Surge protector

Abstract

A surge protector includes a varistor element, a gas discharge tube, a voltage limiting element, a heat-generating element and a heat-conducting terminal with low heat resistance, the heat-generatingelement is connected in series with the voltage limiting element and is connected in parallel with the varistor element, and the series-parallel branch circuit is connected in series with the gas discharge tube to form a single-port combined circuit, wherein, the performance of the varistor element to withstand surge shock is higher than that of the voltage-limiting element to withstand surge shock, and the varistor element's varistor voltage value is higher than that of the voltage-limiting element's on voltage value; one of the two lead-out terminals of the single-port combination circuit isa low thermal resistance thermal conduction terminal, which is thermally coupled with the heating element, or the low thermal resistance thermal conduction terminal is thermally coupled with the voltage limiting element, or the low thermal resistance thermal conduction terminal is thermally coupled with the gas discharge tube. The invention enables the SPD to exit the circuit in an open circuit mode and improves the safety.

Description

technical field The invention relates to the technical field of power supplies, in particular to a surge protector. Background technique Surge protector (SPD for short), as a standard low-voltage electrical appliance, is widely used in low-voltage transmission and distribution lines. Quality and ensuring the safety of electrical appliances have obvious effects. The core component of the SPD is a surge suppression component, the most commonly used is a varistor ceramic chip. Due to the long transmission distance of power transmission and distribution lines and their exposure to the open air, they are more likely to suffer from high-energy surge pulses than indoor electrical equipment. During the design life of the SPD, the varistor ceramic chips are more likely to be damaged beyond the rated specifications The multiple impacts of the high-energy surge caused the deterioration and failure of the varistor. Since the varistor is a short-circuit failure mode, once the breakdo...

AI Technical Summary

Problems solved by technology

Therefore, the two actual conditions that can make the gas discharge arrester 3 return to the disconnected state do not exist or exist with a very small probability, so that if this scheme is put into practical application, it will cause frequent malfunctions of the thermal fuse element 5 and lose use value

Secondly, since the gas discharge arrester 3 and the varistor 4 have completely different working principles, their absorbing capacities for surges of different shapes are also very different. Satisfied that the surge impact resistance of the varistor 4 is greater than that of the gas discharge arrester 3, it may be incorrect under a surge pulse with a width of 2 milliseconds

Since the waveforms of surges in practical applications have various shapes, it is very difficult to achieve correct matching

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