Connecting Power; Connecting Power Cables To A Gtr 8000 Base Radio; Dc Power Connection Wire Gauge Calculations For Integrated Voice And Data - Motorola ASTRO 25 GTR 8000 Manual

3 Lift the device into place on the rack using the pins on the brackets to properly line up the
device.
4 Attach the two brackets to the rack:
a For a Motorola Solutions modular rack, use M6x1x10 thread-forming screws with a black
finish.
b For a Motorola Solutions open rack, use 1224x5/8 thread-forming screws (zinc plated).
c For your own rack, use hardware appropriate for the rack.
d Attach the brackets to both sides of the rack through the upper back openings on the
brackets.
e Attach the brackets to the rack on both sides through the lower back openings.
5 In the front, attach the chassis to the brackets:
a Screw two M6x1x10 thread-forming screws (black finish) through the front holes on one side
of the chassis and into the bracket.
b Screw two M6x1x10 thread-forming screws (black finish) through the front holes on the other
side of the chassis and into the bracket.
3.4.4

Connecting Power

This section covers topics on connecting power cables to the base radio, calculating the length of wire
for various gauges, and mounting the battery temperature sensor.
3.4.4.1

Connecting Power Cables to a GTR 8000 Base Radio

For standalone base radios, AC and DC inputs, provided by your organization, connect to the power
supply through the backplane of the base radio. See
(Integrated Voice and Data) on page
108, and GTR 8000 Base Radio Front Connections on page
3.4.4.2
DC Power Connection Wire Gauge Calculations for Integrated Voice and
Data
Because the power supply disconnects itself from the DC input when it senses that DC voltage has
dropped to 42 VDC, it is important to minimize the voltage drop in the DC power supply loop (the total
length of the 48 VDC hot wire and the DC return wire) to no more than 1 V total. Minimizing the voltage
drop ensures that the maximum energy is removed from the battery before disconnecting the power
supply from the DC input line.
A base radio transmitting at 100 W draws up to 10 A* current when operating from a 54 V source
(nominal 48 VDC system). As voltage decreases (due to the standby battery discharging) the current
increases proportionally (because the base radio appears to be a constant power load). At the low
voltage disconnect point (42 V for a nominal 48 VDC system), the current is up to 13 A*. If a single pair
of 2 AWG wire is used to connect the battery to the back panel, the maximum length of a single
conductor would be 75 m (245 ft). Use of smaller gauge wire would reduce this length depending on
the resistance of the wire.
* = The actual current value can be calculated from the power consumption value in the specifications
tables. See GTR 8000 Base Radio Specifications on page
To determine the maximum length of wire for wire other than 2 AWG, the following relationship can be
used:
GTR 8000 Base Radio Rear Connections
105, GTR 8000 Base Radio Rear Connections (HPD) on page
110.
40.
Chapter 3: GTR 8000 Base Radio Installation
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