Surge protector principle

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Guide: Surge protector (surge protector), the scientific name of the arrester, simply speaking, lightning protection, to prevent lightning and overvoltage and lightning damage caused by electromagnetic pulse system and equipment. This article mainly introduces the function, structure, function and principle of the surge protector . Interested students should pay more attention to it. . .

1. Surge protector principle - introduction

Surge protection device (SPD), also known as "arrester protection device" or "overvoltage protector", is an indispensable device for lightning protection of electronic equipment. Its function is to limit the instantaneous over-voltage of the power line and signal transmission line to the voltage range that the equipment or system can withstand, or to discharge a powerful lightning current into the ground to protect the protected equipment or system from impact and damage.

The application range of SPD is mainly the power protection of low voltage power supply and distribution systems and the signal transmission line protection of electronic information systems in electronic information systems. The former is to suppress the lightning pulse electromagnetic pulse entering from the power line, and the latter is to suppress the lightning impulse electromagnetic pulse interference entered by the signal line. Both of them are protected by electronic information system equipment and devices.

2. Surge protector principle - composition

The type and structure of the surge protector varies from application to application, but it should contain at least one non-linear voltage limiting component. The main components that make up the surge protector are metal oxide varistor (MOV), silicon avalanche diode (SAD) or TRANSORB diodes, gas discharge tubes, and the like.

1) MOV is an effective surge suppression device designed to prevent catastrophic damage to the device, but it requires response time, which means that a very brief spike current may enter the device before the threshold circuit is activated. Therefore, surge protectors designed with MOV alone are not suitable for protecting sensitive devices containing microprocessors. 90% of surge protectors on the market today use this design.

2) Silicon avalanche diodes (SAD) or TRANSORB diodes respond faster than MOV and are very sensitive to surges, but the maximum capacity of such components is also much smaller than the medium-sized MOV.

3) The gas discharge tube has a long response time, but it can absorb a large number of surges. It is generally used as a “last” measure to suppress the AC surge current in the design to prevent the surge of the pre-stage from being filtered.

3. Surge protector principle - working principle

Since it is a surge protector, first introduce the surge. Surge is also called a surge, as the name suggests is a transient overvoltage that exceeds the normal operating voltage. Essentially, a surge is a violent pulse that occurs in just a few millionths of a second, and can be caused by heavy equipment, short circuits, power switching, or large engines. Products containing surge arresters can effectively absorb sudden bursts of energy to protect connected equipment from damage.

Surge protectors are divided into switch type, voltage limiting type, shunt type or turbulent type according to the working principle. The following describes the various types of surge protector principles :

1) Switch type: Its working principle is to exhibit high impedance when there is no transient overvoltage, but once it responds to lightning transient overvoltage, its impedance will suddenly change to low value, allowing lightning current to pass. When used as such a device, the device has: a discharge gap, a gas discharge tube, a thyristor, and the like.

2) Voltage limiting type: Its working principle is high impedance when there is no transient overvoltage, but its impedance will decrease continuously with the increase of surge current and voltage, and its current and voltage characteristics are strongly nonlinear. Devices used as such devices are: zinc oxide, varistors, suppression diodes, avalanche diodes, and the like.

3) Split or turbulent type

Shunt type: in parallel with the protected device, it exhibits low impedance to the lightning pulse and high impedance to the normal operating frequency; turbulence type: in series with the protected device, the lightning pulse appears high impedance, and normal The operating frequency appears as a low impedance. Devices used as such devices are: choke coils, high pass filters, low pass filters, quarter wave shorts, and the like.

The above is the necessary knowledge about the surge protector, I hope to help everyone, there are many related knowledge, Xiaobian carefully selected four articles about the surge protector, I hope everyone can learn more, strengthen the device Understanding. . .

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