JPH1031037A - Capacitor potential divider - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the frequency characteristic and reduce the size by using a vacuum capacitor as a potential dividing capacitor, and setting one of the low voltage side and high voltage side, or the both to a variable capacitor. SOLUTION: Vacuum capacitors are used as a high voltage side capacitor 1 and a low voltage side capacitor 2. A waveform observing device 3 is connected between a detecting terminal 4 and an earth terminal. The vacuum capacitor has no dielectric between electrodes, so that no dielectric loss is caused even in high frequency area. When the distance between the electrodes is regulated by moving at least one electrode, the electrostatic capacity is changed to form a variable capacitor. When an ac high voltage V is applied in waveform observation, distributed voltage, or the voltage to ground of the low voltage side capacitor 2 is added to the input end of the waveform observing device 3. Even when a high frequency component is contained in a voltage to be measured, the high frequency area can be precisely observed because of the vacuum capacity. Further, the withstand voltage characteristic is so excellent that a small size is enough.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a capacitor voltage divider for observing an AC high-voltage waveform.

[0002]

2. Description of the Related Art When observing an AC high-voltage waveform, it is necessary to lower the voltage to a level that can be input to an oscilloscope or a digital waveform observation device. For this purpose, an instrument transformer is generally used, but in the case of a voltage waveform including a high frequency component such as a transient phenomenon, a capacitor voltage divider may be used. FIG. 1 shows an example of the connection.

That is, a capacitor 1 (capacitance C1) and a capacitor 2 (capacitance C2) are connected in series, and an AC high voltage V is applied between both ends (here, the capacitor 2 side is used as a ground terminal). Then, the divided voltage is observed by the waveform observation device 3 connected between the connection point (detection terminal 4) of the capacitors 1 and 2 and the ground terminal. The capacitor 1 has a sufficient withstand voltage characteristic with respect to the voltage to be measured, and its capacitance is C1２C2. At this time, the division ratio k becomes k = C1 / (C1 + C2) ≒ C1 / C2, and the voltage of V / k can be observed as the ground voltage of the capacitor 2.

[0004]

Generally, capacitors 1 and 2 have a structure in which a dielectric is sandwiched between electrodes, and it is necessary to consider the dielectric loss of the capacitor in a high frequency region. . In addition, since the capacitor 1 is required to have high withstand voltage performance, in practice, a plurality of capacitors are connected in series to ensure the withstand voltage performance, and the voltage divider becomes large. Furthermore, since the voltage division ratio is fixed, there are problems that the observation voltage is limited, the measurement accuracy and the SN ratio are reduced. For example, k = 1000
0, when the input range of the waveform observation device 3 is ± 1 V, the measurable AC high voltage is in a range of ± 10000 V (peak value). Therefore, a voltage exceeding this cannot be measured. When the voltage of the measurement target is in the range of ± 1000 V, the waveform observation device 3 has a voltage that is considerably smaller than the input range.
A divided voltage of 0.1 V will be applied, and measurement accuracy and S
The N ratio decreases.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and to provide a capacitor voltage divider which can improve the frequency characteristics and reduce the size, and can easily change the setting of the voltage division ratio.

[0006]

The present invention is characterized in that a vacuum capacitor is used as a voltage dividing capacitor.

The present invention is characterized in that a vacuum capacitor is used as a voltage dividing capacitor, and one or both of the low voltage side and the high voltage side are variable capacitors.

Further, the present invention is characterized in that a plurality of vacuum capacitor elements connected in series or in parallel are used as voltage dividing capacitors.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described by way of an embodiment shown in the drawings. The present invention is characterized in that a vacuum capacitor is used as a voltage dividing capacitor, and the circuit is the same as the conventional one. Embodiment 1 shown in FIG. 1 is a basic circuit in which a vacuum capacitor is used as a high-voltage-side voltage dividing capacitor 1 and a low-voltage side capacitor 2, and a connection point (detection terminal 4) between the two capacitors 1 and 2 and a ground terminal. The waveform observation device 3 is connected between the two. A vacuum capacitor has electrodes facing each other in a vacuum, and there is no dielectric between the electrodes. That is, no dielectric loss occurs even in the high frequency region. Moreover, it has a sufficient withstand voltage performance even with a small size. In addition, when the distance between the electrodes is adjusted by moving at least one of the electrodes, the capacitance changes. That is, it becomes a variable capacitor.

