CN107462760A - A kind of high-voltage switch gear transient state earth testing system being used under forceful electric power magnetic environment - Google Patents

Abstract

The invention discloses a high-voltage switch transient ground potential testing system: a high-voltage switchgear, a high-voltage probe, an attenuator, a matching resistor R ₄ , an oscilloscope, and first, second, and third coaxial cables; Sensing resistance R ₀ , the input end of the high-voltage probe is connected to the high-voltage switchgear; the output end of the high-voltage probe is connected to the input end of the attenuator through the first coaxial cable; the high-voltage probe is used to obtain the ground potential voltage of the shell surface of the high-voltage switchgear signal; inside the attenuator are the first non-inductive resistor R ₁ , the second non-inductive resistor R ₂ , and the third non-inductive resistor R ₃ , which are shielded through the metal shell of the attenuator; the attenuator is used to input the input terminal of the attenuator The voltage signal is divided for the first time; the output end of the attenuator is input to the matching resistor R ₄ at the port of the oscilloscope through the second coaxial cable; the matching resistor R ₄ is used to divide the voltage signal for the second time; the matching resistor R ₄ The output end of the oscilloscope is connected with the oscilloscope; the oscilloscope monitors the voltage waveform of the ground potential.

Description

A high-voltage switch transient ground potential test system for strong electromagnetic environment

technical field

The present invention relates to the technical field of intelligent equipment, and more specifically, relates to a high-voltage switch transient ground potential testing system used in a strong electromagnetic environment.

Background technique

In recent years, with the deepening of the domestic smart grid construction process, many smart substations have been put into operation. Compared with conventional substations, intelligent electronic devices (IED, Intelligent Electronic Device), electronic mutual inductance Intelligent components such as switchgear and its merging unit and switchgear controller can monitor the key performance parameters of the switchgear online, realize the intelligent process of the switchgear, and provide technical support for the life cycle management and operation and maintenance of the high-voltage switchgear. However, the in-situ installation method causes the smart components to be close to the high-voltage switchgear and closer to the electromagnetic disturbance source, which makes the electromagnetic compatibility problem of these electronic equipment more prominent than before, and the electronic equipment is in a very serious electromagnetic pollution background. Environment.

For the electromagnetic compatibility problem in the power system, the interference of the switchgear operation test condition on the control system is its main manifestation. Due to the close connection between electricity and magnetism, the transient process of the primary circuit of the smart substation will pass through various This path enters the smart component and produces various transient disturbances to it. The harsh electromagnetic environment may cause two effects on smart components. One is to destroy the insulation of smart components, and even cause the chips on the electronic circuit to burn out, forming irreversible permanent damage; the other is to interfere with the normal operation of smart components, causing It has the possibility of misoperation, which in turn leads to or expands the failure of the primary equipment side. Therefore, it is particularly important to study the reliability of smart components in the field operating environment. With the gradual advancement of a new generation of smart substations, the operational reliability of smart substations has attracted increasing attention. At present, the electromagnetic compatibility and immunity requirements of secondary equipment in smart substations still follow the standards of traditional substations. However, from the perspective of the installation location of secondary equipment in smart substations, these requirements may be loose. Smart substations put into operation in my country have appeared many times. Transformer data distortion, communication packet loss and other electromagnetic interference problems, so it is necessary to carry out corresponding analysis and research on the electromagnetic compatibility immunity requirements of the secondary equipment of the smart substation, and conduct reliability evaluation of the intelligent equipment. Eliminate hidden dangers of electromagnetic interference during design and operation. At present, because there is no detection method and preventive means of ground potential, damage to smart components is often caused in the test.

Therefore, a technology is needed to solve the problem of testing the transient ground potential of a high-voltage switch in a strong electromagnetic environment.

Contents of the invention

The invention provides a high-voltage switch transient ground potential testing system used in a strong electromagnetic environment to solve the problem of how to test the high-voltage switch transient ground potential in a strong electromagnetic environment.

