CN1188237A - Method for live measuring medium loss of capacitive electric equipment and its device - Google Patents
Method for live measuring medium loss of capacitive electric equipment and its device Download PDFInfo
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- CN1188237A CN1188237A CN97100155A CN97100155A CN1188237A CN 1188237 A CN1188237 A CN 1188237A CN 97100155 A CN97100155 A CN 97100155A CN 97100155 A CN97100155 A CN 97100155A CN 1188237 A CN1188237 A CN 1188237A
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Abstract
The present invention discloses a live line measurement method of medium loss of capacitive electric equipment and its device. Said invention uses balanced bridge principle and capacitor and resistor combined sampling technology to avoid the technical difficulty of previous technology which requires high-accuracy and high-stability current transformer, filter, amplifier, phase shifter and zero cross detector. Said invention possesses high measuring accuracy and stability, and its operation is safe and reliable, so that it has high practical value.
Description
The invention discloses a kind of method and device thereof of live line measurement medium loss of capacitive electric equipment, be suitable for the dielectric loss of live line measurement capacitive electric equipment, belong to electric measurement neck city.
Dielectric loss is one of important indicator that characterizes insulating material electric property quality, in electric system, in order to find the defective of electric insulation aspect,, estimate the insulation status quality of high voltage electric equipment often by parameters such as measurement insulation resistance, dc leakage-current, dielectric losses.
The dielectric loss of high voltage electric equipment is generally all very little, and the accuracy requirement height to measuring when measuring at the scene, is subjected to various forms of interference again easily, therefore wants accurately bigger with the dielectric loss difficulty of stably measuring high voltage electric equipment at the scene.For a long time, people fail to solve well this difficult problem always.
At present, the method for live line measurement medium loss of capacitive electric equipment is a lot, and is commonly used and typically have following two kinds:
One, zero passage detection method.Its measuring principle as shown in Figure 1.
This method utilizes a special current transformer CT to get to flow through the current signal of measured capacitance type electrical equipment X after 0 is pressed in the resistance R power taking, behind amplifier 1-1, phase shifter 1-2, wave filter 1-3, form a voltage 1, get bus normal voltage signal 2 through voltage transformer pt, relatively two voltages sinusoidal wave 1, 2 calculate dielectric loss angle δ by counting circuit 1-5 by frequency and mistiming at the mistiming of zero crossing a, b l through zero-crossing detector 1-4;
This method needs current transformer CT, amplifier, phase shifter, wave filter, the zero-crossing detector of high precision, high stability, and aging, the variation of environment temperature of components and parts, the interference of harmonic wave, be difficult to make above-mentioned device to reach high precision and high stability that people need, therefore, be difficult to accurately, stably measure the dielectric loss value.Though people are being devoted to study current transformer CT, amplifier, phase shifter, wave filter, the zero-crossing detector work of high precision, high stability always, the result is all unsatisfactory, Using such method and device exist above-mentioned shortcoming.
Two, another kind of method is to replace current transformer CT sampling with resistance R, the method also needs the device of high precision and high stability, also fail fundamentally to solve or get around the technological difficulties that need high precision and high stability device, measurement result is also unsatisfactory.
The purpose of this invention is to provide a kind of live line measurement medium loss of capacitive electric equipment method and according to this method and device.
The object of the present invention is achieved like this: a kind of method of live line measurement medium loss of capacitive electric equipment the steps include:
(1). the earth terminal at charged measured capacitance type electrical equipment in series inserts one group of standard capacitance C0 and loss adjusting resistance R 0;
(2). the live end of measured capacitance type electrical equipment has been connected to voltage transformer (VT), at adjustable resistance R1 of secondary side access of voltage transformer (VT);
(3). between the adjustable side of adjustable resistance R1 and standard capacitance C0 and measured capacitance type electrical equipment interface, connect galvanometer J;
(4). regulate adjustable resistance R1 and loss and regulate resistance R 0, make galvanometer J be shown as zero;
(5). measure magnitude of voltage UC0 and UR0 on standard capacitance C0 and the loss adjusting resistance R 0, then the dielectric loss angle tg δ-UR0/UC0 of this equipment under test.
