JP6860439B2 - Discharge frequency meter and current measuring device - Google Patents

Description

Embodiments of the present invention relate to a discharge frequency meter and a current measuring device.

In recent years, the frequency of lightning strikes has increased, so there is a demand for accurate detection of the number of lightning strikes.

A conventional lightning strike detection system is equipped with a lightning arrester and a discharge meter connected to the arrester. When a lightning strikes a line such as a transmission line, the energy of the lightning strike is released to the ground from the lightning arrester connected to the line. At the same time, it is supplied from a lightning arrester to a discharge meter to count the number of lightning strikes.

Further, in addition to a large current when a lightning strike occurs, a small leakage current of about 0.2 to 0.3 mA flows through the arrester. For this reason, many discharge frequency meters are provided with an ammeter for measuring leakage current, and the current measurement range of a standard lightning arrester is, for example, in the range of 0 to 2 mA or 0 to 5 mA. Will be done.

By the way, noise or the like is suddenly generated on the line to which the lightning striker is connected, and a current exceeding the leakage current, for example, a current of several tens of mA or more may temporarily flow. May be counted as a lightning strike, which does not accurately measure the number of lightning strikes.

Therefore, there is a request from the user that noise is not counted as a lightning strike by the discharge frequency meter, but is visually recognized by the deviation of the pointer of the ammeter.

However, when the measurement range is widened to the extent that currents such as noise can be visually recognized with an ammeter for visually recognizing leakage current, a pointer is set between 0 to 30 mA or 0 to 50 mA within a limited display window range. It is necessary to make a scale plate that swings, but in this case, if the scales are evenly spaced, weak current values such as leakage current will not appear even in the range of the smallest 1 scale, and minute changes in current will occur. It becomes impossible to visually confirm.

Japanese Unexamined Patent Publication No. 5-89938 Japanese Unexamined Patent Publication No. 2010-15873

That is, although the conventional discharge frequency meter has a current display function, it can simultaneously measure the leakage current of a standard lightning arrester (a minute current of about 0.2 or 0.3 mA) and a large current with an upper limit of 30 mA or 50 mA. The scale becomes too coarse and the minute current value cannot be visually recognized correctly. Further, when newly designing a wide-range discharge frequency meter, there is a problem that the entire instrument needs to be redesigned in consideration of the airtightness of the container accommodating the measurement circuit, which increases the design cost.

The problem to be solved by the present invention is to provide a wide-range display, low-cost discharge frequency meter and current measuring device capable of visually recognizing a leakage current to a current as large as about 100 times that of a leakage current with a single pointer deviation. There is.

The discharge frequency meter of the embodiment is a discharge frequency meter that counts the number of lightning strikes from the lightning strike current and the leakage current input from the lightning arrester, and is a lightning rod, a non-linear characteristic current generation circuit, a drive coil, a sensitivity adjustment circuit, an ammeter, and the like. Equipped with a scale plate. The lightning protection element releases the lightning current from the lightning arrester to the ground. The non-linear characteristic current generation circuit is configured so that the voltage-current characteristic changes with a threshold value of the current exceeding the range of the leakage current. The drive coil uses a part of the lightning current as energy to count the number of lightning strikes. The sensitivity adjustment circuit slows down the sensitivity of the drive coil for lightning strike counting. Ammeter is connected to the non-linear characteristic current generating circuit to shake the guidance in response to a current input through the drive coil and the non-linear characteristic current generation circuit from the arrester. The scale plate is provided on the ammeter and is provided with scales at different intervals according to the deviation of the pointer of the ammeter.

It is a figure which shows the outline structure of the lightning strike detection system of embodiment. It is a side view of the discharge frequency meter in a lightning strike detection system. It is a figure which shows the display panel of the discharge frequency meter. It is a figure which shows the 1st Embodiment of the circuit structure of the discharge frequency meter. It is a figure which shows the voltage-current characteristic of a general ammeter. It is an image diagram of the voltage-current characteristic of the discharge frequency meter of an embodiment. It is a figure which shows the simulated voltage-current characteristic. It is a figure which shows the other circuit configuration example (second embodiment) of the discharge frequency meter. It is a figure which shows the other circuit configuration example (third embodiment) of the discharge frequency meter.

