Thunder-prevention overvoltage protection device

Abstract

The invention discloses a thunder-prevention overvoltage protection device. The thunder-prevention overvoltage protection device comprises a piezoresistor sheet, a positive temperature coefficient thermistor sheet and a gas discharge tube, wherein the piezoresistor sheet and the positive temperature coefficient thermistor sheet are encapsulated integrally to form an encapsulation body. One end of the positive temperature coefficient thermistor sheet is a first leading-out end. The other end of the positive temperature coefficient thermistor sheet is connected with one end of the piezoresistor sheet to form a public end, and the public end serves as a third leading-out end. The other end of the piezoresistor sheet serves as a second leading-out end. The gas discharge tube is located outside the encapsulation body, and two ends of the gas discharge tube are connected with the first leading-out end and the third leading-out end respectively. The thunder-prevention overvoltage protection device can inhabit operation overvoltage and fault power frequency overvoltage and can play a protecting role of a normal voltage-sensitive element when lightning stroke pulse overvoltage occurs.

Description

technical field [0001] The invention relates to lightning protection and overvoltage protection technology, in particular to a composite lightning protection and overvoltage protection device. Background technique [0002] ZnO varistors have been widely used in power electronic circuits to absorb overvoltage caused by lightning pulses and power frequency overvoltage caused by system operation and system failure. However, the varistor itself has a certain limit for absorbing surge energy. The varistor connected in parallel to the power circuit absorbs overvoltage energy (especially the long-lasting power frequency overvoltage). At the same time, its own temperature rises. When the varistor When the energy absorbed by the resistance is too large, the varistor may explode and catch fire. Nowadays, this problem is usually solved by increasing the varistor voltage and diameter of the varistor, but this reduces the absorption wave of the varistor to a certain extent. The protecti...

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Problems solved by technology

Used in series with the gap, it can prevent the ZnO varistor from aging and failure, but it will increase the breakdown initiation voltage of the line. When the operating overvoltage (power frequency overvoltage) amplitude does not reach the breakdown voltage (ZnO component breakdown voltage When the sum of gap breakdown voltages), no current flows through the components and cannot protect the circuit

[0008] To sum up, in order to reduce the probability of power frequency overvoltage deflagration accidents of varistors, the varistor voltage of varistors can be increased, but this will inevitably increase the pulse residual voltage, and the protected line will be damaged by operating overvoltage and fault power frequency overvoltage The probability of the accident is greatly increased; the three-terminal device combined with the PTC thermal element and the ZnO varistor can reduce the probability of the power frequency overvoltage deflagration accident of the varistor, and can achieve a lower pulse residual voltage at the same time, but the rated work of the protected circuit The current is limited; the application of ZnO varistors in series with the gap can prevent deflagration accidents caused by long-term load aging of varistors, but the protection ability against circuit operation overvoltage and fault power frequency overvoltage is reduced

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