CN203299249U - Comparison circuit for electric energy metering chips - Google Patents
Comparison circuit for electric energy metering chips Download PDFInfo
- Publication number
- CN203299249U CN203299249U CN2013202962581U CN201320296258U CN203299249U CN 203299249 U CN203299249 U CN 203299249U CN 2013202962581 U CN2013202962581 U CN 2013202962581U CN 201320296258 U CN201320296258 U CN 201320296258U CN 203299249 U CN203299249 U CN 203299249U
- Authority
- CN
- China
- Prior art keywords
- module
- current
- active power
- comparison module
- value
- 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 - Lifetime
Links
Images
Landscapes
- Measurement Of Current Or Voltage (AREA)
Abstract
The utility model discloses a comparison circuit for electric energy metering chips. The comparison circuit comprises a first current signal sampling module, a second current signal sampling module, a voltage signal sampling module, a first active power module respectively connected with the first current signal sampling module and the voltage signal sampling module, a second active power module respectively connected with the second current signal sampling module and the voltage signal sampling module, a comparison module respectively connected with the first active power module and the second active power module, a threshold comparison module connected with the comparison module, and a timing module connected with the threshold comparison module. The double-channel comparison structure of two optional modes is used, and the two channels are detected when the two channels are not balanced, thereby detecting whether there is electricity stealing behavior or not.
Description
Technical field
The utility model relates to the anti-theft electricity technology in electric energy metrical, more specifically, is a kind of comparator circuit that is used for electric energy computation chip that can detect electricity filching behavior.
Background technology
Current, the status of the anti-theft electricity technology of electronic electric energy meter in the electric energy meter industry is more and more important, and the electric energy meter market in country variant, area is all at the electricity stealing preventive metering that requires in varying degrees electric energy meter.The stealing electricity phenomenon that people recognize and the type of anti-theft electricity technology are being on the increase, and all can, for new electricity filching behavior, work out corresponding anti-theft electricity technology every year., in the electric energy computation chip field, correspondingly require chip to have anti-electricity-theft detection and function of measuring.
Compare with three-phase electric energy meter, single-phase electric energy meter is paid attention to the anti-theft electricity technology of electric energy meter more.Fig. 1 is not for designing the simple single-phase electric energy table model schematic diagram of anti-stealing electricity function, and it only can measure the current signal of live wire and the voltage signal of electric energy meter end of incoming cables, even and for very simple electricity filching behavior, be helpless yet.
Usually current imbalance is presented as the ground connection pattern, and in fact current imbalance comprises the unbalanced situation of the resulting load current of measurement of any live wire and zero line.Stealing may be the bypass segment electric current, causes the measured value of ammeter less than actual value.As shown in Figure 2, electricity filching person may be thrown with simple metal wedge 3 terminals of ammeter into, and this electricity filching behavior ratio is easier to implement.When the meter reading charging, electricity filching person can remove the metal wedge 3 of by-pass current in several seconds, so be difficult to detect this stealing mode.
Publication No. is CN102749502A, and denomination of invention discloses a kind of double-current comparator circuit that can be used for anti-electricity-theft monitoring for the application for a patent for invention of " the double-current comparator circuit that is used for electric energy computation chip ".This double-current comparator circuit can apply in electric energy computation chip.This double-current comparator circuit comprises two signal sampling modules, be used for respectively live wire current signal and neutral line current signal being sampled, then respectively by high-pass filtering and Integral Processing, entering comparison module compares, comparative result being conveyed into a threshold value comparer and predetermined threshold compares again, thereby the uneven degree of monitoring two-way electric current, judged whether that electricity filching behavior occurs.
As shown in Figure 3, be a kind of application example of this kind electric energy computation chip.As shown in the figure, ammeter needs the extra current transformer 4 that increases, to realize the current detecting of zero line; , due to the isolation reason, can select copper-manganese resistance cheaply on the current channel of the first via, but another road just must the relatively high current transformer of use cost.In Fig. 3, the electric energy computation chip 2 in electronic electric energy meter 1 measures simultaneously through the live wire electric current of copper-manganese resistance sampling with through the neutral line current of current transformer sampling.Under normal circumstances, leakage current is very little, so the electric current in live wire loop and zero line loop is basically identical, can give the percent value n of the stealing of preset two current channels of electric energy computation chip 2, when the difference of two current values during greater than default percent value n, the current imbalance of two current channels of electric energy computation chip 2 judgements, show and have electricity filching behavior to occur.