Hereinafter, embodiments will be described in detail with reference to the drawings.

(First Embodiment)
FIG. 1 is a diagram showing a lightning strike detection system according to the first embodiment.
As shown in FIG. 1, the lightning strike detection system of the first embodiment includes a lightning arrester 1 connected to a power transmission / distribution system (line) such as an electric wire for AC power transmission and a discharge rate meter 2 connected to the lightning arrester 1. Be prepared. The lightning arrester 1 has a line terminal 3 and a ground terminal 4. The line terminal 3 is connected to the power transmission / distribution system. The ground terminal 4 is grounded to the ground (ground).

The lightning arrester 1 contains a lightning rod containing zinc oxide as a main component in an insulating container such as a porcelain tube. The lightning arrester 1 is usually an insulator, becomes a conductor when a high voltage (abnormal voltage) such as a lightning strike is applied, and discharges the abnormal voltage to the ground.

The discharge frequency meter 2 has a relay terminal 5 connected and fixed to the ground terminal 4 of the lightning arrester 1, and a ground terminal 6 grounded on the ground. The relay terminal 5 causes a current (a part of a leakage current and a lightning strike current, etc.) through the lightning arrester 1 to flow through the discharge frequency meter 2. The ground terminal 6 allows the current through the discharge frequency meter 2 to flow to the ground (ground).

As shown in FIG. 2, a display panel 9 provided with a counter 7, an ammeter 8 and the like is provided on the front portion of the discharge frequency meter 2. The ammeter 8 is, for example, a movable coil type, and has an internal circuit (not shown) such as a permanent magnet and a coil, a scale plate 10, and a pointer 11. The pointer 11 operates so as to draw an arc around the fulcrum according to the movement of the coil through which the current flows.

In this way, the ammeter 8 causes a current (leakage current, noise, etc.) other than the lightning strike input from the lightning arrester 1 to flow through the coil, and swings the pointer 11 according to the current flowing through the coil.

As shown in FIG. 3, the scale plate 10 is provided with, for example, a unit 12 such as mA, a scale 13, an auxiliary scale 13a, or the like by printing or engraving. The intervals of the scales 13 are not equal intervals, but are intervals corresponding to the voltage-current characteristics (non-linear characteristics) shown in FIG. The auxiliary scale 13a is provided so as to further subdivide the interval of the scale 13 of 4 mA or less. That is, the scale plate 10 is provided with scales by changing the interval according to the deviation of the pointer of the ammeter 8.

In the voltage-current characteristic shown in FIG. 6, the current value changes linearly from 0 to 4 mA at a ratio of about 1: 1 from 0 to a little less than 4 V at the first inclination angle, and the voltage changes from 4 V to 6 V. In the range of, the rate of change of the current value increases, and the current value changes linearly from 5 mA to 14 mA at a second inclination angle of about 1: 5. In this example, the scale plate 10 is used as the effective value display, but the peak value may be displayed.

As shown in FIG. 4, the discharge frequency meter 2 has a lightning rod element 19 that releases a lightning current from the lightning arrester 1 to the ground, and a lightning rod counting and flow detection circuit 20 connected in parallel with the lightning rod element 19.

The lightning strike counting and flow detection circuit 20 takes in a part of the lightning current that flows through the lightning arrester 1 and a minute leakage current that always flows from the lightning arrester 1, and detects the leakage current. When an abnormal current such as a lightning strike is detected, the number of lightning strikes is counted.

