MTL 4851 Loop-Powered Isolator | 2-Wire, 4-20mA, 1:1, IS, DIN Rail, FM/ATEX/IECEx Specs

MTL 4851 Loop-Powered Isolator | 2-Wire, 4-20mA, 1:1, IS, DIN Rail, FM/ATEX/IECEx Specs

MTL 4851 loop-powered isolator specifications. 2-wire, 4-20mA, 1:1 isolation, 24V DC loop, intrinsic safety. FM/ATEX/IECEx approved for hazardous areas.

Product Overview

The MTL 4851​ is a loop-powered, two-wire signal isolator​ from MTL's 4800 series, designed for intrinsic safety applications​ in hazardous areas. This device provides 1:1 signal isolation​ for 4-20mA current signals, is powered directly from the 4-20mA loop, and carries FM, ATEX, and IECEx approvals​ for Zone 1 hazardous locations. The "4851" designation identifies this specific isolator model. This device protects control systems from ground loops and interference while providing safety isolation for field instruments in explosive atmospheres, featuring low voltage drop and high accuracy.

Technical Specifications

Note: Specifications are based on MTL 4800 series documentation. The 4851 represents an advanced generation with improved performance characteristics. Always verify with the latest product datasheet for your region.

Key Features

• Ultra-Low Voltage Drop:​ Only 5.0V at 20mA, maximizing available loop voltage

• Wide Temperature Range:​ -40°C to +70°C operation for extreme environments

• High Accuracy:​ ±0.1% accuracy for precise signal transmission

• Fast Response:​ < 50 ms response time for dynamic applications

• Loop-Powered Operation:​ No separate power supply required

• 1:1 Isolation:​ Provides galvanic isolation between field and control systems

• Intrinsic Safety:​ Approved for Zone 1 hazardous locations

• Bi-color LED:​ Visual indication of loop operation and fault conditions

• Compact Design:​ Only 12.5mm wide for high-density installations

• Global Approvals:​ Certified for international hazardous area applications

• Maintenance-Free:​ No calibration or maintenance required

Entity Parameters (for Hazardous Area Design)

Note: The 4851 is typically considered a "simple apparatus" when used within its electrical parameters.

LED Status Indication

Performance Characteristics

Note: Minimum loop voltage = Isolator voltage drop + Transmitter minimum voltage + Cable drop

Typical Applications

• Process Control:​ Isolation of 4-20mA signals from field transmitters in hazardous areas

• Temperature Monitoring:​ Isolation for RTD and thermocouple transmitters in extreme temperatures

• Pressure/Level Measurement:​ Signal isolation for pressure/level transmitters

• Flow Measurement:​ Isolation for flow transmitter signals

• Analytical Instruments:​ Signal conditioning for gas detectors and analyzers

• Remote Locations:​ Applications requiring wide temperature range operation

• Marine/Offshore:​ Signal isolation in harsh environmental conditions

• Mining:​ Underground instrumentation signal isolation

• Any application requiring​ intrinsic safety isolation for 4-20mA signals with minimal voltage drop

Important Technical Notes

1. Loop Voltage Calculation:​ Critical for proper operation. Ensure: Power Supply Voltage ≥ (Transmitter Vmin + 4851 Voltage Drop + Cable Drop). Minimum 8.5V required at isolator.

2. Wide Temperature Operation:​ The 4851 operates from -40°C to +70°C. At temperature extremes, accuracy specifications apply over 0-60°C range.

3. System Certification:​ The entire intrinsically safe loop must be properly certified. Use only approved power supplies and field devices.

4. Grounding:​ While the isolator doesn't require a safety ground, proper grounding of the control system is essential for noise immunity and lightning protection.

5. Wiring Practices:​ Use twisted pair cables for noise immunity. Maintain separation between intrinsically safe and non-intrinsically safe wiring (minimum 50mm).

6. Voltage Limitations:​ Do not exceed 30V DC maximum loop voltage. Ensure power supply is current-limited to prevent damage.

7. LED Diagnostics:​ Utilize the bi-color LED for quick troubleshooting. Green indicates normal operation, red indicates a fault condition.

8. Certification Compliance:​ Verify that the isolator's certifications match the hazardous area classification (Zone 1, IIC, T6) and gas groups of your specific application.

9. High-Density Installation:​ The 12.5mm width allows high-density mounting. Ensure adequate spacing for heat dissipation, especially in high ambient temperatures.

10. Moisture Protection:​ While the module is IP20, the screw terminals are exposed. Install in an appropriate enclosure for environmental protection.

Note: This data sheet provides general specifications for the MTL 4851 loop-powered isolator. For complete installation guidelines, certification details, wiring diagrams, and safety instructions, consult the official MTL 4800 Series Technical Manual. Always verify that the product configuration and certifications match your specific application requirements.