JPH06242148A - Impulse voltage measuring device - Google Patents

Abstract

PURPOSE:To suppress an earth capacity in each non-inductive resistor to the extent that can be ignored so as to improve a response characteristic by connecting individual shield rings, which are arranged at equal intervals around the non-inductive resistor, together by a series circuit of the non-inductive resistance and a high voltage capacitor. CONSTITUTION:When a lighting impulse voltage is impressed to a non-inductive resistor 11, a non-inductive resistance 14 and a high voltage capacitor 15 share the voltage equally with each other between individual shield rings 13, so that the voltage is distributed linearly from the top part of the resistor body 11 toward the earth side. Therefore, electric fields between individual rings 13 are generated parallelly with the resistor body 11, and a line of electric force from the resistor body 11 to the earth is almost disappeared, so that an earth capacity of the resistor body 11 is reduced to the extent that can be ignored. Therefore, responsiveness is remarkably improved. On the other hand, a low voltage part compensation circuits 12, 17 constitute a responsiveness characteristic compensation circuit P, so that the responsiveness can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impulse voltage measuring device used to measure an impulse voltage caused by lightning or the like and a wavefront breaking voltage thereof with high accuracy.

[0002]

2. Description of the Related Art FIG. 6 is a circuit diagram showing a conventional impulse voltage measuring device. In the figure, 1 is a voltage divider, R _d is a braking resistor, and R _L is a low-voltage section connected in series to this voltage divider 1. A resistor, 2 is a high-voltage connecting line, and R _H is a high-voltage portion resistor as a braking resistor, which are connected in series as shown in the drawing and an impulse voltage is applied from the measurement terminals A and D.

Further, R ₁ and R ₂ are matching resistors, 3 is a measuring cable, and R ₃ is a voltage dividing resistor, which adjust the voltage to be measured and supply it to the measuring device 4. In the voltage divider 1, a high voltage portion is provided between the terminals B and C, a low voltage portion is provided between the terminals C and E, and
_g is the ground capacity of the high voltage resistance R _H.

In such an impulse voltage measuring device, when a voltage is applied to the voltage divider 1 through the high voltage section resistance R _H and the high voltage connection line 2, the voltage thus divided is obtained at the low voltage section R _L end, This is further input to the measuring device 4 via the measuring cable 3 and measured.

By the way, the frequency characteristic which is the response characteristic of this measuring system is generally represented by a quadrature wave response, and
When a quadrature wave voltage is applied to, the final value of the voltage waveform appearing in the measuring device 4 is normalized and expressed as 1.

FIG. 7 shows the response waveform g (t) of the quadrature wave voltage.
Indicates. Here, the tangent at the wave front is the horizontal axis (time axis)
The point O ₁ that intersects with becomes the origin, and the response characteristic is shown by the area of the shaded area (having a unit of time). Further, in the figure, T ₀ is the initial distortion time, T α is the partial response time, and T _{N is}
(Tα-Tβ + Tγ-Tδ + ...) Is the experimental response time.

The value T (t) obtained by integrating the shaded area from the origin O ₁ to the time t is the stable time and is expressed as follows.

[0008]

[Equation 1]

Then, this T (t) has a waveform as shown in FIG. 8, and with the final value T of this as a reference, T + 'O
´. If a straight line of 02t, T-0.02t is drawn and the time of the final intersection with T (t) is set to t _S , this t _S becomes a stable time.

Further, in a resistive voltage divider, g (t) is not oscillatory and T _N is given by approximately R _H C _g / 6. Since the smaller T _N is, the better the response characteristic is, C _g
In order to improve the response characteristics by reducing the value of, the method of attaching a large shield ring 5 to the head of the voltage divider 1 has been conventionally used as shown in FIG.

[0011]

Since the conventional impulse voltage measuring device is constructed as described above, in the high voltage portion between the terminals B and C of the voltage divider 1, when the impulse voltage is applied, each portion is The voltage sharing in the
Moreover, since the ground capacitances from the respective parts are large and uneven, the lines of electric force directed to the ground are larger than those of the resistor, and there is a problem that there is a limit in improving the response characteristics.

Further, in the structure shown in FIG. 9, since one shield ring 5 is used, it is difficult to completely cancel the ground capacitance C _g of the resistance R _H , and the shield ring 5 becomes large, The capacitance to ground becomes large, and due to the capacitance to ground, the braking resistance R _d, and the inductance L of the high-voltage connection line 2, the voltage waveform applied to the head of the voltage divider 1 becomes gentle, and there is a problem that the response characteristics deteriorate. It was

Furthermore, since the shield ring 5 is mounted considerably below the head of the voltage divider 1, the distance to the ground is shortened and the withstand voltage of the voltage divider 1 is lowered. There was a problem that it could be about / 3.

