Allen-Bradley CompactBlock LDX 1790D-4T0, Руководство пользователя

Страница: 26 / 112

Publication 1790-UM003A-EN-P - May 2002
2-12 Installation and Wiring
Field Wiring Connections System Wiring Guidelines
Consider the following when wiring your system:
General
•
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.
Terminal Block
•
Do not use the module’s NC terminals as connection points.
•
For millivolt sensors, use Belden 8761 shielded, twisted-pair wire
(or equivalent) to ensure proper operation and high immunity to
electrical noise.
•
For a thermocouple, use the shielded, twisted-pair thermocouple
extension lead wires specified by the thermocouple manufacturer.
Using the incorrect type of thermocouple extension wire or not
following the correct polarity will cause invalid readings.
•
To ensures optimum accuracy, limit overall cable impedance by
keeping a cable as short as possible. Locate the module as close to
input devices as the application permits.