RS-485 Bus Surge Protector

SUG-RS485, miniature protector for RS-485 communication bus, protecting against the effects of atmospheric discharges, surges and potential difference jumps. Compatible with modbus and profibus networks.

The SUG-RS485 is designed to protect the RS-485 bus from surges caused by atmospheric discharges and potential differences associated with the operation of industrial devices. It is compatible with networks operating in Modbus and Profibus protocols.

Modern solutions in the form of MOSFET fuses limit the flow of large surge currents through the limiter, resulting in increased durability and significant reduction of the surge voltage reaching the protected device. An additional advantage of this solution is the limitation of equalizing currents, which can protect RS-485 interfaces from potential jumps that lead to current overload.

The structure consists of voltage clipping and limiting stages, as well as a current limiter above 300mA. The product has very low attenuation, making it possible to transmit transmissions at very high speeds.

High-quality window clamps with high current load limit the risk of damage during large surge impulses and momentary current overloads.

The Protector is recommended for installation at the boundary between LPZ0 and LPZ1 zones or higher.


Surge Protection Device SUG-RS485

Simplified internal diagram.


To ensure proper surge protection, it is recommended to use protectors at both ends of the transmission line and to properly ground them.


Surge protection for RS-485 network

Example of proper surge protection in RS-485 network.


Technical specifications

Number of protected channels
Input / output connector Screw
Rated DC voltage (Un)
Maximum DC voltage (Uc)
Maximum AC voltage (Uc) 8V
Nominal current (In)
C1: Line-line discharge current 8/20µs (In)
C2: Line-ground discharge current 8/20µs (In) 10kA
C2: Maximum line-ground discharge current 8/20µs (Imax) 20kA
D1: Maximum lightning current 10/350µs (Iimp)
Protection level 1kV/μs (line-line) Up 15V DC
Series resistance
7Ω / line
Dimensions 57 x 32 x 28 (mm)
Mounting method Freestanding housing
Grounding method Wire
Housing tightness IP20
Operating temperature -40ºC~80ºC