In order to solve the above problems, the present invention provides a high-voltage switch transient ground potential testing system in a strong electromagnetic environment, the system includes: high-voltage switchgear, high-voltage probes, attenuators, matching resistance R ₄ , oscilloscope, UPS power supply, The first coaxial cable, the second coaxial cable, the third coaxial cable, the first grounding point O ₁ , the second grounding point O ₂ , and the third grounding point O ₃ ;

The high-voltage probe includes a zeroth non-inductive resistance R ₀ , the input end of the high-voltage probe is connected to the shell surface of the high-voltage switchgear; the output end of the high-voltage probe is connected to the attenuator through the first coaxial cable The input terminal is connected; the high-voltage probe is used to obtain the ground potential voltage signal of the shell surface of the high-voltage switchgear;

Inside the attenuator are the first non-inductive resistor R ₁ , the second non-inductive resistor R ₂ , the third non-inductive resistor R ₃ , the first non-inductive resistor R ₁ , the second non-inductive resistor R ₂ , The third non-inductive resistor _R3 is shielded by the metal shell of the attenuator; the attenuator is used to divide the voltage signal input by the input terminal of the attenuator for the first time; the output terminal of the attenuator is passed through The second coaxial cable inputs the matching resistor R ₄ at the oscilloscope port; the matching resistor R ₄ is used to divide the voltage signal of the input terminal of the matching resistor R ₄ for the second time; the matching resistor The output terminal of R ₄ is connected with the oscilloscope; the oscilloscope is used for monitoring the ground potential voltage waveform input to the oscilloscope;

The high-voltage switchgear is connected to the _first grounding point O1;

The output shell of the high-voltage probe is connected to the second ground point _O2 through the third coaxial cable; the shell of the high-voltage probe is connected to the shielding layer of the first coaxial cable;

The second ground point O ₂ is far away from the first ground point O ₁ , and the second ground point O ₂ is at least 15 meters away from the first ground point O ₁ .

Preferably, the zeroth non-inductive resistor R ₀ has a resistance of 5kΩ, a power of 25W, and a maximum measured transient voltage of 50kV.

Preferably, the wave impedance of the first coaxial cable, the second coaxial cable and the third coaxial cable is 50Ω;

In order to prevent the wave reflection of the high-frequency transient voltage during the propagation of the coaxial cable and improve the dynamic response, the wave impedance of the coaxial cable is designed to be the same as the load impedance, both of which are 50Ω;

Seen from the first coaxial cable to the attenuator, the impedance is 50Ω, that is, R ₁ //(R ₂ +R ₄ //R ₃ )=50Ω;

The impedance of the second coaxial cable to the attenuator is 50Ω, namely (R ₀ //R ₁ +R ₂ )//R ₃ =50Ω;

Looking at the oscilloscope, the second coaxial cable has an impedance of 50Ω, that is, R ₄ =50Ω.

Preferably, the shielding layer of the third coaxial cable and the signal line of the third coaxial cable are open at the shell of the high voltage probe; the shielding layer of the third coaxial cable is connected to the third coaxial cable The signal lines of the axis cables are short-circuited at the second ground point _O2 .

Preferably, the first coaxial cable and the second coaxial cable are closely laid, and the first coaxial cable and the second coaxial cable are fixed with an insulating material at an interval of no more than 2 meters .

Preferably, the first partial pressure transformation ratio k ₁ is 100, the second partial pressure transformation ratio k ₂ is 10, and the total system partial pressure transformation ratio k is 1000, k=k ₁ ×k ₂ .

Preferably, the first voltage division ratio k ₁ =[R ₀ +R ₁ //(R ₂ +R ₄ //R ₃ )]: [R ₁ // (R ₂ +R ₄ //R ₃ )]=100:1, where R ₀ is the resistance value of the zeroth non-inductive resistor R ₀ , R ₁ is the resistance value of the first non-inductive resistor R ₁ , and R ₂ is the resistance value of the second non-inductive resistor R ₂ , R ₃ is the resistance value of the third non-inductive resistor R ₃ , and R ₄ is the resistance value of the matching resistor R ₄ .

Preferably, the second voltage division ratio k ₂ =(R ₂ +R ₄ //R ₃ ):R ₄ //R ₃ =10:1, where R ₂ is the value of the second non-inductive resistor R ₂ Resistance value, _R3 is the resistance value of the third non _- inductive resistor _R3 , and R4 is the resistance value of the matching resistor R4 _.

Preferably, an independent UPS power supply is included to provide power for the oscilloscope.

Preferably, a test generating device is included, and the test generating device is connected to the third ground point _O3 .

