CN2326962Y - Electricity meter with harmonic wave inhibiting device - Google Patents
Electricity meter with harmonic wave inhibiting device Download PDFInfo
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- CN2326962Y CN2326962Y CN 98230515 CN98230515U CN2326962Y CN 2326962 Y CN2326962 Y CN 2326962Y CN 98230515 CN98230515 CN 98230515 CN 98230515 U CN98230515 U CN 98230515U CN 2326962 Y CN2326962 Y CN 2326962Y
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- Prior art keywords
- signal
- voltage
- suppression apparatus
- resistance
- harmonic suppression
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Abstract
The utility model relates to an electricity meter with a harmonic wave inhibiting device, comprising a meter, current and voltage mutual inductors of each phase which are connected with the meter, an analog-to-digital converter, and a microprocessor which is connected with the analog-to-digital converter. The utility model is characterized in that a harmonic wave inhibiting device which is composed of a power supply unit, a phase-locked frequency multiplication unit, an electric current and voltage sampling unit, a signal filter unit, a signal amplification output unit, etc. is additionally arranged behind a meter output loop and in front of the analog-to-digital converter. The influence of nonlinear load on electric energy metering can be effectively inhibited. The utility model has the advantages of high precision of electric energy metering, small power consumption, small size, stable performance, simple structure, low cost, convenient installation, etc., and is a whole electronic energy meter which can be used for accurately and reasonably measuring the nonlinear load.
Description
The utility model relates to a kind of power measurement device, particularly a kind ofly can effectively suppress the electric energy meter that harmonic wave accurately measures electric weight.
In electric system, because the employing of the surge of harmonic source load and a large amount of nonlinear-loads has produced a large amount of higher hamonic waves, this harmonic wave will have a strong impact on the precision of electric energy metrical, and it is unreasonable that the electricity charge are collected.In order to solve an above-mentioned difficult problem, Hubei Provencial Electric Power Experiment Inst. adopts 8 rank active filter technology of the capacitance resistance ware composition that separates to develop a kind of fundamental frequency electronic electric energy meter, and applied for Chinese patent on March 19th, 1993, the patent No. is 93206362.4, though this electric energy meter can have certain inhibiting effect to harmonic wave, but volume is big, and power consumption is big, and stability is poor.Also has a kind of single-phase electric energy meter that adopts conventional filtering device to constitute by Sichuan Test Inst. of Electric Power Science, it is the nonlinear-load electric energy table, applied for national patent on March 22nd, 1994, the patent No. is 94227332.X, though this technology also is a kind of improvement to the sampled signal treatment circuit, but can not carry out frequency analysis and power measurement, and DeGrain to the three-phase asymmetrical system.
The utility model provides a kind of electric energy meter with harmonic suppression apparatus, and harmonic carcellation improves the precision of electric quantity metering greatly to the influence of electrical measurement effectively, and simple in structure, and power consumption is little, and volume is little, stable performance, and cost is low.
The purpose of this utility model realizes by following approach: the electric energy meter of this band harmonic suppression apparatus is to be based upon on the current ripe advanced full electronic electric energy meter technology, promptly installs a harmonic suppression apparatus additional between table meter input circuit that has the full electronic electric energy meter now and ADC (modulus) transducer.This harmonic suppression apparatus comprises power supply unit again, the phase locking frequency multiplying unit, and electric current, voltage sample and signal filtering and signal amplify output unit.The harmonic component that this electric energy meter that adds the band harmonic suppression apparatus can be decayed and be imported more than the secondary, thereby constitute the novel full electronic electric energy meter of a kind of measurable nonlinear-load institute consuming electric power, the higher hamonic wave that can effectively overcome nonlinear-load and produced is accurately measured the fundamental power that is injected into measurement loop the influence of electric energy metrical.
