CN106291035B - Capacitive voltage divider - Google Patents
Capacitive voltage divider Download PDFInfo
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- CN106291035B CN106291035B CN201510303516.8A CN201510303516A CN106291035B CN 106291035 B CN106291035 B CN 106291035B CN 201510303516 A CN201510303516 A CN 201510303516A CN 106291035 B CN106291035 B CN 106291035B
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Abstract
The invention provides a capacitive voltage divider, which comprises a hollow cylindrical insulating shell, metal flanges coaxially and symmetrically arranged at the outer sides of two ends of the insulating shell, and metal electrodes at the inner sides of the two ends of the insulating shell; the metal electrodes at the two ends are respectively connected with the metal flanges at the two ends, wherein a concentric equalizing ring and a damping resistor connected with a high-voltage lead wire along the axial direction of the equalizing ring are arranged on the metal flange at one end as a high-voltage end; the other end metal flange plate opposite to the high-voltage end is used as a low-voltage end; the low-voltage arm, the data acquisition unit and the wireless data transmitter are arranged in the metal electrode of the high-voltage end or the low-voltage end, and the data acquisition unit acquires the voltages at the two ends of the low-voltage arm and sends the voltages to the external data processor through the wireless data transmitter. The capacitive voltage divider provided by the invention has the advantages of simple and firm structure, convenience in transportation and stable performance, and can further improve the stability and practicality of the scale factors of the capacitive voltage divider.
Description
Technical Field
The present invention relates to voltage dividers, and more particularly to a capacitive voltage divider for measuring impulse voltage signals to calibrate and detect linearity of impulse voltage measurement devices.
Background
The impulse voltage of the power equipment in the withstand voltage test is the lightning impulse voltage suffered by the transmission line of the analog power system and the operation impulse voltage generated when the knife switch is opened and closed. In the test process, the amplitude and time parameters of the impulse voltage are often required to be measured, and an impulse voltage divider in the measurement system is a voltage conversion device and converts a high-voltage impulse voltage signal into a low-voltage signal which can be measured by a secondary measurement device.
The impulse voltage divider mainly comprises a resistor voltage divider and a capacitor voltage divider, and the resistor voltage divider has the advantages of excellent step wave response, small waveform distortion, good scale factor stability and the like, but because of heating of a resistor wire, the voltage level of the resistor voltage divider is generally lower than 1000kV and can only be used for measuring lightning impulse voltage. Currently, most of impact voltage dividers higher than 1000kV at home and abroad adopt capacitive voltage dividers. The capacitive voltage divider has small dielectric loss, does not generate heat, causes waveform distortion oscillation due to the influence of stray inductance on a loop, and develops a voltage divider with serially connected resistance and capacitance for damping the loop oscillation.
Fig. 1 is a schematic diagram of a high voltage arm of a current resistor-capacitor voltage divider, wherein the high voltage arm is formed by serially connecting resistors and capacitors, the capacitors are pulse capacitors insulated by oilpaper, and the resistors are double-line parallel wound noninductive resistors. The capacitance of the current high-voltage arm is generally 400pF, the capacitive voltage divider is easily affected by stray capacitance, and in addition, the capacitance stability of the oilpaper insulated pulse capacitor is poor and dielectric loss is large. The low voltage arm capacitor generally uses a concentrated capacitor (a film capacitor or a mica capacitor), and the wave impedance matching design is performed on the cable input end. Because the medium of the high-low voltage arm is different, the temperature coefficient and the voltage coefficient are also different, the fluctuation of the scale factor is large, the accuracy of 3% can be ensured generally, the linearity can not be ensured, and the method can not be used for measuring transient signals as a standard voltage divider.
In view of the above background, it is desirable to provide a capacitive voltage divider that has a simple structure, is convenient to transport, has stable performance, and can eliminate the influence of coupling capacitance between the voltage divider and the device or the voltage divider, and is used for performing linearity calibration of the impact voltage divider of more than 1000 kV.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides the capacitive voltage divider with the novel structure, which has the advantages of simple and firm structure, convenience in transportation and stable performance, so as to further improve the stability and practicality of the scale factors of the capacitive voltage divider.
