CN203572883U - Novel intelligent frequency-conversion large-current grounding impedance measuring instrument - Google Patents
Novel intelligent frequency-conversion large-current grounding impedance measuring instrument Download PDFInfo
- Publication number
- CN203572883U CN203572883U CN201320257569.7U CN201320257569U CN203572883U CN 203572883 U CN203572883 U CN 203572883U CN 201320257569 U CN201320257569 U CN 201320257569U CN 203572883 U CN203572883 U CN 203572883U
- Authority
- CN
- China
- Prior art keywords
- unit
- frequency
- current
- selecting
- central processing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The utility model relates to a novel intelligent frequency-conversion large-current grounding impedance measuring instrument, and relates to the technical field of measurement. The instrument comprises a power input terminal, a soft start circuit, a rectifier and filter unit, an inverter unit, an isolation output unit, a current transformer, a frequency-selecting current sample unit, a frequency-selecting voltage sample unit, a central processing unit, a user operation unit, a display unit, a printer, a storage unit, a frequency conversion output terminal, a voltage measuring terminal, and the like. The instrument employs a method of frequency conversion and frequency selection, and a sine-wave large alternating current of 45-55 Hz flows into a grounding grid. And then the measurement of frequency selection is carried out, and the instrument can achieve the accurate measurement of the grounding impedance, resistance and reactance of the grounding grid in the environment of strong interference in a high-voltage substation. The instrument provided by the utility model improves the accuracy, convenience and safety of the measurement of grounding impedance, especially in a substation with strong interference and a grounding grid of a power plant.
Description
Technical field
The utility model relates to the measuring equipment in power industry, specifically refers to a kind of grid grounding impedance measurement instrument of measuring for earthing device.
Background technology
Generating plant, grounding net of transformer substation are except providing common reference ground for various electrical equipments, more importantly, in system generation earth fault or while being struck by lightning, play the fault current of fast and effeciently releasing, improving grounded screen and earth's surface, place earth potential distributes, ensureing the effect of first and second equipment and personal security, is the important measures of safeguarding power system security reliability service, support personnel and device security.
Impedance ground (custom is called " stake resistance ", and real is the resistance value with perceptual weight) is reflection grounded screen performance and the most important parameter of state quality, and the significance of its Measurement accuracy is self-evident.
DL/T475-2006 < < earthing device characterisitic parameter is measured guide rule > >: the impedance of earthing device to distant place zero potential point.On numerical value, be the potential difference (PD) between earthing device and distant place zero potential point, with the ratio that passes through the electric current in earthing device inflow place.The impedance ground of trying to achieve by dash current is called impulse grounding impedance; The impedance ground of trying to achieve by power current is called power-frequency earthing impedance.Generally without special instruction, all refer to power-frequency earthing impedance.
The Grounding impedance of large-scale substation, power plant is less, generally all below 0.5 Ω.Suppose that a large-scale earth mat impedance ground calculates by 0.5 Ω, this earth mat is injected to the electric current of 1A, the current potential of its relative distant place zero potential point is upgraded to 0.5V.In-site measurement impedance ground is also this principle, to earth mat Injection Current I, measures the potential rise U of earth mat, calculates impedance ground Z=U/I.
Owing to existing very strong 50Hz to disturb in transformer station, power station environment, maximum can reach tens of volts.So on-the-spot faint test signal often brings very large error even cannot measure because disturbing strongly.At present conventional grid grounding impedance measurement instrument, measuring principle, is divided into several as follows:
(1) DC low current method of testing: measuring current is the DC current of mA level.The method advantage is that equipment volume is little, and cost is low, and technology is simple.Shortcoming is that from principle, to record be direct current resistance, but not impedance.And measuring current is very little, data are easily interfered and occur very large deviation.
(2) the little testing current method of high-frequency ac: the little electric current of interchange more than instrument output 100Hz is measured.The method advantage is with DC low current method of testing.Shortcoming is good not with 50Hz power frequency impedance equivalence, and under strong jamming, data are inaccurate.
(3) power frequency heavy-current method: utilize large capacity pressure regulator and isolating transformer, earth mat is injected to large electric current more than 50A, make the potential change of earth mat enough obvious.The method advantage is that measuring current is larger, and potential change is more obviously convenient to measure.Shortcoming is that measuring current and on-the-spot 50Hz disturb with frequently, and test signal cannot be separated with undesired signal.
