JP7142921B2 - Surge current measuring device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surge current measuring device having a function of measuring a surge current caused by a lightning strike or the like and recording the state of occurrence of the surge current.

If part of the lightning current flows into an electrical device due to a lightning strike, or if induced lightning occurs in the ground line or power line of the electrical device, the lightning surge may damage peripheral devices.

Therefore, in order to protect peripheral devices from lightning surges, lightning arresters are installed at locations where lightning surges are expected to occur. In addition, a surge counter is attached to the ground wire of the lightning arrester to record the occurrence of lightning surges.

Some surge counters of this type use a battery as a power source for driving internal circuits. As described above, when using a battery, it is necessary to replace the battery periodically, so maintenance for battery replacement is troublesome.

On the other hand, there is also a surge counter that uses an AC 100V AC power supply as a power supply for driving internal circuits. Thus, when using an AC power supply, it is difficult to use a surge counter in a place where there is no AC power supply.

In addition, in order to use the surge counter at a location remote from the AC power supply, the AC power supply must be drawn up to the surge counter, which limits the use of the surge counter.

Furthermore, when a surge current enters the surge counter, the surge current may flow out to the AC power supply side, in which case peripheral devices of the surge counter will be damaged.

In order to solve this problem, the present applicant has previously proposed a non-powered surge counter that does not include a battery or an AC 100V AC power source (see, for example, Patent Document 1).

The surge counter disclosed in Patent Document 1 detects a surge current flowing in the ground line of a lightning arrester by a current transformer, rectifies the secondary current of the current transformer by a bridge-type rectifier circuit, and rectifies the bridge-type rectifier circuit. The output current charges a capacitor.

Due to this charging, the electromagnetic counter is driven by the energy stored in the capacitor, and the number of surge occurrences is counted by the electromagnetic counter to integrate the number of operations of the lightning arrester.

In this way, a non-powered surge counter that does not require a battery or an AC 100V AC power supply, is maintenance-free, is not subject to restrictions on where it can be used, and does not adversely affect peripheral devices is realized. .

JP 2011-187218 A

By the way, the surge counter of Patent Document 1 is installed at a place where a lightning surge is expected to occur, and whether or not a lightning surge has occurred is confirmed by the surge counter. In this case, it is unknown when the lightning surge will occur, and it may not occur for a long time.

Therefore, the surge counter disclosed in Patent Document 1 is installed so that it can be recorded even in places where the probability of occurrence of a lightning surge is low.

However, the surge counter of Patent Document 1 simply counts the number of surge current intrusions, and if the surge current detection level is set to, for example, 100 A, only surge currents equal to or higher than the set level are detected. I can't.

On the other hand, in order to prevent damage to peripheral equipment due to lightning surges, lightning arresters are often installed in important facilities, and damage to peripheral equipment is prevented by absorbing surge currents caused by small-scale lightning with lightning arrestors. .

Moreover, when a surge current caused by a large-scale lightning strikes the arrester, the arrester may be damaged. In this case, the arrester must be promptly replaced.

Thus, it is extremely important to determine whether the surge current is due to a lightning of a small scale or a surge current due to a lightning of a large scale.

In other words, it is necessary to determine the magnitude of the surge current in order to confirm whether the lightning arrester is operating normally or to determine whether the lightning arrester needs to be replaced.

Therefore, the present invention has been proposed in view of the above-mentioned problems, and its object is to measure a surge current that can determine the magnitude of the surge current by a non-power supply method that does not include a battery or an AC 100V AC power supply. It is to provide a device.

A surge current measuring device according to the present invention detects a surge current flowing through a grounding wire of a lightning arrester using a current transformer, and measures the surge current based on the secondary current of the current transformer.

As a technical means for achieving the above object, the surge current measuring device of the present invention includes a rectifier circuit that rectifies the secondary current of a current transformer, a storage circuit that is charged by the output of the rectifier circuit, and a transformer. Equipped with a level detection circuit for detecting the peak value of the secondary current of the current generator and a storage circuit driven by the output of the storage circuit, the number of surge current intrusions and the peak value for each intrusion based on the output of the level detection circuit is recorded in the memory circuit.

