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I.L. 41-496.52D
5.5.
AB – Combination
Set V
= 70 volts. V
CN
AN
voltage on small PC board located just behind R1-R4
potentiometers terminal "10" (positive) located
behind R1 potentiometer (second from the bottom)
and relay terminal "2". It should measure 10 to 22
volts. Reset V
= V
AN
BN
disappear.
5.5.1. BC – Combination
Same check as for AB except first set V
V
= V
= 10 volts and then reset V
BN
CN
volts.
5.5.2. CA – Combination
Same check as for AB except first set V
V
= V
= 10 volts and then reset V
CN
AN
volts.
5.6.
Overcurrent Unit
Check operation of the overcurrent unit by using test
connection No. 5 of Figure 9. Set V
= 70 volts. The .2 - 4.35 ohm relay should operate at
.75 - .83 amperes, and the 1 - 31.0 ohms relay
should operate at .37 - .420 amperes. If not, check
adjustment of R63 potentiometer.
5.7.
Indicating Contactor Switch
(ICS)
With the SDGT relay tripping, pass sufficient dc cur-
rent through the trip circuit to close the contact of the
ICS. This value of current should be not less than 1.0
ampere or greater than 1.2 amperes, for the 1
ampere ICS. The current should not be greater than
the particular ICS tap setting being used for the 0.2
— 2.0 ampere ICS. The operation indicator target
should drop freely.
The contact gap should be approximately 0.047" for
the 0.2 - 2.0 ampere unit and 0.07" for the 1.0
ampere unit between the bridging moving contact
and the adjustable stationary contacts. The bridging
moving contact should touch both stationary contacts
simultaneously.
6.
ROUTINE MAINTENANCE
The relays should be inspected periodically, at such
intervals as may be dictated by experience, to insure
that the relays have retained their calibration and are
in proper operating condition.
18
= V
= 10 volts. Check dc
BN
70 volts. Dc output should
= 70 volts.
AN
= V
= 70
BN
CN
= 70 volts.
AN
= V
= 70
CN
AN
= 0, V
= V
AN
BN
In-Service Test
(If Relay is Set for S = 1 Only)
(SDG-2T Only)
In-service testing is performed as follows:
1. Open relay trip circuit by opening red handle
switch No. 11.
2. Open relay voltage terminal 7.
3. Press white push-button. Push-button light
should light.
This test checks the operation of the magnitude com-
parator and output circuitry.
When push-button is used for direct breaker trip,
depress push-button for short time only.
7.
REPAIR CALIBRATION
Use the following procedure for calibrating the relay if
the relay has been taken apart for repairs or the
adjustments disturbed. Printed circuit boards styles
and components are identified on Figures 5 to 8.
Component location as per Figures 20 to 27.
CN
For easier access to the parts, the relay should be
tested out of the case.
Use Figure 15 for Test Point Traces reference.
Part A Preliminary Settings
1. Remove the printed circuit board(s) (PCB) in the
rear of the relay.
2. Set R
, R
, R
1
2
clockwise for maximum resistance.
3. Set relay for S = 1, M = +18 ("L" lead over "R"
lead), all T = 8.7, T
relays and for the .2 - 4.35 ohms relay all T =
1.23 T
= 3.69.
0
Part B Voltage Circuit Tests
1. Apply 3-phase balanced voltages as per test 1 of
Figure 9 except no current is applied.
2. Set V
= V
AN
BN
lowing ac voltages.
From relay terminal 6 to S
Volts.
From relay terminal 6 to S
volts.
, R
potentiometers fully counter-
3
4
= 26.1 for the 1.0 - 31.0 ohm
0
= V
= 70 volts ac. Measure fol-
CN
= 1 Tap 70 (±1)
A
= 2 Tap 140 (±2)
A
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