The technical scheme provided by the invention is as follows: in a capacitive voltage divider, the improvement comprising: the capacitive voltage divider comprises a hollow cylindrical insulating shell, metal flanges coaxially and symmetrically arranged at the outer sides of two ends of the insulating shell, and metal electrodes at the inner sides of the two ends of the insulating shell; the metal electrodes at the two ends are respectively connected with the metal flanges at the two ends, wherein a concentric equalizing ring and a damping resistor connected with a high-voltage lead wire along the axial direction of the equalizing ring are arranged on the metal flange at one end as a high-voltage end; the other end metal flange plate opposite to the high-voltage end is used as a low-voltage end; the low-voltage arm, the data acquisition unit and the wireless data transmitter are arranged in the metal electrode of the high-voltage end or the low-voltage end, and the data acquisition unit acquires the voltages at the two ends of the low-voltage arm and sends the voltages to the external data processor through the wireless data transmitter.
Preferably, the metal electrode is conical, and one end with larger cross-section area is detachably connected to the inner side surface of the metal flange.
Further, the metal electrode at the high voltage end or the low voltage end is a whole metal aluminum electrode, and the metal conductor and the insulating material ring between the metal conductor and the metal electrode are concentrically arranged at the end with smaller cross section area relative to the metal electrode at the other end of the whole metal aluminum electrode.
Further, the edge of the end of the metal electrode with smaller cross-sectional area is a curved surface protruding outwards.
Further, SF6 gas of 3 atmospheres is filled between the insulating housing and the metal electrode, between the low voltage arm and the metal electrode.
Preferably, the low voltage arm, the data acquisition unit and the wireless data transmitter are respectively fixed on two sides of the supporting plate perpendicular to the axis of the insulating shell.
Further, the metal flange plate is installed at two ends of the insulating shell through fastening screws, and a gas sealing ring is further installed between the metal flange plate and the insulating shell.
Further, a barometer for monitoring SF6 gas pressure in the insulating shell and an air inlet valve for exchanging air or supplementing gas are fixed on the metal flange plate, and the air inlet valve is connected with the air bottle.
Preferably, the metal flange plate at the low-voltage end is grounded, and the high-voltage lead is a metal guide rod.
Compared with the closest technical scheme, the invention has the following remarkable progress:
(1) Compared with the traditional resistor-capacitor voltage divider, the capacitor voltage divider provided by the invention has the advantages of simple structure, stable performance, movable connection of all parts and convenience in installation and transportation.
(2) The data acquisition unit is built-in, adopts a wireless signal transmitter to transmit data, does not need to carry out impedance matching, and eliminates the problems of signal refraction and reflection.
(3) The capacitive voltage divider is of a symmetrical structure, the equalizing ring can be arranged on the metal flange plate at any one end of the capacitive voltage divider, the metal flange plate provided with the equalizing ring is connected with the high-voltage lead through the damping resistor, the metal flange plate is used as the high-voltage end of the capacitive voltage divider, the other end of the metal flange plate is used as the low-voltage end of the capacitive voltage divider, and the high-voltage end and the low-voltage end of the capacitive voltage divider can be interchanged randomly through the structure, so that the capacitive voltage divider is convenient to use.
(4) The metal electrode is conical in design, and one end with larger cross section area is fixed on the inner side of the metal flange, so that the potential distribution of the upper part and the lower part of the shell can be uniformly insulated. There is no need to design a flange with uniform potential distribution.
(5) The metal electrode is conical in design, the edge of the smaller end of the cross section area of the metal electrode is in an annular shape protruding outwards, an electric field can be uniform, and the stability of the capacitive voltage divider is improved.
(6) The metal conductor and the insulating material ring positioned between the metal conductor and the metal electrode are concentrically arranged at one end of the insulating shell, which is smaller in cross section area, so that the high-voltage arm capacitor is arranged between the shielding capacitors, the influence of external stray capacitors is avoided, and the stability of the capacitive voltage divider is improved.
