The Yokogawa MTC series terminal board operates as a dedicated hardware component for signal termination and cold junction compensation (CJC) within distributed control system (DCS) platforms.

Hardware Specifications

Cold Junction Compensation and Signal Integrity

The MTC terminal board serves as the critical interface between field-mounted thermocouples and the DCS analog input modules. Because thermocouples operate by generating a low-millivolt potential based on the Seebeck effect, the terminal board incorporates high-precision temperature sensing elements to perform cold junction compensation (CJC). This ensures that the voltage reference at the terminal connection is factored into the temperature calculation, maintaining measurement accuracy. The design utilizes specialized thermocouple-grade alloys in the termination pins to prevent parasitic thermal EMFs that would otherwise degrade signal linearity.

Frequently Asked Questions

Q: Does the MTC terminal board require external power for operation?

A: No. The MTC is a passive terminal interface. While the board facilitates the transmission of thermocouple signals, the actual excitation and digitization occur at the connected analog input module.

Q: Is it possible to use standard copper wire for connections between the thermocouple and the MTC terminal board?

A: No. Thermocouple extension wire must be used for all connections from the sensing point to the MTC terminal board to prevent the formation of unwanted thermocouple junctions that would result in measurement errors.

Field Installation Guidelines

• Mount the terminal board securely on a DIN rail, ensuring the grounding lug is connected to the cabinet's protective earth to minimize electromagnetic interference.
• Use a calibrated torque screwdriver to secure wires into the terminals; excessive force can damage the terminal block pins, while insufficient force leads to high-resistance connections.
• Ensure proper polarity matching between the thermocouple extension wire and the MTC terminal input markings (typically labeled '+' and '-').
• Maintain a stable thermal environment inside the cabinet; direct drafts or localized heat sources near the terminal board can cause fluctuations in CJC accuracy.