The technical scheme of the present invention provides a transient ground potential test system for high-voltage switches in a strong electromagnetic environment, which makes full use of the short duration of the transient ground potential, and uses a small-value resistor as the high-voltage arm of the voltage divider to reduce the The time delay caused by the distributed capacitance of the arm improves the dynamic response speed of the test signal, and the non-inductive resistance further improves the dynamic response. The technical solution of the present invention adopts impedance matching technology to prevent high-frequency signal reflection. The technical scheme of the invention adopts the single-point grounding technology to solve the interference of the space electromagnetic interference signal on the signal line connecting the measurement point and the remote reference ground.

Description of drawings

A more complete understanding of the exemplary embodiments of the present invention can be had by referring to the following drawings:

Fig. 1 is a kind of high voltage switch transient ground potential test system structural diagram for under the strong electromagnetic environment according to the embodiment of the present invention; And

Fig. 2 is a schematic diagram of a test system for transient ground potential of a high voltage switch in a strong electromagnetic environment according to an embodiment of the present invention.

detailed description

Exemplary embodiments of the present invention will now be described with reference to the drawings; however, the present invention may be embodied in many different forms and are not limited to the embodiments described herein, which are provided for the purpose of exhaustively and completely disclosing the present invention. invention and fully convey the scope of the invention to those skilled in the art. The terms used in the exemplary embodiments shown in the drawings are not limiting of the present invention. In the figures, the same units/elements are given the same reference numerals.

Unless otherwise stated, the terms (including scientific and technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it can be understood that the terms defined by commonly used dictionaries should be understood as having consistent meanings in the context of their related fields, and should not be understood as idealized or overly formal meanings.

Fig. 1 is a structural diagram of a transient ground potential test system for a high-voltage switch in a strong electromagnetic environment according to an embodiment of the present invention. The embodiment of the present invention proposes a transient ground potential test system for high-voltage switches in a strong electromagnetic environment, which is used to test the transient ground potential level of a high-voltage switchgear shell in a strong electromagnetic Accurate measurement of ground potential transient voltage in experiments such as high voltage, short-circuit current breaking, etc., provides a basis for the design of intelligent components to withstand strong electromagnetic environments, so as to improve the overall reliability of intelligent switchgear. As shown in FIG. 1 , the system 100 includes: a high-voltage switchgear 101 , a high-voltage probe 102 , an attenuator 103 , a matching resistor R ₄ , an oscilloscope 104 , a first coaxial cable, a second coaxial cable, and a third coaxial cable.

The high-voltage probe 102 includes a zeroth non-inductive resistance R ₀ , the input end of the high-voltage probe 102 is connected to the shell surface of the high-voltage switchgear; the output end of the high-voltage probe 102 is connected to the input end of the attenuator 103 through the first coaxial cable; The high voltage probe 102 is used to acquire a voltage signal of the ground potential of the shell surface of the high voltage switchgear.

Inside the attenuator 103 are the first non-inductive resistor R ₁ , the second non-inductive resistor R ₂ , the third non-inductive resistor R ₃ , the first non-inductive resistor R ₁ , the second non-inductive resistor R ₂ , and the third non-inductive resistor R ₃ is shielded by the metal shell of the attenuator 103; the attenuator 103 is used to divide the voltage signal input by the input terminal of the attenuator 103 for the first time; the output terminal of the attenuator 103 is input to the oscilloscope 104 through the second coaxial cable Matching resistor R ₄ at the port; matching resistor R ₄ is used to divide the voltage signal of the input terminal of matching resistor R ₄ for the second time; the output terminal of matching resistor R ₄ is connected with oscilloscope 104; oscilloscope 104 is used to monitor the input to the ground potential voltage waveform of the oscilloscope 104 .

The high-voltage switchgear is connected to the _first ground point O1 to reduce interference to the ground potential signal.

The output shell of the high-voltage probe 102 is connected with the second grounding point _O2 through the third coaxial cable; the shell of the high-voltage probe 102 is connected with the shielding layer of the first coaxial cable; the shell of the high-voltage probe 102, the first coaxial cable , the attenuator 103, the second coaxial cable and the oscilloscope 104 are connected to the second ground point _O2 .

The second ground point O ₂ is far away from the first ground point O ₁ , and the distance between the second ground point O ₂ and the first ground point O ₁ is at least 15 meters.

The ground wires of the first ground point O ₁ , the second ground point O ₂ and the third ground point O ₃ in the embodiment of the present invention are flat copper wires. The second grounding point O ₂ should be far away from the third grounding point O ₃ of the high-voltage switchgear main circuit test generator and the first grounding point O ₁ of the high-voltage switchgear 101 shell, so as to reduce the interference to the ground potential signal.