(7) SF6 gas with 3 atmospheres is filled between the insulating shell and the metal electrode and between the low-voltage arm and the metal electrode, so that the high-voltage arm and the low-voltage arm are arranged in the same medium, the voltage coefficient and the temperature coefficient are the same, and the change of the scale factors is small.
(8) The high-voltage lead adopts a metal guide rod, so that the stray inductance is low and the damping resistance is small.
Drawings
FIG. 1 is a schematic diagram of a prior art resistive-capacitive voltage divider high voltage arm;
FIG. 2 is a schematic diagram of a capacitive voltage divider according to the present invention;
FIG. 3 is a schematic diagram of the electrical principle of the capacitive divider according to the present invention;
wherein: 1-equalizing ring I, 2-flange I, 3-insulating shell, 4-metal electrode I, 5-central conductor, 6-insulating material ring, 7-low voltage arm, 8-metal electrode II, 9-data acquisition unit and wireless signal transmitter, 10-equalizing ring II, 11-flange II, 12-damping resistor, 13-high voltage lead, 14-barometer, 15-air inlet valve, C 0 -shielding capacitance, C 1 High voltage arm capacitance, C 2 -low voltage arm capacitance.
Detailed Description
For a better understanding of the present invention, reference is made to the following description, taken in conjunction with the accompanying drawings and examples, in which:
as shown in fig. 2, the capacitive voltage divider provided by the invention has a cylindrical symmetrical structure as a whole and consists of a grading ring, an insulating shell, a metal electrode I, a metal electrode II, a metal flange I, a metal flange II, a low-voltage arm, a data acquisition unit, a wireless signal transmitter, a damping resistor, a high-voltage lead, a barometer, an inflation valve and the like.
The insulating shell is a cylindrical shell made of epoxy material and is sized according to the rated voltage of the voltage divider.
The metal flange plates are coaxially arranged at two ends of the insulating shell and used for fixing the metal electrode, the damping resistor and the equalizing ring. The metal flange plate is movably connected with the insulating shell through the fastening screw, the installation and the disassembly are convenient, and in order to ensure the air tightness of the insulating shell, the gas sealing ring is also installed between the metal flange plate and the insulating shell.
The equalizing ring is concentrically fixed on the metal flange plate at any end of the insulating shell, one end of the voltage divider, which is fixed with the equalizing ring, is the high-voltage end of the voltage divider, and the other end of the voltage divider is the low-voltage end, so that the high-voltage end and the low-voltage end of the voltage divider can be interchanged, and the voltage divider is convenient to use; the equalizing ring is used for homogenizing the electric field at the high-voltage end of the voltage divider, weakening corona, and the diameter of the equalizing ring is determined according to the rated voltage of the voltage divider.
The damping resistor is vertically fixed in the middle of a metal flange at the high-voltage end of the voltage divider and is connected with the high-voltage lead; the damping resistor is used for damping oscillation caused by stray inductance of the high-voltage guide tube, the high-voltage guide tube adopts a metal guide rod, the stray inductance is low, and the damping resistor is small.
The barometer and the inflation valve are arranged on the metal flange. The barometer is used for monitoring the air pressure of SF6 gas in the equipment; the charging valve is connected with the gas cylinder and is used for exchanging or supplementing gas.
The metal electrode is conical in design, one end with larger cross section area is detachably connected to the inner side surface of the metal flange, potential distribution of the surface of the insulating shell can be uniform, and the angle between the metal electrode and the insulating shell is calculated according to the rated voltage of the voltage divider, capacitance of the high-voltage arm, electric field distribution and other factors.
The metal electrode I is made of integral metal aluminum, a central conductor is arranged in the middle of the top end of the metal electrode II, and the central conductor and the metal electrode II are isolated by an insulating material ring (such as a nylon ring). In order to increase the curvature radius and even the electric field, the edge of the smaller end of the cross section area of the metal electrode is processed into a circular ring shape. SF6 gas with 3 atmospheres is filled between the insulating shell and the electrode and between the low-voltage arm and the electrode 2.
