Allen-Bradley 1771-WI Thermocouple Wiring Arm

The Allen-Bradley 1771-WI, also cataloged as the 1771-WI Thermocouple Wiring Arm, operates as a dedicated hardware component for field sensor signal termination and module interface wiring within Allen-Bradley 1771 Universal I/O chassis platforms.

Hardware Specifications

Process Control Signal Termination & CJC Isolation

The 1771-WI mounts directly onto the front pivot bar of a 1771-IXE thermocouple input module, facilitating 18-point screw terminal access for field-side thermocouple wire pairs without requiring module removal during maintenance. To maintain high accuracy across millivolt-level temperature signals, the wiring arm incorporates cold junction compensation (CJC) thermistors across its terminal strip. Onboard galvanic isolation and dedicated shield terminals prevent channel-to-channel crosstalk and isolate low-level analog signals from severe industrial electromagnetic interference.

Frequently Asked Questions

Q: Does the 1771-WI wiring arm require external DC power or draw backplane current?

A: No, the 1771-WI is a passive field wiring connector arm. It draws 0 mA from the 1771 backplane bus and requires no external power connections.

Q: Which Allen-Bradley 1771 I/O module is specifically paired with the 1771-WI wiring arm?

A: The 1771-WI is engineered specifically for use with the 1771-IXE high-resolution thermocouple/millivolt input module to provide accurate cold junction compensation.

Field Installation Guidelines

1. Chassis Latching: Engage the lower pivot hooks of the 1771-WI arm onto the 1771 chassis pivot bar, then swing the arm upward until it snaps firmly into the 1771-IXE module faceplate connector.
2. Thermocouple Wiring: Connect field thermocouple extension leads directly to the 18 screw terminals using correct polarity. Ensure thermocouple extension wire alloy matches the specific thermocouple type (e.g., Type J, K, T) connected.
3. CJC Sensor Preservation: Avoid touching or modifying the onboard cold junction compensation thermistors embedded near the terminal block, as mechanical stress or contamination alters temperature measurement accuracy.
4. Shield Wire Grounding: Terminate individual thermocouple wire shield drain wires strictly at the designated shield terminals on the wiring arm to prevent high-frequency ground loop currents.
5. Strain Relief: Fasten field wire bundles using the bottom cable tie bar to ensure mechanical strain is not transferred directly to the terminal screw clamps.