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28.5 VDC Ground Power Unit
Models:
11A6647-1000/1010
11B6647-1000/1010
11C6647-1000/1010
11D6647-1000/1010
11A6647C1000/1010
11B6647C1000/1010
11C6647C1000/1010
11D6647C1000/1010
11A6655-1000/1020
11B6655-1000/1020
11C6655-1000/1020
11A6655C1000/1020
11B6655C1000/1020
11C6655C1000/1020
11D6655C1000/1020
11A6665-1000/1010
11B6665-1000/1010
11C6665-1000/1010
11A6666-1000
11B6666-1000
11C6666-1000
12/2006 - Rev. 04
- 16 -
4.4
STORAGE
4.4.3
Altitude, Temperature & Humidity
The 28V DC GPU is designed for an installation altitude of up to 1000 meters above mean sea
level, an ambient temperature of -20 to 40
o
C / -4 to +104
o
F and a relative humidity of up to 95%.
The optimum temperature is around 68
o
F. Please ensure that any existing air-conditioning plant
meets these conditions and is also able to remove the unit's dissipated heat. Details are shown in
the Technical Data (Section 2). The cooling air must always be free of corrosive agents. You
should consult your Tronair representative if planning an installation above 1000 meters.
4.5
ELECTRICAL CONNECTIONS (POWER)
4.5.1
Cable Entry
The input and output cables are connected in the lower part of the cubicle. The cables can be brought up
to the cubicle from the left (input cable ) and the right (output cable) and led in through end panel of the
cubicle. Please refer to table below for the cable sizes, which must conform to local electrical code.
Always ensure that the phases of the three-phase input connections are correct (clockwise rotating field),
since incorrect connections could cause damage to the equipment.
Cables must be properly gasketed with a screwed gasket fitted with a strain-relief device and sealing ring.
4.5.2
Cable Sizing
Cables should be sized in accordance with the rating of the next protective device upstream,
taking into account temperature, voltage-drop and installation method factors, as per the
appropriate standard for the site. In general, Tronair recommends that the voltage-drop for both
input and output power cables should not exceed 1.5%, and that the connecting cables should be
as short as possible especially the output cable (less than 10 m/30 feet is recommended). Tronair
should be consulted if these requirements cannot be met.
When specifying the cable lengths allow for about 0.5 m/20 in. inside the cubicle. The
table on the following page shows the recommended cable types:
Equipment Type
Line
Voltage
Rated
Amps
Input Cable (If Less Than 30´)/
Copper Size
Output Cable
28V DC GPU 600A
208
56
1 x NYY 4 x 10 RE/10 or #4
2 x NYY 120 or 2x 4/0 cables
230
51
1 x NYY 4 x 10 RE/10 or #4
400
29
1 x NYY 4 x 6 RE/6 or #8
480
24
1 x NYY 4 x 4 RE/4 or #8
575
20
1 x NYY 4 x 4 RE/4 or #8