SURGE PROTECTION DEVICE STRUCTURE

A surge protection device capable of avoiding current leakage and deterioration includes a first pin installed onto a varistor and electrically coupled to a first electrode, an insulation pad attached onto a side of the varistor and having a through hole configured to be corresponsive to a second electrode; a conductive component attached onto a side of the insulation pad, and the conductive component and the varistor sealing the through hole to form an air gap, and a second pin installed on the conductive component and passed through the air gap through a transient overvoltage to electrically conduct the second electrode.

FIELD OF THE INVENTION

This disclosure relates to a surge protection device, and more particularly to the surge protection device capable of avoiding current leakage and deterioration.

BACKGROUND OF THE INVENTION

To prevent surges such as pulse voltage or pulse current, a circuit generally comes with a surge protection device (SPD) connected in parallel with the circuit to protect a load device or other electronic components of the circuit. A common surge protection device (SPD) includes a metal oxide varistor (MOV) and a gas discharge tube (GDT).

However, the conventional MOV has the drawbacks of current leakage and deterioration, since the current may leak under the load of a power supply, and the leakage becomes increasingly greater with the ageing of the product. In addition, if the SPD simply adopts the MOV, both overheat and deterioration disengaging devices can be operated only if the MOV is damaged, but the current leakage and deterioration of the MOV cannot be prevented. On the other hand, when the GDT is used for power lightning protection, the GDT and power system may be damaged because the GDT has a follow current after lightning.

In view of the aforementioned drawbacks of the prior art, the discloser of this disclosure based on years of experience to conduct extensive research and experiment, and finally provided a feasible solution to overcome the drawbacks of the prior art.

SUMMARY OF THE INVENTION

Therefore, it is a primary objective of this disclosure to provide a surge protection device structure connected in series with a varistor and an air gap to achieve the effects of avoiding current leakage and extending service life.

To achieve the aforementioned and other objectives, this disclosure provides a surge protection device structure comprising a varistor, a first pin, an insulation pad, a conductive component and a second pin. The first pin is installed onto the varistor and electrically coupled to a first electrode; the insulation pad is attached onto a side of the varistor and has a through hole configured to be corresponsive to a second electrode; the conductive component is attached onto a side of the insulation pad, and the conductive component and the varistor seal the through hole to form an air gap; and the second pin is installed onto the conductive component and passed through the air gap through a transient overvoltage to conduct with the second electrode.

Compared with the prior art, the surge protection device structure of this disclosure combines the varistor and the air gap, and when the surge protection device is connected in series with a power circuit, the resistance of the air gap is much greater than that of the varistor, so that the voltage is allocated to the air gap, and the varistor has no current leakage. In addition, when the lightning intrudes into the power circuit, and the surge protection device structure is operated, not much voltage allocated to the air gap remains. Since the resistance of the varistor is greater than that of the air gap, the voltage at the air gap is very small and there will be no operation, and the air gap will not produce a follow current. Such arrangement achieves the effects of avoiding the occurrence of current leakage and extending the service life.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The technical contents of this disclosure will become apparent with the detailed description of preferred embodiments accompanied with the illustration of related drawings as follows. It is intended that the embodiments and figures disclosed herein are to be considered illustrative rather than restrictive.

With reference toFIGS. 1 to 3for an exploded view, a perspective view, and a cross-sectional view of a surge protection device structure in accordance with this disclosure respectively, the surge protection device structure1comprises a varistor10, a first pin20, an insulation pad30, a conductive component40and a second pin50. The insulation pad30has a through hole31, and the insulation pad30is sandwiched between the varistor10and the conductive component40. In addition, the first pin20is installed on an outer side of the varistor10, and the second pin50is installed on an outer side of the conductive component40, and these components form the surge protection device structure1. The surge protection device structure1will be described in details below.

The varistor10has a first electrode11and a second electrode12disposed opposite to each other. In this preferred embodiment, the varistor10is a standalone metal oxide varistor (MOV). Of course, the varistor10of this disclosure is not limited to MOV only.

It is noteworthy that the varistor10in a conducted status has a specific internal resistance and will have a voltage drop when a surge flows through the varistor10, so that the varistor10is a conductive component with the feature of limited voltage. Further, the installation of the varistor10has the advantages of large flow capacity, quick response, no follow current, and long service life. On the other hand, the varistor10has the disadvantages of creating a current leakage under the load of a power supply and the current leakage increasing with the ageing of the product.

