Eaton MTL 4850 – Surge Protection for RS485 Communication Lines

Protection Technology

The MTL 4850 utilizes a hybrid protection circuit combining fast-acting suppression diodes and gas discharge tubes. This multi-stage design ensures very low let-through voltage and high surge current handling capability. The device responds within nanoseconds to transients, diverting harmful energy to ground while maintaining signal integrity for the RS485 bus.

Key Features

• Universal Compatibility: Suitable for RS485, RS422, and similar differential data lines up to 100 Mbps.

• Low Clamping Voltage: Protects against surges with minimal impact on signal quality; series resistance<10 Ω.

• High Surge Rating: Withstands 10 kA 8/20 µs impulse current per line (line-to-ground).

• Compact Housing: Slim 12 mm wide package for high-density DIN-rail mounting, saving panel space.

• Plug-in Terminals: Removable screw terminals for easy wiring and maintenance without disconnecting wires.

• Grounding: Direct DIN-rail grounding or separate ground terminal for reliable earthing.

Technical Specifications

• Nominal Voltage: 5 V (for RS485 lines)

• Max. Continuous Operating Voltage: 6 V DC

• Max. Load Current: 300 mA per line

• Series Resistance:<10 Ω per line

• Capacitance: < 50 pF (line-to-line)

• Protection Modes: Line-Line, Line-Ground

• Response Time: < 1 ns

• Operating Temperature: -40°C to +80°C

• Enclosure Material: Polyamide, UL94 V-0

• Connection: Screw terminals for 0.2-2.5 mm² (AWG 24-12) wire

• Mounting: 35 mm DIN rail (EN 60715)

Typical Applications

The MTL 4850 is widely used in:

• Industrial Ethernet and fieldbus networks (Profibus, Modbus RTU)

• SCADA systems and remote terminal units (RTUs)

• Building automation – protecting BACnet MS/TP lines

• Process industries – safeguarding RS485 links between instruments and controllers

• Renewable energy – communication in solar and wind farms

Installation and Compliance

The device is designed for easy installation on standard DIN rails. It meets relevant standards for surge protective devices, including IEC 61643-21. When used with proper grounding and equipotential bonding, the MTL 4850 ensures the integrity of your RS485 network against transient overvoltages.

By integrating Eaton's MTL surge protection into your communication lines, you reduce downtime and maintenance costs while increasing the reliability of your automated processes.