Preferably, the resistance of the zeroth non-inductive resistor R ₀ is 5kΩ, the power is 25W, and the maximum measured transient voltage is 50kV.

Preferably, the wave impedance of the first coaxial cable, the second coaxial cable and the third coaxial cable is 50Ω. The wave impedance of the first coaxial cable, the second coaxial cable and the third coaxial cable are matched with the resistance value of the low voltage arm to prevent signal distortion caused by wave reflection.

In order to prevent the wave reflection of the high-frequency transient voltage during the propagation of the coaxial cable and improve the dynamic response, the wave impedance of the coaxial cable is designed to be the same as the load impedance, both of which are 50Ω.

Seen from the first coaxial cable to the attenuator, the impedance is 50Ω, that is, R ₁ //(R ₂ +R ₄ //R ₃ )=50Ω;

The impedance of the second coaxial cable to the attenuator is 50Ω, namely (R ₀ //R ₁ +R ₂ )//R ₃ =50Ω;

Looking at the oscilloscope, the second coaxial cable has an impedance of 50Ω, that is, R ₄ =50Ω.

Preferably, the shielding layer of the third coaxial cable and the signal line of the third coaxial cable are open at the shell of the high voltage probe 102; Point _O2 is shorted.

Preferably, the first coaxial cable and the second coaxial cable are closely laid, and the first coaxial cable and the second coaxial cable are fixed with an insulating material at an interval not exceeding 2 meters. In the embodiment of the present invention, the first coaxial cable L1 and the third coaxial cable L3 are closely laid, and are wound and fixed with insulating tape every about 2 meters, so as to reduce the area formed by the test signal transmission path and reduce the impact of external space radiation. The effect of the test signal.

Preferably, the first voltage division ratio k ₁ is 100, the second voltage division ratio k ₂ is 10, the total system voltage division ratio k is 1000, and k=k ₁ ×k ₂ .

Preferably, the first voltage division ratio k ₁ =[R ₀ +R ₁ //(R ₂ +R ₄ //R ₃ )]: [R ₁ //(R ₂ + R ₄ //R ₃ ) ]=100:1, wherein R ₀ is the resistance value of the zeroth non-inductive resistor R ₀ , R ₁ is the resistance value of the first non-inductive resistor R ₁ , R ₂ is the resistance value of the second non-inductive resistor R ₂ , R ₃ is the resistance value of the third non _- inductive resistor _R3 , and R4 is the resistance value of the matching resistor R4 _.

Preferably, the second voltage division ratio k ₂ =(R ₂ +R ₄ //R ₃ ):R ₄ //R ₃ =10:1, where R ₂ is the resistance value of the second non-inductive resistor R ₂ , R ₃ is the resistance value of the third non-inductive resistor R ₃ , and R ₄ is the resistance value of the matching resistor R ₄ .

Preferably, an independent UPS power supply is included to provide power for the oscilloscope 104 . In the embodiment of the present invention, the oscilloscope is powered by an independent UPS power supply, which is completely isolated from the test power supply, so as to avoid the power supply from interfering with the test system.

Preferably, a test generating device is included, and the test generating device is connected to the third ground point _O3 .

In the embodiment of the present invention, based on the characteristics of short transient voltage duration and high peak value, in the test process of lightning impulse withstand voltage and short-circuit current breaking of high-voltage switches, a non-inductive small-value resistor with fast dynamic response is used as a branch The high-voltage probe of the transformer is connected to the shell of the high-voltage switchgear 101. The shell of the high-voltage switchgear 101 includes the installation point of the SF6 gas sensor, the shell of the electronic transformer, the shell of the intelligent component cabinet, etc., and the high-voltage probe 102 is connected to the attenuation The attenuator 103 is connected, and the output end of the attenuator 103 is connected to the matching resistor R4 through the second coaxial cable. _The embodiment of the present invention adopts impedance matching technology to prevent high-frequency signal reflection, and is finally connected to the oscilloscope 104, and the oscilloscope 104 is connected to the independent power supply of the UPS 105 for power supply. The embodiment of the present invention adopts the single-point grounding technology to solve the interference of the space electromagnetic interference signal on the measurement point of the high-voltage switchgear 101 and the signal line connected to the remote reference ground. The grounding point of the support of the high-voltage switchgear 101 is the first grounding point O ₁ . The grounding point of the generating device is the third grounding point O ₃ , the ground potential signal is 5kΩ resistance along the high-voltage switch shell, the internal resistance R ₀ of the high-voltage probe 102, the inner core of the first coaxial coaxial cable L1, the attenuator 103, the second The inner core of the coaxial cable L2, the oscilloscope 104, the outer layer of the second coaxial cable L2, the shell of the attenuator 103, and the shell of the output end of the high voltage probe 102 are connected to the second ground point _O2 . Combined with the transfer function of the electronic transformer, etc., the influence of electromagnetic interference on the SF6 gas sensor, the electronic transformer acquisition unit, and the intelligent components can be further analyzed, so that the typical switch test conditions that have a greater impact on the reliability of the intelligent components are proposed. Based on this, a more rigorous intelligent high-voltage switch performance testing scheme is formulated to improve the network connection reliability of intelligent high-voltage switches.

