Allen-Bradley Compact 1769-IR6, Руководство пользователя, Страница: 22 / 116

Publication 1769-UM005A-EN-P
2-4 Quick Start for Experienced Users
•
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.
•
Use Belden shielded, twisted-pair wire to ensure proper operation
and high immunity to electrical noise. See the table below for
recommended types.
•
Keep cable shield connection to ground as short as possible.
•
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 1769-IR6 module end.
•
If noise persists for a device, try grounding the opposite end of the
cable. (You can only ground one end at a time.)
•
Refer to
Industrial Automation Wiring and Grounding Guidelines
,
Allen-Bradley publication 1770-4.1, for additional information.
RTD Wiring Considerations
•
The module requires three wires to compensate for lead resistance
error.
•
If using a 3-wire configuration for module connections, select cable to
ensure that lead wire resistances match as closely as possible.
Consider the following:
– To ensure temperature or resistance value accuracy, the resistance
difference of the cable lead wires must be less than or equal to
0.01
Ω
.
– Keep lead wire resistance as small as possible and less than 25
Ω
.
– Use quality cable that has a small tolerance impedance rating and
consistent impedance throughout its length.
– Use a heavy gauge lead wire with less resistance per foot.
Configuration
Recommended Cable
(1)
2-wire Belden™ 9501 or equivalent
3-wire
less than 30.48 m (100ft.) Belden™ 9533 or equivalent
3-wire
greater than 30.48 m (100 ft.) or high humidity conditions Belden™ 83503 or equivalent
(1) For additional information, see page A-4.