ABB KD-10 Instruction Leaflet page 31

Type KD-10 and KD-11 Compensator Distance Relay
3.3 SUGGESTED PROCEDURE FOR DETECT-
ING AND REPLACING DEFECTIVE C
CAPACITOR FOR KD-4, KD-5 AND
KD-10 RELAYS
Step 1 __________________________________
Set S = 1 for the 3-phase unit.
Apply approximately 120 volts to relay terminal 7 and
8 and short-out terminals 7 and 9 (for KD-5 between
terminals 6 and 9 and some short reach KD-4).
If contacts of the 3-phase unit close, then the C
pacitor is under suspicion, but improperly adjusted
R can be suspected as well.
3A
Step 2 __________________________________
Remove the connections made in Step 1.
Apply approximately 120 volts (i.e., 100-130 volts) to
terminals 8 and 9 = V .
89
Measure the voltage across the C
high impedance voltmeter - 5000 ohms/volt.
For .75 – 20 ohms reach KD-4 relays, the minimum
voltage should be V
min
than 3.85 x V then replace C
89
For .2 – 4.35 ohms reach KD-4 and KD-5 the mini-
mum voltage should be V
less than 2.82 x V then replace C
89
For all ranges KD-10 use same procedure as for .75
– 20 ohm reach.
Step 3 __________________________________
Relays which fail step 1, or have C
placed after failing step 2, or after C
replaced, will require readjustment of R
Repeat step 1 and adjust R
just open.
Omit this procedure for KD-10 relays.
a. For .75 – 20 ohm reach KD-4 relays:
When the relay is preheated as per Instruction
Leaflet, decrease R
R and R resistance.
3F 3A
OR
For a cold relay repeat step 1 and adjust R
the contact just opens. No further adjustment is
required.
3C
3C
capacitor with a
3C
= 3.5 x V . If V is less
89 min
.
3C
= 2.82 x V . If V
min 89 min
.
3C
capacitor re-
3C
capacitor is
3A
or P
3A
or P so that contacts
3A 3A
setting by 10% of total
3A
3A
b. For .2 – 4.35 ohm reach KD-4 relays with sub "A"
in style number.
If the relay is cold, decrease R
total R + R
3A
If the relay is hot, decrease R
tal R + R
3A
c. For .2 – 4.35 ohm relays without sub "A" in style
number.
ca-
If the relay is cold, decrease R
total R + R
3A
If the relay is hot, decrease R
tal R + R
3A
NOTE: R range of adjustment may occasion-
3A
ally be insufficient. If so, set R
maximum resistance, or replace R
sistor with higher value.
d. For KD-10 follow Instruction Leaflet to adjust
R or P
3A 3A
e. Suggested procedure for C
KD-11 relays:
1) No voltage test is required across the C
is
pacitor.
2) If C has been found bad (shorted or leaky)
3C
repeat P
3.4 SUGGESTED PROCEDURE FOR
REPLACEMENT OF C
CAPACITORS
.
3A
After the capacitors have been replaced:
a. Open relay switch 9 (phase C potential).
b. Short terminals 7 and 9 on relay side and apply
approximately 120 volts to terminals 7 and 8.
c. Adjust R
CA
for KD-10-11 relays so contact just floats, favor-
ing contact opening direction.
d. If desired, repeat 2.5 volts calibration point.
so
e. For KD and KD-1 relays, follow procedure for
R and R
MA
3A
resistance.
3F
setting 5% of to-
3A
resistance.
3F
3A
resistance.
3F
setting 4% of to-
3A
resistance.
3F
.
for KD-1, KD-41,
3C
or R adjustment above.
3A 3A
, C
2C 2A
resistor for KD-4-41 relays and XL
calibration.
MC
41-490J
setting 8% of
setting 7% of
for
3F
re-
3F
ca-
3C
AC
31