Westinghouse KRD-4, Installation, Operation, & Maintenance Instruction

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RATI NGS O F DI R ECTI ONA L AN D OV ERCURRENT U N I TS
OV E RCU R R E N T U N I T Dl R E C T I ONAL U N I T
CON T I N UOUS ONE SECOND
CON T I N UOUS ONE S E CON D
RAN G E RAT I NG
RAT I N G RAT I N G RAT I N G
0. 5- 2 Amps
5 1 00 8
200
1-4 8
1 4 0 8
200
2-8 8 140
8 200
4-16 1 0
200 1 0
230
10-40
10 200 10
280
20-80 10
200 10
280
t
The rmal capaci ti es for short times other than one s econd may be calculated on th e basi s o f tim e being
inversely proportional to the square of the cu rrent.
D I R ECTI ONA L UNI T POLARI ZING CI RCU I T B U RDEN
The burden at 1 20V, 60 cycl e s , i s 12.5 volt-amp eres at 1 5 d egrees. ( cu rrent leadi ng voltage).
S E T T I N G S
I n s ta n t a n e o u s O v e r c u rrent U n i t {I)
The only setting required is the pickup current
setting wh ich is m ad e by m ean s of the connector
screw l ocated o n the tap plate. By placing the con­
nector s c rew in the desired tap, the relay will j u st
close its contacts at the tap value current.
C A u T 10 N
Since the tap block connector screw car­
ri es operating current , be sure that the screw is
turn ed ti ght.
I n order to avoid opening the current transformer
circuits when c hanging taps under load, connect the
spare tap screw in the desired tap position before re­
moving the other tap screw from the original tap pos­
ition.
D i rec t i o n a l U n i t { D )
No setting i s requi red.
I n d i c a ti n g C o n t o c to r S w i t c h U n i t { I C S )
No setting i s required.
A u x i l i a ry S wi t c h ( C S- 1 )
N o setting required o n th e CS- 1 unit ex cept for
the selection o f the required 24, 4 8 , 1 25 or 250 volt­
age on the tapped resistor. This c onn ection can be
made by referring to Fig. 6 .
6
I N S T A L L A T I O N
The relay s should be mounted on switchbo ard
panels or their equival ent in a l ocation free from dirt,
moisture, exces sive vibration and h eat. Mount the
relay verti cally by m ean s o f the two mounting studs
for proj ection mou nting or by m eans of the fou r mount­
ing holes on the flange fo r the semi-flush m ounting.
Eith er of the studs or the m ounti ng screws may b e
utilized for grounding t h e relay. The el ectri cal con­
n ections may be m ad e directly to the terminal s by
m eans of screws for steel panel mounting or to ter­
minal studs furnished with the relay for thick panel
m ounting. The terminal stu ds m ay be easily removed
or inserted b y locking two nuts on the studs an d then
turning the proper nut with a wrench.
-li<
For detail ed i nformation o n the P T Case, refer to
I . L .
4 1- 0 76.
The external connections of the directio nal
ov ercurrent relays are shown in Fig. 7 .
A D J U S T M E N T S A N D M A I N T E N A N C E
The proper adju stm ents to i nsure co rrect op era­
tion of this relay have b e en mad e at the factory. Upon
receipt of the relay, no custo m er adj u stm ent s, other
than tho s e covered under "SETTINGS " , s hould be
required.
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