The discharge frequency meter 2 includes a lightning protection element 19 such as a low resistance zinc oxide element ZnO connected between terminals P1-terminal P8, a capacitor C connected between terminals P2-terminal P4 connected to terminal P1, and a capacitor C thereof. A drive coil T connected to the capacitor C via a resistor element R0, a capacitor C1 connected in parallel with the drive coil T between terminals P3-terminal P4, and a protection gap G connected between terminals P4-terminal P8. A non-linear characteristic current generation circuit 22 connected between the terminal P4 and the terminal P6, and a current meter 8 connected to the non-linear characteristic current generation circuit 22. Of the circuits shown in FIG. 4, the circuit excluding the lightning rod element 19 is the lightning rod counting and flow detection circuit 20.

The non-linear characteristic current generation circuit 22 has a voltage-current characteristic (FIG. 6) with a predetermined current value (for example, around 4 mA or 5 mA) exceeding the range of the normal leakage current (about 0.2 mA, 0.3 mA) of the lightning arrester 1. (See) is a circuit configured to change. That is, the non-linear characteristic current generation circuit 22 is configured to generate a non-linear characteristic current in which the current characteristics change with a predetermined threshold value exceeding the leakage current range.

Specifically, the non-linear characteristic current generation circuit 22 includes a resistance element R1 connected between terminals P4-terminal P5, a Zener diode ZD connected between terminals P5-terminal P6, terminals P5, and a current meter 8. It has resistance elements R2 and R3 connected between the two, and a reverse parallel connection type diode group D connected between terminals P7 and terminals P6 between the resistance elements R2 and R3.

The protection gap G is a gap (discharge element) for protecting the ammeter 8 and the like connected between the terminals P4- and P8.

The Zener diode ZD is for piping so that a current higher than the Zener voltage (above a constant voltage) does not flow through the ammeter 8 and protects the ammeter 8 from an excessive current. That is, the Zener diode ZD is used for the purpose of protecting the ammeter 8 from being damaged by an excessive current flowing through it.

The ammeter 8 swings the pointer according to the current input from the lightning arrester 1 through the drive coil T and the nonlinear current circuit 22. That is, the ammeter 8 is an analog type ammeter that swings the pointer 11 according to a current such as a leakage current or noise flowing from the lightning arrester 1 to the discharge meter 2.

The capacitor C stores a part of the energy of the lightning strike flowing through the lightning protection element 19, and supplies the stored part of the energy to the drive coil T and the capacitor C1 through the resistance element R0.

The drive coil T is for operating the counter 7 by the energy supplied from the capacitor C to count the number of lightning strikes (lightning strikes).

The sensitivity adjustment circuit 21 is composed of the resistance element R0 and the capacitor C1. The sensitivity adjustment circuit 21 is a circuit that slows down the sensitivity of the drive coil T for counting lightning strikes. The sensitivity of the drive coil T can be changed (adjusted) by changing the constants of the resistance element R0 and the capacitor C1 of this circuit. That is, the sensitivity adjustment circuit 21 is a circuit for adjusting the sensitivity at the time of lightning strike count-up.

In this example, the constants of the resistance element R0 and the capacitor C1 are set so that the drive coil T performs the counting operation with a current 100 times or more the leakage current of the lightning arrester 1 (for example, a current of 100 A or more). In this example, the constant of the resistance element R0 is, for example, 5.1 KΩ. The constant of the resistance element R0 may be applied in the range of 5KΩ to 10KΩ.

The capacitor C1 stores a part of the energy supplied from the capacitor C when a lightning strike occurs, thereby reducing the energy supplied to the drive coil T and adjusting the sensitivity of the drive coil T.

Normally, the drive coil T operates with an alternating current of about several tens of mA. Therefore, the capacitor C1 changes the impedance to lower the operating sensitivity (adjust the sensitivity) so that the drive coil T does not operate with a current of about 50 mA. belongs to.

That is, the capacitor C1 connected in parallel to the drive coil T and the resistance element R0 connected between the capacitor C and the drive coil T absorb a part of the energy from the capacitor C to the drive coil T to absorb a part of the energy from the capacitor C to the drive coil T. It is an element for adjusting the sensitivity that lowers the sensitivity of the coil.