The power supply unit of above-mentioned harmonic suppression apparatus comprises two power transformer, to exchange 100 volts from electrical network mutual inductor secondary voltage by these two power transformer and be transformed to 16 volts of interchanges, the output terminal of these two power transformer connects an end of a full-wave rectification bridge respectively, alternating voltage is made into DC voltage, and the two ends in addition of full-wave rectification bridge respectively connect a three terminal regulator as output terminal; In these two three terminal regulators, + 12 volts of one of them voltage stabilizing outputs,-12 volts of another voltage stabilizing outputs, the output terminal of these two three terminal regulators links to each other with the both ends of power that electric current, voltage sample and signal filtering and signal amplify the operational amplifier in the output unit respectively, provides working power to operational amplifier.Also each links to each other with the input end of another three terminal regulator the output terminal of above-mentioned two three terminal regulators respectively simultaneously, two or three end voltage stabilizer voltage stabilizing output ± 5V through being connected again, one of them three terminal regulator output+5V, another three terminal regulator output-5V, the output terminal of these two three terminal regulators links to each other with the both ends of power that electric current, voltage sample and signal filtering and signal amplify 8 rank Butterworth LPF in the output unit respectively, provides working power to them.The output terminal of the three terminal regulator of above-mentioned output+5V also links to each other with the phaselocked loop of phase locking frequency multiplying unit and the power input of frequency divider respectively simultaneously, makes the work power supply for it and uses.
The phase locking frequency multiplying unit of above-mentioned harmonic suppression apparatus, comprise that the mutual inductor secondary voltage that gets access to grid exchanges the connection-peg of 100V, this connection-peg is connected in series resistance and diode successively, be used for taking the mains frequency signal from power transformer, close device and phaselocked loop by a diode resistance and the photoelectricity consumption of connecting successively again, in addition be parallel with a voltage stabilizing diode and be used for amplitude limit with resistance, phaselocked loop carries out the electrical network fundamental frequency to be followed the tracks of, the output terminal of phaselocked loop connects a frequency divider, form the phase locking frequency multiplying circuit jointly by phaselocked loop and frequency divider, offer the work clock signal of 8 rank Butterworth LPF, promptly the output terminal of clock of frequency divider links to each other with the work clock input end of each 8 rank Butterworth LPF respectively.
The electric current of above-mentioned harmonic suppression apparatus, voltage sample and signal filtering and signal amplify output unit and comprise that three current samples and signal filtering and signal amplify output mechanism, and three voltage samples and signal filtering and signal amplify output mechanism.Every phase current, voltage sample and signal filtering and signal amplify output mechanism and all adopt structure and composition and principle of work same or similar, but the component parameter of forming can be different, form the same or analogous current-voltage sampling of 6 line structures and signal filtering and signal amplification output circuit by it.With wherein any one the tunnel be example, all at first sample to voltage or electric current by a potentiometer in each road, the middle contact of this potentiometer links to each other with the signal input part of one 8 rank Butterworth LPF again, by its higher hamonic wave more than the filtering secondary, signal is become near pure first-harmonic, the working power terminals of 8 rank Butterworth LPF link to each other with power supply unit, provide its working power by power supply unit, the output terminal of 8 rank Butterworth LPF is received the input end of an operational amplifier by resistance, the power end of operational amplifier links to each other with power supply unit, voltage or current signal are after operational amplifier is done the signal adjustment, export to the signal input part of microprocessor, calculated by microprocessor, this numerical value is exactly the electric weight of user's actual consumption.
The utility model is compared background technology and is had following characteristics:
1, owing to adopt highly integrated capacitance switch mode filter, i.e. 8 rank Butterworth LPF, and the phase-locked letter frequency of electrical network come electric current and voltage is carried out automatic tracking filter, thereby make this electric energy meter have the characteristics high to the electrical measurement precision.
2, Zhuan Zhi element all adopts the cmos device of low-power consumption, key element such as operational amplifier usability price be than high product, and power supply unit then adopts is transformer in the electronic electric energy meter, thereby it is little to have power consumption, volume is little, the characteristics of stable performance.
3, owing to be on existing full-electronic electric energy meter, to install the harmonic source load electronic formula electric energy meter that harmonic suppression apparatus just can constitute pin-point accuracy additional, thus have simple in structure, characteristics such as cost is low, and is easy for installation.
Fig. 1 is the theory diagram of the electric energy meter of the utility model band harmonic suppression apparatus.
Fig. 2 is the power unit circuit schematic diagram of the utility model harmonic suppression apparatus.
Fig. 3 is the phase locking frequency multiplying element circuit schematic diagram of the utility model harmonic suppression apparatus.
Fig. 4 is the current signal sampling of harmonic suppression apparatus of the present utility model and the circuit theory diagrams of signal filtering and signal amplification output mechanism.