In addition, Granted publication number discloses a kind of double current effective values comparison circuit for the utility model patent of CN201589801U, different from foregoing circuit is, this circuit carries out effective value calculating to the live wire current signal after sampling and neutral line current signal respectively, then two kinds of watt current signals are compared, and carry difference to the threshold value comparer, and judge based on above-mentioned percent value whether electric current is uneven, occur to have judged whether electricity filching behavior.
The utility model content
The purpose of this utility model, be existing circuit with anti-stealing electricity function is improved, thereby a kind of new comparator circuit that is used for electric energy computation chip is provided.
Aspect one of the present utility model, should be used for the comparator circuit of electric energy computation chip, comprising:
The first current signal sampling module, it is used for the live wire current signal of outside input is sampled and is converted to the first sample rate current signal of digital signal form;
The second current signal sampling module, it is used for the neutral line current signal of outside input is sampled and is converted to the second sample rate current signal of digital signal form;
The voltage signal sampling module, it is used for the voltage signal of outside input is sampled and is converted to the sampled voltage signal of digital signal form;
The the first active power module that is connected with this voltage signal sampling module with this first current signal sampling module respectively, it is used for receiving this first sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this first sample rate current signal and this sampled voltage signal, acquisition the first active power value;
The the second active power module that is connected with this voltage signal sampling module with this second current signal sampling module respectively, it is used for receiving this second sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this second sample rate current signal and this sampled voltage signal, acquisition the second active power value;
The comparison module that is connected with this second active power module with this first active power module respectively, it is used for this first active power value and this second active power value are compared, and exports the power difference between this first active power value and this second active power value;
The threshold value comparison module that is connected with this comparison module, it be used for to receive the power difference of this comparison module output, and relatively this power difference and predetermined threshold;
With the timing module that this threshold value comparison module is connected, it is used for when this power difference is all the time greater than this predetermined threshold in the given time, to uneven indicator signal of this threshold value comparison module feedback.
Aspect another, should be used for the comparator circuit of electric energy computation chip of the present utility model, comprise:
The first current signal sampling module, it is used for the live wire current signal of outside input is sampled and is converted to the first sample rate current signal of digital signal form;
The second current signal sampling module, it is used for the neutral line current signal of outside input is sampled and is converted to the second sample rate current signal of digital signal form;
The voltage signal sampling module, it is used for the voltage signal of outside input is sampled and is converted to the sampled voltage signal of digital signal form;
The the first current effective value module that is connected with this first current signal sampling module, be used for that this first sample rate current signal is carried out effective value and calculate, and export the first current effective value;
The the second current effective value module that is connected with this second current signal sampling module, be used for that this second sample rate current signal is carried out effective value and calculate, and export the second current effective value;
The the first active power module that is connected with this voltage signal sampling module with this first current signal sampling module respectively, it is used for receiving this first sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this first sample rate current signal and this sampled voltage signal, acquisition the first active power value;
The the second active power module that is connected with this voltage signal sampling module with this second current signal sampling module respectively, it is used for receiving this second sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this second sample rate current signal and this sampled voltage signal, acquisition the second active power value;
Comparison module, this comparison module comprise the first comparison module and the second comparison module, wherein,
This first comparison module is connected with this second current effective value module with this first current effective value module respectively, it is used for this first current effective value and this second current effective value are compared, and exports the current effective value difference between this first current effective value and this second current effective value;
This second comparison module is connected with this second active power module with this first active power module respectively, it is used for this first active power value and this second active power value are compared, and exports the power difference between this first active power value and this second active power value;
The threshold value comparison module, this threshold value comparison module comprises first threshold comparison module and Second Threshold comparison module, wherein,
This first threshold comparison module is connected with this first comparison module, and it be used for to receive the current effective value difference of this first comparison module output, and relatively this current effective value difference and scheduled current effective value threshold value;
This Second Threshold comparison module is connected with this second comparison module, and it be used for to receive the power difference of this second comparison module output, and relatively this power difference and predetermined threshold;
The timing module that is connected with this threshold value comparison module, it is used for when this current effective value difference is all the time greater than this scheduled current effective value threshold value in the given time, to uneven indicator signal of this threshold value comparison module feedback, and be used for feeding back this imbalance indicator signal to this threshold value comparison module when this power difference is all the time greater than this predetermined threshold in the given time;
The manner of comparison that is connected with this comparison module is selected module, is used for the first comparison module and the second comparison module are selected.