The resistance element R2 and the resistance element R3 are resistors that divide the current into the ammeter 8 and the diode group D.

The anti-parallel connection type diode group D is a group of two diodes having different connection directions connected in parallel. Since this example is applied to an alternating current (current having a characteristic that the phase is inverted with time) circuit, a form of antiparallel connection in which two diode groups are connected in parallel in opposite directions is adopted.

In this example, the diode group D in which a plurality of diodes are connected is used, but in addition, a switching element group such as a transistor group that can be controlled from the outside may be used. In this case, the point Q (see FIG. 6) at the point where the non-linear characteristic is obtained can be changed by external control.

That is, this antiparallel connection type diode group D causes a current in a certain direction to flow to the ammeter 8 even when the polarity of the current is reversed by an alternating current, and the pointer 11 of the ammeter 8 is directed to the scale 13 of the scale plate 10. It is for shaking.

The lightning rod element 19 functions as a protection circuit that bypasses most of the large current from the lightning arrester 1 due to a lightning strike and allows it to flow to the ground (ground). The lightning rod 19 has the same performance as the lightning rod of the lightning arrester 1.

The operation and effect of this lightning strike detection system will be described below.
When there is no diode group D, if the current flowing through the resistor R3 and the ammeter 8 is I0 and the voltage at the terminal P7 is V0, a linear current-voltage characteristic as shown in FIG. 5 is obtained. = I0 × Z0.

On the other hand, when the diode group D is connected to the ammeter 8 as in the present embodiment, as shown in FIG. 6, the resistance element R3 starts from the vicinity of the on-voltage (point Q in FIG. 6) of each diode in the diode group D until then. The current flowing only through the ammeter 8 is split through the resistance element R2 and also flows into the diode group D.

Assuming that the current flowing through the resistance element R3 and the ammeter 8 at this time is I0', the impedance of the diode group D is Z1, the current flowing through the diode group D is I1, and the voltage of the terminal P5 is V1, V1 = I1 × Z1 = I0. ´ × Z0.

Although FIG. 6 is an image diagram for explanation, it actually has a non-linear current-voltage characteristic as shown in FIG. 7.

In this embodiment, a diode having an ON voltage of about 1.2 V is used for the diode group D. In this case, the resistance element R2 uses a resistance element of 30Ω, and the resistance element R3 uses a resistance value (about 100Ω) that is approximately three times that of the resistance element R2.

As a result, a current according to the non-linear characteristic as shown in FIG. 7 flows through the actual ammeter 8, so that the scale plate 10 of the ammeter 8 is shown in FIG. 3 according to this characteristic. , The scale plate 10 has a different spacing between the scales 13. The spacing between the scales 13 shall be finely adjusted according to the actual measurement, taking into consideration the individual differences of the parts used as well as the above characteristics.

In this embodiment, the values of newly introduced components (capacitor C1, diode group D, resistance elements R2, R3, etc.) and the intervals of the scales 13 are adjusted, and the current value range is fine in the range of 0-3 mA. Auxiliary scales 13a were provided to improve reading accuracy, and scales 13 in the range of 3 mA to 50 mA were thinned out, but in addition to this example, component values and scale intervals are adjusted according to other required performance. Therefore, it is possible to change to a high-precision reading and a thinned reading.

As described above, according to the lightning detection system of this embodiment, new parts (capacitor C1 with adjusted component constants, resistance element R3, diode group D, etc.) are added to a part of the circuit of the existing discharge ammeter. By exchanging the scale plate 10 of the ammeter 8, for example, from a leakage current of about 0.2 mA or 0.3 mA to a current about 100 times larger than that (about 30 mA or 50 mA) can be visually recognized with the deflection of one pointer 11. It is possible to provide a low-cost discharge ammeter 2 with a wide range display. The display range can be, for example, about 10 mA to 100 mA.

