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

Page: 33 / 114

DIR ECTIONAL OVERCU R R ENT GROUND R ELAYS
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SEC.
1
2 l
SATUUTliiCi TRUSFOIN£1
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DE V I C E IIUMIU CMAIT
171
-
DIIECTI OIIAL
OWUCUI.IIEII.T lliOIJIID
IEU.Y
""[
uc
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-
OVfiCUUEMT U II I T
Of
TY!Jf
UC
1
c
UCi.
tp -
D l t f C: f iO..L iiii i T Of TYr£ UC
U • NWEI
C I ICU I T IIUlU
ICI • IIDIUTIU COITACJOI SI I TCII
• •
IIUUI it.II I L U.U COITACT
JC
•
IILUU
T i l ,. COIL
183A968
Fig.
7.
External Schematic of the Type KR C Relay.
off the stationary contact 3/4 of one turn for a con­
tact gap of .020" to . 024 " . The c lamp holding the
stationary contact housing need not
be
loosened for
the adj ustment since the clamp utilizes a spring-type
action in holding the stationary contact in position.
3. Insert tap screw of overcurrent unit in highest
tap . The sensitivity adj ustment is
;n�tle
by varying
the tension of the spiral spring attached to the mov­
i n g element assembly. The spring is adjusted by
placing a screwdriver or similar tool into one of the
notc h es l ocated on the periphery of the spring ad­
j uster and rotating it. The s pring adj uster is located
on the underside of the bridge and is held in place
by a spring type clamp that does not have to be
loosened prior to makin g the necessary adjustments.
The spring is
to be
adjusted such that the con­
tacts will close as indicated by a neon lamp in the
contact circuit when ena-gized with the required cur­
rent and voltage
as shown in Table
1 .
Thi s table in­
dicates that the spring can be adjusted when the phase
angle relationship between the op erating circuit and
the polarizing circuit is at the maximum torque angle
or
when the circuit relationship has the operating and
polarizing .circuits in phase.
12
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STATUM
IUS
SATURUIIICi nusronu
1 2 l
SfC
DEVICE IIUNIER CIIA.RJ
I'OS
Ul
671t -
DIRECTIOUL OHIICUIIIIUH
!OM0\.110 IUL.U
DC TIIP IUS
1'0
TYf"E
KRP
II
'V -
DlllECTI IJfiiAL
UM I T OF
TYPE KRP
�� -
OV EIICUIIIIUT U lt i T OF TYI'E
UP
S2 -
�ER CIRCUIT tuiEA.lER
ICS - IIDICATIIIG
c.otiTACTOa
SWITCH
I
- IIIIUU:il
AUX I L I ARY COitTACT
5711
T C
-
BIEA.:El T i l l' COIL
I
IECi.
1
c
183A969
Fig.
8.
External Schematic of the Type KRP Relay.
4. The magnetic plugs are used to reverse any
unwanted spurious torques that may be present when
the relay is energized on current alone .
The reversing of the s Il.lfious torques is accom­
J)lished by using the adjusting plugs in the following
manner:
a) Voltage circuit terminals on the voltage
polarized relays (KRP and KRD voltage polarized
unit) are short-circuited.
b) The polarizing circuit of the current polarized
relays (KRC and KRD current polarized unit) are open­
circuited.
Upon completion of either "a" or " b " , current is
applied to the op erating c ircuit terminals as per
Table 2.
Plug adjustment is then made per Table II such that
the spurious torques are reversed. The plugs are
held in position by upper and lower plug clips.
These clips need not be disturbed in any manner
when making the necessary adjustment.
The magnetic plug adjustment may be utilized to
positively close the contacts on current alone . This
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