User Manual

Chapter 3: Installation and Wiring 25
Field Wiring
Connections
System Wiring
Guidelines
Consider the following when wiring your system:
General
Power and input wiring must be in accordance with Class 1, Division
2 wiring methods, Article 501-4(b) of the National Electric Code,
NFPA 70, and in accordance with the authority having jurisdiction.
Channels are isolated from one another by ±10 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.
If multiple power supplies are used with analog millivolt inputs, the
power supply commons must be connected.
Provision shall be made to prevent the rated voltage being exceeded
by the transient disturbances of more than 40%.
The system shall be mounted in an ATEX certified enclosure with a
minimum ingress protection rating of at least IP54 as defined in
IEC60529 or EN60529 and used in an environment of not more than
pollution degree 2.
Earthing is accomplished through mounting of modules on rail.
Subject devices are for operation in Ambient Temperature Range: 0 C
to +60 C
Terminal Block
Do not remove the CJC sensor from the terminal block if
thermocouples are to be utilized. Removal of the sensor will reduce
accuracy.
For millivolt and current sensors, use Belden 8761 shielded,
twisted-pair wire (or equivalent) to ensure proper operation and high
immunity to electrical noise.
For RTD and resistance sensors, use Belden 9501 (2 wire), 9533 (3
wire) and 83503 ( for runs over 100 feet) or equivalent.
For a thermocouple, use the shielded, twisted-pair thermocouple
extension lead wires specified by the thermocouple manufacturer.