According to this method and device, it has standard capacitance C0, loss to regulate resistance R 0, adjustable resistance R1, terminal A, P, Q, M, N, Y1, Y2, Y3; Terminal A is the terminal that connects the former earth terminal of equipment under test, terminals P, Q are the terminals that connects the galvanometer input end, terminal M, N are two stiff ends that connect the terminal of voltage transformer secondary side output and be connected to adjustable resistance R1 respectively, and terminal Y1, Y2, Y3 are the terminals that reads standard capacitance C0 and loss adjusting resistance R 0 voltage; The end of standard capacitance C0 connects with terminal A, Q, Y1, the other end of standard capacitance C0 connects with the end that resistance R 0 is regulated in loss, regulate 0 leading-out terminal Y2 of resistance R at standard capacitance C0 and loss, the other end that resistance R 0 is regulated in loss connects with terminal Y3, N and ground connection, and the adjustable side of adjustable resistance R1 is connected to terminals P.
Ben Dingming compares with existing method and device has following advantage:
The present invention adopts principle of balance bridge and electric capacity, resistance to unite sampling, the assembly such as current transformer CT, amplifier, phase shifter, wave filter, zero-crossing detector that does not need high precision, high stability, the technological difficulties of dielectric loss have been avoided measuring in the past, have very high measuring accuracy and degree of stability, and it is safe in utilization, simple, very high practical value is arranged, thoroughly solved the defective that precision of measuring media loss in the past and stability are difficult to guarantee.Specify as follows:
1, because the present invention's bridge balance mode makes this device have very high measuring accuracy.The balance of electric bridge is to be undertaken by the loss of adjustable resistance R1 adjusting PT1 voltage, standard capacitance C0 and loss adjusting resistance R 0 adjusting measured capacitance type electrical equipment side, when regulation loss was regulated resistance R 0 and adjustable resistance R1 the EFFECTIVE MEDIUM loss of electric bridge low-voltage arm is equated with the real medium loss of measured capacitance type electrical equipment, electric bridge reached balance.This method is regulated simple, and it has good convergence.
Simultaneously, the measuring accuracy of device of the present invention does not make the stability that relies arm resistance, and the variation of the arm resistance value that therefore work temperature rise and environment temperature rise cause does not influence the measuring accuracy of dielectric loss; And existing technology resistance change can have a strong impact on the measuring accuracy of dielectric loss.
During bridge balance of the present invention, the harmonic wave of PT1 side is equated substantially with the harmonic wave size and the harmonic phase of measured capacitance type electrical equipment side, offset the influence of harmonic wave effectively, not need high-precision wave filter measurement; And existing technology must use high-precision filter to filter the influence of both sides harmonic wave to measuring at bilateral.
2, the present invention unites sampling with electric capacity, resistance, and the signal of adopting can reach tens volts, and the back need not to amplify again, just can directly measure, and the electric capacity self characteristics can make the voltage and current on it differ 90 degree, does not need to carry out phase shift with phase shifter, has saved phase shifter; And existing technology is taken a sample with CT, and consolidating the tested signal of body has only tens milliamperes, just can measure after must handling with amplifier, in addition, when 1 and the comparison of 2 (see figure 1)s, must make 0 move 90 degree with phase shifter earlier.
3, the phase shifter that is equipped with on the electric bridge of the present invention, be the fixed phase drift that is used to compensate high pressure P T, isolates PT1, standard capacitance C0, to less demanding the stability of PT angle error and standard capacitance C0 dielectric loss (but will guarantee) of the dielectric loss of the angle error of PT and standard capacitance C0.
4, the present invention uses adjustable resistance to replace resistance box, can reduce and alleviate the volume and weight of electric bridge greatly.
5, the present invention uses little power consumption active filter and digital AC millivoltmeter, is to use dry cell power supply, without AC power, can, connect the trouble of instrument power supply line when removing in-site measurement from,, once upgrade battery and can use more than half a year by using calculating in one hour every day.
