JPS63310331A - Arrester for spark gap type high sensitivity low voltage circuit - Google Patents

Abstract

PURPOSE:To protect a thermo-switch by inserting an inductance to the part of the connecting line of a circuit in which the switch is connected in series with a gas discharge tube to absorb an abnormal voltage. CONSTITUTION:A series circuit II of a gas discharge tube H and a thermo- switch S is connected in parallel with a spark gap G to form an arrester. A ferrite tube F is inserted to work as an inductance to the part of the connecting line of the circuit II. The tube H is initially operated by means of a lightning surge, a voltage between the terminals of the circuit II temporarily extremely drops. Thus, it is difficult to fire a lightning surge current at the gap G as it is. However, the switch S is opened immediately before the tube H is thermally broken down due to an increase in the current to protect the tube H, and the gap G is fired by a high voltage generated at both ends of the tube F at the moment that the current is interrupted.

Description

[Detailed Description of the Invention] [Field of Industrial Application] In recent years, automation has spread to a wide range of areas, including factories and research institutes, golf courses and other sports facilities, and agricultural facilities. Many electronics-related devices are used. Those devices are truly vulnerable to lightning surge voltages.

Surge voltages infiltrate not only from the power supply side (but also from the side of weak electric circuits such as signal circuits), so of course lightning protection measures are required on both sides.Many of the facilities mentioned above are located in lightning-rich areas, so There are many opportunities for lightning to strike in the vicinity of the ground.Furthermore, in mountainous areas or riverbeds, the ground resistivity of that location is high, so the *S current is not dissipated underground, but travels along power lines and spreads across a wide area. As the virus spreads to surrounding areas, the damage will be greater.

On the other hand, as automation progresses, the number of unmanned facilities will also increase. Due to unmanned systems, even if a lightning arrester malfunctions, maintenance personnel will have to be dispatched from afar. Therefore, the demand for m* devices will continue to increase in the future, but they can withstand considerably more energy than conventional ones, and are useful not only for protecting equipment from repeated penetration of powerful lightning surges. Light castles are requesting for maintenance and management costs to be made to prevent the Ji ware itself from burning out.

Since the spark gap type high-sensitivity low-voltage circuit lightning arrester of the present invention was proposed for such a purpose, it has wide application in various fields.

[Conventional technology]

Conventionally, lightning arresters are broadly classified into the following five types.

1.Spark gap 2.Gas discharge tube 3.Semiconductor type lightning arrester 4.Series circuit of (2) and (3) 5.Parallel circuit of (2) and (3)However, (I) is not suitable for multiple lightning strikes or continuous discharge. lightning surge associated with
Although it is easy to obtain a device that can withstand large amounts of energy such as a nearby lightning strike, it has the disadvantage of slow response time when starting operation, and (2) has a small capacitance and a relatively large current capacity. However, when used in a power supply circuit, it has the disadvantage that follow-on current due to the power supply voltage cannot be interrupted immediately after discharge. (3) is sensitive to the principle of lightning, but if a voltage that exceeds the limit voltage is applied frequently, the voltage at which the element starts to operate will be too low, and a sudden ignition will occur just by the voltage applied to the circuit. , there is a risk of a short circuit condition. A device with a large surge resistance has the disadvantage that the static ':Hgm' becomes large and the volume of the element becomes large. In (4), there is no fear of follow-on current even when used in a 1u source circuit, and the capacitance can be reduced, but the acidity and voltage width are relatively small, and on the other hand, lightning surges due to continuous discharge can invade due to the long energization time. However, there remains the problem of burnout due to insufficient energy resistance against lightning surges caused by multiple lightning strikes or multiple lightning strikes. In (5), if a suitable combination can be obtained, a sensitive and relatively large energy capacity can be obtained, or a power supply circuit still has the disadvantage that the continuation A cannot be cut off, even when used in a weak current circuit.
There is no guarantee that it will be able to withstand multiple lightning surges.

[Problem to be solved]

It can be used between any line and the ground, without disturbing the line or interfering with the operation of equipment, and can be used to quickly protect against lightning surges of all waveforms and abnormal high voltages caused by nearby lightning strikes. Since the voltage of the circuit is limited to a certain level, it operates safely and reliably, and not only does it not cause damage to the protected property, but also does not cause the lightning arrester itself to explode or catch fire.
The objective is to have no deterioration in performance F at all in practical terms.

Means for Solving the ε Problem] The present invention connects a highly reliable spark gap with a large energy capacity in parallel with a semiconductor lightning arrester element or a gas discharge tube with no delay in operation start time, thereby improving the operation of both. The aim is to promote cooperation between the two parties. In a circuit (I) in which a semiconductor lightning arrester element and a thermoswitch (a switch whose contacts quickly open due to temperature rise) are connected in series, the upper limit of the limiting voltage of the semiconductor lightning arrester element is the spark gap discharge starting voltage. A circuit (II) in which spark gaps are connected in parallel and connected together, or a gas discharge tube and a thermoswitch are connected in parallel, with a spark gap adjusted so that the discharge starting voltage is as small as possible is connected in parallel. A spark gap type high-sensitivity low-voltage circuit surge arrester with an inductance inserted into a part of the connection wire of circuit (I) or (II) for the purpose of promoting spark gap discharge. This is a proposal.