In the surge current measuring device of the present invention, by recording the number of surge current intrusions and the peak value for each intrusion in the storage circuit based on the output of the level detection circuit, the surge current measuring device can be operated without a battery or an AC 100V AC power source. , the peak value (magnitude) of the surge current can be determined as well as the number of surge current intrusions.

A surge current measuring device of the present invention includes a first current transformer connected to a memory circuit via a rectifying circuit, and a second current transformer connected to the memory circuit via a level detection circuit. A circuit configuration is desirable.

By adopting such a circuit configuration, the storage circuit is driven by the charge output of the storage circuit based on the surge current detected by the first current transformer, and the surge current detected by the second current transformer drives the storage circuit. Based on this, the peak value of the surge current is detected by the level detection circuit.

The surge current measuring device of the present invention preferably has a circuit configuration including a single current transformer connected to the memory circuit via the rectifier circuit and connected to the memory circuit via the level detection circuit.

By adopting such a circuit configuration, the storage circuit is driven by the charge output of the storage circuit based on the surge current detected by the single current transformer, and the peak value of the surge current is detected by the level detection circuit. .

Preferably, the level detection circuit in the present invention is composed of a plurality of thyristors.

By adopting such a configuration, the surge current detection range and detection accuracy can be arbitrarily set according to the characteristics and the number of thyristors.

According to the present invention, by recording the number of surge current intrusions and the peak value for each intrusion in the storage circuit based on the output of the level detection circuit, the surge current can be detected by a non-powered system that does not include a battery or AC 100V AC power supply. not only the number of intrusions but also the magnitude of the surge current can be determined.

As a result, it is possible to easily realize a surge current measuring device capable of confirming whether or not the lightning arrestor is operating normally and determining whether or not the lightning arrestor needs to be replaced.

1 is a schematic configuration diagram showing a surge current measuring device having two current transformers in an embodiment of the present invention; FIG. FIG. 4 is a schematic configuration diagram showing a surge current measuring device having a single current transformer in another embodiment of the present invention; It is a schematic block diagram which shows the surge current measuring device which provided the indicator in the battery side by the modification of FIG. It is a schematic block diagram which shows the surge current measuring device which provided the indicator in the battery side by the modification of FIG.

An embodiment of a surge current measuring device according to the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, the main parts of the surge current measuring device of this embodiment are a first current transformer 11 and a second current transformer 12, a first rectifier circuit 13 and a second rectifier circuit 14. , a capacitor 15 as a storage circuit, a microcomputer 16 as a storage circuit, a level detection circuit 17 and a display 18 .

A ground wire 19 of a lightning arrester (not shown) is inserted through the first current transformer 11 and the second current transformer 12 . As the first current transformer 11 and the second current transformer 12, either a ring-shaped penetrating type through which the grounding wire 19 is inserted or a split type that can be attached to the grounding wire 19 in a one-touch manner can be used. It is possible.

In the embodiment shown in FIG. 1, two current transformers 11 and 12 are used, with the first current transformer 11 for driving a microcomputer and the second current transformer 12 for surge current measurement.

The first rectifier circuit 13 and the second rectifier circuit 14 are circuit-configured, for example, by a diode bridge. The input of the first rectifier circuit 13 is connected to the secondary winding 20 of the first current transformer 11 . The input of the second rectifier circuit 14 is connected to the secondary winding 21 of the second current transformer 12 .

The secondary winding 20 of the first current transformer 11 has a smaller number of turns than the secondary winding 21 of the second current transformer 12 (for example, several turns to several tens of turns), that is, the microcomputer 16 is driven is the number of turns at which possible energy can be obtained.

The secondary winding 21 of the second current transformer 12 has more turns than the secondary winding 20 of the first current transformer 11 (for example, several tens to several hundred turns), that is, the surge current waveform The number of turns is set so that a secondary current waveform approximating to is obtained.

The first rectifier circuit 13 is essential for outputting a DC voltage for driving the microcomputer 16 . On the other hand, the second rectifier circuit 14 is not necessarily required for detecting the peak value of the surge current.

When the second rectifier circuit 14 is provided, the absolute value of the secondary current can be obtained by rectifying the secondary current of the second current transformer 12 . On the other hand, when the second rectifier circuit 14 is not present, not only the peak value of the surge current but also the polarity of the surge current can be determined from the secondary current waveform of the second current transformer 12 .