The utility model adopts the binary channels comparative structure of two kinds of alternative modes, can realize two detections of passage when imbalance, thereby whether detecting has electricity filching behavior to occur, guarantee that electric energy computation chip has anti-stealing electricity function, greatly reduce the ammeter manufacturing cost of the uneven stealing of anti-electric current, provide maximum design flexibility to the user simultaneously, and whole binary channels comparative structure is simple in structure, is easy to realize.
Description of drawings
Fig. 1 is not for being designed with the simple single-phase electric energy table model schematic diagram of anti-stealing electricity function;
Fig. 2 is for adopting the single-phase electric energy table model schematic diagram of current imbalance electricity filching behavior;
Fig. 3 is the Anti-fraudulent use electrisity model schematic diagram of the uneven electricity filching behavior of anti-electric current in a kind of prior art;
Fig. 4 is the composition schematic diagram of the comparator circuit that is used for electric energy computation chip of an embodiment of the present utility model;
Fig. 5 is the composition schematic diagram of the comparator circuit that is used for electric energy computation chip of another embodiment of utility model.
Embodiment
Below in conjunction with the drawings and specific embodiments, the structure of the comparator circuit for electric energy computation chip of the present utility model is formed and principle of work is elaborated.
In conjunction with Fig. 3, in general, improved comparator circuit of the present utility model, can be used in electric energy computation chip 2, and can receive live wire electric current, neutral line current and the voltage signal of ammeter again.Under normal circumstances, leakage current is very little, so the electric current in live wire loop and zero line loop is basically identical, and then the active power in two loops is also basically identical.When electricity filching behavior occurred, the active power in two loops will create a difference.Therefore, a predeterminable power difference threshold, during greater than this threshold value, be judged as two current channel imbalances when the difference of two active power, shows and have electricity filching behavior to occur.Easily understand, this difference threshold can be an absolute difference amount with power unit, also can be preferably a nondimensional relative percentage amount.
Specifically, with reference to figure 4, be the circuit diagram of an embodiment of the present utility model.As shown in the figure, this circuit comprises the first current signal sampling module 410, the second current signal sampling module 420, voltage signal sampling module 430, the first active power module 440, the second active power module 450, comparison module 460, threshold value comparison module 470 and timing module 480.
More specifically, in conjunction with Fig. 4, the first current signal sampling module 410 is used for the live wire current signal of outside input is sampled and is converted to the first sample rate current signal of digital signal form.
The second current signal sampling module 420 is used for the neutral line current signal of outside input is sampled and is converted to the second sample rate current signal of digital signal form.
Above-mentioned the first current signal sampling module 410 and the second current signal sampling module 420 can adopt conventional current signal sample circuit to sample to live wire current signal and neutral line current signal, and be converted to respectively digital signal, and then again digital signal separately is sent to respectively the first active power module 440 and the second active power module 450.
Voltage signal sampling module 430 is used for the voltage signal of outside input is sampled and is converted to the sampled voltage signal of digital signal form.Voltage signal sampling module 430 can adopt conventional voltage signal sampling circuits built, after the voltage signal that it will sample carries out digital conversion, forms the sampled voltage signal, and is sent to the first active power module 440 and the second active power module 450.
The first active power module 440 is connected with voltage signal sampling module 430 with the first current signal sampling module 410 respectively, be used for receiving the first sample rate current signal and sampled voltage signal, and to processings of multiplying each other of the first sample rate current signal and this sampled voltage signal, acquisition the first active power value.The first active power module 440 can be conventional power calculation circuit, such as multiplier etc.
Similar with the first active power module 440, the second active power module 450 is connected with voltage signal sampling module 430 with the second current signal sampling module 420 respectively, be used for receiving the second sample rate current signal and sampled voltage signal, and to processings of multiplying each other of the second sample rate current signal and this sampled voltage signal, acquisition the second active power value.
Threshold value comparison module 470 is connected with comparison module 460, is used for receiving the power difference of comparison module output, and compares power difference and predetermined threshold.Threshold value comparison module 470 can comprise conventional subtraction circuit, and the comparative result that compares power difference and reservation threshold value can be sent to timing module 480 be used for starting or the zero clearing timing module.
