AMM21T | Yokogawa CENTUM Thermocouple Input Module

Product Overview

The Yokogawa AMM21T functions as a high-precision thermocouple input module designed for the CENTUM distributed control system (DCS) architecture. This module interfaces directly with a wide array of industrial thermocouples to provide accurate temperature monitoring across an expansive range of -200°C to +1800°C. It converts low-millivolt sensor signals into standard 4-20 mA outputs for the control station's logic processing. We supply this unit as 100% Brand New and original, ensuring factory-sealed integrity for critical thermal management applications.

Technical Specifications

The AMM21T provides industry-leading measurement sensitivity and robust signal conversion parameters:

• Thermocouple Compatibility: Types J, K, T, E, R, S, B, N

• Input Range: -200°C to +1800°C (Sensor dependent)

• Input Impedance: > 100 MΩ

• Common Mode Rejection Ratio (CMRR): > 60 dB

• Output Range: 0 to 20 mA or 4 to 20 mA

• Measurement Accuracy: ±0.25% of full scale

• Response Time: ≤ 2 s

• Power Consumption: ≤ 10 W

• Operating Temperature: -20°C to +60°C

• Storage Temperature: -40°C to +70°C

• Operating Humidity: 0 to 95% RH (Non-condensing)

• Condition: 100% Brand New and Original

Engineering Advantages

The AMM21T solves specific technical challenges encountered in high-temperature process environments:

• Universal Sensor Interfacing: This module accepts eight different thermocouple types (J through N). This versatility eliminates the need to stock multiple specialized modules, significantly simplifying spare parts inventory and allowing for heterogeneous sensor arrays on a single I/O rack.

• Superior Noise Suppression: With a Common Mode Rejection Ratio exceeding 60 dB and high input impedance, the AMM21T effectively filters out electromagnetic interference (EMI). This ensures stable temperature readings even when thermocouple wires run parallel to high-voltage power lines or heavy motor machinery.

• High-Precision Signal Linearization: The module's internal circuitry achieves an output accuracy of ±0.25%. This precision allows for tighter control over temperature-sensitive reactions in chemical and pharmaceutical processing, reducing waste and improving product consistency.

• Robust Environmental Adaptation: An operating temperature range of -20°C to +60°C permits installation in field-mounted cabinets without the immediate need for supplemental cooling or heating units. The 0-95% humidity tolerance safeguards the internal logic against moisture-induced corrosion in humid plant environments.

FAQs

Which thermocouple type provides the best results with the AMM21T?

The module maintains high accuracy across all supported types. However, you must match the thermocouple type to your specific process temperature. For instance, Type K offers excellent general-purpose range, while Type B or S handles extreme temperatures up to 1800°C.

How does the high input impedance benefit the system?

The >100 MΩ input impedance ensures that the AMM21T does not "load" the thermocouple circuit. This prevents voltage drops across the lead wires, maintaining the integrity of the millivolt signal over long cable runs.

Is external cold-junction compensation (CJC) required?

The AMM21T typically utilizes internal CJC when paired with the correct Yokogawa terminal board. This simplifies wiring by allowing you to terminate thermocouple extension wires directly at the module's interface.

Can the AMM21T detect a broken sensor wire?

Yes. The module incorporates burnout detection logic. If a thermocouple wire breaks, the module drives the output signal to a pre-defined "upscale" or "downscale" value, immediately alerting the DCS operator to the hardware fault.