The present invention has been made to solve the above problems, and provides an impulse voltage measuring apparatus capable of greatly improving the response characteristics by suppressing the ground capacitance in each part of the non-inductive resistor to a negligible level. The purpose is to get.

[0015]

An impulse voltage measuring device according to the present invention comprises a cylindrical non-inductive resistor for voltage division, to which an impulse voltage is applied through a high voltage connecting line,
Arranged concentrically and at equal intervals around the non-inductive resistor,
From a non-inductive resistance and a high-voltage capacitor that connect a plurality of shield rings, the top one being connected to the top of the inductive resistor and the bottom one being connected to the ground side, and adjacent ones of the shield rings. And a response characteristic compensation circuit is connected to the low voltage portion of the non-inductive resistor.

[0016]

The impulse voltage measuring device according to the present invention comprises:
The shield rings are connected in series with a small-capacity high-voltage capacitor and a non-inductive resistor, and when the impulse voltage is applied to the non-inductive resistor for voltage division,
An even voltage is shared between each shield ring, the voltage is linearly distributed from the top of the non-inductive resistor toward the ground side, and an electric field between the shield rings is generated in parallel with the non-inductive resistor. It functions to make the line of electric force from the non-inductive resistor to the ground almost zero.

[0017]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 11 is a vertically standing cylindrical non-inductive resistor for voltage division, for example, the total length is 23
The resistance value is set to 20 mm and the resistance value is set to 10Ω, and an impulse voltage due to lightning or the like is applied to the top of the resistance value through a high-voltage connection line. Reference numeral 12 is a low voltage compensating circuit connected between the lower end of the non-inductive resistor 11 and the ground.

Further, around the non-inductive resistor 11,
On the other hand, a plurality of annular shield rings 13 are concentrically arranged at equal intervals in the vertical direction, and these shield rings 13 have, for example, an outer diameter of 330 mm and a thickness of 30 mm, and are located at the uppermost portion of these. Things are non-inductive resistors 1
1 is electrically connected to the top, and the lowermost one is grounded via a case K for housing the low voltage compensating circuit 12 via a non-inductive resistance and a high voltage capacitor.

Further, 14 has, for example, a resistance value of several tens of Ω.
Non-inductive resistance of several hundred Ω, 15 is connected in series with this non-inductive resistance 14, for example, capacity is several tens pF to several thousand.
This is a pF high-voltage capacitor, and these series circuits are connected between the respective shield rings 13 and between the lowermost shield ring 13 and the ground.

At the connection point between the lower end of the non-inductive resistor 11 and the lowered portion compensation circuit 12, another low voltage portion compensation circuit 17 and a measuring device 18 such as a digital recorder or an oscilloscope are provided via a measurement cable 16. They are connected in sequence. The two low voltage compensating circuits 12 and 17 form a response characteristic compensating circuit P.

FIG. 2 shows a concrete example of the low-voltage compensating circuit 17, which constitutes the response characteristic compensating circuit P, and a resistor R
A series circuit in which _a is 50 Ω and inductance L _a is 1.3 μH, and resistance R _b is 10 Ω and inductance L _b is 3
The μH and the capacitor C consist of a 650 pF series circuit connected in parallel. The low-voltage compensating circuit 1
For example, a resistance of 50Ω is used as 2.

Next, the operation will be described. With the impulse voltage measuring device having such a configuration, when the lightning impulse voltage is applied to the non-inductive resistor 11, each shield ring 13
In the meantime, the non-inductive resistor 14 and the high-voltage capacitor 15 share the same voltage, and the voltage is linearly distributed from the top of the non-inductive resistor 11 toward the ground side.

Therefore, the electric field between the shield rings 13 is generated in parallel with the resistors, and the lines of electric force directed to the ground from the non-inductive resistor 11 almost disappear, and the ground capacitance of the non-inductive resistor 11 is so small that it can be ignored. Therefore, the response characteristics are greatly improved. Further, according to the present invention, the low voltage compensating circuit 17
By using the optimum circuit constants as shown in FIG. 2, it is possible to improve the performance of the response characteristic in one step.

As the low-voltage compensating circuits 12 and 17, a series circuit of an inductance l ₁ and a resistance r ₁ may be used as shown in FIG. 3 (a), or FIG. 3 (b).
As shown in, a series circuit of an inductance l ₁ and a resistance r _{1 and} a series circuit of an inductance l ₂ , a capacitor C and a resistance r ₂ may be connected in parallel,
In addition, one of the low-voltage compensating circuits 12 and 17 is provided in FIG.
(A) or FIG. 3 (b), and the other may be a non-inductive resistor.