Fig. 5 is the voltage signal sampling of harmonic suppression apparatus of the present utility model and the circuit theory diagrams of signal filtering and signal amplification output mechanism.
Fig. 6 is the circuit theory diagrams of harmonic suppression apparatus of the present utility model.
Now with embodiment structure of the present utility model and principle of work are described in further detail with reference to the accompanying drawings.
As shown in Figure 1, the gauge outfit of electric energy meter on watchcase of band harmonic suppression apparatus connects three-phase current respectively, voltage, three-phase current, after the voltage input, by becoming weak current and light current pressure behind each phase current mutual inductor CT that is attached thereto in showing and the voltage transformer pt respectively, be input to the signal sampling mechanism of the harmonic suppression apparatus M that joins with it then, after harmonic suppression apparatus M filtering higher hamonic wave wherein, intimate pure current and voltage harmonic is input to the A-D converter W that is attached thereto the former full electronic electric energy meter that connects, by A-D converter W with electric current, the analog signal conversion of voltage becomes digital signal digital signal to be input to the microprocessor Q that is attached thereto again, and carries out computing and data processing and gets first-harmonic electric weight numerical value.
For the anti-pushing electric network of higher hamonic wave that the primary electron electric energy meter is produced by customer charge, will offset the fundamental energy that electrical network is carried, the reading from the electric energy meter is lower than the fundamental energy of user's actual consumption thus, causes error in dipping.By after installing harmonic suppression apparatus additional on the former full electronic electric energy meter, having solved the problems referred to above well, make reading on the electric energy meter more near the fundamental energy of user's actual consumption.
As shown in Figure 2, the power supply unit of harmonic suppression apparatus of the present utility model comprises and exchanges two power transformer T that 100 volts of power supplys link with electrical network mutual inductor secondary voltage
1And T
2, at power transformer T
1, T
2Low-pressure side obtain the alternating voltage of 16V, power transformer T
1, T
2Low-pressure side connects rectifier bridge B respectively
1Input end.Rectifier bridge B
1One end of output positive voltage is by electrochemical capacitor E
1Ground connection also connects three terminal regulator U simultaneously
9Input end; Rectifier bridge B
1One end of output negative voltage is by electrochemical capacitor E
2Ground connection also connects three terminal regulator U simultaneously
11Input end; Three terminal regulator U
9Output terminal output+12V voltage and by electrochemical capacitor E
3Ground connection is also passed through resistance R simultaneously
27With three terminal regulator U
7Input end link to each other capacitor C
17Be connected three-terminal voltage-stabilizing pipe U
7The same resistance R of input end
27Between tie point and the ground, three terminal regulator U
7+ 5 volts of voltages of output terminal output also pass through capacitor C simultaneously
3Ground connection.Three terminal regulator U
11Output terminal output-12V voltage and by electrochemical capacitor E
4Ground connection is also passed through resistance R simultaneously
28With three terminal regulator U
8Input end link to each other capacitor C
18Be connected three terminal regulator U
8The same resistance R of input end
28Between tie point and the ground, three terminal regulator U
8Output terminal output-5V voltage also passes through capacitor C simultaneously
4Ground connection.Three terminal regulator U
9, U
11, U
7, U
8The equal ground connection of the 3rd end GND.Draw to connect by terminals like this and offer the unit or the mechanism that need different voltages the harmonic suppression apparatus and make the work power supply from power supply unit ± 12V voltage and ± 5V voltage.