At the time of waveform observation, a vacuum capacitor was used.
When an AC high voltage V is applied across the voltage divider composed of the capacitors 1 and 2, the divided voltage, that is, the ground voltage of the capacitor 2 is applied to the input terminal of the waveform observation device 3. In this case, even if a high frequency component is contained in the voltage to be measured, since the voltage dividing capacitors 1 and 2 are vacuum capacitors, accurate observation up to a high frequency region is possible. Further, the vacuum capacitor has excellent withstand voltage characteristics, and a small high-voltage capacitor 1 having a large shared voltage is sufficient.

Another embodiment of the present invention (Embodiments 2 to 8)
Are shown in FIGS. In the second embodiment (FIG. 2), the variable capacitor 1 ′ is provided on the high voltage side, in the third embodiment (FIG. 3), the variable capacitor 2 ′ is provided on the low voltage side, and in the fourth embodiment (FIG. 4), the variable capacitor 1 ′ is provided on the high voltage side and the low voltage side. 'And 2' are used, respectively.

When the variable capacitors 1 'and 2' are used as described above, it is easy to select the voltage division ratio k to an appropriate value according to the voltage at the time of observation, and to make full use of the capability of the waveform observation device 3. it can. That is, it is possible to always ensure high measurement accuracy and SN ratio.

In a fifth embodiment (FIG. 5), a plurality of capacitor elements are connected in series to constitute a high voltage side (low voltage side) voltage dividing capacitor 1s (2s). Are connected in parallel to form a high-voltage side (low-voltage side) voltage dividing capacitor 1p (2p). Dividing capacitor 1s (2s), 1p (2p ) is constructed using the variable capacitor element C ₁₂ or configuration, or all with a fixed capacitor element C ₁₁ and the variable capacitor element C _12.

Also in this case, the voltage dividing ratio k can be selected to an appropriate value according to the voltage, as in the above-described embodiments 2 to 4.

The seventh embodiment (FIG. 7) and the eighth embodiment (FIG. 8) show a case where the present invention is applied to a resistance-capacitance voltage divider combining a resistor and a capacitor. In the seventh embodiment, the resistors 5 and 6 are connected in series to the high voltage side and low voltage side voltage dividing capacitors 1 and 2 using a vacuum capacitor. In the eighth embodiment, the resistors 5 ′ and 6 ′ are connected in parallel to the high voltage side and low voltage side voltage dividing capacitors 1 and 2 using a vacuum capacitor.

When a vacuum capacitor is used as the resistance-capacitance voltage divider as described above, the capacitance is kept constant even when the DC voltage is divided, so that high measurement accuracy can be obtained.

[0017]

As described above, according to the present invention, since the dielectric loss of the voltage dividing capacitor can be ignored, the frequency characteristics are improved. In addition, vacuum capacitors have excellent withstand voltage characteristics, so even if they are connected in series, only a small number is required.
The size can be reduced. Further, since the capacitance easily and accurately changes by adjusting the distance between the electrodes, the voltage division ratio can be set arbitrarily, and the measurement accuracy and the SN ratio can be improved.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing a first embodiment of the present invention.

FIG. 2 is a connection diagram showing a second embodiment of the present invention.

FIG. 3 is a connection diagram showing a third embodiment of the present invention.

FIG. 4 is a connection diagram showing a fourth embodiment of the present invention.

FIG. 5 is a connection diagram showing a fifth embodiment of the present invention.

FIG. 6 is a connection diagram showing a sixth embodiment of the present invention.

FIG. 7 is a connection diagram showing a seventh embodiment of the present invention.

FIG. 8 is a connection diagram showing an eighth embodiment of the present invention.

[Explanation of symbols]

1, 1 ', 1s, 1p: High-voltage side voltage dividing capacitor (vacuum capacitor) 2, 2', 2s, 2p: Low-voltage side voltage dividing capacitor (vacuum capacitor) 3: Waveform observation device 5, 6: Resistance C1: High voltage side Capacitance of voltage dividing capacitor 1 C2 ... Capacitance of low voltage side voltage dividing capacitor 2 V ... AC high voltage to be measured k ... Division ratio

Claims (3)

[Claims] 1. A capacitor voltage divider using a vacuum capacitor as a voltage dividing capacitor. 2. The capacitor voltage divider according to claim 1, wherein one or both of the low voltage side and the high voltage side of the voltage dividing capacitor are variable capacitors. 3. The capacitor voltage divider according to claim 1, wherein the voltage dividing capacitor is composed of a plurality of capacitor elements connected in series or in parallel.