JPH01176685A - Surge absorber - Google Patents

Abstract

PURPOSE:To enable a discharge gap tube to be protected from joule energy by limiting an AC current that flows continuously into a surge absorber using a positive characteristic thermister. CONSTITUTION:A positive characteristic thermister 14 which is, directly or through an electrode plate, combined thermally is joined to either electrode of the two electrodes 8a and 8b whose convexes are opposed, inside a hollow insulation cylinder 10, to each other at both ends of the hollow insulation cylinder 10, and an electric terminal is taken out from each of the common electrode for the discharge gap tube and the positive characteristic thermister 14, the other electrode of the discharge gap, and the other electrode of the positive characteristic thermister. Hereby, even if it becomes great joule energy as the time of AC current application, the discharge part of the electrode is never fused and broken, and when the AC overvoltage is gone the function as a surge absorber returns, and further the positive characteristic thermister works as a surge impedance, which enables decrease of limit voltage and break of dynamic current.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a surge absorber for protecting communication equipment and electronic equipment from abnormal electrodes such as lightning surges.

BACKGROUND OF THE INVENTION In recent years, as electronic equipment has become more multi-functional, computerization has been promoted in the fields of home appliances, information and communication equipment, and industrial equipment. IC used for this computerization.

Although LII (Large Scale Integrated Circuit) etc. have excellent functions, they are extremely sensitive to abnormal electrodes such as surge electrodes and AC overcurrent electrodes, which may cause electronic equipment to malfunction or even be destroyed. There are also quite a few. Therefore, from the viewpoint of ensuring and improving the reliability of electronic devices, measures against surge electrodes for these electronic devices are extremely important. In particular, in the field of telephone communications, surge absorbers are required to have small capacitance and no leakage current, so discharge gap type surge absorbers are often used as surge absorbers.

Conventionally, the internal structure of this type of surge absorber was as shown in FIG. FIG. 4 shows a cross section of the surge absorber. In FIG. 4, reference numerals 1a and 1b are disc-shaped electrodes having a convex portion in the center, and the convex portions are located opposite to each other. These electrodes 1a, 1b are usually made of iron, nickel,
Made of alloys such as cobalt. This is to match the coefficient of thermal expansion with the hollow insulating cylinder described later. 2 is electrode 1
a.

This is a gap portion formed between the poles of the convex portion of 1b.

The discharge starting electrode is determined by the length between the electrodes. 3
is a hollow insulating tube made of glass, ceramics, etc. This hollow insulating cylinder 3 insulates between the electrodes 11L and Ib. Further, in order to stabilize the state of the space in the gap portion 2, the end face portion of the hollow insulating tube 3 and the electrodes 1a, 1k) are sealed by glass fusing or metal brazing. Furthermore, the gas inside the gap part 2 is nitrogen, argon,
It is an inert gas such as neon, and is set at 1 atmosphere or less than 1 atmosphere. A discharge gap tube is formed by the above configuration. 4a and 4b are electrodes 1a
, 1b, and is a terminal connected to a power supply line or a communication line.

FIG. 6 is an example of a connection diagram of a surge absorber to an electric circuit. 6 is a telephone communication device, 6 is a signal line connected to the telephone communication vA6, and 7 is a surge absorber connected between the signal lines 6.

The behavior of the conventional discharge gap type surge absorber configured as described above when absorbing a surge current will be described below. First, a lightning surge electrode is applied between the voltage Wi1a and Wi1b of the surge absorber, and the electrode is connected to the gap portion 2.
When the voltage is higher than the discharge starting electrode, the gap portion 2 starts discharging, the surge current associated with those electrodes flows to the surge absorber, and the electrodes at both ends of the surge absorber are suppressed. In addition, the surge absorber generates discharge not only when the surge electrode is applied but also when an AC overcurrent electrode is applied, suppressing the electrodes at both ends of the surge absorber.

Problems to be Solved by the Invention However, in such a conventional configuration, an AC overload electrode is applied to the surge absorber, and when AC current is applied for a long time, the electrode 11L,
1b melts to form a through hole.

