACTOR SWI TCH IN HPE CO RELAY
OI - OPERAT I ON I N D I CATOR IN TYPE CO RELAY
52 - POWER C I RCU I T BREAKER
TC - BREAKER TR I P CO I L
SUB. 1
183A2l�
Fig. 1 1 . External Schematic of the Circuit Open in g Type
CO R elay for Phase Overcurrent Protection on a
Three Phase System.
tap position.
INSTANTANEOUS RECLOSING
The
factory adjustment of
the
CO unit
contact
provides a contact follow. Where instantaneous circuit
breaker reclosing will be initiated upon the c losure
of the CO contact, this contact follow must be elim
inated by loosening the stationary contact mounting
scre w , removing the contact plate and then re placing
the p late with the bent end resting against the c on
tact sprin g . With this change and the contact mount
ing screw tightene d , the stationary contact will re st
solidly against its backsto p .
DE ION CONT ACTOR S\NITCH (CS)
No setting is required on this unit.
OPERATION INDIC ATOR (OI)
No setting is required on this unit .
13
www
. ElectricalPartManuals
. com