(4) the little current method of alien frequencies: the little current method of alien frequencies adopts converter technique, and earth mat is injected to the little electric current of 1～5A alien frequencies, then adopts the filtering technique based on hardware circuit, and filtering part 50Hz disturbs.The method has improved measurement accuracy and antijamming capability greatly, progressively becomes the main equipment of large-scale earth mat test.
But the little current method of alien frequencies is in test, and some are large-scale, during ultra-large type earth mat, on the one hand because the impedance ground of earth mat itself is less, while injecting 1～5A electric current, caused potential rise is only 0.1～2V left and right, and on-the-spot strong 50Hz disturbs and can reach tens of volts on the other hand; And the antijamming capability deficiency of instrument Measurement accuracy under so low signal to noise ratio (S/N ratio).So when disturbing stronger large-scale earth mat, still there is certain deficiency in the method.
The relative merits of comprehensive above several method, the utility model proposes the large current earthing impedometer of a kind of novel intelligent frequency conversion, adopt frequency conversion and frequency-selecting measuring method, can get rid of the disturbing effect of on-the-spot 50Hz; 5～the 50A of instrument output simultaneously high-current test, improves signal to noise ratio (S/N ratio) greatly; Can reach under strong interference the object of the large-scale earth mat that Measurement accuracy impedance ground is very little.
For reaching above object, the utility model adopts modular design, by each Function Decomposition of instrument, is each relatively independent module that is mutually related again, is controlled function and the input and output of coordinating between each module by CPU (central processing unit).
Frequency conversion method of testing will reach this final purpose of interference-free Measurement accuracy, relates to the technology of two aspects: frequency conversion and frequency-selecting.Frequency conversion is the mains supply of 50Hz to be transformed into all adjustable sinusoidal wave variable-frequency power sourcess of voltage and frequency, frequency-selecting be in the interference of various complexity at the scene by the weak signal extraction after frequency conversion out, and carry out Measurement accuracy.Frequency variation signal source, as the source in " source-Biao " measuring system, does not relate to the output of measurements and calculations result.It is generally all isolated by isolating transformer and external interference simultaneously, is difficult for being disturbed impact.How its difficult point is, under less volume and weight, to produce powerful sinusoidal wave frequency variation signal.Will obtain sinusoidal wave frequency variation signal in the past, and generally all adopt the linear amplification mode of transistor, the efficiency which transforms is lower, and volume and weight is larger, so testing tool cannot be exported very large measuring current.The utility model adopts insulated gate bipolar transistor (IGBT) as power device.The compound full-control type voltage driven type power semiconductor device that IGBT is comprised of BJT (double pole triode) and MOS (insulating gate type field effect tube), the advantage that has the high input impedance of MOSFET and low conduction voltage drop two aspects of GTR concurrently can realize high power contravariant in very little volume.
It is complicated a lot of that frequency-selecting technology is wanted comparatively speaking, and object is under the disturbed condition of various complexity, isolates faint frequency variation signal and measures Output rusults.Often the useful frequency variation signal amplitude of jam-to-signal strong several times to tens times, useful frequency variation signal " is flooded " in various undesired signals.And power frequency interference, high frequency interference, humorous wave interference in the signal of surveying, have been comprised, be superimposed with again frequency variation signal, it is disorderly and unsystematic complicated and changeable without clear and definite rule that waveform has become, in the waveform of so mixed and disorderly complexity, reduce to extract useful feeble signal and also want Measurement accuracy, and difficulty is very large.And test frequency and interfering frequency nearer, the difficulty of frequency-selecting is just larger.Obviously, frequency-selecting technology direct relation the accuracy of complete frequency conversion measuring system result, is that can integrated system reach the gordian technique of getting rid of this final purpose of interference Measurement accuracy, is the technical bottleneck of integrated system.The core of alien frequencies earth resistance tester frequency selection circuit was all based on hardware filtering circuit in the past, and hardware filtering circuit has simple in structure, with low cost, responds the advantages such as quick, but also exist interference rejection capability a little less than, the problem such as error is larger.For addressing the above problem, the utility model adopts the method based on the spectrum analysis of waveform software, and core frequency-selective filtering system adopts the method for software and hardware combining, has greatly improved antijamming capability, can meet and under very strong interference, measure faint signal.