The output of the first rectifier circuit 13 is connected to the input of the microcomputer 16 via the capacitor 15 . The capacitor 15 must have good high-frequency characteristics so that it can be charged based on a surge current having a large current value and instantaneously flowing.

The output of the second rectifier circuit 14 is connected to the input of the microcomputer 16 through the level detection circuit 17 . The level detection circuit 17 is composed of a plurality of (three in this embodiment) thyristors 22 .

The detection range and detection accuracy of the surge current can be set by the characteristics and the number of the thyristors 22 of the level detection circuit 17 .

In other words, by changing the threshold value for turning on the three thyristors 22 by changing the resistance value or the like, the surge current detection range can be set. Also, the accuracy of surge current detection can be set by the number of thyristors 22 . For example, if the number is increased, it is possible to improve the detection accuracy of the surge current.

It should be noted that the level detection circuit 17 can be configured by a peak hold circuit or an A/D conversion circuit instead of being configured by a plurality of thyristors 22 .

An output of the microcomputer 16 is connected to a display device 18 such as an LCD. A battery 24 can be connected to an input terminal 23 of the microcomputer 16 as a simple external power source for driving the microcomputer 16 at any time so that the number and magnitude of surge currents can be checked on the display 18 as needed. there is

The surge current measuring device configured as described above measures a surge current caused by a lightning strike or the like in the following manner.

When a surge current due to a lightning strike or the like flows through the ground wire 19 of the lightning arrestor, the surge current flowing through the ground wire 19 is detected by the first current transformer 11 and the second current transformer 12 . A secondary current flowing through the secondary winding 20 of the first current transformer 11 is rectified by the first rectifier circuit 13 .

The output from the first rectifier circuit 13 charges the capacitor 15 . This charging drives the microcomputer 16 with the energy accumulated in the capacitor 15 . By driving the microcomputer 16, it is possible to record the number of surge current intrusions and the magnitude of each intrusion.

On the other hand, the secondary current flowing through the secondary winding 21 of the second current transformer 12 is rectified by the second rectifier circuit 14 . The peak value of the secondary current is detected by the level detection circuit 17 based on the output from the second rectifier circuit 14 .

Detection of this crest value is performed based on the threshold at which the thyristor 22 is turned on. If the thresholds for turning on the three thyristors 22 are set to, for example, 100 A, 500 A, and 1000 A, it becomes possible to detect surge currents at these thresholds.

The peak value of the secondary current is detected by the level detection circuit 17 each time a surge current flows through the ground wire 19 of the lightning arrester, that is, each time a surge current enters. Thus, if the timings for detecting the crest value of the secondary current are accumulated, it becomes the number of surge current intrusions.

In this way, the magnitude of the surge current is recorded in the memory of the microcomputer 16 each time the surge current enters. As a result, the number of surge current intrusions and the magnitude (peak value) of each intrusion can be recorded in the memory of the microcomputer 16 .

The number and magnitude of surge currents recorded in the microcomputer 16 can be reset or transmitted to an external device each time a predetermined period elapses. Data recorded by the microcomputer 16 may include the date and time of surge current intrusion, in addition to the number and magnitude of surge current intrusion.

The microcomputer 16 records the number and magnitude of surge currents in a short period of time each time a surge current flows through the ground wire 19 of the lightning arrester. The capacitor 15 drives the microcomputer 16 for a short period of time (for example, several ms to several tens of ms). When the surge current does not flow through the ground line 19, the microcomputer 16 is not driven.

For this reason, the battery 24 is connected to the input terminal 23 of the microcomputer 16 when it is desired to check the number and magnitude of surge current intrusion. The battery 24 drives the microcomputer 16 . By driving the microcomputer 16 and displaying the number and magnitude of the surge current on the display 18, the recorded data can be easily confirmed.

Here, damage to peripheral devices is prevented by absorbing a surge current caused by lightning of a small scale with a lightning arrester. In addition, when a surge current due to a large-scale lightning strikes, the lightning arrester is damaged and must be replaced.

Therefore, by recording the magnitude of the surge current, it can be determined whether the surge current is due to lightning of a small scale or a surge current due to lightning of a large scale. In other words, it is possible to easily check whether the lightning arrester is operating normally or whether it is necessary to replace the lightning arrester.