Fig. 1 is existing zero passage detection method schematic diagram;
Fig. 2 is the inventive method principle schematic;
Fig. 3 is the device panel synoptic diagram among the embodiment 1;
Fig. 4 is embodiment 1 a device electrical schematics;
Fig. 5 is the device panel synoptic diagram among the embodiment 2;
Fig. 6 is the inventive method bridge balance polar plot;
Fig. 7 is that apparatus of the present invention are measured the dielectric loss wiring schematic diagram;
Utilize accompanying drawing below, the present invention is described in further detail in conjunction with the embodiments:
Embodiment 1:
As shown in Figure 2, a kind of method of live line measurement medium loss of capacitive electric equipment the steps include:
(1). in series insert one group of standard capacitance C0 and loss adjusting resistance R 0 at charged measured capacitance type electrical equipment X earth terminal;
(2). the live end of measured capacitance type electrical equipment X has been connected to high voltage potential transformer PT, at its a secondary side access adjustable resistance R1 (playing the effect of voltage adjuster);
(3). between the adjustable side of adjustable resistance R1 and standard capacitance C0 and measured capacitance type electrical equipment X interface, connect galvanometer J;
(4). measure the leakage current Ix on the measured capacitance type electrical equipment X, and, in one group of standard capacitance, select suitable standard capacitance C0 according to the size of leakage current lx;
Measuring method is measured the pressure drop on the standard capacitor C0 routinely, and regulates adjustable resistance R1, the voltage U on the voltage transformer (VT) 2 adjust to standard capacitance C0 on pressure drop identical substantially;
Resistance R 0 is regulated in meticulous adjusting adjustable resistance R1 and loss, and making galvanometer J pointer is zero, bridge balance;
(5). measuring method routinely, measure standard capacitance C0 and loss and regulate magnitude of voltage UC0 and UR0 on the resistance R 0, then the dielectric loss angle tg δ-UR0/UC0 of this equipment under test;
Also can directly show the dielectric loss angle tangent value tg δ of equipment under test by dielectric loss numerical value display for UR0/UC0 with after proofreading and correct the divider processing.
As shown in Figure 4, the device that gets according to said method, it has standard capacitance C0, loss to regulate resistance R 0, adjustable resistance R1, terminal A, W1, W2;
Terminal A is the terminal that connects the former earth terminal of equipment under test, and terminal W1, W2 are the terminals that connects high voltage potential transformer PT secondary side;
The end of standard capacitance C0 and terminal A, the input end of wave filter L connects, capacitance voltage reading device Jc and K switch 1 series connection back are in parallel with standard capacitance C0, the other end of standard capacitance C0 connects with the end that resistance R 0 is regulated in loss, resistive voltage reading device Jr and K switch 2 serial connection backs are in parallel with loss adjusting resistance R 0, the other end that resistance R 0 is regulated in loss connects with adjustable resistance R1 one end and ground connection, two stiff ends of adjustable resistance R1 are connected to the secondary side of isolated voltage transformer PT1 respectively, phase shifter Y is serially connected between adjustable resistance R1 and isolated voltage transformer PT1, the adjustable side of adjustable resistance R1 is connected to another input end of wave filter L, the galvanometric input end of output termination of wave filter L, resistive voltage reading device Jr, the output terminal of capacitance voltage reading device Jc is connected to the input end of proofreading and correct divider CFQ, and the output terminal of proofreading and correct divider CFQ is connected to display XS;
Above-mentioned galvanometer J, capacitance voltage reading device Jc, resistive voltage reading device Jr all are millivoltmeters of high impedance.
Galvanometer J, capacitance voltage reading device Jc, resistive voltage reading device Jr also can be the millivoltmeters of same high impedance, can connect wave filter L, standard capacitance C0, loss adjusting resistance R 0 respectively through many logical switches (replacing K switch 1 and K2).
What one group of standard capacitance C0 all was that dielectric loss is very little, degree of stability is high is the capacitor of medium with tygon and polypropylene etc.;
It can be the variable resistor that multiturn potentiometer etc. can accurately be adjusted the resistance size that resistance R 0 is regulated in loss;
Isolated voltage transformer PT1 is provided with for isolating ground connection, and its angular difference is little and angular difference stable;
Adjustable resistance R1 is used to regulate the size of 2, is the variable resistor that multiturn potentiometer etc. can accurately be adjusted the resistance size;
Phase shifter Y can compensate the angle error of PT, PT1, and the dielectric loss of standard capacitance C0 itself.Because of the angle error of PT, PT1, and the dielectric loss of C0 is all very little, and requiring phase shifter is that the phase shift angle is very little, and keeps phase shifting angle stable, phase shifter that again can meticulous adjustment phase shifting angle;
Wave filter L can be the 50Hz bandpass filter; The harmonic components that it can elimination PT, PT1 itself produces, the harmonic component in the circuit, the composition of after PT and PT1 generating unit are divided phase shift, failing to cancel each other fully;
Proofreading and correct divider CFQ can be any circuit that can obtain two voltage ratios;
Numerical value display XS is a conventional display.
