The Yokogawa AST143 TC/mV Input Module is a 16-channel isolated analog input module designed for Yokogawa CENTUM VP and CENTUM CS 3000 Distributed Control Systems (DCS). The module accepts thermocouple (TC) and millivolt (mV) signals, providing accurate temperature and low-level voltage measurements for industrial process control. Each channel can be independently configured for either thermocouple or millivolt input, allowing mixed signal types within the same module. The AST143 supports IEC 60584-1 thermocouple types B, E, J, K, N, R, S, and T, as well as mV ranges of -100 to 150 mV and -50 to 75 mV.

Contents

• 1. Product Overview
• 2. Main Features
• 3. Typical Applications
• 4. Installation Preparation
• 5. Module Installation
• 6. Thermocouple and mV Wiring
• 7. System Configuration
• 8. Commissioning Procedure
• 9. Functional Verification
• 10. Preventive Maintenance
• 11. Practical Installation Case
• 12. Frequently Asked Questions

Product Overview

The AST143 converts thermocouple temperature signals and millivolt input signals into digital process values for the DCS controller. It provides sixteen isolated input channels, each configurable for either TC or mV input independently. Built-in cold junction compensation ensures accurate thermocouple measurements. The module provides 1500 VAC isolation and supports allowable input voltages up to ±5 V.

Main Features

• 16 isolated analog input channels
• Independent TC or mV configuration for each channel
• Supports thermocouple types B, E, J, K, N, R, S and T
• Supports -100 to 150 mV and -50 to 75 mV input ranges
• Built-in cold junction compensation
• 1500 VAC channel isolation
• High measurement accuracy
• Continuous self-diagnostic functions

Typical Applications

• Furnace temperature monitoring
• Boiler temperature measurement
• Heat treatment systems
• Gas turbine exhaust monitoring
• Reactor temperature measurement
• Kiln process monitoring
• Laboratory millivolt measurements
• Petrochemical and power generation plants

Installation Preparation

• Verify the AST143 module model.
• Prepare ATST4S or ATST4D terminal assemblies.
• Inspect thermocouple extension cables.
• Verify thermocouple type.
• Check cabinet grounding.
• Review wiring diagrams.
• Avoid installing the module near heat-generating equipment.

Module Installation

1. Switch off cabinet power.
2. Insert the AST143 into the designated slot.
3. Secure the module firmly.
4. Install the appropriate terminal block.
5. Connect thermocouple or mV wiring.
6. Verify channel assignments.
7. Inspect all wiring before applying power.

Thermocouple and mV Wiring

• Use matching thermocouple extension wire.
• Maintain correct thermocouple polarity.
• Use shielded instrumentation cable for mV signals.
• Ground cable shields at one end only.
• Separate signal wiring from power cables.
• Label all measurement loops.

System Configuration

• Create the AST143 module in CENTUM engineering software.
• Configure each channel as TC or mV independently.
• Select the correct thermocouple type.
• Configure engineering units.
• Download the controller configuration.
• Verify module diagnostics.

Commissioning Procedure

VERIFY MODULE INSTALLATION
VERIFY SENSOR WIRING
CHECK THERMOCOUPLE POLARITY
POWER UP SYSTEM
CONFIGURE CHANNEL TYPES
VERIFY TEMPERATURE VALUES
CHECK DIAGNOSTICS
CONFIRM NORMAL OPERATION

Functional Verification

• Verify all sixteen channels operate correctly.
• Compare readings with calibrated instruments.
• Check cold junction compensation.
• Verify engineering units.
• Review module diagnostics.
• Confirm stable measurements.

Preventive Maintenance

• Inspect thermocouple connections regularly.
• Verify extension cable condition.
• Keep terminal blocks clean.
• Review diagnostic history.
• Maintain cabinet ventilation.
• Perform scheduled calibration verification.

Practical Installation Case

A petrochemical plant installed AST143 modules to monitor reactor temperatures using Type K and Type R thermocouples. Additional channels were configured for millivolt signals from laboratory analyzers. After installation, configuration, and calibration verification, all sixteen channels provided stable and accurate measurements, improving process control and operational safety.

Frequently Asked Questions

How many input channels does the AST143 provide?

The AST143 provides sixteen isolated input channels, each independently configurable for thermocouple or millivolt measurement.

Which thermocouple types are supported?

The module supports IEC 60584-1 thermocouple types B, E, J, K, N, R, S, and T.

Are there any installation restrictions?

Yes. To maintain cold junction compensation accuracy, Yokogawa recommends not installing heat-generating modules directly below the AST143, avoiding direct airflow across the module, and leaving at least one empty slot beside the module if adjacent modules are not AST143 or ASR133.

Summary

The Yokogawa AST143 TC/mV Input Module provides high-accuracy acquisition of thermocouple and millivolt signals for Yokogawa CENTUM Distributed Control Systems. Proper installation, correct thermocouple wiring, appropriate channel configuration, and adherence to Yokogawa installation spacing recommendations ensure accurate temperature measurement and reliable long-term operation.