In addition, since the structure is based on the existing discharge frequency meter (existing product), the airtight container and circuit parts of the discharge frequency meter 2 can be diverted, so the manufacturing cost can be kept low and the discharge frequency meter 2 as a product can be inexpensive. Can be provided.

In addition, the ammeter 8 is also based on the existing product, and a compression scale (scale 13 with varying intervals: see FIG. 3) is adopted for the scale plate 10, and the interval of the scale 13 is further subdivided in the range of 3 mA or less. By providing the auxiliary scale 13a in the shape of a sword, the current (leakage current) in the range to be normally measured can be read accurately, and even for a large current of about 50 mA, the current is observed while observing the deflection of the pointer 11 on the same display panel 9. The change in can be visually confirmed.

In the above embodiment, the discharge frequency meter 2 has been described as an example, but this embodiment can also be applied to an ammeter having no function of countering the discharge frequency, that is, a current display device alone.

Further, in the above embodiment, the AC discharge frequency meter has been described, but as shown in FIG. 8, it can also be applied to the DC discharge frequency meter 31 connected to the DC power transmission line 30.

In this case, the capacitor C1 is connected in parallel with the drive coil T, and is connected in series to the filter circuit F (composed of the capacitors 41, 43, the resistance element R2, the diodes 44, 45, etc.) in the previous stage of the DC ammeter 47. The type diode group D1 and the Zener diode ZD1 are connected. Since this example is a DC circuit, the diode group D1 and the Zener diode ZD1 are used in only one direction.

Further, as the scale plate of the DC ammeter 47, the scale plate 10 shown in FIG. 3 is used. Reference numeral 33 is a diode bridge, reference numerals 19 and 39 are low-resistance ZnO elements, and reference numeral 48 is a magnetically magnetized coil.

According to this example, by adding components such as a capacitor C1, a diode group D1, and a Zener diode ZD1 to the DC ammeter 47 of the DC discharge meter 31 connected to the DC transmission line 30, it is used for a DC circuit. The leakage current of a lightning arrester can be monitored in a wide range, and a lightning detection system can be provided for a DC electric line.

Further, as shown in FIG. 9, an alarm relay 52 is connected to the drive coil T (count-up coil) of the discharge frequency meter 2 shown in FIG. 1 via a relay coil 51, and the contact 53 of the alarm relay 52 is connected. Is provided in the case 50 of the discharge meter 2, so that the discharge meter 2 can be connected to the relay and the contact signal at the time of the lightning protection operation can be output from the discharge meter 2 to the relay.

In the above embodiment, the discharge frequency meter 2 having the ammeter 8 built-in has been described, but the discharge frequency meter 2 and the ammeter 8 may be separated. That is, even if a current measuring device is connected to a discharge meter that has a lightning rod element 19 for releasing the lightning current from the lightning arrester 1 to the ground, counts the number of lightning strikes, and outputs a leakage current from the lightning arrester 1 other than the lightning strike. Good.

In this case, the lightning arrester element 19 that releases the lightning current from the lightning arrester 1 to the ground and the function of counting the number of lightning strikes use the circuit of FIG. 4 (capacitors C, C1, resistance element R0, drive coil T, etc.). A port for outputting the leakage current from the lightning arrester 1 other than the lightning strike to the outside shall be provided.

The current measuring device is provided with a non-linear characteristic current generation circuit 22, an ammeter 8 (see FIG. 4) connected to the non-linear characteristic current generation circuit 22, and a scale 13 according to the deviation of the pointer of the ammeter 8. It is provided with a scale plate 10 (see FIG. 3).

The nonlinear characteristic current generation circuit 22 is configured so that the voltage-current characteristic (see FIG. 6) changes with a threshold value (near 5 mA) of a current exceeding the range of the leakage current as a boundary. The ammeter 8 measures the leakage current input from the discharge frequency meter through the nonlinear characteristic current generation circuit 22.

Further, even if the lightning arrester 1 is provided with a port for outputting a current (leakage current) other than a lightning strike, a current measuring device is connected to this port, and the current measuring device measures the leakage current input from the lightning arrester 1. Good.

