Surge Protection Product for Digital Ports of PLC Controller

SUG-IO24-2/DIN, surge protection product for digital PLC input and output ports with 24V voltage

SUG-IO24-2/DIN is a surge protection product used in industrial automation to protect digital input or output ports in PLC controllers. It can be used wherever the control current does not exceed 300mA (including impulse) and the control voltage does not exceed 24V DC.

In case of the need for surge protection of high-current outputs, for example for controlling contactors, a typical power supply limiter, model SUG-24VDC/DIN, should be used.

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 digital ports from potential jumps that lead to overcurrent.

The protective product has two independent protection channels, which can be used for two digital inputs of the PLC controller, two digital outputs, or can protect one input and one output. Additionally, the cable shield is also protected.

SUG-IO24-2/DIN is designed for mounting on a DIN 35mm rail. High-quality spring terminals with high current load limit the risk of damage during large shock impulses and temporary current overloads. The device occupies the width of one DIN standard module.

Surge protection products should be installed at the boundary between LPZ0 and LPZ1 zones or higher. It can be used with a voltage of 24V, including with an alternating component, as it can transmit fast data transmissions.


PLC Surge Protection

Simplified internal diagram.


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


PLC surge protection

Example of surge protection for the controller input and measurement element power supply.


PLC ports surge protection

Example of using surge protection for input and output of a PLC controller, with a measurement and execution element.


Short technical specification

Number of protected channels
Input / output connector
Rated DC voltage (Un)
Maximum DC voltage (Uc)
Maximum AC voltage (Uc) 19V
Nominal current (In)
Maximum nominal current
Decoupling element
C1: Discharge current line-line 8/20µs (In)
C2: Discharge current line-ground 8/20µs (In) 10kA
C2: Maximum discharge current line-ground 8/20µs (Imax) 20kA
D1: Maximum lightning current 10/350µs (Iimp)
Protection level 1kV/μs (line-line) Up 30V DC
Series resistance
7Ω / line
Dimensions 17.5 x 90 x 57 (mm)
Mounting method TH rail (DIN) 35mm
Grounding method
Rail occupancy
1 module
Enclosure protection IP20
Operating Temperature -40ºC~80ºC