Protection of RS-232, RS-485, and 4–20 mA RTU Signals Against Overvoltage

RS 232 and RS 485, which are communication protocols we frequently see in industrial automation and factories, are commonly encountered and are among the primary areas where sudden overvoltage impulses spread. Similarly, we frequently encounter 4-20 mA signals in sensitive electronic and automation systems.

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Table of contents

4-20 mA Protection (RTU Protection)

The RayDat PLP 24 overvoltage protection device is designed for the protection of data circuits such as 4-20 mA current loops in industrial environments. Its 3/4 inch pipe fitting makes it ideal for applications such as protecting sensors, transducers, and RTUs. The unit can be arranged in line with the conduit and sensor terminals or in a “T” configuration.

Technical Specifications

• Operating Voltage: 24VDC
• Maximum Operating Voltage: 28VDC
• Frequency: 3.0MHz
• Discharge Capacity: In: 10kA, Imax: 20kA
• 3/4 Stainless Steel Mounting Pipe 2.5 mm
• Compliant with IEC / EN 61643-21

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RS 485 and RS 422 Protection

RayDat RS 485 has been developed to protect the 2-way data transmission circuit for RS 485, RS 422, and V.11 protocols. The circuit consists of two balanced paths with equipotential bonding between them. During a sudden overvoltage impulse, equipotential bonding is provided between the signal ground and the protective earth to prevent equipment damage caused by ground potential.

Technical Specifications

• Operating Voltage: 5 V
• Maximum Operating Voltage: 6 V
• Series Inductance: 1.7..1.9 ohm
• Frequency: 1 Mhz
• Rail Mounting
• Compliant with IEC / EN 61643-21

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