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

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D I RECTIONAL OVE RC U R R EN T GROUND R E LAYS
E N E RGY R EQUIR EMENTS
-
60
CYCLES
D I R ECTIONAL UNIT POLARIZING C I RCUIT BURDEN
R ELAY TYP E RAT I NG VOLT AMP E R E S
6
POWER FACT OR ANGL E ¢
KRC
230
T
1 .45
ffJ
Lag
Amperes
KRP 208 7T 1 1 . 2 28°
Lead
Volts
KRD Current 230
T
1 . 45 8°
Lag
Unit
Amperes
KRD Voltage 208 7T 1 1 . 2 28°
Lead
Unit Volts
¢ Degrees current leads or lags voltage at
120
volts on voltage polarized units and
5
amperes on current
polarized units.
6
Burden of voltage polarized units taken at
120
volts. Burden of current polarized units taken at
5
amperes.
T
One second rating
7T 30
second rating. The
10
second rating is
345
volts. The continuous rating is
1 20
volts.
Either of the studs or the mounting screws may be
utilized for grounding the relay. The electrical con­
nections may be made directly to the terminals by
means of screws for steel panel mounting or to ter­
minal studs furnished with the relay for thick panel
mounting. The terminal studs may be easily removed
or inserted by locking two nuts on the studs and then
turning the proper nut with a wrench.
For detailed information, refer to I.L.
41-076.
The external a-c connections of the directional
overcurrent relays are shown in Figs.
7, 8
and
9 .
If
no voltage polarizing source is to be connected to
the KRD relay, short-circuit the voltage p�larizing
circuit at the terminals of the relay.
A D J U ST M E N T S A N D M A I N T E N A N C E
The proper adjustments to insure correct opera­
tion of this relay have been made at the factory. Upon
receipt of the relay, no customer adjustments,other
than those covered under "SETTINGS" , should be
required.
A cceptance C heck
The following check is recommended to insure
that the relay is in proper working order;
O vercurrent U n i t ( I )
1.
Contact Gap - The gap between the stationary
and moving contacts with the relay in the de-ener­
gized position should
be
approximately
.020".
2.
Minimum Trip Current - The normally-closed
contact of the directional unit should be blocked open
when checking the pick-up of the overcurrent unit.
The pick-up of the overcurrent unit can be checked
by inserting the tap screw in the desired tap hole and
applying rated tap value current. The contact should
close within
±5%
of tap value current.
D i rect i on a l U n i t ( D )
1 .
Contact Gap - The gap between the station­
ary contact and moving contact with the relay in the
de-energized position should be approximately
. 02 0 " .
2 .
Sensitivity - The respective directional units
should trip with value of energization and phase
angle relationships as indicated in Table
1 .
3 .
Spurious Torque Adjustments - There should
be no spurious closing torques when the operating
circuits are energized per Table
2
with the polarizing
circuits short-circuited for the voltage polarized units
and open-circuited for the current polarized units.
I n d i c at i n g C ontactor S w i t c h ( I C S )
Close the main relay contacts and pass sufficient
d-e current through the trip circuit
to
close the con­
tacts of the ICS. This value of current should be
between
1
and
1 . 2
amperes. The indicator target
should drop freely.
The contact gap should be approximately
5/64 "
be-
9
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