High Voltage Test Technics of the IEC (International Standard) draft that is currently being revised, Part 2: Measuring System (high voltag)
estettechniques, part2: me
1992, the response conditions of the standard voltage divider for measuring the full-wave lightning impulse and the wavefront cut-off lightning impulse voltage are specified as shown in the table of FIG.

According to the present invention, the non-inductive resistor 1 having a high voltage portion resistance (resistance value 10 KΩ) for 1000 KV.
1 was prototyped and the response performance was measured. T _N ≈0,
t _S ≦ 100 to 150 ns, Tα <10 ns, T ₀ ≈
Very good characteristics were obtained, such as 0.05 ns. At present, this performance is at the highest level inside and outside.

As described above, the inductive resistor 11 of the present invention is essentially a resistance voltage divider, and the voltage division ratio is determined by the resistance values of the high-voltage part and the low-voltage part, and the resistance uses a resistance wire such as manganin-camalloy. , Temperature change and secular change are extremely small, and the influence on the partial pressure ratio can be ignored.

Further, although there is a 1% to 2% change in the capacity of the high-voltage capacitor 15 connecting the shield rings 13 with temperature and aging, even if it changes by 10%, the influence on the response parameter is almost eliminated. It was confirmed by actual measurement that there was not.

Since the capacitor C used in the low-voltage compensating circuits 12 and 17 has a low operating voltage (several hundreds of V or less) and a small capacitance, it is possible to easily and inexpensively obtain good characteristics and monitor the capacitance value. And can be easily held constant.

FIG. 5 shows response waveforms actually measured for the above-mentioned prototype plot type for 1000 KV. The constants of the compensating circuit are the same as those explained with reference to FIGS. 1 and 2, but the high voltage connection line 2 and the braking circuit are used. It is necessary to select an optimum value according to the value of the resistance R _d . In this measurement example, the high voltage connection line 2 is 3 m, and the braking resistance R _d is 100Ω.
And As a result, T _N ≈0, t _S ≈110 μs, T
α≈10 ns and T ₀ ≈0.04 ns were obtained.

[0031]

As described above, according to the present invention, a cylindrical non-inductive resistor for voltage division to which an impulse voltage is applied through a high-voltage connecting line, and a concentric ring around the non-inductive resistor. In addition, a plurality of shield rings, which are arranged at equal intervals and whose uppermost one is connected to the top of the inductive resistor and whose lowermost one is connected to the ground side, respectively, and the adjacent ones of the shield rings are not connected to each other. Since a series circuit composed of an inductive resistance and a high voltage capacitor is provided and the response characteristic compensation circuit is connected to the low voltage part of the non-inductive resistor, the ground capacitance of the non-inductive resistor which is the high voltage part resistor is configured. Can be made almost zero, and therefore, the response characteristic as the voltage divider can be improved, and further, the response characteristic compensating circuit of the low voltage section can improve the response characteristic by one step. .

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an impulse voltage measuring device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram specifically showing a low voltage compensating circuit in FIG.

3 is a circuit diagram showing another specific example of the low-voltage compensating circuit in FIG.

FIG. 4 is a table showing response parameters required for a standard voltage divider according to the IEC standard being revised.

FIG. 5 is a waveform diagram showing an actually measured response waveform by a 1000 KV prototype impulse voltage measuring device.

FIG. 6 is a circuit diagram showing a conventional impulse voltage measuring device.

FIG. 7 is a waveform diagram showing a response waveform by the impulse voltage measuring device of FIG.

8 is a characteristic diagram showing the stabilization time of the response waveform of FIG.

FIG. 9 is a conceptual diagram showing a conventional resistance voltage divider using a shield ring.

[Explanation of symbols]

 2 High-voltage connection line 11 Non-inductive resistor 13 Shield ring 14 Non-inductive resistance 15 High-voltage capacitor P Response characteristic compensation circuit

Claims (1)

[Claims] 1. A cylindrical non-inductive resistor for voltage division, to which an impulse voltage is applied through a high-voltage connecting line, and concentric and equidistantly arranged around the non-inductive resistor, the uppermost one. Is a series circuit composed of a plurality of shield rings, the bottom one of which is connected to the ground side, and a non-inductive resistor and a high-voltage capacitor that connect adjacent ones of the shield rings to the top of the inductive resistor. An impulse voltage measuring device comprising: a response characteristic compensation circuit connected to the low voltage portion of the non-inductive resistor.