Particularly, in a preferred implementation of the present utility model, when the power difference is not more than predetermined threshold, do not start timing module 480.And when the power difference during greater than this predetermined threshold, start timing module 480, and: 1, after timing module 480 starts, when the power difference is not more than this predetermined threshold in the given time, show and only be instantaneous current imbalance phenomenon, but not the electricity filching behavior generation, therefore timing module 480 zero clearings; Perhaps, 2, after timing module 480 starts, when the power difference is constantly greater than this predetermined threshold in the given time, show current imbalance constantly, there is electricity filching behavior, therefore to the described uneven indicator signal of this threshold value comparison module feedback, and the described timing module of zero clearing, to re-start detection.After the threshold value comparison module receives uneven indicator signal, can externally send this imbalance indicator signal by chip, sending mechanism can be pilot lamp, can be also other similar digital indicator.This imbalance indicator signal also can be received by controller chip, and finally is presented on display interfaces.Easily understand, uneven indicator signal also can directly externally be sent by timing module 480.
Threshold value comparison module 470 and corresponding timing module 480 are set, and are for preventing the electricity filching behavior judgement that makes a mistake.In actual measurement, because various electricity consumption situations are different, can there be little difference in the active power of two-way, thus need to preset a threshold value according to actual conditions, to guarantee the accurate judgement to current imbalance.And the setting of timing module 480 is the erroneous judgements that cause because of instantaneous current imbalance for preventing.
As shown in Figure 5, be another circuit diagram in embodiment more preferably of the present utility model.In this embodiment, on active power basis relatively, increased by two current effective value modules, and, by the comparison to two current effective values, judged whether that the current imbalance situation occurs.The user can select module by manner of comparison, according to practical application, two kinds of comparison judgment models is selected.Similarly, for the comparison of current effective value, a predeterminable electric current difference threshold,, by the difference of two-way electric current (live wire electric current and neutral line current) effective value and the comparison of electric current difference threshold, judged whether that electricity filching behavior occurs.Easily understand, the difference of this current effective value difference threshold and two-way current effective value, can be the actual difference with current unit, also nondimensional percentage difference preferably.For example, can be according to practical application, it is a nondimensional percent value n that the current effective value difference threshold is set, and when the effective value difference of two-way electric current, during greater than this percent value n, judges the current imbalance of two current channels, shows and has electricity filching behavior to occur.
Particularly, with reference to Fig. 5, in this embodiment, comparator circuit comprises the first current signal sampling module 510, the second current signal sampling module 520, voltage signal sampling module 530, the first current effective value module 542, the second current effective value module 544, the first active power module 552, the second active power module 554, comparison module 560, threshold value comparison module 570, timing module 580 and manner of comparison selection module 590.
Identical with above-mentioned embodiment, the first current signal sampling module 510 is used for the live wire current signal of outside input is sampled and is converted to the first sample rate current signal of digital signal form; The second current signal sampling module 520 is used for the neutral line current signal of outside input is sampled and is converted to the second sample rate current signal of digital signal form; Voltage signal sampling module 530 is used for the voltage signal of outside input is sampled and is converted to the sampled voltage signal of digital signal form.
The first current effective value module 542 is connected with the first current signal sampling module 510, is used for that the first sample rate current signal is carried out effective value and calculates, and export the first current effective value; The second current effective value module 544 is connected with the second current signal sampling module 520, is used for that the second sample rate current signal is carried out effective value and calculates, and export the second current effective value.The first current effective value module 542 and the second current effective value module 544 all can adopt existing effective value counting circuit to form.
Similar with above-mentioned embodiment, the first active power module 552 is connected with voltage signal sampling module 530 with the first current signal sampling module 510 respectively, be used for receiving the first sample rate current signal and sampled voltage signal, and, to the processing of multiplying each other of the first sample rate current signal and sampled voltage signal, obtain the first active power value; The second active power module 554 is connected with voltage signal sampling module 530 with the second current signal sampling module 520 respectively, it is used for receiving the second sample rate current signal and sampled voltage signal, and, to the processing of multiplying each other of the second sample rate current signal and sampled voltage signal, obtain the second active power value.
