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 TM 55-1905-223-24-3
(c) Check to make sure the engine rpm or frequency is at the specified
value.
(d) If all the above are correct, there is a defect in the generator rotor winding.
(27)
Stop the engine. Remove the generator from the engine. Refer to paragraph 3-12.
(28)
Remove the rotor from the generator. Refer to Disassembly procedures.
(29)
If the X to XX is below 5 volts:
(a) The frequency may be too high.
(b) The generator output voltage may be too low.
(c) The generator leads may be incorrectly connected.
k. Automatic voltage regulator adjustments.
NOTE
A quick test for proper operation of the AVR is to operate the engine at 1500 rpm, turn the voltage
adjust rheostat on the AVR from maximum to minimum volts, and observe the generator output
voltage change.
Before installing a new AVR, check to see that the top jumper is installed on the top "C" (common)
and "60 volt" terminals. This jumper sets the protective voltage level in the AVR.
Check to see that the bottom jumper is installed between the bottom "C" and the "4P60" (4 pole, 60
Hz) terminals. The placement of this jumper determines the speed range where underfrequency
protection begins.
(1)
Connect all ten leads to the AVR. Mount the AVR in the AVR box using the four threaded pillars
(2)
Turn the AVR coarse voltage control (1, Figure 4-5) all the way counterclockwise.
(3)
Start and bring the engine up to rated speed.
(4)
Turn the coarse voltage control (1) clockwise until the generator is producing approximately rated
voltage. Turn the remote voltage trimmer control to obtain the voltage required.
(5)
The AVR gain control (2) is difficult to locate. It is on the main AVR control board and is accessible
through a 0.160 in. (4 mm) diameter hole
4-19
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