The high-voltage switchgear in the present invention uses a gas-insulated metal-enclosed switchgear ("GIS" for short).

Fig. 2 is a schematic diagram of a transient ground potential testing system for a high-voltage switch in a strong electromagnetic environment according to an embodiment of the present invention. As shown in Figure ₂ , the high-voltage probe 201 is connected with the attenuator 202 through the first coaxial cable L1, and the output end of the attenuator 202 is connected with the matching resistor R4 through the second coaxial cable L2, and the embodiment of the present invention adopts impedance matching technology Prevent high-frequency signal reflection, and finally connect to the oscilloscope 203, and the oscilloscope 203 is powered by an independent UPS power supply. The high-voltage probe 201 includes the zeroth non-inductive resistance R ₀ , the input end of the high-voltage probe 201 is connected to the high-voltage switchgear body; the output end of the high-voltage probe 201 is connected to the input end of the attenuator 202 through the first coaxial cable L1; 201 is used to obtain the voltage signal in the high voltage switchgear body. Inside the attenuator 202 are the first non-inductive resistor R ₁ , the second non-inductive resistor R ₂ , the third non-inductive resistor R ₃ , the first non-inductive resistor R ₁ , the second non-inductive resistor R ₂ , and the third non-inductive resistor R ₃ is shielded by the metal shell of the attenuator 202 . The attenuator 202 is used to divide the voltage signal input by the input end of the attenuator 202 for the first time; the output end of the attenuator 202 is input to the matching resistor R ₄ at the port of the oscilloscope 204 through the second coaxial cable L2; the matching resistor R ₄ is used to divide the voltage signal at the input terminal of the matching resistor R4 for the second time _; the output terminal of the matching resistor R4 is connected to the oscilloscope 203 _; the oscilloscope 203 is used to monitor the voltage signal input to the oscilloscope 203.

Preferably, the first voltage division ratio k ₁ is 100, the second voltage division ratio k ₂ is 10, the total system voltage division ratio k is 1000, and k=k ₁ ×k ₂ .

Preferably, the first voltage division ratio k ₁ =[R ₀ +R ₁ //(R ₂ +R ₄ //R ₃ )]: [R ₁ //(R ₂ + R ₄ //R ₃ ) ]=100:1, wherein R ₀ is the resistance value of the zeroth non-inductive resistor R ₀ , R ₁ is the resistance value of the first non-inductive resistor R ₁ , R ₂ is the resistance value of the second non-inductive resistor R ₂ , R ₃ is the resistance value of the third non _- inductive resistor _R3 , and R4 is the resistance value of the matching resistor R4 _.

Preferably, the second voltage division ratio k ₂ =(R ₂ +R ₄ //R ₃ ):R ₄ //R ₃ =10:1, where R ₂ is the resistance value of the second non-inductive resistor R ₂ , R ₃ is the resistance value of the third non-inductive resistor R ₃ , and R ₄ is the resistance value of the matching resistor R ₄ .

The output shell of the high-voltage probe 201 is connected with the second ground point _O2 through the third coaxial cable L3; the shell of the high-voltage probe 201 is connected with the shielding layer of the first coaxial cable L1; the shell of the high-voltage probe 201, the first coaxial The axial cable L1, the attenuator 202, the second coaxial cable L2 and the oscilloscope 203 are connected to the second ground point _O2 .

