Micromod Micro-DCI: 53MC5000 Multi-Loop Process Controller Instruction Manual - Manual (Page 51)

2.7 POWER CONNECTIONS FOR CONTROLLER AND ITBs
An overview illustration of power connections to the controller and ITBs is provided in Figure 2-11.
The Comm ITB does not require power; therefore, it is not shown in the illustration. It should be
noted that power input requirements for the 16DI/DO ITB are dependent upon the modules in-
stalled on the board (5 V dc or 24 V dc modules, which can not be intermixed), and that the Cord
Set ITB receives +24 V dc power for the transmitters at J3 (not shown) from a controller cable.
The Cord Set ITB, however, still requires power common and chassis safety ground connections.
It should also be noted that TB3-3 (Chassis Ground) of the 6DI/4DO ITB is always connected; how-
ever, TB3-1&2 are connected only if DIs requiring +24 V dc power are wired to the ITB.
Assigned power input terminals for the controller, Cord Set ITB (power common and chassis safety
grounds), Dual Relay ITB, Analog ITB, 16DI/DO ITB, 6DI/4DO ITB, and SCADA Adapter, are illus-
trated in Figure 2-12 Sheets 1-4.
All wiring is supplied by the customer.
A controller can be ordered to operate with either a +24 V dc input or with ac inputs of 110/120 V
or 220/240 V. Procedures to connect the controller to +24 V dc (negative ground), +24 V dc
(floating ground), 110/120 V ac, 220/240 V ac, and 220 (208)/240 V ac (no neutral) are pro-
vided in Sections 2.7.1 through 2.7.5.
WARNING
Instruments that are powered from an ac line service constitute a
potential electric shock hazard to the user. Make certain that these
system ac power lines are disconnected from the operating branch
circuit before attempting electrical connections.
GROUNDING
Installations are expected to have access to a high quality, noise-free
point of earth reference. Connection should be through a low
resistance (less than one ohm) lead wire directly to the installation’s
point of earth reference which can be an independent grounding rod or
ground grid mesh that penetrates the permanent moisture level below
the frost line in accordance with Article 250 of ANSI/NFPA 70, the
National Electrical Code, or other code(s) acceptable to the authority
having jurisdiction over the installation.
COMMON BUS BAR
Use of a common bus bar that is connected to the earth ground through
a low resistance (less than one ohm) lead wire is recommended to
minimize potential voltage differences that may occur as a result of
ground loops, e.g., potential differences between separate power
grounds, signal grounds, etc.
METAL CONDUIT
In noisy locations, the power wiring should be enclosed in metal
electrical conduit and not routed in close proximity to signal wiring.
53MC5000 Process Control Station
2-12