Users Manual Part 1

4.5.3.1
-48 VDC Input Power and Backup Battery Charging Connections
The -48 VDC connectors are used for:
• Supplying the MTS with power in the DC only mode – in DC only mode the MTS takes the power
from a separate -48 VDC facility power system
• For charging backup batteries in the AC mode
CAUTION: An external disconnect device is required on the DC power supply line.
CAUTION: If the DC input on the station is connected to backup batteries, an external Low
Voltage Disconnect (LVD) device should be introduced directly in the power line in order to
protect the batteries against deep discharge. On the MTS 2, one relay rated min. 20A/55 VDC
should be introduced. And for the MTS 4, two of these units should be used, one for each of the
two incoming DC lines. Alternatively for the MTS 4, one relay rated 40A/55 VDC can be used if
the two DC lines are connected to one battery pack. The relays should be controlled in a way
that they disconnect the batteries once the voltage drops below 40.5 V, where the PSU in the
MTS shuts down. Two Motorola Solutions kits are available for this purpose:
• MTS2 LVD RELAY RETROFIT KIT (Kit Number: GMDN2206A)
• MTS4 LVD RELAY RETROFIT KIT (Kit Number: GMDN2207A)
NOTICE: -48 VDC Connection on the MTS 2 Junction Panel and -48 VDC Connections on the
MTS 4 Junction Panel depict the newer version of the MTS Junction Panel. There may be small
differences in older configurations.
6802800U74-AP
Chapter 4: Hardware Installation
106