A supporting plate is arranged in the metal electrode II and used for fixing the low-voltage arm, the data acquisition unit and the wireless signal transmitter; the low-voltage arm, the data acquisition unit and the wireless signal transmitter can also be arranged in the metal electrode I.
The schematic diagram of the electrical principle formed by the capacitive divider of FIG. 1 is shown in FIG. 2, in which a high voltage arm capacitor C is formed between the center conductors of metal electrode I and metal electrode II 1 A shielding capacitor C is formed between the metal electrode I and the metal electrode II 0 Ensure the high voltage arm capacitance C 1 Stability of capacitance. The electric field between the metal electrode i and the center conductor is approximately uniform. When other charged bodies exist outside, the voltage dividerThe coupling capacitance with other charged objects only changes the shielding capacitance C 0 Is not required.
The data acquisition unit and the wireless signal transmitter are arranged in the metal electrode II, when the device is used, the metal electrode at the low voltage end is grounded, the high-voltage lead is connected with the impulse voltage generator and the capacitive voltage divider, the data acquisition unit acquires the voltage on the low-voltage arm capacitor C2 and transmits a voltage signal to the PC through the wireless signal transmitter, and the PC performs data calculation and analysis without impedance matching.
The capacitive voltage divider provided by the invention is designed through the following steps:
s1, according to rated voltage V of voltage divider e And the creepage flashover voltage V of the insulating housing s Determining the height H of the insulating housing: h=v e ×V；
S2, determining the distance d between two metal electrodes according to the breakdown voltage critical value of SF6 gas 1 The method comprises the steps of carrying out a first treatment on the surface of the The breakdown voltage of SF6 gas determines that the distance between two metal electrodes must be greater than a certain threshold value, d 1 Taking the critical value;
s3, according to the distance d between the two metal electrodes 1 Capacitance C of high voltage arm 1 Dielectric constant epsilon of SF6 gas r And vacuum dielectric constant ε 0 The area S of the center conductor is determined:
s4, according to the shielding capacitance C 0 Calculating the area S of the smaller end of the cross section of the metal electrode I 1 ：
S5, according to the high-voltage arm capacitor C 1 And the divider scale factor K determines the divider low voltage arm capacitance C 2 ：C 2 ＝C 1 ×K；
S6, according to the height H of the insulating shell and the distance d between the two metal electrodes 1 Determining the height h of the metal electrode:
s7, determining the diameter D of the insulating shell according to the reserved margin;
s8, determining an included angle theta between the metal electrode and the insulating shell according to the diameter D of the insulating shell, the diameter D of the smaller end of the cross section of the metal electrode and the height h of the metal electrode:
the foregoing is illustrative of the present invention and is not to be construed as limiting thereof, but rather as providing for the use of additional embodiments within the spirit and scope of the present invention.
Claims (5)
1. A capacitive voltage divider, characterized by: the capacitive voltage divider comprises a hollow cylindrical insulating shell, metal flanges coaxially and symmetrically arranged at the outer sides of two ends of the insulating shell, and metal electrodes at the inner sides of the two ends of the insulating shell; the metal electrodes at the two ends are respectively connected with the metal flanges at the two ends, wherein a concentric equalizing ring is arranged on the metal flange at one end, a damping resistor of a high-voltage lead is connected along the axis direction of the metal flange, and the equalizing ring and the damping resistor are used as high-voltage ends; the other end metal flange plate opposite to the high-voltage end is used as a low-voltage end; the metal electrode of the low-voltage end is internally provided with a low-voltage arm, a data acquisition unit and a wireless data transmitter, wherein the data acquisition unit acquires voltages at two ends of the low-voltage arm and sends the voltages to an external data processor through the wireless data transmitter; the metal electrode is conical, and one end with larger cross section area is detachably connected to the inner side surface of the metal flange; the metal electrode of the high-voltage end or the low-voltage end is an integral metal aluminum electrode, one end of the integral metal aluminum electrode with smaller relative cross section area is provided with a metal conductor, and an insulating material ring is positioned between the metal conductor and the integral metal aluminum electrode; the edge of the end of the metal electrode with smaller cross section area is a curved surface protruding outwards; SF6 gas with 3 atmospheres is filled between the insulating shell and the metal electrode and between the low-voltage arm and the metal electrode.
