MTL 5573 Eaton MTL5500 Series Temperature Converter (RTD / THC)

Product Overview

The MTL 5573 (MTL5573) is a sophisticated, single-channel temperature converter designed to interface with thermocouples (THC) or resistance temperature detectors (RTD) located in hazardous areas. As a key component of the MTL5500 series, this module converts low-level signals from the field into a high-level 4-20 mA current signal suitable for DCS or PLC inputs. It is widely utilized in refineries, thermal power plants, and cryogenic storage facilities where precise temperature monitoring is vital for safety and process efficiency. By providing galvanic isolation and intrinsic safety, the MTL 5573 protects control room instrumentation from high-voltage transients while ensuring accurate data transmission over long cable runs.

Technical Configuration (Deep Dive)

The MTL 5573 is highly versatile, featuring software-programmable parameters that allow it to adapt to a wide variety of industrial sensors.

• Sensor Compatibility: The module supports almost all standard thermocouples (Types J, K, T, E, R, S, B, N) and RTDs (2-, 3-, or 4-wire Pt100, Pt500, Pt1000, and various Ni/Cu sensors).

• Cold Junction Compensation (CJC): For thermocouple applications, the unit provides internal CJC to maintain accuracy despite fluctuations in the ambient temperature at the terminal connection.

• Galvanic Isolation: Features 3-port isolation between the input, output, and power supply. This prevents ground loop currents from distorting the temperature signal and enhances overall system noise immunity.

• Fault Detection: The module includes intelligent sensor-failure monitoring. In the event of a wire break or short circuit, the output can be programmed to drive "Upscale" or "Downscale," providing immediate notification to the control system.

Technical Specifications

Technical FAQs

Q1: How is the MTL 5573 configured for specific sensor types?

A1: Configuration is performed using a personal computer equipped with the MTL PCS45 configuration software and a PCL45USB serial interface link. This allows users to set the sensor type, temperature range, and burnout preferences.

Q2: Can the module handle 4-wire RTD measurements?

A2: Yes, the MTL 5573 supports 4-wire RTD connections, which is the preferred method for high-precision applications as it completely eliminates lead-wire resistance errors.

Q3: What happens if the thermocouple lead breaks?

A3: The unit will detect an open circuit and drive the 4-20 mA output to a pre-defined safety level (typically >21 mA or <3.6 mA), triggering an alarm in the DCS to prevent incorrect process control.

Engineering & Installation Guide

• RTD Wiring Precision: For 3-wire RTD setups, ensure all three leads have identical resistance. Discrepancies in lead resistance will result in a measurement offset that cannot be easily compensated by the module.

• CJC Accuracy: When using thermocouples, ensure that the module terminals are not exposed to direct drafts or rapid temperature changes, as this can affect the accuracy of the internal Cold Junction Compensation.

• DIN Rail Grounding: Ensure the 35 mm DIN rail is properly bonded to the plant's instrument earth. While the module is isolated, a stable ground reference for the rail assists in draining induced RFI/EMI.

Engineering Advantages

The MTL 5573 stands out for its high packing density, with a slim 16 mm profile that saves significant cabinet space. Its high conversion resolution and low thermal drift (typically <0.1 uV per deg C) make it suitable for custody transfer applications and critical safety instrumented systems (SIS). Furthermore, the module's ability to be configured while powered simplifies commissioning and reduces the need for external calibrators in the field.