The spark gap type high-sensitivity low-voltage circuit lightning arrester of the present invention protects the thermoswitch by absorbing the abnormal voltage that occurs at the contacts when the thermoswitch operates, and at the same time prevents discharge of the spark gap, similar to the function of the inductance described above. For the purpose of promoting this, we also propose a method of connecting semiconductor lightning arrester elements to both ends of the connection terminal of the thermoswitch.

[For production]

In the case of semiconductor lightning arrester elements, they behave like good insulators below the response voltage, but above that the current is 15% of the voltage.
Since it can be considered as a nonlinear resistor that increases by the 30th power, the response speed is fast and there is almost no time delay even in response to an impact voltage. By connecting a suitable semiconductor lightning arrester element in parallel to the spark gap, overvoltages due to the unavoidable ignition delay of the spark gap can in fact be completely avoided. In other words, when the surge voltage increases rapidly, the spark gap discharge starting voltage becomes quite high, but in reality, the upper limit of the limiting voltage of the semiconductor lightning arrester element is the same as the spark gap discharge starting voltage. The response time delay caused by the spark gap can be compensated for by combining overlapping lightning arrester elements. In other words, in the case of a steep surge voltage, the current flowing through the semiconductor type lightning arrester element increases dramatically, so the terminal voltage increases due to the internal resistance of the semiconductor type lightning arrester element, thereby igniting the spark gap. If the internal inopedance of the spark gap after ignition is designed to be smaller than the internal impedance of the semiconductor lightning arrester, the arrester current will be commutated from the semiconductor lightning arrester to the spark gap. Since the spark gap can be easily designed to have an extremely large current withstand capacity, even in the case of a fairly large surge current, the semiconductor lightning arrester element only needs to have the capacity for a short operating time until it ignites into the spark gap. Burnout due to overload can be completely avoided. However, when taking actual lightning voltage as an example, not only the magnitude of the voltage, but also the current waveform and multiplicity are often significantly different. It is difficult to coordinate the operation of the IT element and the spark gap, and it is difficult to achieve operational coordination between the semiconductor type lightning arrester element and the spark gap. The I element can withstand overload.
Burnout is often seen. semiconductor type jl
'ilI! If the device breaks down, there is a risk that an internal short circuit will occur in the device or the mold will catch fire. Often, if a semiconductor type lightning arrester operates at a point exceeding the maximum limiting voltage,
Even on sunny days, the device may suddenly start operating below the maximum allowable circuit voltage, causing a continuous ground fault current to flow due to the circuit voltage and causing the device to catch fire.

In a lightning arrester with a spark gap connected in parallel to a gas discharge tube,
As mentioned above, there was a drawback that it was difficult to follow or block the flow during operation.

If an appropriate spark gap is connected in parallel to the circuit (I) in which a thermoswitch is connected in series to a semiconductor lightning arrester element or the circuit (II) in which a thermoswitch is connected in series to a gas discharge tube, the above-mentioned danger will not occur.

When the lightning current is commutated from the semiconductor lightning arrester to the spark gap, or when the gas discharge tube is overloaded, the thermoswitch operates and the semiconductor lightning arrester or gas discharge tube is disconnected from the circuit. protected because of Thermoswitches have a delay due to their operating principle, but damage to semiconductor elements or gas discharge tubes is often caused by thermal damage, which also involves a time delay, so by coordinating the time delays of the two, Alternatively, by inserting an inductance into a part of the connection wire of circuits (I) and (II), when the thermoswitch is turned off, the high voltage generated at both ends of the inductance can actively ignite the spark gap, which achieves the above purpose. easily achieved.

Since the thermoswitch automatically resets immediately after activation, it does not affect the performance of the spark-type high-sensitivity low-voltage circuit lightning arrester.

A circuit in which the thermoswitch of the present invention and a semiconductor lightning arrester are connected in series (or a circuit in which gas discharge tubes are connected in series)
Connect a suitable spark gap to (II), (I) (II)
In a spark gap type high-sensitivity low-voltage circuit lightning arrester in which a reactance is inserted in a part of the connection line of the circuit, if semiconductor type lightning arrester elements are connected in parallel to the tubes of both terminals of the thermoswitch, there will be a drop between the contacts during operation. It can easily absorb the high voltage generated. In the case of circuit (I), when a steep and large lightning surge current acts, (I) one semiconductor lightning arrester operates first, (I-) then the thermoswitch operates, and when the switch opens, two two semiconductor types
! The circuit configuration changes to one that can be considered as a series of lightning #-I- (
iii) Since the lightning arrester operates in a three-step sequence, with the lightning surge finally being commutated to the spark gap, it becomes easy to transfer the lightning surge from the semiconductor type lightning arrester element to the spark gap.

〔Example〕

Here, one embodiment of the spark gap type high-sensitivity low-voltage circuit lightning arrester according to the present invention will be described with reference to the drawings.