As shown in Figure 3, there are two joints that connect AC power the phase locking frequency multiplying unit of harmonic suppression apparatus, wherein a joint series resistor R
14After branch into two, branch road series diode D successively wherein
1, resistance R
26After meet photoelectrical coupler U
13Input end, stabilivolt Z
1With resistance R
26Parallel connection plays the amplitude limit effect; Wherein meet photoelectrical coupler U behind another branch road serial connection voltage dependent resistor (VDR) YM
13Input end, photoelectrical coupler U
13Output terminal receive phaselocked loop U
1AIN end, the series resistor R of this two tip nodes place
25After receive power supply unit+the 5V output terminal, and pass through capacitor C
19Ground connection.Photoelectrical coupler U
13E end and phaselocked loop U
1GND end, INH end and form frequency divider U
2The U of frequency division mechanism
2: the GND end of A, R end, the U of frequency division mechanism
2: CLK end and the R of B hold equal ground connection.Phaselocked loop U
1BIN end and the U of frequency division mechanism
2:BQ
3End U2P14 links to each other, its working power UCC termination power unit+the 5V output terminal, phaselocked loop U
1CA end serial connection capacitor C
5After connect another gust end CB end, phaselocked loop U
1PC2 end series resistor R
2Series resistor R successively again behind back and its UCIN end
3And capacitor C
6Back ground connection.Phaselocked loop U
1Output terminal UCOUT termination frequency divider U
2In the U of frequency division mechanism
2:ACLK end, the U of frequency division mechanism
2:AEN termination power unit+5V output terminal, and by capacitor C 7 ground connection.The U of frequency division mechanism
2:AOutput meet Q
3With the U of frequency division mechanism
2: the EN end of B links to each other.Above-mentioned phase locking frequency multiplying unit is by resistance R
14, diode D
1Take the mains frequency signal from power transformer, through stabilivolt Z
1Amplitude limit is again through photoelectrical coupler U
13Send phaselocked loop U
1Carry out the electrical network fundamental frequency and follow the tracks of, simultaneously phaselocked loop U
1With frequency divider U
2Form frequency multiplier circuit, the work clock signal of filtering circuit is provided.
As shown in Figure 5, the voltage signal sampling of harmonic suppression apparatus of the present utility model and signal filtering and signal amplification output mechanism comprises an adjustable potentiometer P who links with input voltage
6, its slider and switching capacity filter U
6Input end IN link to each other, play the signal sampling effect, capacitor filter U
6Input end of clock fetch clock signal from the frequency multiplication phase locking unit, the OPO end span is connected on capacitor C
22And resistance R
11Between, the OPI end span is connected on resistance R
19With capacitor C
22Between, V+ termination power unit+the 5V output terminal, V-termination power unit-5V output terminal, GND holds ground connection, capacitor filter U
6Output terminal OUT be connected in series electrochemical capacitor E successively
5, resistance R
17, capacitor C
1Back ground connection is in resistance R
17, capacitor C
1Junction and capacitor C
22, resistance R
11Junction cross-over connection resistance R
18, in resistance R
17, capacitor C
1The junction pass through resistance R
19After meet capacitor filter U
6OPI end U
6-4Resistance R
11One end and operational amplifier U
5:AOne end links to each other.Operational amplifier U
5:AThe other end pass through resistance R
16Ground connection, operational amplifier U
5:AThe positive termination power supply unit of working power+12V voltage output end, negative terminal meets power supply unit-12V voltage output end, operational amplifier U
5:AOutput terminal U
AOThe adjustable rheostat P of end serial connection
7Back and resistance R
16Join, and link to each other with A-D converter W.
In harmonic suppression apparatus of the present utility model, also have two line structures and form fully with above-mentioned voltage signal and amplify the output mechanism identical mechanism, do not repeat them here with sampling and signal filtering and signal.
As shown in Figure 4, harmonic suppression apparatus of the present utility model also has three line structures and forms mutually same current signal sampling and signal filtering and signal amplification output mechanism, it and aforesaid voltage signal sampling and signal filtering and signal amplify the structure of output mechanism and form basic identically, and difference is in resistance R
12With capacitor C
25The junction by an adjustable rheostat P
14Ground connection.
6 line structures in harmonic suppression apparatus of the present utility model and the same or analogous electric current of composition, voltage signal sampling and signal filtering and signal amplify output mechanism, are example with that road among Fig. 5, the voltage signal U of input
AtAfter adjustable rheostat sampling, through 8 rank Butterworth LPF U
6The higher hamonic wave that the filtering secondary is above becomes near pure first-harmonic signal, delivers to operational amplifier U again
5:AAfter doing the signal adjustment, export to electric energy meter microprocessor of the present utility model and carry out computing.