Then, arc gas blows out on the side of the electrode where the through hole is formed, giving a great shadow to peripheral equipment and parts.

In particular, if arc gas blows between electrical contacts or between poles, there is a high possibility that a short circuit will occur, resulting in a major accident.

The present invention aims to solve these problems,
The purpose of this is to limit the alternating current that continuously flows into the surge absorber using a positive characteristic thermistor to protect the surge absorber from continuous alternating current overcurrent.

Means for Solving the Problems In order to solve the above problems, the present invention thermally couples a positive temperature coefficient thermistor to one of the two electrodes forming the discharge gap tube of the surge absorber. This is intended to limit the AC current that continuously flows into the surge absorber and protect the surge absorber from continuous AC overload.

Effect of the present invention With the above-described configuration, the convex portion of the electrode is heated by large Joule energy as when AC current is applied, and during the time until penetration, the heat of the electrode is transferred to the PTC thermistor, and the heat is absorbed. This rapidly increases the resistance of the positive temperature coefficient thermistor connected in series with the signal line, limits the continuous alternating current flowing into the discharge gap tube, and protects the discharge gap tube from Joule energy.

Embodiment FIG. 1 shows an embodiment of the surge absorber of the present invention, and this figure is a sectional view of the surge absorber. In Figure 1, aa
, sb is an electrode, 9 is a gap portion, and 10 is a hollow insulating tube, which form a discharge gap tube, and these correspond to the conventional electric discharge tube, gap portion 2, and hollow insulating tube 3, respectively. be. In addition, hollow insulating tube 1
0 and the electrodes sa and sb are glass fused or metal brazed as in the past, and the gap portion is kept sealed. Furthermore, the same inert gas as in the past is used as the filler gas.

11, 12, and 13 are electrode plates with spring properties, respectively.
14 is a plate-shaped positive temperature coefficient thermistor. and,
The electrode plate 11 and the electrode plate 12 sandwich the discharge gap tube,
Further, a positive temperature coefficient thermistor 14 is sandwiched between the electrode plate 12 and the electrode plate 13. These insertions may be done by pressure welding or soldering. 15 is a terminal block for fixing the electrode plates 11, 12, and 13, respectively, and is made of an insulating material such as resin. Normally, the electrode plates 11, 12, 13 are connected to the electric circuit by being attached to a printed circuit board or the like on the back side of the terminal block 16. FIG. 2 is an example of a connection diagram of the surge absorber 1 of the present invention to an electric circuit. 16 is a telephone communication device, 17 is a signal line connected to the telephone communication 111e, and 18 is a surge absorber connected between the signal lines 17.

Next, the operation of the surge absorber configured as above will be explained. Similar to the conventional example, when a lightning surge electrode is applied between the electrodes sa and sb of the discharge gap tube, and that electrode is higher than the discharge starting electrode of the gap section 9, the gap section 9 starts discharging, and the voltage accompanying those electrodes increases. A surge current flows into the discharge gap tube via the positive temperature coefficient thermistor 14, and the electrodes at both ends of the discharge gap tube are suppressed. Further, the discharge gap tube generates discharge not only when a surge electrode is applied but also when an AC overcurrent electrode is applied, and the electrodes at both ends of the discharge gap tube are suppressed. These do not differ from the operation of conventional discharge gap tubes, except that the surge current flows through the positive temperature coefficient thermistor 14. However, when a current such as an alternating current continues to discharge for a long time, the electric current I#isa, sb starts to generate heat due to the arc heat and Joule energy. Here, the electrode 81L is in pressure contact with the electrode plate 12, and the heat of the electrode 8IL is immediately transmitted to the electrode plate 12 and further to the positive temperature coefficient thermistor 14. When the PTC thermistor 14 is heated in this way, the resistance of the PTC thermistor 14 suddenly increases, and the current passing through the PTC thermistor 14 is limited, and the current value is limited to an extremely low value. Here, the positive temperature coefficient thermistor 14 is connected to the signal line 17.
Since the discharge gap tube is connected in series with the discharge gap tube and at the front stage of the discharge gap tube, the current flowing into the discharge gap tube is also suppressed.

