Spectrum-controls 1769sc-IR6I Manual de usuario descargar pdf (Pagina 18)

2-4 Compact™ IO Isolated RTD/Resistance Module

User’s Manual Pub. 0300241-01 Rev. A

Follow the guidelines below when wiring the module.

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 500V dc maximum.

• Route field wiring away from any other wiring and keep it 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.

• To ensure 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.

Grounding

• 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.

• Keep cable shield connections to ground as short as possible.

• Ground the shield drain wire at one end only. The preferred location is as

follows.

o For grounded thermocouples or millivolt sensors, this is at the sensor

end.

o For insulated/ungrounded thermocouples, this is at the module end.

Contact your sensor manufacturer for additional details.

• 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:

o To ensure temperature or resistance value accuracy, the resistance

difference of the cable lead wires must be less than or equal to 0.01  .

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Spectrum-controls 1769sc-IR6I Manual de usuario Pagina 18