Figure 1 shows the most basic circuit. In the figure, (L) is the line connection terminal, (E) is the ground, and the semiconductor lightning arrester (A
,), a thermoswitch (S), a series circuit I, and a spark gap (G) are connected in parallel to form an integrated unit.A ferrite tube (F) is used as an inductance in a part of the connecting wire of the circuit (■). is inserted, but you can use either the coil or the back of the ferrite tube depending on your convenience. There are thermoswitches that operate in air, or those that are housed in a vacuum or special gas-sealed tube, but any type of thermoswitch is applicable. Spark gap (G)
can be applied to metal electrodes or carbon electrodes. Normally, the operating voltage of the semiconductor lightning arrester (A) must be lower than the withstand voltage of the light electrical equipment and higher than the applied circuit voltage. The discharge starting voltage of the spark gap (G) is preferably equal to or lower than the limiting voltage of the semiconductor lightning arrester (A+).

Figure 2 shows the thermo switch (S) and gas release 1'ti pipe (I).
In a type of lightning arrester in which a spark gap (G) is connected in parallel to a circuit (■) connected in series with (1), a ferrite tube (F) is inserted as an inductance in a part of the connecting wire of the circuit (■). . 1 for each material
Applying the ideas of KI.

Due to the lightning surge, the gas discharge tube (H) first operates, and the voltage between the terminals of circuit H temporarily drops to an extreme level. If this continues, it will be difficult to ignite the lightning surge current into the spark gap (G) , due to the increase in current the gas discharge tube (I1)
Just before thermal breakdown occurs, the thermoswitch opens, protecting the gas discharge tube (■), and at the moment the current is cut off, the spark gap (G) is ignited by the high voltage generated across the ferrite tube.

Although thermoswitches (S) can effectively protect semiconductor lightning arresters (Ad) and gas discharge tubes (I1), they are weak against the high voltage that occurs when the switch contacts open. , if a semiconductor type lightning arrester (A2) is connected between both terminals of the thermoswitch (S) as shown in Fig. 3 (a) and (b), the high voltage generated at the contact point when the thermoswitch (S) is operated. can be absorbed, so the thermoswitch is protected.Furthermore, taking the case of Fig. 3(a) as an example, if the thermoswitch (S) is opened, the semiconductor lightning arrester (S) is protected.
80 (A2) is connected in series, so the voltage corresponding to the discharge starting voltage of the spark gap is connected to the two lightning arresters (A+).
(Az) (usually it is said that the minimum discharge starting voltage of the spark gap cannot be made smaller than 300μ), the first stage lightning arrester element (
80 allows you to select elements with a low activation voltage, which improves the reliability of the lightning arrester.

〔effect〕

The spark gap type high-sensitivity low-voltage circuit lightning arrester of the present invention carefully adjusts the spark gap gap and is a semiconductor type! ! Lightning; A
A circuit 11 in which T- and a thermoswitch are connected in series, or a circuit ■ in which a gas discharge tube and a thermoswitch are connected in series,
If the combination of connections is selected, it is possible to construct a Jl lightning arrester that operates more sensitively and skillfully and has a larger current resistance M than using each lightning arrester separately for the reasons stated in the previous section. Therefore, the arrester will not burn out and provide a wide range of protection even if a fairly large surge voltage enters, or if the waveform is different from the standard waveform and the steepness or current value is relatively small but the energization time is long, or if multiple lightning strikes occur. It is effective and can easily protect many electrical equipment, including light electrical equipment, from damage caused by lightning. Therefore, the number of cases in which the lightning arrester itself burns out is significantly reduced, and the effort required to maintain the lightning arrester is greatly reduced, greatly contributing to labor savings.

[Brief explanation of the drawing]

An embodiment of the spark gap type high-sensitivity low-voltage circuit lightning arrester according to the present invention is shown in FIGS. 1 to 3(a) and 3(b), both of which are actual circuit diagrams.

[Brief explanation of symbols]

(A+)...Semiconductor type lightning arrester (A2)...
...Same as above (II)...Gas discharge tube (S), fist◆, lug, thermoswitch (G)...Spark gap (L)...Line connection terminal (E)...Earth ε System 1 area (Qn 过3 fig. 2nd G O<b)

Claims (1)

[Claims] 1) In a lightning arrester integrated with a circuit (I) in which a thermoswitch and a semiconductor lightning arrester are connected in series, and a spark gap connected in parallel, a part of the connection line of the circuit (I). A lightning arrester for high-sensitivity low-voltage circuits with an inductance inserted into it. 2) A circuit in which a thermoswitch and a gas discharge tube are connected in series (
A lightning arrester for high-sensitivity low-voltage circuits in which an inductance is inserted in a part of the connection wire of circuit (II) in a type of lightning arrester that is integrated with circuit (II) and a spark gap connected in parallel. 3) A lightning arrester for a high-sensitivity low-voltage circuit according to claims 1 and 2, wherein a semiconductor lightning arrester element is connected in parallel to the connection terminal of the thermoswitch.