Moreover, the heat generation of the electrodes 8L and 8b is also greatly reduced, and it is possible to avoid penetration failure of the discharge gap tube.

Further, when the AC over-electrode disappears and the normal circuit electrode returns, the temperature of the positive temperature coefficient thermistor 14 also decreases, and the original function of the surge absorber is restored. Furthermore, the positive temperature coefficient thermistor 14 acts as a surge impedance, and has a surge suppressing effect superior to the conventional one and an effect of blocking follow-on current from the discharge gap tube.

Next, a second embodiment of the present invention will be described with reference to FIG. The figure shows a sectional view of the surge absorber of the second embodiment. The difference from the first embodiment is that the electrode plate 11.1
The second function is performed by the electrode of the discharge gap tube, and furthermore, the positive temperature coefficient thermistor is in direct contact with the electrode of the discharge gap tube. In FIG. 3, reference numerals 19&, 19b are electrode terminals which have the functions of electrodes of the discharge gap tube and electrode plates for connection to the circuit. This electrode terminal 19a.

19b is made of the same metal material as the electrodes sa and sb. The operation of the surge absorber constructed in this way is also similar to that of the first embodiment. However, electrode plate 11.12
can be omitted, and since the positive temperature coefficient thermistor 14 is in direct contact with the electrode terminal 19a of the discharge gap tube, the electrode terminal 1
9I! This has the effect of improving the conduction of heat from L and increasing the speed at which the above-mentioned effects are exerted.

In the above embodiment, an insulating case and a resin coating covering the discharge gap tube and the positive temperature coefficient thermistor were not provided, but the functions and effects are the same even if these are provided.

Effects of the Invention As described above, according to the present invention, the convex portions at both ends of a hollow insulating cylinder are attached to either one of the two electrodes facing each other in the hollow insulating cylinder, either directly or through an electrode plate. A thermally coupled positive temperature coefficient thermistor is joined, a common electrode of the discharge gap tube and the positive coefficient thermistor, the other electrode of the discharge gap tube,
In addition, the surge absorber has electrical terminals taken out from the other electrode of the positive temperature coefficient thermistor, and the discharge part of the electrode does not melt and break even when exposed to large Joule energy such as when AC current is applied, and the AC over-electrode does not melt. When it disappears, the function as a surge absorber is restored, and the positive temperature coefficient thermistor also acts as a surge impedance, exhibiting the effect of reducing the limiting electrode and blocking the following current.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a surge absorber according to a first embodiment of the present invention, Fig. 2 is a circuit diagram showing a connection circuit of a surge absorber according to a first embodiment of the present invention, and Fig. 3 is a cross-sectional view of a surge absorber according to a first embodiment of the present invention. FIG. 4 is a sectional view of a conventional surge absorber, and FIG. 6 is a circuit diagram showing a connection circuit of the conventional surge absorber. 8a, 8b... Electrode, 9... Gap portion, 1°... Hollow insulating cylinder, 11.12.13...
... Electrode plate, 14 ... Positive characteristic thermistor, 1
6...Terminal block, 16...Telephone communication device, 17
...Signal line, 191L. 19b... Electrode terminal. Name of agent: Patent attorney Toshio Nakao and 1 other person 3α
, δb-Dentori 171-Anonymous Blind Figure 2

Claims (1)

[Claims] It consists of a hollow insulating cylinder and two electrodes, each having a convex portion at both ends of the hollow insulating cylinder and facing each other within the hollow insulating cylinder, and the ends of the hollow insulating cylinder are joined and sealed with the electrodes to generate a discharge. A gap tube is configured, a positive temperature coefficient thermistor is thermally coupled to one of the electrodes directly or through an electrode plate, and a common electrode of the discharge gap tube and the positive coefficient thermistor is connected to the discharge gap tube. A surge absorber characterized in that electrical terminals are respectively taken out from the other electrode and the other electrode of the positive temperature coefficient thermistor.