The invention has been described with reference to a small number of embodiments. However, it is clear to a person skilled in the art that other embodiments than the invention disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise therein. All references to "a/the/the [means, component, etc.]" are to be construed openly as at least one instance of said means, component, etc., unless expressly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

Claims (10)

1. the high-voltage switch gear transient state earth testing system under a kind of forceful electric power magnetic environment, the system include：High-tension switch gear, High-voltage probe, attenuator, build-out resistor R₄, it is oscillograph, ups power, the first coaxial cable, the second coaxial cable, the 3rd coaxial Cable, the first earth point O₁, the second earth point O₂, the 3rd earth point O₃；

The high-voltage probe includes the 0th noninductive resistance R₀, the input of the high-voltage probe is connected to the high-tension switch gear Surface of shell；The output end of the high-voltage probe is connected by the first coaxial cable with the input of the attenuator；Institute State the ground potential voltage signal that high-voltage probe is used to obtain the surface of shell of the high-tension switch gear；

It is the first noninductive resistance R inside the attenuator₁, the second noninductive resistance R₂, the 3rd noninductive resistance R₃, described first is noninductive Resistance R₁, the second noninductive resistance R₂, the 3rd noninductive resistance R₃Shielding is realized by the metal shell of attenuator；It is described The voltage signal that attenuator is used to input the input of the attenuator carries out first time partial pressure；The output end of the attenuator The build-out resistor R inputted by the second coaxial cable at the oscillograph port₄；The build-out resistor R₄For by described in Build-out resistor R₄Input voltage signal carry out second of partial pressure；The build-out resistor R₄Output end and the oscillograph It is connected；The oscillograph is used to monitor the ground potential voltage waveform for being input to the oscillograph；

The high-tension switch gear and the first earth point O₁It is connected；

The output end housing of the high-voltage probe passes through the triaxial cable and the second earth point O₂It is connected；The high pressure The shell of probe is connected with the screen layer of first coaxial cable；

The second earth point O₂Away from the first earth point O₁, the second earth point O₂With the first earth point O₁At least it is spaced 15 meters.

2. system according to claim 1, the 0th noninductive resistance R₀Resistance be 5k Ω, power 25W, maximum is surveyed Amount transient voltage is 50kV.

3. system according to claim 1, first coaxial cable, second coaxial cable and described 3rd coaxial The wave impedance of cable is 50 Ω；

In order to prevent wave reflection of the high frequency transient voltages in coaxial cable communication process, dynamic response is improved, designs coaxial electrical The wave impedance of cable is identical with load impedance, is all 50 Ω；

In terms of from the first coaxial cable to attenuator, impedance is 50 Ω, i.e. R₁//(R₂+R₄//R₃The Ω of)=50；

Second coaxial cable sees that impedance is 50 Ω, i.e. (R to attenuator₀//R₁+R₂)//R₃=50 Ω；

Second coaxial cable sees that impedance is 50 Ω, i.e. R to oscillograph₄=50 Ω.

4. system according to claim 1, the screen layer of the triaxial cable and the letter of the triaxial cable Number line is opened a way at the shell of the high-voltage probe；The screen layer of the triaxial cable and the letter of the triaxial cable Number line is in the second earth point O₂Short circuit.

5. system according to claim 1, it is closely to spread between first coaxial cable and second coaxial cable If first coaxial cable and second coaxial cable are fixed with insulating materials with the interval no more than 2 meters.

6. system according to claim 1, the first time partial pressure no-load voltage ratio k₁For 100, second of partial pressure no-load voltage ratio k₂For 10, the system total score buckling is 1000, k=k than k₁×k₂。

7. system according to claim 6, the first time partial pressure no-load voltage ratio k₁=[R₀+R₁//(R₂+R₄//R₃)]：[R₁// (R₂+R₄//R₃)]=100:1, wherein R₀For the 0th noninductive resistance R₀Resistance, R₁For the first noninductive resistance R₁Resistance, R₂For Two noninductive resistance R₂Resistance, R₃For the 3rd noninductive resistance R₃Resistance, R₄For build-out resistor R₄Resistance.

8. system according to claim 6, second of partial pressure no-load voltage ratio k₂=(R₂+R₄//R₃):R₄//R₃=10:1, its Middle R₂For the second noninductive resistance R₂Resistance, R₃For the 3rd noninductive resistance R₃Resistance, R₄For build-out resistor R₄Resistance.

9. system according to claim 1, including UPS independent current sources, it is powered for the oscillograph.

10. system according to claim 1, including experiment generating means, the experiment generating means and the 3rd earth point O₃ It is connected.