In this case, the current measuring device shall include a non-linear characteristic current generation circuit 22, an ammeter 8 connected to the non-linear characteristic current generation circuit 22, and a scale plate 10 provided on the ammeter 8.

The non-linear characteristic current generation circuit 22 is configured so that the voltage-current characteristic changes with a threshold value (near 5 mA) of a current exceeding the range of the leakage current as a boundary. The ammeter 8 measures the current of the lightning arrester 1 input from the lightning arrester 1 in addition to the lightning strike, and swings the pointer according to the measured current. The scale plate 10 is provided with a scale 13 according to the deviation of the pointer of the ammeter 8.

Although embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. This novel embodiment can be implemented in various other embodiments, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... lightning arrester, 2 ... discharge frequency meter, 3 ... line terminal, 4 ... ground terminal, 5 ... relay terminal, 6 ... ground terminal, 7 ... counter, 8 ... current meter, 9 ... display panel, 10 ... scale plate, 11 ... pointer, 13 ... scale, 13a ... auxiliary scale, 19 ... lightning protection element, 20 ... lightning strike counting and detection circuit, 21 ... sensitivity adjustment circuit, 22 ... non-linear characteristic current generation circuit, 30 ... DC transmission line, 31 ... DC discharge Frequency meter, 41 ... capacitor, 44, 45 ... diode, 47 ... DC current meter, 48 ... magnetic coil, 50 ... case, 51 ... relay coil, 52 ... alarm relay, 53 ... contact, C ..., C1 ... capacitor , D, D1 ... Diode group, F ... Filter circuit, G ... Protection gap, P1-P8 ... Terminal, R0, R1, R2, R3 ... Resistance element, T ... Drive coil, ZD, ZD1 ... Zener diode, ZnO ... Low Resistant zinc oxide element.

Claims (5)

In a discharge frequency meter that counts the number of lightning strikes from the lightning current and leakage current input from the arrester.
A lightning rod that releases the lightning current from the lightning arrester to the ground,
A drive coil that counts the number of lightning strikes using a part of the lightning current as energy,
A sensitivity adjustment circuit that slows down the sensitivity of the drive coil for lightning strike counting,
A non-linear characteristic current generation circuit configured to generate a non-linear characteristic current whose current characteristics change with a predetermined threshold value exceeding the leakage current range, and a non-linear characteristic current generation circuit.
Is connected to the non-linear characteristic current generating circuit, and a current meter for swinging the pointer in response to a current input through the drive coil and the non-linear characteristics current generation circuit from the arrester,
A discharge frequency meter provided on the ammeter and provided with a scale plate having a scale at different intervals according to the deviation of the pointer of the ammeter. The sensitivity adjustment circuit
The discharge frequency meter according to claim 1, wherein the sensitivity of the drive coil T is adjusted so that the drive coil T performs a counting operation with a lightning current of 100 times or more the leakage current of the lightning arrester. The discharge frequency meter according to claim 1 or 2, further comprising a contact for external output connected to the drive coil via a relay coil. The nonlinear characteristic current generation circuit
Of the current that flows through the drive coil from the arrester, a Zener diode to bypass the certain level of current to the I power sale grounded end does not flow into the ammeter,
The discharge frequency meter according to any one of claims 1 to 3, further comprising a group of switching elements for flowing a non-linear characteristic current whose current characteristics change with a certain threshold value in one direction to the ammeter. In a current measuring device that measures current other than lightning strikes input from a lightning arrester or a discharge frequency meter connected to a lightning arrester.
A non-linear characteristic current generation circuit configured so that the voltage-current characteristic changes at the threshold value of the input current that exceeds the range of the leakage current from the arrester.
And ammeter to shake the pointer connected to said non-linear characteristic current generating circuit, in response to the current input through the non-linear characteristics current generation circuit from the arrester,
A current measuring device including a scale plate having a scale changed at intervals according to the deviation of the pointer of the ammeter.

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