MTL5082 Resistance Temperature Device Isolator

MTL5082 RTD Isolated Repeater – 1-Channel for Hazardous Areas

Product Introduction

The MTL5082 connects to a 2-wire, 3-wire, or 4-wire RTD located in Zone 0, IIC, T4 hazardous areas or Div. 1, Group A locations. It isolates the RTD signal and repeats the resistance value to a monitoring system in the safe area. This module works particularly well with Pt100 3-wire RTDs to BS 1904/DIN 43760 standards.

You can consider the MTL5082 as a simpler alternative to the MTL5074. It is non-configurable and serves applications where a resistance input is preferred instead of a 4-20mA signal. The design focuses on ease of use and excellent repeatability.

Key Features and Benefits

The number of wires connected on the safe-area side is independent of the hazardous-area wiring configuration. This flexibility simplifies installation. Additionally, the module drives the output upscale (to 420Ω nominal) when it detects an open-circuit sensor fault. This safety feature helps your control system recognize a wiring failure immediately.

Switches located on top of the module let you select 2-, 3-, or 4-wire RTD connection. The factory setting is 3-wire, which is the most common configuration for Pt100 sensors.

Technical Specifications

Input Characteristics

• Number of channels: 1

• RTD type: 2, 3, or 4-wire RTDs to BS 1904/DIN 43760 (100Ω at 0°C)

• Resistance range: 10Ω to 400Ω

• RTD excitation current: 200μA nominal

• Hazardous-area location: Zone 0, IIC, T4 / Div. 1, Group A

Output Characteristics

• Output configuration: 2, 3, or 4 wires (independent from input mode)

• Output range: 10Ω to 400Ω (from a 100μA to 5mA source)

Performance

• Temperature drift: ±10mΩ/°C typical (0.01%/°C at 100Ω)

• Response time: Within 4% of final value in 1 second

• Open-circuit sensor drive: Upscale to 420Ω nominal

LED Indicator

• Green LED: Provides power and status indication

Power and Safety Specifications

Isolation

• 250V ac between safe-area circuits, hazardous-area circuits, and power supply

Safety Description for Terminals 1 and 3

• Uo = 1.1V

• Io = 4mA

• Po = 1mW

• These terminals meet clause 5.4 of EN50020:1994 for simple apparatus (U ≤ 1.5V, I ≤ 0.1A, P ≤ 25mW). They can be connected into any IS loop with open circuit voltage up to 10V without further certification.

Safety Description for Terminals 1, 3, 4, and 5

• Uo = 6.6V

• Io = 27mA

• Po = 50mW

Mechanical and Environmental Information

Operating Conditions

• Ambient temperature: -20°C to +60°C

• Storage temperature: -40°C to +80°C

• Humidity: 5% to 95% non-condensing

Mounting
The MTL5082 mounts on a standard DIN rail. It requires no external calibration or configuration software. All settings are made using physical switches on top of the module.

Frequently Asked Questions (FAQ)

1. Can the MTL5082 work with a 2-wire Pt100 sensor?
Yes. You simply select 2-wire mode using the switches on top of the module. However, a 3-wire connection provides better lead resistance cancellation.

2. What happens if the RTD sensor fails or disconnects?
The MTL5082 detects the open circuit and drives the output upscale to 420Ω nominal. Your monitoring system will see this out-of-range value and trigger an alarm.

3. Is the MTL5082 configurable via software?
No. The MTL5082 is a non-configurable alternative to the MTL5074. All settings are made using physical switches. This design makes it very easy to use in the field.

4. Can I use the MTL5082 with a potentiometer instead of an RTD?
Yes. The module accepts any resistance source between 10Ω and 400Ω. You can connect a potentiometer located in the hazardous area.

5. What is the response time of the MTL5082?
The response time is fast. The output reaches within 4% of the final value in just 1 second. This suits most temperature monitoring applications.