Utility model content
The utility model provides a kind of novel intelligent frequency conversion large current earthing impedometer, and object is to overcome the deficiency in currently available technology, designs a kind of grid grounding impedance measurement instrument that can export the large electric current of frequency conversion.High-power sinusoidal wave variable-frequency power sources that this grid grounding impedance measurement instrument is integrated, frequency-selecting voltage measurement, frequency-selecting current measurement and data operation function, when measuring large-scale earth mat, can produce the large electric current of frequency conversion of 5-50A, the digital frequency-selective filtering technology that simultaneously adopts software and hardware combining, has improved in-site measurement precision and accuracy greatly.
For addressing the above problem, the utility model adopts following technical scheme: the large current earthing impedometer of a kind of novel intelligent frequency conversion, comprises power input terminal, soft-start circuit, rectification filtering unit, inversion unit, isolation output unit, current transformer, frequency-selecting current sampling unit, frequency-selecting voltage sample unit, CPU (central processing unit), user operation unit, display unit, printer, storage unit, frequency conversion lead-out terminal, voltage measurement terminal.
Power input terminal is linked rectification filtering unit after soft-start circuit, interchange is become to level and smooth direct current and output to inversion unit, be converted to the frequency variation signal of 45-55Hz, then after isolated location isolation, be connected to frequency variation signal lead-out terminal, this grid grounding impedance measurement instrument adopts and includes frequency-selecting current sampling unit, can get rid of strong 50Hz and disturb, accurately measure the current signal under selected frequency between 45-55Hz; This grid grounding impedance measurement instrument adopts and includes frequency-selecting voltage sample unit, can get rid of strong 50Hz and disturb, and accurately measures the voltage signal under selected frequency between 45-55Hz.
Before current transformer is through frequency conversion lead-out terminal, frequency-selecting current sampling unit is linked in the output of current transformer, and frequency-selecting current sampling unit is also linked CPU (central processing unit).Voltage measurement terminal is linked frequency-selecting voltage measurement unit, and frequency-selecting voltage measurement unit is also linked CPU (central processing unit).
CPU (central processing unit) also in succession inversion unit, user operation unit, display unit, data storage cell and printer.
Compared with prior art, the large current earthing impedometer of intelligent frequency-conversion of the present utility model tool has the following advantages: (1) adopts frequency conversion electricity current method, and measuring current is brought up to original 10 times, has greatly improved signal to noise ratio (S/N ratio).(2) adopt the mode of software and hardware combining to carry out the anti-filtering of frequency-selecting, antijamming capability improves greatly.The utility model can improve the measuring accuracy of large-scale earth mat impedance ground under strong jamming greatly.
The utility model is in electric measurement field, and particularly the large-scale earth mat fields of measurement under strong jamming background has a wide range of applications and economic worth.
accompanying drawing explanation
Fig. 1 is the utility model structural representation.
embodiment
With best embodiment, the utility model is described in detail below.
As shown in Figure 1, the large current earthing impedometer of a kind of novel intelligent frequency conversion, object is to overcome the deficiency in currently available technology, designs a kind of grid grounding impedance measurement instrument that can export the large electric current of frequency conversion.High-power sinusoidal wave variable-frequency power sources that this grid grounding impedance measurement instrument is integrated, frequency-selecting voltage measurement, frequency-selecting current measurement and data operation function, when measuring large-scale earth mat, can produce the large electric current of frequency conversion of 5-50A, the digital frequency-selective filtering technology that simultaneously adopts software and hardware combining, has improved in-site measurement precision and accuracy greatly.
For addressing the above problem, the utility model adopts following technical scheme: the large current earthing impedometer of a kind of novel intelligent frequency conversion, comprises power input terminal, soft-start circuit, rectification filtering unit, inversion unit, isolation output unit, current transformer, frequency-selecting current sampling unit, frequency-selecting voltage sample unit, CPU (central processing unit), user operation unit, display unit, printer, storage unit, frequency conversion lead-out terminal, voltage measurement terminal.
Power input terminal is linked rectification filtering unit after soft-start circuit, interchange is become to level and smooth direct current and output to inversion unit, be converted to the frequency variation signal of 45-55Hz, then after isolated location isolation, be connected to frequency variation signal lead-out terminal, this grid grounding impedance measurement instrument adopts and includes frequency-selecting current sampling unit, can get rid of strong 50Hz and disturb, accurately measure the current signal under selected frequency between 45-55Hz; This grid grounding impedance measurement instrument adopts and includes frequency-selecting voltage sample unit, can get rid of strong 50Hz and disturb, and accurately measures the voltage signal under selected frequency between 45-55Hz.
