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4. Some of the more common component pro-
blems may be detected as follows:
With the relay mounted on a panel and energ-
ized by station C. T.'s & P. T.'s, open all
trip circuits and all current switch positions
12, 13, 14, 16, 17, 18, 19, and, phase C voltage
switches (terminal 9) and if applicable an
additional switch position on the separately-
energized 38 unit. Check the internal schematic
for your particular relay. Jumper terminal 7
to terminal 9 and to any other applicable switch
normally connected to phase C, on the relay
side (upper half of the switch). The contacts
of both operating units should stay open. If
the 3-phase unit contact closes, it indicates
misadjustment -of resistor, R3A, or potentio-
meter, P3A
common cause), or a de-
(most
fective capacitor, C3C, follow the instructions
for troubleshooting in Section E for KD-4 and
KD-5 relays and the proper instruction leaflet
for KD, KD-1, and KD-10 and KD-11 relays.
If phase-to-phase unit closes, recheck for:
KD & KD-1 relays
KD-4, KD-5, &
KD-41 relay
KD-10 & KD-11
CALIBRATION AND TROUBLE
SHOOTING HINTS:
A. Experience has shown that calibration of the
relay for maximum torque angle is the pro-
cedure most suscetible to error. Two poten-
tial sources of error are most common:
1. Instrumentation errors - Be sure of the
accuracy of calibration of all instruments
and phase shifters used. Instruments should
be chosen and ranges selected so that
readings are taken with the instrument
reading in the top third of the scale.
When a phase shifter is used, attention
should be paid to the fact that voltage
and current settings will change as the
angle is varied. To avoid inaccuracies due
to this effect, check the voltage and current
settings when contact operation indicates
that maximum torque angle check point
has been reached.
RMA & RMC-Calibration
RAC-Calibration
2. Failure or miscalibration of components not
connected with angle adjustment to distin-
guish between the two sources of error it is re-
commended to perform compensator nulling
test as follows:
B. For KD-4, 41, 5, 10, and 11 relays
Phase-to-phase unit (TAB and TBC
compensators) Maximum Sensitivity Angle
1.
Use "PH-PH-1-2 Phase Test" - connec-
tion for TAB-compensator, and "PH-PH-
2-3" Test connection for TBC compen-
sator. Refer to the figure in the I.L. titled
"Test Connections."
2.
Measure voltage across C2A for TAB and
across C2C for TBC.
3.
Set current equal to:
VlF2F
RELAY SETTING
The current should be high enough to pro-
vide an accurate phase angle meter reading,
or any convenient value if a phase-shifter
is used for direct angle reading.
4.
Set the phase shifter for the desired maxi-
mum torque angle value.
Note the voltage.
5.
Vary the phase angle in both directions of
the set value, to see that a low voltage
(below 1 volt) is obtained at the maximum
torque angle setting. If within +2 degrees,
it can be left undisturbed. If the minimum
voltage is obtained at some other angle,
readjust phase shifting resistor or potentio-
meter at the desired angle.
C. For KD and KD-1 Relays
Follow procedure above except:
1. For Ta compensator, use connection #2
omit voltage connection to terminal 9, dis-
connect LA-lead, insert voltmeter to mea-
sure open circuit voltage and use twice
the current value obtained for KD-10 tests.
Follow procedure outlined above except
adjust R2A when required.
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