In the embodiment shown in FIG. 1, two current transformers 11 and 12 are used, the first current transformer 11 for driving the microcomputer and the second current transformer 12 for measuring surge current. However, it may be configured as in the embodiment shown in FIG.

In the embodiment shown in FIG. 2, a single current transformer 25 is used for both microcomputer driving and surge current measurement. In this case, one secondary winding 20 of the current transformer 25 is connected to the first rectifier circuit 13 and the other secondary winding 21 is connected to the second rectifier circuit 14 .

In FIG. 2, the same reference numerals are given to the same parts as in FIG. Since the configuration and operation other than the number of current transformers 25 are the same between the embodiment of FIG. 1 and the embodiment of FIG. 2, redundant description will be omitted.

In the embodiment shown in FIGS. 1 and 2, the case where the indicator 18 is provided in the surge current measuring device is exemplified, but it may be configured as in the embodiment shown in FIGS.

In the embodiment shown in FIGS. 3 and 4, indicator 26 is provided on battery 24 . When it is desired to check the number and magnitude of surge current, the battery 24 is connected to the input terminal 23 of the microcomputer 16 and the display 26 is connected to the output terminal 27 of the microcomputer 16 .

As a result, the battery 24 drives the microcomputer 16 . By driving the microcomputer 16 and displaying the number and magnitude of the surge current on the display 26, it is possible to easily confirm the recorded data.

3 is a modification of FIG. 1, and FIG. 4 is a modification of FIG. 3 and 4, the same parts as in FIGS. 1 and 2 are denoted by the same reference numerals. The configuration and operation of the display device 26 other than the connection form are the same between the embodiment of FIG. 1 and the embodiment of FIG. 3, and the embodiment of FIG. 2 and the embodiment of FIG. .

The present invention is by no means limited to the above-described embodiments, and can of course be embodied in various forms without departing from the gist of the present invention. It is defined by the claims, and includes all changes within the meaning of equivalents and the scope of the claims.

11 first current transformer 12 second current transformer 13, 14 rectifier circuit 15 storage circuit (capacitor)
16 memory circuit (microcomputer)
17 level detection circuit 19 ground wire 22 thyristor 25 single current transformer

Claims (4)

A surge current measuring device for detecting a surge current flowing in a ground wire of a lightning arrester by a current transformer and measuring the surge current based on the secondary current of the current transformer,
A rectifying circuit that rectifies the secondary current of the current transformer, a storage circuit that is charged by the output of the rectifying circuit, a level detection circuit that detects the peak value of the secondary current, and is driven by the output of the storage circuit. and a memory circuit for
The current transformer includes a first current transformer connected to the memory circuit via the rectifier circuit, and a second current transformer connected to the memory circuit via the level detection circuit. ,
A surge current measuring device, wherein the number of surge current intrusions and the peak value for each intrusion are recorded in the storage circuit based on the output of the level detection circuit. 2. A surge current measuring device according to claim 1 , wherein said level detection circuit comprises a plurality of thyristors. A surge current measuring device for detecting a surge current flowing in a ground wire of a lightning arrester by a current transformer and measuring the surge current based on the secondary current of the current transformer,
A rectifying circuit that rectifies the secondary current of the current transformer, a storage circuit that is charged by the output of the rectifying circuit, a level detection circuit that detects the peak value of the secondary current, and is driven by the output of the storage circuit. and a memory circuit for
The level detection circuit is composed of a plurality of thyristors,
A surge current measuring device, wherein the number of surge current intrusions and a peak value for each intrusion are recorded in the storage circuit based on the output of the level detection circuit. A surge current measuring device for detecting a surge current flowing in a ground wire of a lightning arrester by a current transformer and measuring the surge current based on the secondary current of the current transformer,
A rectifying circuit that rectifies the secondary current of the current transformer, a storage circuit that is charged by the output of the rectifying circuit, a level detection circuit that detects the peak value of the secondary current, and is driven by the output of the storage circuit. and a memory circuit for
The current transformer comprises a single current transformer comprising a first secondary winding and a second secondary winding having different numbers of turns,
The first secondary winding is connected to the memory circuit via the rectifying circuit and the storage circuit, and the second secondary winding is connected to the memory circuit via the level detection circuit. A surge current measuring device characterized by:

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