2. A capacitive voltage divider as claimed in claim 1, characterized in that:
the low-voltage arm, the data acquisition unit and the wireless data transmitter are respectively fixed on two sides of the supporting plate perpendicular to the axis of the insulating shell.
3. A capacitive voltage divider as claimed in claim 2, characterized in that:
the metal flange plates are installed at two ends of the insulating shell through fastening screws, and a gas sealing ring is further installed between the metal flange plates and the insulating shell.
4. A capacitive voltage divider as claimed in claim 2, characterized in that:
the metal flange plate is fixedly provided with a barometer for monitoring SF6 gas pressure in the insulating shell and an air inlet valve for exchanging air or supplementing gas, and the air inlet valve is connected with the air bottle.
5. A capacitive voltage divider as claimed in claim 1, characterized in that:
the metal flange plate at the low-voltage end is grounded, and the high-voltage lead is a metal guide rod.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201510303516.8A CN106291035B (en) | 2015-06-04 | 2015-06-04 | Capacitive voltage divider |
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| CN201510303516.8A CN106291035B (en) | 2015-06-04 | 2015-06-04 | Capacitive voltage divider |
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| CN106291035A CN106291035A (en) | 2017-01-04 |
| CN106291035B true CN106291035B (en) | 2023-09-22 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN106019199B (en) * | 2016-06-30 | 2019-12-27 | 中国电力科学研究院 | Annular capacitive voltage divider for linearity calibration of impulse voltage divider |
| CN107121583B (en) * | 2017-06-30 | 2020-09-25 | 中国西电电气股份有限公司 | Non-inductive resistance unit |
| CN109324305B (en) * | 2018-11-19 | 2022-10-04 | 中国电力科学研究院有限公司 | Capacitive voltage divider for linearity calibration of impulse voltage divider |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3835353A (en) * | 1972-03-29 | 1974-09-10 | Siemens Ag | Capacitive voltage-dividing arrangement for high voltage measuring apparatus |
| CN2574061Y (en) * | 2002-06-30 | 2003-09-17 | 武汉高压研究所 | High voltage capacitance divider |
| CN102128964A (en) * | 2011-01-14 | 2011-07-20 | 西北核技术研究所 | Capacitive voltage divider used for measuring radiation diode parameters and installation method |
| CN202362345U (en) * | 2011-12-07 | 2012-08-01 | 重庆市电力公司电力科学研究院 | Standard capacitance divider and induced voltage measurement device |
| CN204228795U (en) * | 2014-11-20 | 2015-03-25 | 国家电网公司 | A kind of compact broadband capacitive divider measured for square-wave voltage |
-
2015
- 2015-06-04 CN CN201510303516.8A patent/CN106291035B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3835353A (en) * | 1972-03-29 | 1974-09-10 | Siemens Ag | Capacitive voltage-dividing arrangement for high voltage measuring apparatus |
| CN2574061Y (en) * | 2002-06-30 | 2003-09-17 | 武汉高压研究所 | High voltage capacitance divider |
| CN102128964A (en) * | 2011-01-14 | 2011-07-20 | 西北核技术研究所 | Capacitive voltage divider used for measuring radiation diode parameters and installation method |
| CN202362345U (en) * | 2011-12-07 | 2012-08-01 | 重庆市电力公司电力科学研究院 | Standard capacitance divider and induced voltage measurement device |
| CN204228795U (en) * | 2014-11-20 | 2015-03-25 | 国家电网公司 | A kind of compact broadband capacitive divider measured for square-wave voltage |
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