The measuring principle of the present invention and the course of work (as shown in Figure 7) are:
Method and apparatus of the present invention can measure any can with ground isolated or have a dielectric loss of the capacitor type high-voltage electrical equipment of electric current in 2 milliamperes to 50 milliamperes scopes of end screen tap.
At first, disconnect by the earth terminal of side apparatus, the terminal A of device of the present invention (referring to Fig. 3) is connected on the former earth terminal of charged equipment under test, terminal W1, W2 are connected on the secondary side with the joining high voltage potential transformer PT of the live end of equipment under test; (wherein the Kd among Fig. 3 is the earth terminal of apparatus, and Kr1 is the by-pass cock of adjustable resistance R1, and Kr0 is the by-pass cock that resistance R 0 is regulated in loss, and Kc is the switch of choice criteria capacitor C 0)
Shown in Fig. 7,6, the voltage that applies on the former limit of high pressure P T is 1, through the output voltage behind isolation PT1, the adjustable resistance R1 is 2, regulating adjustable resistance R1 can make 2 adjust the amplitude size along 1 direction vector, because standard capacitance C0 and the voltage on the pressure drop ratio equipment under test on the loss adjusting resistance R 0 in the series connection of equipment under test earth terminal are much smaller, therefore, the leakage current on this loop
Size and direction vector determine that by equipment under test 0 pair of leakage current of resistance R is regulated in the sampling standard capacitor C 0 of series connection and loss
Influence can ignore;
Leakage current
Pressure drop on standard capacitance C0 and loss adjusting resistance R 0 is respectively C0 and R0, C0 ratio
The quadrature lagging electric angle, R0 with
Homophase, when adjusting adjustable resistance R1, R0 along with
Parallel straight line ab changes;
Adjust adjustable resistance R1 and loss and regulate resistance R 0, make bridge balance, at this moment, resultant vector cR that C0 and R0 constitute and 2 consistent (galvanometer is designated as zero), behind the bridge balance, Closing Switch K1 measures capacitive voltage component UC0 by the capacitance voltage reading device; Afterwards, disconnect the closed K2 of K1 again, measure resistive component of voltage UR0, calculate UR0/UC0-tg δ, show through display XS by proofreading and correct divider by the resistive voltage reading device; Also can get dielectric loss value after the calculating of being divided by by manually measuring capacitive voltage component UC0 and resistive component of voltage UR0 respectively.
Embodiment 2:
A kind of method of live line measurement medium loss of capacitive electric equipment, its step is with embodiment 1 unanimity.
When satisfying following condition, device of the present invention can not connect wave filter L, phase shifter Y, isolated voltage transformer PT1;
(1). the harmonic wave that high voltage potential transformer produces and the harmonic wave of electric system are all very little, and the measuring error that makes electric bridge can not connect wave filter still in specialized range the time.
(2). the very little or known definite angle error value of the angular difference of high voltage potential transformer, can after measurement, calculate when revising, can not connect phase shifter Y.
(3). when guaranteeing safety really, and with the line of the ground end of high voltage potential transformer PT enough in short-term, can not connect isolated voltage transformer PT1.
There are standard capacitance C0, loss to regulate resistance R 0, adjustable resistance R1, terminal A, P, Q, M, N, Y1, Y2, Y3 as the frame of broken lines shown device among Fig. 4;
Terminal A is the terminal that connects the former earth terminal of equipment under test, terminals P, Q are the terminals that connects the galvanometer input end, terminal M, N are the terminals that connects voltage transformer secondary side output, and terminal Y1, Y2, Y3 are the terminals that reads standard capacitance C0 and loss adjusting resistance R 0 voltage;
The end of standard capacitance C0 connects with terminal A, Q, Y1, the other end of standard capacitance C0 connects with the end that resistance R 0 is regulated in loss, regulate 0 leading-out terminal Y2 of resistance R at standard capacitance C0 and loss, the other end that resistance R 0 is regulated in loss connects with terminal Y3, N and ground connection, two stiff ends of adjustable resistance R1 are connected to terminal M, N, and the adjustable side of adjustable resistance R1 is connected to terminals P.
