Rockwell Automation 1746-NT8 SLC 500 Thermocouple/mV Analog Input Module/ Instructions - Manual (Page 13)

SLC 500 Thermocouple/mV Analog Input Module 13
Publication 1746-IN015C-EN-P - July 2001
Exposed Junction Thermocouples
Cable Wiring Considerations
Follow these guidelines to wire your input signal cables:
•
Power, input, and output (I/O) wiring must be in accordance with Class 1,
Division 2 wiring methods [Article 501-4(b) of the National Electrical Code,
NFPA 70] and in accordance with the authority having jurisdiction.
•
Route the 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 120 V of power.
•
Routing the field wiring in a grounded conduit can reduce electrical noise
further.
•
If the field wiring must cross ac or power cables, ensure that they cross at
right angles.
•
To limit the pickup of electrical noise, keep thermocouple and millivolt
signal wires as far from power and load lines as possible.
•
For high immunity to electrical noise, use Belden™ 8761 (shielded, twisted
pair) or equivalent wire for millivolt sensors; you can also use shielded,
twisted pair thermocouple extension lead wire specified by the
thermocouple manufacturer. Using the incorrect type of thermocouple
extension wire or not following the correct polarity may cause invalid
readings.
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1746-NT8
Conductive Material
Exposed junction with
shielded cable
CH 0
MUXES
Nonconductive Material
Exposed junction with
shielded cable
CH 3