Threshold value comparison module 570 comprises first threshold comparison module 572 and Second Threshold comparison module 574, wherein, first threshold comparison module 572 is connected with the first comparison module 562, be used for to receive the current effective value difference of the first comparison module 562 outputs, and relatively this current effective value difference and scheduled current effective value threshold value; Second Threshold comparison module 574 is connected with the second comparison module 564, be used for to receive the power difference of the second comparison module 564 outputs, and relatively this power difference and predetermined threshold.As mentioned above, two threshold value comparison modules 572,574 can adopt conventional subtracter to form.
Manner of comparison selects module 590 to be connected with comparison module 560, is used for the first comparison module 562 and the second comparison module 564 are selected.Manner of comparison selects module 590 can adopt conventional selector switch to form.In an embodiment of the present utility model, it can be a register that communicates with comparison module 560 that manner of comparison is selected module 590,, according in register, one or two selects position, determine only to open the first comparison module, only open the second comparison module or two comparison modules are opened simultaneously.For example, can arrange two in register and select position, during for " 01 ", select the first comparison module 562, during for " 10 ", select the second comparison module 564, during for " 11 ", select simultaneously two comparison modules.After one of them comparison module was selected, the threshold value comparison module that it is corresponding and timing module further carried out threshold value and relatively reach the current stabilization judgement.
In sum, the utility model adopts the binary channels comparative structure of two kinds of alternative modes, can realize two detections of passage when imbalance, thereby whether detecting has electricity filching behavior to occur, guarantee that electric energy computation chip has anti-stealing electricity function, greatly reduce the ammeter manufacturing cost of the uneven stealing of anti-electric current, provide maximum design flexibility to the user simultaneously, and whole binary channels comparative structure is simple in structure, is easy to realize.
Claims (2)
1. a comparator circuit that is used for electric energy computation chip, is characterized in that, comprising:
The first current signal sampling module, it is used for the live wire current signal of outside input is sampled and is converted to the first sample rate current signal of digital signal form;
The second current signal sampling module, it is used for the neutral line current signal of outside input is sampled and is converted to the second sample rate current signal of digital signal form;
The voltage signal sampling module, it is used for the voltage signal of outside input is sampled and is converted to the sampled voltage signal of digital signal form;
The the first active power module that is connected with this voltage signal sampling module with this first current signal sampling module respectively, it is used for receiving this first sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this first sample rate current signal and this sampled voltage signal, acquisition the first active power value;
The the second active power module that is connected with this voltage signal sampling module with this second current signal sampling module respectively, it is used for receiving this second sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this second sample rate current signal and this sampled voltage signal, acquisition the second active power value;
The comparison module that is connected with this second active power module with this first active power module respectively, it is used for this first active power value and this second active power value are compared, and exports the power difference between this first active power value and this second active power value;
The threshold value comparison module that is connected with this comparison module, it be used for to receive the power difference of this comparison module output, and relatively this power difference and predetermined threshold;
With the timing module that this threshold value comparison module is connected, it is used for when this power difference is all the time greater than this predetermined threshold in the given time, to uneven indicator signal of this threshold value comparison module feedback.
