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9.1.1. Routine maintenance
All contacts should be periodically cleaned. A contact
burnisher Style #182A836H01 is recommended for
this purpose. The use of abrasive material for clean-
ing contacts is not recommended, because of the
danger of embedding small particles in the face of
the soft silver and thus impairing the contacts.
9.2. REPAIR CALIBRATION
A. Auto-transformer Check
Auto-transformers may be checked for turns ratio
and polarity by applying ac voltage to terminals 4 and
5 and following the procedures outlined below:
1. Set S
and S
A
C
leads of M
and M
A
the "L" leads. Adjust the voltage for 90 volts.
Measure voltage from terminal 5 to the tap
#1 of S
. It should be 30 volts. Measure volt-
A
age from terminal 5 to the tap #1 of S
should be 30 volts (±1). From terminal 5 to
tap #2 of S
should be 60 volts. The same
A
procedure should be followed for taps #1 and
#2 of S
.
C
2. Set S
and S
A
C
the relay terminals for 100 volts. Measure
voltage drop from terminals 5 to each of the
MA and M
taps. This voltage should be
C
equal to 100 (±1) plus the sum of values
between R and tap being measured. Exam-
ple 100 (1 + .03 + .06) = 109 volts.
Transformers that have an output different
from nominal by more than 1.0 volt probably
have
been
damaged
replaced.
B. Distance Unit (Middle Unit) Calibration
Make following tap plate settings:
T
= 15.8; T
= 5.1
A
C
S
= S
= 1
C
C
Make M
= M
A
C
"L" lead should be connected to the "0" insert
"R" lead should be connected to the upper ".06"
insert. (-.03 -.06 .06 = -.15 between L & R).
on tap number 3. Set the "R"
all on 0.0 and disconnect
C
on 1 and adjust the voltage at
and
should
= -.15 settings:
For the most accurate calibration preheat
relay for at least an hour by energizing termi-
nals 4, 5, 6, & 7 with 70 volts, phase-to-neu-
tral or terminals 5, 6, 7 with 3-phase 120
volts phase-to-phase voltages.
The links in the middle tap block should be
set for the + T
1) Contact Gap Adjustment
The spring type pressure clamp holding the
stationary contact in position should not be
loosened to make the necessary gap adjust-
ments.
With moving contact in the opened position,
i.e. against right stop on bridge, screw in sta-
tionary contact until both contacts just make
(use neon light for indication). Then screw
the stationary contact away from the moving
contact 1-1/3 turn for contact gap of .040".
. It
2) With relay deenergized adjust the restraint
A
spring so that contact arm just floats.
C. Impedance Characteristic Check
1) Maximum Torque Angle
Adjust the adjustable reactor for about 5
turns out. Applying 60 volts ac to terminals 5
and 4 and passing 4.8 amperes, through the
current circuit turn the phase shifter until the
moving contact opens. Turn the phase
shifter back (few degrees) until contacts
close. Note degrees. Continue to turn the
phase shifter until contact opens, then swing
phase shifter back until contact closes again.
Note degrees. The maximum torque angle
be
should be (±1˚) computes as follows:
Degrees to Close Contacts at Left +
Degrees to Close Contacts at Right
Adjust reactor XC until the correct maxi-
mum-torque angle is obtained.
2) Sensitivity Adjustment
Using the connections of figure 9, apply 5
volts ac 90˚ leading, to terminals 4 and 5
pass .325 amperes through current circuit
I.L. 41-748.1F
direction.
C
2
= 90 ˚
17
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