Common Signal Surge Protective Devices and Their Industry Applications

What is a Signal Surge Protective Device

A signal surge protective device is an electronic device that protects instruments, equipment, or systems on the signal line from damage caused by lightning strikes or other transient over-voltage conditions.

The main principle of a signal surge protective device is to discharge the high-voltage surge generated on the line to the ground, limiting it to a range that the protected object can withstand, thereby providing over-voltage protection.

The main components of a signal surge protective device include discharge tubes, varistors, suppression diodes, and choke coils. Based on their working principle, they can be divided into voltage switch type, voltage limiting type, and combination type.

The Role of Signal Surge Protective Devices

Signal surge protective devices can effectively prevent surge voltage on signal lines caused by lightning strikes or other reasons, thereby avoiding faults, damage, or data loss of instruments, equipment, or systems.

Signal surge protective devices can improve the reliability and safety of instruments, equipment, or systems, extend their service life, and reduce maintenance costs and downtime losses.

Signal surge protective devices can adapt to various signal types and transmission methods, such as analog signals, digital signals, serial communication, parallel communication, etc.

Classification and Uses of Signal Surge Protective Devices

Signal surge protective devices can be classified into the following three categories based on their working principles:

Voltage Switch Type

This type of product mainly uses components such as discharge tubes. It remains in a high-impedance state during normal operation and quickly conducts when excessive voltage appears on the line, discharging the over-voltage to the ground. This type of product features large discharge current, fast response time, and low cost but has poor voltage limiting effects and cannot be used alone. It needs to be used in conjunction with voltage limiting type products.

Voltage Limiting Type

This type of product mainly uses components such as varistors. It remains in a low-impedance state during normal operation and increases resistance when excessive voltage appears on the line, limiting the over-voltage within a certain range. This type of product has good voltage limiting effects, wide frequency bandwidth, and minimal impact on signals, but features small discharge current, slow response time, and relatively high cost. It cannot be used alone and must be used with voltage switch type products.

Combination Type

This type of product combines components such as discharge tubes and varistors, featuring the advantages of both voltage switch type and voltage limiting type. It can be used alone or in conjunction with other types of products. This type of product is currently the most commonly used.

Industry Applications of Signal Surge Protective Devices

Signal surge protective devices are widely used in various industries and fields, such as industrial automation, power systems, communication networks, security monitoring, and instrumentation.

The requirements and standards for signal surge protective devices vary across different industries and fields, and appropriate products and solutions need to be selected based on specific situations.

Industrial Automation

In the field of industrial automation, common signal types include 4~20mA, 0~10V, RS232/485/422, etc. These signal lines are often installed over long distances outdoors or in complex environments, making them susceptible to lightning strikes or other interferences. Installing signal surge protective devices between sensors, actuators, controllers, and other equipment can effectively prevent equipment damage or data errors.

Power Systems

In power systems, common signal types include telemetry, remote control, and remote signaling. These signal lines are usually arranged parallel or cross with high-voltage power lines, easily generating induced lightning or switching over-voltage. Installing signal surge protective devices between substations, distribution rooms, generators, and other equipment can effectively prevent equipment damage or malfunction.

Communication Networks

In communication networks, common signal types include Ethernet, telephone, optical fiber, etc. These signal lines often span large areas or tall buildings, making them susceptible to direct lightning strikes or induced lightning. Installing signal surge protective devices between switches, routers, servers, and other equipment can effectively prevent equipment damage or data loss.

Security Monitoring

In the field of security monitoring, common signal types include video, audio, alarms, etc. These signal lines are often installed outdoors or in exposed locations, making them susceptible to lightning strikes or other interferences. Installing signal surge protective devices between cameras, recorders, and alarm devices can effectively prevent equipment damage or image distortion.