62 Rockwell Automation Publication ICSTT-RM448M-EN-P - February 2021
Chapter 4 Before You Begin
The power supply protection of the controller is in the modules, the power
distribution arrangement must have a circuit breaker on the input side of each
power source. The controller is designed to be resistant to a reverse polarity
connection without permanent damage.
The power sources must come from a commercially available industrial un-
interruptible power supply (UPS) system. An applicable UPS must have the
capacity sufficient to satisfy the entire system load (including field devices and
the controller) and an applicable contingency allowance for projected future
expansion.
Power Arrangements for Field Devices
Output modules use an external source of power for field devices. This may be
the power source used for the controller or a separate power source.
• For digital and analogue outputs a field power supply of +24 Vdc within a
range of 18-32 Vdc is required.
Recommended field circuits are given for each type of I/O module later in the
section "Connecting Field Wiring".
Power Distribution Protection
The power distribution circuit for each field input and for each output module
must be protected, externally to the controller. Rockwell Automation
recommend that power distribution must meet national and local panel wiring
protection standards.
Digital Output Field Power
Special fusing arrangements are required for Digital Output field supplies for
UL, ATEX and IECEx approved installations, (see topic on field loops for
Digital Output Modules).
Estimating Power
Consumption
To estimate the power supply requirements (power supply sizing) you need to
know the power consumption of all the modules. Use the following table to
estimate the system power consumption.
WARNING: The power supplies must satisfy the electrical requirements
and tests specified in IEC 61131 EN 61010-1 and EN 60950 and must be big
enough for the system requirements.
IMPORTANT
It is highly recommended that the negative side of the field
supply be connected to earth (ground). This will avoid possible
fail danger conditions that can be caused by some earth fault
monitors used with floating power supplies.
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