Before current transformer is through frequency conversion lead-out terminal, frequency-selecting current sampling unit is linked in the output of current transformer, and frequency-selecting current sampling unit is also linked CPU (central processing unit).Voltage measurement terminal is linked frequency-selecting voltage measurement unit, and frequency-selecting voltage measurement unit is also linked CPU (central processing unit).
CPU (central processing unit) also in succession inversion unit, user operation unit, display unit, data storage cell and printer.
The utility model adopts modular design philosophy, by each Function Decomposition of instrument relatively independent module that is mutually related again one by one.In integrated product structure, the function of parts and product function are the relations of multi-to-multi, cause like this change in design meeting of certain parts to have influence on a plurality of functions of product, also will cause the modification of the parts of uncertain region, in order to realize a certain function of product, improve equally, also can cause the modification of a lot of parts.And in modular product structure, the function of parts and product function are man-to-man relations, for the change of parts and the improvement of product function, can not cause the adjustment of other parts and function like this, namely that the function of product is abstract separated with the specific implementation of product component, the independent change of module self can not affect other modules.Instrument internal comprises soft-start circuit, rectification filtering unit, inversion unit, isolation output unit, current transformer, frequency-selecting current sampling unit, frequency-selecting voltage sample unit, CPU (central processing unit), user operation unit, display unit, printer, storage unit etc.Wherein soft-start circuit, rectification filtering unit, inversion unit, isolation output unit have formed a sinusoidal wave power transformation power circuit, and its output parameter is controlled by instruction by CPU (central processing unit).Current transformer, frequency-selecting current sampling unit can complete frequency-selecting current measurement function, and frequency-selecting voltage sample unit can complete voltage measurement function.The core of central processing unit in system, controls and coordinates each unit co-ordination, completes computing, Output rusults simultaneously.Such design can make full use of existing mature experience, and reusing of module and knowledge can reduce design cost greatly, shortened the R&D cycle, guaranteed smooth realization and the reliability of product function.
Soft-start circuit of the present utility model consists of a high-power charging resistor and large electric current A.C. contactor, and wherein charging resistor is connected in parallel on the two ends of contactor normally opened contact.After instrument powers on, first pass through charging resistor, the rectification circuit current-limiting charge to rear end, through after a period of time, the rectification circuit DC voltage of rear end approaches and is full of, and by CPU (central processing unit), sends instruction, and control contactor is closed, and charging resistor is deactivated.The object of soft-start circuit is large electric current when powering on, and avoids the impact to power supply and instrument internal element.Arranging filter unit has rectifier bridge and jumbo electrochemical capacitor to form, and AC power rectifying and wave-filtering is become to level and smooth direct current.The inversion unit core of rear end is IGBT or IPM module, by CPU, controlled, and by commutation inversion, be the controlled frequency-changing AC signal of voltage and frequency.Rear end adds filtering circuit, and output is become to smooth frequency conversion sine wave signal, the frequency conversion lead-out terminal of then exporting through transformer isolation.
Frequency-selecting voltage measurement function is by voltage measurement terminal, range automatic switching circuit, selective frequency filter circuit, isolating amplifier circuit, its current measurement function front-end circuit is by current measurement terminal, current transformer, automatic range switching unit, filter unit, operation amplifier unit forms, the voltage signal input range commutation circuit of voltage measurement terminal, range switch circuit is received filter unit, isolating amplifier circuit is received in filtering circuit output, and isolating amplifier circuit output is connected to CPU (central processing unit), by CPU (central processing unit), carries out analyzing and processing.The current signal of current measurement terminal is input to range switch circuit through current transformer, filtering circuit is received in range switch circuit output, filtering circuit is received operational amplification circuit, and operational amplification circuit output is connected to CPU (central processing unit), by CPU (central processing unit), carries out analyzing and processing.Display unit, SD storage card, printer, menu operation knob is all linked CPU (central processing unit).
Voltage range commutation circuit is in series by the resistance of a plurality of different resistances, separates 5 ranges in different positions, the corresponding 20mV of difference, 200mV, 2V, 20V, 200V range.After range switches, voltage is sent into filtering circuit, and signal is sent by filtering circuit, receives isolated amplifier, receives the AD pin of CPU by isolated amplifier after being isolated, and carries out sampling analysis.
