TM 55-4920-221-14
CHAPTER 4
DS AND GS MAINTENANCE INSTRUCTION
Section. I. SPECIAL TOOLS AND EQUIPMENT
No special tools or equipment are required to perform DS or GS maintenance on test stand.
Section II. TROUBLESHOOTING
to energize meter circuits
range selector S6 in 20
97. GENERAL.
kw position.
This section provides information in diagnosing
Switch S5 defective.............Replace.
and correcting unsatisfactory operation or failure of test
Dirty or pitted normally-
Clean contactors with bur-
stand or it- components. Each trouble symptom stated
open contactors on relay
nishing tool.
is followed by a list of probable causes. The possible
K2
remedy recommended is described opposite probable
Burned contactors, open
Replace (paragraph 130).
cause. Units, parts, or hardware found defective and
coil, or defective arma-
not repairable shall be replaced.
Controls and
ture on relay (K2).
instrument referred to in this section have been
Fuses F2 or F3 defective Replace.
symbolized and identified on schematic Wiring diagram
Circuit selector switch S28 Replace (paragraph 118).
defective
98. LOAD RACK OVERHEATING.
Ammeter phase selector
Replace (paragraph 118).
Probable Cause
Possible remedy
switch S29 defective
Thermostats S41 or S42
Replace (paragraph 144).
Meter M10 or M11 defective....Replace (paragraph 91).
defective
101. METER M4 NOT INDICATING.
Motors B1 or B2 defective ...Replace (paragraph 143).
Probable Cause
Possible remedy
99. METERS Ml and M2 NOT INDICATING.
Improper position of load Position load disconnect links
Probable Cause
Possible remedy
disconnect links E1 on con- in accordance with instruc-
Switch S2 in OFF or CEN Place switch in ON position.
nection board
tion plate on connection
TER position
board.
Single-phase ammeter and Depress total load disconnect
Position of voltmeter phase Rotate switch and phase for
wattmeter range S1 not
switch in ON position and
selector switch S3 not in
voltage to be measured.
in highest position to en-
place single-phase am-
phase with meter and unit
ergize meter circuits
meter
and
wattmeter
under test
range selector S1 in the
Defective voltmeter phase Replace (paragraph 124).
20 kw position.
selector switch
Switch S5 defective.............Replace.
Meter M4 defective .............Replace (paragraph 91).
Dirty or pitted contactors
Clean contacts with burnish-
102. METER M5 OR M6 NOT INDICATING.
on relay K1
ing tool.
Probable Cause
Possible remedy
Burned contacts, open coil, Replace (paragraph 130).
High-low switch S4 in wring Place switch in either the
or defective armature on
position
HIGH or LOW position,
relay K
depending upon the input
Meters M1 and M2 defective ...Replace (paragraph 91).
being measured.
100. METERS M10 AND M11 NOT INDICATING.
Loose or incorrect place-
Tighten and/or position load
Probable Cause
Possible remedy
ment of connection board links E2 and load discon-
Switch S2 in OFF or CEN Place switch in ON position.
links
nect E1 in accordance to
TER position
connection board
Three-phase ammeter and Open load disconnect switch
instruction plate.
wattmeter range selector
S7 and place three-phase
S6 not in higher position
ammeter and wattmeter
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