2. a comparator circuit that is used for electric energy computation chip, is characterized in that, comprising:
The first current signal sampling module, it is used for the live wire current signal of outside input is sampled and is converted to the first sample rate current signal of digital signal form;
The second current signal sampling module, it is used for the neutral line current signal of outside input is sampled and is converted to the second sample rate current signal of digital signal form;
The voltage signal sampling module, it is used for the voltage signal of outside input is sampled and is converted to the sampled voltage signal of digital signal form;
The the first current effective value module that is connected with this first current signal sampling module, be used for that this first sample rate current signal is carried out effective value and calculate, and export the first current effective value;
The the second current effective value module that is connected with this second current signal sampling module, be used for that this second sample rate current signal is carried out effective value and calculate, and export the second current effective value;
The the first active power module that is connected with this voltage signal sampling module with this first current signal sampling module respectively, it is used for receiving this first sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this first sample rate current signal and this sampled voltage signal, acquisition the first active power value;
The the second active power module that is connected with this voltage signal sampling module with this second current signal sampling module respectively, it is used for receiving this second sample rate current signal and this sampled voltage signal, and to processings of multiplying each other of this second sample rate current signal and this sampled voltage signal, acquisition the second active power value;
Comparison module, this comparison module comprise the first comparison module and the second comparison module, wherein,
This first comparison module is connected with this second current effective value module with this first current effective value module respectively, it is used for this first current effective value and this second current effective value are compared, and exports the current effective value difference between this first current effective value and this second current effective value;
This second comparison module is connected with this second active power module with this first active power module respectively, it is used for this first active power value and this second active power value are compared, and exports the power difference between this first active power value and this second active power value;
The threshold value comparison module, this threshold value comparison module comprises first threshold comparison module and Second Threshold comparison module, wherein,
This first threshold comparison module is connected with this first comparison module, and it be used for to receive the current effective value difference of this first comparison module output, and relatively this current effective value difference and scheduled current effective value threshold value;
This Second Threshold comparison module is connected with this second comparison module, and it be used for to receive the power difference of this second comparison module output, and relatively this power difference and predetermined threshold;
The timing module that is connected with this threshold value comparison module, it is used for when this current effective value difference is all the time greater than this scheduled current effective value threshold value in the given time, to uneven indicator signal of this threshold value comparison module feedback, and be used for feeding back this imbalance indicator signal to this threshold value comparison module when this power difference is all the time greater than this predetermined threshold in the given time;
The manner of comparison that is connected with this comparison module is selected module, is used for the first comparison module and the second comparison module are selected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013202962581U CN203299249U (en) | 2013-05-27 | 2013-05-27 | Comparison circuit for electric energy metering chips |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2013202962581U CN203299249U (en) | 2013-05-27 | 2013-05-27 | Comparison circuit for electric energy metering chips |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN203299249U true CN203299249U (en) | 2013-11-20 |
Family
ID=49575254
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2013202962581U Expired - Lifetime CN203299249U (en) | 2013-05-27 | 2013-05-27 | Comparison circuit for electric energy metering chips |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN203299249U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103278679A (en) * | 2013-05-27 | 2013-09-04 | 上海贝岭股份有限公司 | Comparison circuit for electric energy measuring chip |
-
2013
- 2013-05-27 CN CN2013202962581U patent/CN203299249U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103278679A (en) * | 2013-05-27 | 2013-09-04 | 上海贝岭股份有限公司 | Comparison circuit for electric energy measuring chip |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN105807230B (en) | Remaining battery capacity and health status rapid detection method and device | |
| CN103278679A (en) | Comparison circuit for electric energy measuring chip | |
| US7772829B2 (en) | Power meter and method for measuring power consumption | |
| CN102608404B (en) | Voltage sampling circuit and controller applicable to dual-power automatic transfer switch | |
| CN103439587B (en) | The detection method of three-phase alternating current | |
| TW201538993A (en) | High-sensitive detecting method and circuit of ungrounded DC power supply insulation resistor | |
| CN210982557U (en) | Electrical safety detection device and smart electric meter | |
| CN202471828U (en) | Voltage sampling circuit suitable for dual-power automatic transfer switch and controller | |
| CN103439625A (en) | Cable system fault positioning and load monitoring method | |
| CN203811727U (en) | Device for detecting commercial power | |
| CN106841773A (en) | Recognize the method and system of bad load | |
| CN102944712A (en) | Multi-range automatic selection device of electronic type current transformer | |
| CN102590587A (en) | Device and method for identifying short-circuit current of medium-voltage high-current direct current circuit breaker | |
| CN102323461A (en) | Unit multi-user intelligent electric energy meter box | |
| CN102749502B (en) | Double-current comparison circuit for electric energy metering chip | |
| CN101750528A (en) | Enhancing type method for preventing electricity stealing and electric energy meter thereof | |
| CN205608084U (en) | Single -phase single line metering circuit | |
| CN203299249U (en) | Comparison circuit for electric energy metering chips | |
| CN201133914Y (en) | Electric energy metering chip double-current comparing structure | |
| CN205049679U (en) | Residual current transformer sampling circuit | |
| CN201589801U (en) | Double current effective values comparison circuit | |
| CN105699740A (en) | Method for measuring all-scale range current | |
| CN202075369U (en) | Circuit for detecting open and short circuit states of current transformer | |
| CN201583594U (en) | Single-phase carrier electric energy meter | |
| CN105137268A (en) | Sampling circuit for residual current transformer |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20131120 |
|
| CX01 | Expiry of patent term |