TM 55-4920-221-14
switch of inverter load switches (47) for three-phase
66. RELAY PAD.
inverter inputs. Close 0-10A switch of dc generator load
The relay pad (27, figure 6) is used for testing
switches (45) for dc generator inputs.
reverse-current cutout coils and contacts.
70. VOLTMETER PHASE SELECTOR.
NOTE
Voltmeter phase selectors (59, figure 6) selects
Electrical connections shall be made
single- or three-phase voltage input for the ac voltmeter
to corresponding BATT., GEN.,
along each phase of the selector's six positions. Single-
SWITCH, APP., and GND. terminals
phase voltages can be read on line and N terminal.
on relay pad when using cutout. A
71. T2 VARIABLE CONTROL.
link between BATT. and GEN. must
T2 variable control (61, figure 6) varies load in
be installed if cutout is not used.
T2 terminal (37) from 0 to 1 kw for single- or three-
67. DC GENERATOR LOAD SWITCHES.
phase input. Close T2 switch of ac generator load
switches (49) for single- and three-phase generator
are used for applying fixed or varying loads from 0 to
input. Close switch T2 of inverter load switches (47) for
500 amp.
three-phase inverter input.
68. PHASE SEQUENCE INDICATOR.
72. AC-DC SWITCH.
The phase sequence indicator bulbs (60, figure
Ac-dc switch (32, figure 6) enables a voltage
and frequency reading to be taken on ac bus if switch is
HIGH-LOW switch below indicating bulbs is used in
in ac position. Alternators should be operating at no
conjunction with the high-low frequency meter (6). Bulb
load and with load disconnect switch (21) open.
representing 1-2-3 must light for correct phase
NOTE
sequence. To correct phase, change any two leads of
DC and ALTERNATOR positions of
T1, T2, or T3 terminals (37).
the
ac-dc
switch
eliminates
69. T3 VARIABLE CONTROL.
possibility of reading existing on
The T3 variable control (46, figure 6) varies the
single-phase wattmeter (38).
load in line T3, terminal (37) from 0 to 1 kw for single- or
73. ALTERNATOR FIELD SWITCH.
three-phase input, and from 0 to 10 amp for dc input.
Alternator field switch (62, figure 6) eliminates
Close T3 switch of ac generator load switches (49) for
field excitation during testing of alternators.
single- and three-phase generator inputs. Close T3
Section III. OPERATION UNDER USUAL CONDITIONS
74. GENERAL.
Instructions in this section are published for the
and wattmeter range selector (64), and three-phase
information and guidance of personnel responsible for
the operation of this equipment. It is essential that the
counterclockwise for maximum resistance.
operator knows how to perform every operation for
e. Position load links and load disconnect links, as
which the equipment is capable.
instructed in paragraph 13.
75. PREPARATION FOR OPERATION.
f. Position links between BAT and GEN terminals
a. Check zero setting of meters, and zero adjust, if
of relay pad.
necessary.
76. OPERATING TEST PROCEDURE.
a. Dc Generator Test.
(1) Perform before operations described in
position.
c. Position fan OFF-ON switch (10) in ON position.
(2) Attach leads from generator under test to
terminals on control panel as follows:
13