As shown in Figure 6, harmonic suppression apparatus of the present utility model is by power unit circuit, the phase locking frequency multiplying element circuit, and electric current and voltage signal sampling, signal filtering, signal amplifies output unit circuit and electric current, voltage input and output connection-peg P
10-6PIN
2With P
12-6PIN
2Deng composition, wherein power supply unit produce and output ± 12V and ± voltage of 5V, and the unit or the mechanism that offer other voltages that need vary in size such as current and voltage signals sampling, signal filtering, signal amplification output unit circuit and phase locking frequency multiplying element circuit respectively make the work power supply.The phase locking frequency multiplying element circuit produces the work clock signal, and offers electric current, voltage signal sampling, signal filtering, signal respectively and amplify each wave filter in output unit circuit clock signal of working.By 6 line structures with forms same or analogous electric current, voltage signal sampling, signal filtering, signal and amplify electric current that output mechanism forms, voltage signal sampling, signal filtering, signal amplification output unit under the condition that possesses working power and work clock signal, signal is respectively through six 8 rank Butterworth LPF U
6, U
16, U
10, U
3, U
14, U
4The higher hamonic wave that the filtering secondary is above becomes near pure first-harmonic signal, send the operational amplifier U of six correspondences more respectively
5:A, U
15:A, U
12:A, U
5:B, U
15:B, U
12:BAfter doing the signal adjustment, export to the electric energy meter microprocessor and calculate, reach and eliminate higher hamonic wave produces error to electric energy metrical purpose.
8 above-mentioned rank Bart's water low-pass filter U
6, U
16, U
10, U
9, U
14, U
4Can adopt MAX291 type or other integrated 8 rank Butterworth LPF.
Above-mentioned operational amplifier U
5:A, U
5:B, U
15:A, U
15:B, U
12:A, U
12:BCan adopt MAX498 type or other amplifier integrated circuit.
Above-mentioned phaselocked loop U
1Be 4046 type integrated circuit.
Above-mentioned three terminal regulator U
7, U
6, U
9, U
11Adopt 78.79 serial three terminal regulators.
Claims (9)
1, the electric energy meter of band harmonic suppression apparatus comprises the gauge outfit that connects three-phase current, voltage, each phase current mutual inductor (CT) and the voltage transformer (VT) (PT) that link to each other with gauge outfit at Biao Nei, A-D converter (W) and the microprocessor (Q) that links to each other with A-D converter (W), it is characterized in that table meter input circuit be current transformer (CT) and voltage transformer (VT) (PT) afterwards, A-D converter (W) connects before and installs one additional by power supply unit, phase locking frequency multiplying unit, and electric current and voltage sample, signal filtering, signal amplify the harmonic suppression apparatus (M) that output unit etc. is formed.
2, the electric energy meter of band harmonic suppression apparatus according to claim 1 is characterized in that voltage signal sampling and signal filtering and signal output mechanism comprise an adjustable potentiometer that links with input voltage (P6), its slider and capacitor filter (U
6) input end (IN) link to each other capacitor filter (U
6) input end of clock fetch clock signal from the frequency multiplication phase locking unit, (OPO) end span is connected on electric capacity (C
22) and resistance (R
11) between, (OPI) end span is connected on resistance (R
19) and electric capacity (C
22) between, (V+) the termination power unit+the 5V output terminal, (V-) termination power unit-5V output terminal, (GND) end ground connection, capacitor filter (U
6) output terminal (OUT) be connected in series electrochemical capacitor (E successively
5), resistance (R
17), electric capacity (C
1) back ground connection, at resistance (R
17), electric capacity (C
1) junction and electric capacity (C
22), resistance (R
11) junction cross-over connection resistance (R
18), at resistance (R
17), electric capacity (C
1) the junction by resistance (R
19) after meet capacitor filter (U
6) (OPI) end, resistance (R
11) an end and operational amplifier (U
5:A) end links to each other operational amplifier (U
5:A) the other end by resistance (R
16) ground connection, operational amplifier (U
5:A) the positive termination power supply unit of working power+12V voltage output end, negative terminal meets power supply unit-12V voltage output end, operational amplifier (U
5:A) output terminal be connected in series adjustable rheostat (P
7) back and resistance R
18Link to each other operational amplifier (U
5:A) output terminal also link to each other with A-D converter (W).