The wire of frequency conversion output is through current transformer, and current transformer induces signal and receives range switch unit, and the resistance that range switches by a plurality of different resistances is in series, and separates 4 ranges in different positions, the corresponding 20mA of difference, 200mA, 2A, 20A range.CPU procedure identification is also automatically controlled and is switched corresponding relay, makes signal amplitude size in best measurement range.After range switches, voltage is sent into filter unit, and signal is sent by filter unit, receives the AD pin of CPU (central processing unit) after amplifier unit amplifies, and carries out sampling analysis.
The different AD pin that voltage, current signal divide two-way to send into CPU (central processing unit), carries out high-speed sampling analog to digital conversion, the discernible digital signal of the program that converts to through the built-in A/D convertor circuit of CPU (central processing unit).Then CPU (central processing unit) is carried out analytic operation by program to waveform, isolates the sine wave signal of selected frequency from complicated waveform, can isolate the voltage under assigned frequency simultaneously, and current signal also calculates phase differential between the two.CPU (central processing unit) is control store simultaneously also, prints, and shows the functions such as menu operation.
Above-mentioned CPU (central processing unit) is generally a kind of microprocessor with special construction, the Harvard structure that inner employing program and data are separated, has special hardware multiplier, extensively adopts stream line operation, special instruction is provided, can be used for realizing rapidly various signal processing algorithms.According to the requirement of digital signal processing, CPU generally has some following principal features: (1) can complete multiplication and a sub-addition within an instruction cycle.(2) program and data space separately, can while access instruction and data.(3) in sheet, there is quick RAM, conventionally can be by independently data bus access simultaneously in two.(4) there is low expense or without the hardware supported of expense circulation and redirect.(5) interrupting fast processing and Hardware I/O supports.(6) there are a plurality of hardware address generators that operate within the monocycle.(7) can a plurality of operations of executed in parallel.(8) support stream line operation, the operations such as fetching, decoding and execution can overlappingly be carried out.
Finally it should be noted that: obviously, above-described embodiment is only for the utility model example is clearly described, and the not restriction to embodiment.For those of ordinary skill in the field, can also make other changes in different forms on the basis of the above description.Here exhaustive without also giving all embodiments.And the apparent variation of being amplified out thus or change are still among protection domain of the present utility model.
Claims (2)
1. the large current earthing impedometer of novel intelligent frequency conversion, it is characterized in that, comprise power input terminal, soft-start circuit, rectification filtering unit, inversion unit, isolation output unit, current transformer, frequency-selecting current sampling unit, frequency-selecting voltage sample unit, CPU (central processing unit), user operation unit, display unit, printer, storage unit, frequency conversion lead-out terminal, voltage measurement terminal;
Power input terminal is linked rectification filtering unit after soft-start circuit, interchange is become to level and smooth direct current and output to inversion unit, is converted to the frequency variation signal of 45-55Hz, then after isolated location isolation, is connected to frequency variation signal lead-out terminal;
Before current transformer is through frequency conversion lead-out terminal, frequency-selecting current sampling unit is linked in the output of current transformer, frequency-selecting current sampling unit is also linked CPU (central processing unit), and voltage measurement terminal is linked frequency-selecting voltage measurement unit, and frequency-selecting voltage measurement unit is also linked CPU (central processing unit);
CPU (central processing unit) also in succession inversion unit, user operation unit, display unit, data storage cell and printer.