The first pin20is installed onto the varistor10and electrically coupled to the first electrode11. In this preferred embodiment, the first pin20is a bent conductive pin.

The insulation pad30is attached onto a side of the varistor10, and the insulation pad30has a through hole31configured to be corresponsive to the second electrode12. Specifically, the insulation pad30is made of an insulating material, and preferably the insulation pad30is in a shape corresponding to the shape of the varistor10, and both of them are in a circular shape.

In addition, the conductive component40is attached onto a side of the insulation pad30. In addition, the conductive component40and the varistor10seal the through hole31of the insulation pad30to form an air gap300. In this preferred embodiment, the conductive component40is a conductive plate. Of course, the actual implementation is not limited to such arrangement only, but the conductive component40can also be an electrode plate or another varistor.

It is noteworthy that both sides of the insulation pad30have a soldering material (not shown in the figures) disposed thereon to facilitate soldering the varistor10or the conductive component40in order to provide a tight connection and form a path.

The second pin50is installed onto the conductive component40and passed through the air gap300through a transient overvoltage and electrically conducted with the second electrode12.

It is noteworthy that when the air gap300is situated at a conducted status, the internal resistance drops drastically, and finally approaches zero. This is a switch type feature. The air gap300has the advantages of large flow capacity, low residual voltage, no current leakage, and long service life. On the other hand, the air gap300has the disadvantages of having a follow current when the air gap300is used in DC or power frequency voltage, and a too-slow response time.

With reference toFIG. 3for a preferred embodiment of this disclosure, the air gap300is formed between the varistor10and the conductive component40by the configuration of the insulation pad30and its through hole31.

More specifically, the applications of the varistor10and the air gap300in the field of surge and overvoltage protection have similar features such as large flow capacity, low residual voltage, etc. However, the varistor10in the conducted status has current leakage but no follow current. On the other hand, the air gap300has follow current but no current leakage.

The surge protection device structure1of this disclosure combines the varistor10and the air gap300. When the surge protection device structure1is connected in series with a power circuit, the resistance of the air gap300of the surge protection device structure1is much greater than that of the varistor10, so that almost the whole of the voltage is allocated to the air gap300, and the voltage at the varistor10is very small, and normally there is no current leakage of the varistor10. When lightning intrudes into a power circuit, the surge protection device structure1is operated, and the varistor10is a voltage limiting component having a voltage greater than the working voltage of the power supply, and not much of the voltage allocated to the air gap300remains. In the meantime, the resistance of the varistor10is greater than that of the air gap300. Now, the voltage at the air gap300is very small, and there is no operation, so that the air gap300will not produce a follow current.

Therefore, the surge protection device structure1of this disclosure has the features of large flow capacity, low residual voltage, no follow current, no current leakage, and an uneasily aged varistor10. When the surge protection device structure1is applied to a power cable, situations such as spontaneous combustions or explosions will not occur easily. Therefore, the surge protection device structure1of this disclosure is preferably connected in series with the varistor10and the air gap300to achieve a better effect.

With reference toFIGS. 4 to 6for an exploded view, a perspective view and a schematic view of a surge protection device structure in accordance with another implementation mode of this disclosure, the surge protection device structure1aas shown inFIG. 4comprises a varistor10a, a first pin20a, an insulation pad30a, a conductive component40aand a second pin50a, and the insulation pad30ahas a through hole31a. The conductive component40aand the varistor10aseal the through hole31aof the insulation pad30ato form an air gap300a.

The difference between this preferred embodiment and the previous embodiment resides on that the conductive component40ais another varistor. InFIG. 5, the insulation pad30ais sandwiched between the varistor10aand the conductive component40a. Specifically, the insulation pad30aof this preferred embodiment is installed between the two varistors, wherein the two varistors are conductive electrodes. Further, the first pin20aand the second pin50aare installed on the outer sides of the two varistors respectively to form the surge protection device structure1a.

InFIG. 6, the surge protection device structure1aof this disclosure further comprises a housing60afor covering the varistor10a, the insulation pad30aand the conductive component40aand exposing a portion of the first pin20aand the second pin50a. Such single varistor10aand the air gap300aare used to gain the advantages of low price and good feature and comply with the light, thin, short and compact requirements of components.