The course of work of this device is:
At first, disconnect by the earth terminal of side apparatus, the terminal A of device of the present invention (referring to Fig. 5) is connected on the former earth terminal of charged equipment under test, terminal M, N are connected to the secondary side with the joining high voltage potential transformer PT of the live end of equipment under test;
Measure the leakage current on the measured capacitance type electrical equipment X with galvanometer at terminal Y1, Y2 or Y2, Y3 intermittent gauging,, in one group of standard capacitance, select suitable standard capacitance C0 according to a conventional method according to the size of leakage current;
Having held Y1, Y2 to measure pressure drop on the standard capacitor C0, between terminals P, Q, insert galvanometer with galvanometer again; Regulate adjustable resistance R1, the voltage U on the voltage transformer (VT) 2 adjust to standard capacitance C0 on pressure drop identical substantially;
Resistance R 0 is regulated in meticulous adjusting adjustable resistance R1 and loss, and making the galvanometer pointer is zero, bridge balance;
Measure standard capacitance C0 and loss at terminal Y1, Y2 and Y2, Y3 intermittent gauging respectively with galvanometer and regulate magnitude of voltage UC0 and UR0 on the resistance R 0, then the dielectric loss angle tg δ=UR0/UC0 of this equipment under test.
Its principle of work is all identical with embodiment 1 with used device.
Claims (8)
1. the method for a live line measurement medium loss of capacitive electric equipment; It is characterized in that step is as follows:
(1). the earth terminal at charged measured capacitance type electrical equipment in series inserts one group of standard capacitance C0 and loss adjusting resistance R 0;
(2). the live end of measured capacitance type electrical equipment has been connected to voltage transformer (VT), at adjustable resistance R1 of secondary side access of voltage transformer (VT);
(3). between the adjustable side of adjustable resistance R1 and standard capacitance C0 and measured capacitance type electrical equipment interface, connect galvanometer;
(4). regulate adjustable resistance R1 and loss and regulate resistance R 0, make galvanometer be shown as zero;
(5). measure magnitude of voltage UcO and UR0 on standard capacitance C0 and the loss adjusting resistance R 0, then the dielectric loss angle tg δ-UR0/UC0 of this equipment under test.
2. the method for a kind of live line measurement medium loss of capacitive electric equipment according to claim 1 and device, it is characterized in that: it has standard capacitance C0, loss to regulate resistance R 0, adjustable resistance R1, terminal A, P, Q, M, N, Y1, Y2, Y3; Terminal A is the terminal that connects the former earth terminal of equipment under test, terminals P, Q are the terminals that connects the galvanometer input end, terminal M, N are two stiff ends that connect the terminal of voltage transformer secondary side output and be connected to adjustable resistance R1 respectively, and terminal Y1, Y2, Y3 are the terminals that reads standard capacitance C0 and loss adjusting resistance R 0 voltage; The end of standard capacitance C0 connects with terminal A, Q, Y1, the other end of standard capacitance C0 connects with the end that resistance R 0 is regulated in loss, regulate 0 leading-out terminal Y2 of resistance R at standard capacitance C0 and loss, the other end that resistance R 0 is regulated in loss connects with terminal Y3, N and ground connection, and the adjustable side of adjustable resistance R1 is connected to terminals P.
3. the device of a kind of live line measurement medium loss of capacitive electric equipment as claimed in claim 2 is characterized in that: be connected to galvanometer J between connection terminal P, Q.
4. the device of a kind of live line measurement medium loss of capacitive electric equipment as claimed in claim 3 is characterized in that: be connected to wave filter L before the input end of galvanometer J.
5. the device of a kind of live line measurement medium loss of capacitive electric equipment as claimed in claim 3 is characterized in that: be connected to isolated voltage transformer PT1 between the two ends of adjustable resistance R1.
6. the device of a kind of live line measurement medium loss of capacitive electric equipment as claimed in claim 5 is characterized in that: between isolated voltage transformer PT1 and adjustable resistance R1, be connected to phase shifter Y.
