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MTL Barries - MTL5575 - TEMPERATURE CONVERTER
(THC or RTD input + Alarm)
The MTL5575 is an intrinsically safe temperature converter that takes low-level signals from thermocouples (THC) or RTDs (Resistance Temperature Detectors) in hazardous areas and converts them into a standard, robust 4/20mA current signal for safe-area control systems, using galvanic isolation to protect circuits, featuring software-selectable inputs, ranging, linearization, and alarm outputs for reliable, explosion-proof temperature monitoring.
Core Working Principle:
- Hazardous Area Input: A temperature sensor (thermocouple or RTD) in a potentially explosive environment (Zone 0, 1, 2) sends a tiny electrical signal to the MTL5575.
- Intrinsic Safety & Isolation: The MTL5575 acts as an isolator, using advanced design (like Zener barriers or isolating transformers) to limit the energy (voltage and current) entering the hazardous zone, preventing sparks that could ignite flammable gases or dust.
- Signal Conversion: Inside the device, the low-level signal is processed, linearized (if needed for non-linear sensors), and scaled to a standard 4-20mA range, which is proportional to the measured temperature.
- Safe Area Output: This isolated 4-20mA signal is then transmitted to a control system (like a PLC or DCS) in a safe area for monitoring, logging, and control.
- Alarm Function: It includes an alarm output that can be configured for process alarms or to detect early thermocouple failure (e.g., burnout), enhancing safety.
| TEMPERATURE CONVERTER - (THC or RTD input + Alarm) |
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Key Features:
- Universal Input: Accepts various thermocouple types (J, K, T, etc.) and RTDs (Pt100, etc.).
- Galvanic Isolation: Separates hazardous and safe circuits, eliminating earth loops.
- DIN-Rail Mounting: Simplifies installation.
- PC Configuration: Allows easy setup of ranges, alarms, and sensor types.
In essence, the MTL5575 bridges the gap between harsh, hazardous environments and safe control rooms, ensuring accurate temperature measurement while maintaining explosion protection.
The MTL5575 is a single-channel, intrinsically safe temperature converter (isolator) that converts a low-level DC signal from a temperature sensor in a hazardous area into a safe, proportional 4-20mA current signal for use by control systems in a safe area.
Its working principle revolves around the use of advanced circuit design and innovative isolating transformer construction to provide galvanic isolation. This means there is no direct electrical connection between the hazardous area and the safe area circuits, which prevents high energy from the safe area from reaching the hazardous area and potentially causing an explosion.
Key Operational Steps and Features
- Signal Conversion: The device accepts input from various temperature sensors, including different types of thermocouples (J, K, T, E, R, S, B, N) and 2-, 3-, or 4-wire RTDs (Pt100, Pt500, Pt1000, etc.). It processes this low-level voltage or resistance signal, performing linearization and ranging (which can be configured via PC software) to accurately represent the measured temperature value.
- Galvanic Isolation: This is a core function of the MTL4500 series. The unit uses innovative "One-Core" technology and isolating transformer construction to provide complete galvanic isolation between the hazardous-area field circuits and the safe-area control circuits. This isolation is critical for safety, as it prevents high voltages or energy surges in the safe area from reaching the hazardous area and potentially igniting flammable gases or dust. The design limits current and voltage in the hazardous area to intrinsically safe levels.
- Signal Transmission: The processed and isolated signal is output as a standard 4–20mA current signal, suitable for driving a safe-area load or connecting to a control system (DCS, PLC, etc.). It also provides a configurable alarm relay output for process alarms or sensor failure alerts (e.g., early burnout detection for thermocouples).
- Configuration and Monitoring: The device is software-configurable via a personal computer. This allows users to select the sensor type, set the measurement range, apply linearisation, and configure a single alarm output for process alarms or thermocouple failure notification.
The core working principle is to act as a safety interface that protects personnel and equipment by ensuring that only intrinsically safe energy levels are present in the hazardous location, while accurately transmitting process data to the control system.
For detailed technical specifications and installation guidelines, you can refer to the official Eaton MTL5500 instruction manual or the product datasheet.
 Full Datasheet
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