Engineering Documentation

Table Of Contents
Chapter 4 Equipment Controllers
BACnet DXR2 Room Automation Station
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Metal Oxide Varistors (MOVs)
All DOs are normally open, 24 Vac switched triacs. Metal oxide varistors (MOVs) must
be used across the DO terminals when connected to loads. MOVs are factory-installed
in all ATEC, PTEC, and TEC products.
When installing MOVs across the DO relay contacts on termination boards, keeping
the MOV leads as short as possible makes the MOV more effective at reducing spikes
from field wiring or controlled devices. Remove and reinstall any MOVs with leads
longer than 1 inch (2.5 cm). See the section Controlling Transients [ 23] for MOV
part numbers.
BACnet DXR2 Room Automation Station
The information in this section also applies to DXP controllers and P1 DXR automation
stations except where noted.
Power Data
DXR2
Power Supply
Operating Voltage AC 24V -15%/+20%
Frequency 50/60 Hz
Internal fuse 4 A irreversible
Class 2 Transformer 4 A resettable or replaceable
Controller Voltage Input Required for Attached
Field Devices (Triac) 19.2V
AC 20.4V minimum
Increase this value by the voltage drop of the wire to the
remote field device.
Actuating DXR2 and Lab DXR2
Power supply
Operating voltage AC 24 V -15%/+20%
Frequency 50/60 Hz
Internal fuse 4 A irreversible
Class 2 Transformer 4 A resettable or replaceable
Controller Voltage Input Required for Attached
Field Devices (Triac) 19.2V
AC 19.5V minimum
Increase this value by the voltage drop of the wire to
the remote field device.
CAUTION
Observe Polarity of AC 24 V~ Power Cable.
Reversing HOT ~ and COMMON wires on 24V~ connector input can destroy DXR2.
Observe color of wire used for HOT and COMMON throughout the power trunk.
COMMON originates on the neutral side of the 24 Vac power transformer, which
must be tied to earth at the transformer, and only at this point.