Spectrum Controls 1769sc-IR6I - Manual (Page 28)

3-8 Compact™ IO Isolated RTD/Resistance Module
User’s Manual Pub. 0300241-01 Rev. A
Section 3.7
Field Wiring
Connections
3.7.1 System Wiring Guidelines
Consider the following when wiring your system:
General
•
This product is intended to be mounted to a well-grounded mounting surface
such as a metal panel. Additional grounding connections from the module’s
mounting tabs or DIN rail (if used) are not required unless the mounting surface
cannot be grounded.
•
Channels are isolated from one another by 500 Vdc maximum.
•
Route field wiring away from any other wiring and as far as possible from
sources of electrical noise, such as motors, transformers, contactors, and ac
devices. As a general rule, allow at least 15.2 cm (6 in.) of separation for every
120V of power.
•
Routing field wiring in a grounded conduit can reduce electrical noise.
•
If field wiring must cross ac or power cables, ensure that they cross at right
angles.
•
To ensure optimum accuracy, limit overall cable impedance by keeping your
cable as short as possible. Locate the I/O system as close to your sensors or
actuators as your application will permit.
•
Tighten terminal screws with care. Excessive tightening can strip a screw.
Shield Grounding
•
Use Belden shielded, twisted-pair wire to ensure proper operation and high
immunity to electrical noise. Refer to the following table and the RTD Wiring
Considerations below.
Configuration Recommended Cable
2-wire Belden™ 9501 or equivalent
3-wire
Less than 30.38 m (100 ft.) Belden™ 9533 or equivalent
3-wire
Greater than 30.48 m (100 ft.) or high humidity
conditions Belden™ 83503 or
equivalent
•
Under normal conditions, the drain wire and shield junction should be connected
to earth ground, via a panel or DIN rail mounting screw at the 1769sc-IR6I
module end.
•
Keep shield connection to ground as short as possible.
•
If noise persists for a device, try grounding the opposite end of the cable. (You
can only ground one end at a time.)