3, the electric energy meter of band harmonic suppression apparatus according to claim 1 is characterized in that the phase locking frequency multiplying unit in the harmonic suppression apparatus comprises two joints that connect AC power, wherein a joint series resistor (R
14) after branch into two, branch road series diode (D successively wherein
1) resistance (R
26) after meet photoelectrical coupler (U
13) input end, stabilivolt (Z
1) and resistance (R
26) in parallel play the amplitude limit effect; Wherein meet photoelectrical coupler (U after another branch road serial connection voltage dependent resistor (VDR) (YM)
13) input end, photoelectrical coupler (U
13) output terminal receive phaselocked loop (U
1) (AIN) end, at the series resistor (R of this two tip nodes place
25) after connect power supply unit+the 5V output terminal, and by electric capacity (C
19) ground connection.Photoelectrical coupler (U
13) (E) end and phaselocked loop (U
1) (GND) end, (INH) end and form frequency divider (U
2:A) (U of frequency division mechanism
2:A) (GND) end, (R) end, (the U of frequency division mechanism
2:B) (CLK) end and (R) hold equal ground connection.Phaselocked loop (U
1) (BIN) end with the (U of frequency division mechanism
2:B) (Q
3) hold (U2P14) to link to each other, its working power (UCC) termination power unit+the 5V output terminal, phaselocked loop (U
1) (CA) end serial connection electric capacity (C
5) after connect the other end (CB) end, (Pc2) end series resistor (R of phaselocked loop (U1)
2) back and its (UCIN) hold and to link to each other after series resistor (R successively again
3) and electric capacity (C
6) back ground connection, phaselocked loop (U
1) output terminal (UCOUT) termination frequency divider (U
2) in (the U of frequency division mechanism
2:A) (CLK) end, (the U of frequency division mechanism
2:A) (EN) termination power unit+5V output terminal, and by electric capacity G ground connection.(the U of frequency division mechanism
2:A) output terminal (Q
3) and (U of frequency division mechanism
2: (EN) end B) links to each other phaselocked loop (U
1) output terminal (UCOUT) end and the (U of frequency division mechanism
2:A) the tie point place of clock signal terminal (CLK) end connect each electric current, voltage signal sampling, signal filtering and signal and amplify 8 rank Butterworth LPF (U in the output unit
3, U
14, U
4, U
8, U
16, U
10) clock signal input terminal (CLK) end.
4, the electric energy meter of band harmonic suppression apparatus according to claim 1 is characterized in that containing in the harmonic suppression apparatus three line structures and forms identical voltage signal sampling and signal filtering and signal amplification output mechanism.
5, the electric energy meter of band harmonic suppression apparatus according to claim 1 is characterized in that containing in the harmonic suppression apparatus three line structures and forms identical current signal sampling and signal filtering and signal amplification output mechanism.
6, the electric energy meter of band harmonic suppression apparatus according to claim 1, it is characterized in that structure that the current signal sampling of every road, signal filtering, signal in the harmonic suppression apparatus amplify output mechanism and composition and every road voltage signal sampling, signal filtering, signal amplify the structure and the composition of output mechanism can be same or similar.
7, the electric energy meter of band harmonic suppression apparatus according to claim 1 is characterized in that 8 rank Butterworth LPF (U
6, U
16, U
10, U
3, U
14, U
4) can adopt MA * 291 types or other integrated 8 rank Butterworth LPF.
8, the electric energy meter of band harmonic suppression apparatus according to claim 1 is characterized in that operational amplifier (U
5:A, U
5:B, U
15:A, U
15:B, U
12:A, U
12:B) can adopt MA * 498 types or other computing amplification circuit.
9, the electric energy meter of band harmonic suppression apparatus according to claim 1 is characterized in that three terminal regulator (U
7, U
8, U
9, U
11) can adopt 78,79 serial three terminal regulators.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98230515 CN2326962Y (en) | 1998-04-08 | 1998-04-08 | Electricity meter with harmonic wave inhibiting device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98230515 CN2326962Y (en) | 1998-04-08 | 1998-04-08 | Electricity meter with harmonic wave inhibiting device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2326962Y true CN2326962Y (en) | 1999-06-30 |
Family
ID=33980136
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98230515 Expired - Fee Related CN2326962Y (en) | 1998-04-08 | 1998-04-08 | Electricity meter with harmonic wave inhibiting device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN2326962Y (en) |
-
1998
- 1998-04-08 CN CN 98230515 patent/CN2326962Y/en not_active Expired - Fee Related
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C19 | Lapse of patent right due to non-payment of the annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |