User's Guide

Quantum 2200 Installation Guide v2.1
Page 31
8 Connecting DC Power and Ground
8.1 Base Station Single-Point Grounding
Extensive analysis and investigation of installations has led to the belief that the root cause at the heart
of the majority of power-related failures is likely to be the presence of multi-point grounding of
equipment. Single point grounding eliminates ground voltage differentials and thus dramatically
increases equipment survivability during surges.
Single point grounding requires that the grounding leads from antennas, base station, and surge
protection devices for a particular sector are bonded together at the same point on the tower or in the
shelter, in the case of an indoor installation. It is not necessary to bond all sectors together.
An insulated crimp ring has been supplied as part of the PureWave Quantum Basic DC Installation Kit
(Table 7), along with the hardware required to mount it to the base station GND terminal connection.
Furthermore, if the optional PureWave Quantum Surge Protection Kit (Table 5) has been installed then it
includes a set of crimp rings for mounting on the ground terminals of the supplied grounding bar.
Conductors from each installed crimp ring should be connected together, and then tied to a single-point
common grounding point.
The following grounding guidelines apply, whether or not the PureWave Quantum Surge Protection Kit
has been installed:
Surge protection devices generally connect to ground by using a ground wire. Cut any extra
ground wire length when finished connecting it to the single point earth ground.
Never loop or coil up the ground wire, and avoid sharp bends. Always connect it straight to
ground.
A good earth ground impedance is less than 1.0 ohm.
Measure ground impedance at the point where the protector ground wire is connected and not
at the ground rod.
Connect the protector ground wire and equipment ground (both power ground and telecomm.
ground) to a single common ground.
Make sure all connections are fastened securely.
8.2 Preparing the DC Power Connector
The DC power source to a PureWave Quantum Base Station must be capable of delivering up to 10
Amps of current at -48 VDC. The base station requires ~6 Amps max at -48VDC (range -40VDC to -
57VDC, -38VDC min).
The power connector used on the base station will accommodate 14 to 18 gauge wire. Remember to
take account of the voltage drop when running long power cable runs. For example, for 18 AWG and a
cable length of 100 feet, a nominal 48VDC supply delivering into a 6A load will have a voltage drop of 9.3
volts.