CHAPTER 3: INSTALLATION
MDU Solutions
®
– UCrypt
®
IP to Analog 2
nd
Generation – Installation & Operation Manual
3-11
3.12 DC Power Supplies
3.12.1 DC Power Supply Connections
The optional redundant DC switching type power supply system is intended to operate on nominal -48 VDC power systems
but functions between -40 and -57.2 VDC. A pair of
insulated #12 AWG
DC power wires must be field installed for each of the
two modules using permanent wiring methods. Wire insulation colors must be different for each of the two conductors clearly
indicating the polarity of the voltage. It is recommended that stranded conductors be used for DC power and that RED wire be
used for the 0V conductor and BLACK for the -48V conductor. Crimped on style Ring or Spade terminals may be used and it
is also permissible to strip the wire 8mm, twist the stranded conductors tightly and clamp the wire in the provided wire clamp
as illustrated in Figure 3-11.
3.12.2 DC Disconnect and Fusing
Each DC power module should be externally fused or otherwise adequately protected at no more that 20 Amperes and
must be provided with it’s own external readily accessible disconnect device. Each disconnect must be prominently labeled
indicating the units being powered and with adequate instructions for the removal of all power from the unit being serviced.
The disconnect must be turned off for BOTH power modules before removing supply wires from the module terminal blocks
when replacing a power supply module or otherwise servicing the unit.
3.13 Power Supply Redundancy
For the redundant power supplies, either power module on its own can provide the required power safely if one fails. To retain
the redundancy feature, replace a failed power module as soon as possible. A power module failure or the failure of the supply
current or protection fuse will be indicated by an audible alarm within the encoder power modules and the green power status
LED on the power module will be extinguished. Silence the audible alarm with the red rear panel
Alarm Reset
switch adjacent
to the power supply modules, Figure 3-12.
3.13.1 Redundant Power Module Replacement
AC Version
WARNING:
The power cords for
BOTH
power modules must be disconnected before attempting
to remove the power modules or otherwise servicing the unit.
Power module failure will be indicated by the alarm being sounded and the green status light on the module will no longer be
lit. This power module may be replaced by first disconnecting the AC power cord from the IEC input socket of BOTH power
modules, then release the module by pressing to the left on the thumb latch at the bottom of each module. Extract the module
and replace with an identical replacement module only.
Figure 3-11: DC Power Module Connections
0 Volts In
-48 Volts In
Latch
Mute
Alarm
Safety
Ground
Figure 3-12: Redundant DC Power Supply
