TM 5-6115-434-12
(3)
Release clamp on mounting flange of generator. Remove clamp on mounting flange of generator.
(4)
Loosen twelve mounting nuts on mounting flange of generator. Note. Note position of generator terminal
board and inlet air cover to aid in positioning generator at installation.
(5)
Rotate generator counterclockwise slightly to allow large opening of mounting holes on mounting flange
to pass through mounting nuts. Remove generator from mounting flange.
Warning
Have suitable hoisting or support equipment attached to generator as injury to personnel and
equipment may result if hoisting is attempted without required equipment.
b.
Test.
(1)
Start the power unit as described in paragraph 2-14. Operate the 60 Hz electrical system as described in
paragraph 2-16a. With the 60 Hz electrical system operating, disconnect plug (;P32) voltage -regulator (VR2). Using
an adjustable potentiometer, apply 24v ac through a 50 watt resistor into pins J and E on plug (P32). Adjust
potentiometer until voltage begins to increase on panel ac voltmeter (fig. 2-19). If load contactor trip indicator lamp
illuminates, reset load contactor switch (fig. 2-19) and increase voltage to 120v ac line to neutral. If 120 volts are not
obtainable, 60 Hz generator has failed.
(2)
With the power unit not operating, disconnect plug (P33) from the 60 Hz generator. Use a multimeter and
check resistance across receptacle J;33 pins AB, AC, and BC. Each check should indicate a resistance of 0.8 ohms. If
resistance is otherwise, permanent magnet generator (PMG) has failed and generator shall be replaced. Check
resistance across pins D + and E- which shall be 5.0 ohms. Check resistance across pins E+ and D- which shall be .0
ohms. If resistance is otherwise, exciter field has failed and generator shall be replaced.
c.
Installation. Install generator in reverse order of removal procedures.
Note
Use caution when meshing generator drive with gas turbine engine drive coupling.
Section XII. COOLED AIR SYSTEM
3-66. General
The cooled air system consists of two ,independent 10-ton vapor cycle refrigerating systems, system 1 and system 2.
Each system is capable of being operated independently, or together for 20-ton total capacity. Each 10-ton system
consists of a 120/208 volt, -wire, 3-phase, 400 Hz electric-motor driven centrifugal compressor with an integral
overtemperature switch, an air cooled refrigerant condenser, two condenser cooling fans, a refrigerant receiver, an
expansion valve, an evaporator, two recirculating air fans, a refrigeration solenoid valve, a compressor bypass solenoid
valve, an overpressure switch, a refrigeration de-icing system, a filter-drier, a refrigerant level sight glass, and connecting
tubing and fittings. The compressor compresses low-pressure, low-temperature refrigerant to high-pressure, high-
temperature refrigerant gas. The overtemperature switch shuts off the compressor in the event of excessive temperature
in the refrigerant loop. The overpressure switch shuts off the compressor in the event of excessive pressure in the
refrigerant loop. The condenser fans produce a flow of cooling air across the refrigerant condenser. The refrigerant
condenser removes heat from the high-pressure, high-temperature gas and converts the gas to a liquid. The refrigerant
receiver collects the liquid from the condenser. The expansion valve converts liquid refrigerant from high-pressure to
low pressure. A portion of the liquid is evaporated in ;the expansion valve, producing a liquid gas combination. The
evaporator recirculating fans provide a flow of air across the evaporator. The evaporator produces a further pressure
drop in the liquid-gas refrigerant. Heat is transferred from the recirculated air to the area ,to be cooled. The normally
open refrigeration valve shuts off flow of liquid refrigerant from ,the receiver to the expansion valve when the desired
cooled air temperature
3-85