7. the device of a kind of live line measurement medium loss of capacitive electric equipment as claimed in claim 6, it is characterized in that: read at voltage and be serially connected with K switch 1 and capacitance voltage reading device Jc between connection terminal Y1, Y2, read at voltage and to be serially connected with K switch 2 and resistive voltage reading device Jr between connection terminal Y2, Y3, the output termination of capacitance voltage reading device Jc and resistive voltage reading device Jr is proofreaied and correct the input end of divider CFQ, proofreaies and correct the output termination display XS of divider CFQ.
8. the device of a kind of live line measurement medium loss of capacitive electric equipment as claimed in claim 7, it is characterized in that: galvanometer J, capacitance voltage reading device Jc, resistive voltage reading device Jr are the millivoltmeters of same high impedance, connect connection terminal P, Q respectively through many logical switches, or voltage reads connection terminal Y1, Y2, or voltage reads connection terminal Y2, Y3.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97100155A CN1188237A (en) | 1997-01-13 | 1997-01-13 | Method for live measuring medium loss of capacitive electric equipment and its device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97100155A CN1188237A (en) | 1997-01-13 | 1997-01-13 | Method for live measuring medium loss of capacitive electric equipment and its device |
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| CN1188237A true CN1188237A (en) | 1998-07-22 |
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| CN97100155A Pending CN1188237A (en) | 1997-01-13 | 1997-01-13 | Method for live measuring medium loss of capacitive electric equipment and its device |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101833043A (en) * | 2010-03-30 | 2010-09-15 | 广元电业局 | Method for measuring electric capacity and dielectric loss of capacitance type voltage transformer |
| CN101285860B (en) * | 2008-06-06 | 2010-12-15 | 西安四方机电有限责任公司 | Device for testing high voltage large-capacity electrical apparatus dielectric loss tangent value |
| CN103701380A (en) * | 2013-12-31 | 2014-04-02 | 卢庆港 | Wide-range adaptive CT (Current Transformer) energy harvesting method using regulated-flux and enhanced-permeability iron core |
| CN109374978A (en) * | 2018-08-24 | 2019-02-22 | 国网天津市电力公司电力科学研究院 | A kind of cable dielectric loss improvement measuring circuit and method based on bridge method |
| CN109581264A (en) * | 2019-01-08 | 2019-04-05 | 任守华 | A kind of capacitance and dielectric loss standard |
| CN113702714A (en) * | 2021-07-20 | 2021-11-26 | 中国电力科学研究院有限公司 | Method for measuring capacitance value of high-voltage arm of direct-current voltage transformer |
-
1997
- 1997-01-13 CN CN97100155A patent/CN1188237A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101285860B (en) * | 2008-06-06 | 2010-12-15 | 西安四方机电有限责任公司 | Device for testing high voltage large-capacity electrical apparatus dielectric loss tangent value |
| CN101833043A (en) * | 2010-03-30 | 2010-09-15 | 广元电业局 | Method for measuring electric capacity and dielectric loss of capacitance type voltage transformer |
| CN101833043B (en) * | 2010-03-30 | 2013-06-19 | 广元电业局 | Method for measuring electric capacity and dielectric loss of capacitance type voltage transformer |
| CN103701380A (en) * | 2013-12-31 | 2014-04-02 | 卢庆港 | Wide-range adaptive CT (Current Transformer) energy harvesting method using regulated-flux and enhanced-permeability iron core |
| CN103701380B (en) * | 2013-12-31 | 2016-01-27 | 卢庆港 | The control method of magnetic flux regulation and control unshakable in one's determination and strengthening magnetic conduction adaptive CT electricity getting device |
| CN109374978A (en) * | 2018-08-24 | 2019-02-22 | 国网天津市电力公司电力科学研究院 | A kind of cable dielectric loss improvement measuring circuit and method based on bridge method |
| CN109581264A (en) * | 2019-01-08 | 2019-04-05 | 任守华 | A kind of capacitance and dielectric loss standard |
| CN113702714A (en) * | 2021-07-20 | 2021-11-26 | 中国电力科学研究院有限公司 | Method for measuring capacitance value of high-voltage arm of direct-current voltage transformer |
| CN113702714B (en) * | 2021-07-20 | 2023-12-08 | 中国电力科学研究院有限公司 | Method for measuring capacitance value of high-voltage arm of direct-current voltage transformer |
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