2. the large current earthing impedometer of novel intelligent frequency conversion as claimed in claim 1, is characterized in that, inversion unit wherein adopts IGBT as power device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320257569.7U CN203572883U (en) | 2013-05-13 | 2013-05-13 | Novel intelligent frequency-conversion large-current grounding impedance measuring instrument |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201320257569.7U CN203572883U (en) | 2013-05-13 | 2013-05-13 | Novel intelligent frequency-conversion large-current grounding impedance measuring instrument |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203572883U true CN203572883U (en) | 2014-04-30 |
Family
ID=50540610
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201320257569.7U Expired - Fee Related CN203572883U (en) | 2013-05-13 | 2013-05-13 | Novel intelligent frequency-conversion large-current grounding impedance measuring instrument |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203572883U (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105785135A (en) * | 2016-04-11 | 2016-07-20 | 国网安徽省电力公司电力科学研究院 | Frequency conversion ground impedometer |
| CN107102207A (en) * | 2016-12-02 | 2017-08-29 | 国家电网公司 | A kind of earth loop impedance test instrument controlled based on microcomputer with signal transacting |
| CN110456164A (en) * | 2019-10-09 | 2019-11-15 | 长沙润迅通信设备有限公司 | A kind of earth resistance metering device and measurement method |
| CN111736105A (en) * | 2020-08-04 | 2020-10-02 | 云南电力技术有限责任公司 | Device and method for testing anti-interference performance of frequency-selecting voltmeter |
| CN112730990A (en) * | 2020-12-31 | 2021-04-30 | 国网河南省电力公司检修公司 | Large-scale grounding grid impedance testing arrangement |
| CN114062875A (en) * | 2021-11-18 | 2022-02-18 | 株洲时代新材料科技股份有限公司 | Device and method for testing impedance characteristics of rail insulation and parts thereof |
| CN116593785A (en) * | 2023-01-30 | 2023-08-15 | 云南电力试验研究院(集团)有限公司 | Variable-frequency grounding impedance testing system and method |
-
2013
- 2013-05-13 CN CN201320257569.7U patent/CN203572883U/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105785135A (en) * | 2016-04-11 | 2016-07-20 | 国网安徽省电力公司电力科学研究院 | Frequency conversion ground impedometer |
| CN107102207A (en) * | 2016-12-02 | 2017-08-29 | 国家电网公司 | A kind of earth loop impedance test instrument controlled based on microcomputer with signal transacting |
| CN110456164A (en) * | 2019-10-09 | 2019-11-15 | 长沙润迅通信设备有限公司 | A kind of earth resistance metering device and measurement method |
| CN111736105A (en) * | 2020-08-04 | 2020-10-02 | 云南电力技术有限责任公司 | Device and method for testing anti-interference performance of frequency-selecting voltmeter |
| CN112730990A (en) * | 2020-12-31 | 2021-04-30 | 国网河南省电力公司检修公司 | Large-scale grounding grid impedance testing arrangement |
| CN114062875A (en) * | 2021-11-18 | 2022-02-18 | 株洲时代新材料科技股份有限公司 | Device and method for testing impedance characteristics of rail insulation and parts thereof |
| CN116593785A (en) * | 2023-01-30 | 2023-08-15 | 云南电力试验研究院(集团)有限公司 | Variable-frequency grounding impedance testing system and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN203572883U (en) | Novel intelligent frequency-conversion large-current grounding impedance measuring instrument | |
| CN202502204U (en) | GIS internal discharge test detection system | |
| CN103698677B (en) | Low-tension arc fault test and analytical system | |
| CN104237831A (en) | Set for calibrating tester of arrester counter | |
| CN205038273U (en) | Measurement device for earthing device power frequency and impact characteristic parameter | |
| CN109917192A (en) | The test device of power MOSFET device conducting resistance and output capacitance based on attenuation oscillasion impulse | |
| CN203069685U (en) | Comprehensive test instrument for capacitor or inductor switching test | |
| CN105785135A (en) | Frequency conversion ground impedometer | |
| CN204101715U (en) | A kind of counter of lightning arrester tester calibration device | |
| CN203965489U (en) | A kind of shelf depreciation high voltage pulse generation device | |
| CN205539204U (en) | Frequency conversion earth impedance measuring apparatu | |
| CN107144732B (en) | User-side harmonic source localization method based on lumped power | |
| CN102645577A (en) | Digital frequency selection measuring system capable of resisting one hundred thousand times of interference | |
| CN101975878B (en) | Bistable radiation comb signal source | |
| CN202351329U (en) | Constant current different frequency voltage limiting type anti-interference ground grid resistance test system | |
| CN203037716U (en) | Transformer and reactor entrance VFTO high-frequency signal test device for GIS transformer station | |
| CN204008864U (en) | Power-frequency earthing impedance instrument | |
| CN204330849U (en) | A kind of Multi-function experimental virtual instrument | |
| CN207424128U (en) | For low tension switch and control device harmonic wave jamming immunity tester | |
| CN203465372U (en) | Once through-flow three-phase simultaneous measurement detector for transformer station device | |
| CN111122954B (en) | Portable high-voltage line digital electricity test indicator and indication method thereof | |
| CN203376440U (en) | Three-phase distribution induction withstand voltage test instrument | |
| CN103389431A (en) | Intelligent on-load comprehensive test device for transformer substation | |
| CN203950010U (en) | Cable local discharge detection device | |
| CN203881861U (en) | Multifunctional power grounding parameter tester |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20140430 |
|
| CF01 | Termination of patent right due to non-payment of annual fee |