TLD GPU-406, Manual

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Creation: 17.10.2013 2-5-1
GPU - 406
GPU - 409
B. Adjustments
The GPU-409 ground power unit uses the TLD-designed Generator Control Module which
eliminates the need for periodic switch and relay setting adjustments. The following is a list of
adjustments that are available to maintenance and operations personnel, depending on different
airline requirements.
Operations Personnel Adjustments
Current Limiting for optional 28.5 VDC output – use this adjustment to limit the maximum
DC current that is supplied to the airplane.
1. With the GPU running, press the GREEN button to activate the 28VDC output.
2. When the output information is available on the screen, press the rotary dial
button once to toggle to the current limit setting.
3. Turn the dial left or right to decrease or increase the current limit. The current
limit will appear on the screen.
4. Press the rotary dial to exit the setting. Note that the setting will reset to a
default setting next time the 28VDC output is used.
Maintenance Personnel Adjustments
400 Hz AC voltage setting – Units are factory set at 115 VAC, no load. A large setting
range is provided to allow for proving the over and under voltage protection settings are
functioning properly.
1. Apply a magnet to the GCM2 to the left side of the GCM. There is a cut-out in the holding bracket for this
purpose.
2. Press and hold the rotary dial until the adjustment bar appears across the top of the display.
3. Rotate the dial to scroll to the setting named “ACV Target Cts”.
4. Press the rotary dial button to enter the setting.
5. Rotate the dial left or right to decrease or increase the adjustment.
6. When the adjustment is complete, press and hold the rotary dial until the adjustment bar disappears from
the top of the screen.
400 Hz AC line drop compensation – Units are factory set at 6%, assuming a standard 30’
cable is used. If older or longer cables are used, increase the setting to compensate for the
increased resistance in the cable. The setting is correct when 115 VAC is maintained at the
load bank with a 90 kVA load applied.
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