CN202276131U - Novel electronic ground fault protection release - Google Patents
Novel electronic ground fault protection release Download PDFInfo
- Publication number
- CN202276131U CN202276131U CN201120382144XU CN201120382144U CN202276131U CN 202276131 U CN202276131 U CN 202276131U CN 201120382144X U CN201120382144X U CN 201120382144XU CN 201120382144 U CN201120382144 U CN 201120382144U CN 202276131 U CN202276131 U CN 202276131U
- Authority
- CN
- China
- Prior art keywords
- circuit
- current
- mentioned
- output
- signal
- 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
- Emergency Protection Circuit Devices (AREA)
Abstract
The utility model discloses a novel electronic ground fault protection release. Based on the circuit structure of a non-ground-fault protection product, a zero sequence current transformer, a reference voltage and a grounding signal processing circuit are additionally arranged, and vector and superposition induction of current output by the secondary sides of phase current transformers are realized via the zero sequence current transformer, thereby obtaining electrical network ground fault signals through secondary conversion. The circuit structure of the release is quite simple, the number of electronic components can be minimized, and the circuit board of the release is small in size. No double CT design is necessary, no isolation power supply is needed, and an expensive differential operation amplifier needs not to be adopted, so that the release is low in overall cost and highly competitive.
Description
Technical field
The utility model relates to the electric equipment field, in particular for cutting off the circuit breaker of electric current, is specifically related to have the electronic type release of the circuit breaker of earth fault protection.
Background technology
Breaker of plastic casing is a moulded case circuit breaker, can be used to connect and the disjunction load circuit, also can be used to control the not motor of Fraquent start.Its function is equivalent to electrical appliance part or whole function summations such as knife switch, overcurrent relay, no-voltage relay, thermal relay and earth leakage protective device, is a kind of important protection electrical equipment in the low-voltage network.
The breaker of plastic casing of electronic type uses instrument transformer to gather each phase current size, compares with set point, and microprocessor sends signal when current anomaly, makes electronic trip unit drive the operating mechanism action.
The electronic type release of breaker of plastic casing generally adopts CT (current transformer) power supply self-powered, and CT (current transformer) both as power supply power supply usefulness, also used as sample of signal; Therefore, between CT (current transformer) signal ground and the power supply ground common ground reference must be arranged.
At present, the electronic type molded case circuit breaker label of peddling on the market is a lot, and function difference is very big, generally all possesses excess current protective function (the 4P product also comprises neutral line protection), has earth fault protection but differ to establish a capital; Therefore, according to whether having the earth fault protection function, electronic type release can be divided into two kinds on earth fault protection type and non-earth fault protection type; Wherein non-earth fault protection type product, the relative simple economy of its circuit design, volume is also less, and its circuit theory is as shown in Figure 1; The sort circuit structure is relatively independent because of its each phase current signal, after the full-wave rectification anti-phase is amplified, obtains, so can't or be difficult to the signal after the rectification is carried out vector and computing is beneficial to earth fault protection.
Earth fault protection type product also can be divided into three types, and the first adopts twin coil CT design, and promptly fast saturated CT and signal divide with hollow CT to be opened, and is respectively applied for power supply power supply and sample of signal, and its typical circuit principle is as shown in Figure 2; Though the sort circuit structure is easy to obtain the ground protection signal through each phase signals vector and computing, the CT design is the twin coil mode, and volume is bigger, and circuit structure is also comparatively complicated, and cost is higher; It two is to adopt the differential design mode, and its typical circuit principle is as shown in Figure 3, the sort circuit structure; Adopt each phase CT current phasor and ground signalling is taken a sample, but, do not have common reference point between current signal ground and the power supply ground because of single CT design; Must adopt can the achieve a butt joint sampling of earth signal of expensive high-accuracy difference amplifier to handle, can guarantee that signal waveform does not distort, price is very expensive; And amplifier palpus dual power supply, the power supply design is comparatively complicated.
It three is that (application number: mentioned employing insulating power supply design 201110112750.4), its typical circuit principle is as shown in Figure 4, comprises four current transformer CT for our company 2011.05 patent of invention " earth fault protection type electronic type release " of filing an application; Signal sampling circuit, signal processing circuit, current rectifying and wave filtering circuit; Current-to-voltage converting circuit, insulating power supply module, low pressure difference linear voltage regulator; Trip circuit, microprocessor and peripheral peripheral circuit thereof; Each current transformer is series at respectively among A, B, C triple line and the neutral line N of electrical network main circuit; Electric current to A, B, C triple line and neutral line N carries out the sensing conversion; Realize induction of signal and circuit energy supply; The output of each current transformer connects current rectifying and wave filtering circuit, current-to-voltage converting circuit, isolation Voltage stabilizing module, low pressure difference linear voltage regulator successively, and the output of low pressure difference linear voltage regulator is system works voltage; Isolate Voltage stabilizing module through between the input of the output of current-to-voltage converting circuit and above-mentioned low pressure difference linear voltage regulator, being connected with DC-DC; Realize earthy isolation between microprocessor and the current-to-voltage converting circuit, earth potential does not between the two have common reference point; Signal processing circuit comprises signal boost circuit and operational amplification circuit; The input of signal sampling circuit is connected to the sampling end of each current transformer; And realize being promoted to reference voltage V ref to the reference potential of signal sampling circuit by 0 by the signal boost circuit, the output of signal sampling circuit is connected in the input of operational amplification circuit, and the dropout output of microprocessor is connected to the trigger end of trip circuit; When unusual condition appears in the electrical network main circuit; Microprocessor provides triggering signal to trip circuit, and load circuit is cut off in trip circuit work, and load is protected.In the signal sampling circuit; The end of the current transformer current sampling resistor Ra of each phase, Rb, Rc, Rn respectively with corresponding being connected of current sample end of each phase current mutual inductor; The other end then connect mutually and with the end short circuit of ground signalling sample resistance Rf, form a common node; Ground signalling is obtained by ground signalling sample resistance Rf conversion, and the other end of ground signalling sample resistance Rf is connected with the middle common port of the rectification of current rectifying and wave filtering circuit.The sort circuit structure is isolated Voltage stabilizing module owing to introduce DC-DC, and signal processing is simple relatively, needn't adopt accurate differential amplifier, and base amplifier just can be realized signal processing; And this DC-DC isolates Voltage stabilizing module and belongs to the Switching Power Supply category, and power supply conversion efficiency is higher, allows to work the power network current value thereby reduce, and enlarges the current work scope of electronic type release; But it is high slightly to isolate the Voltage stabilizing module cost, and its whole cost price is still expensive a lot of than non-earth fault protection type product.
The utility model content
In order to solve the problems referred to above of prior art, the purpose of the utility model provides the very low novel earthing fault protection electronic type release of a kind of whole cost.
To achieve these goals, the utility model adopts following technical scheme:
Novel earthing fault protection electronic type release comprises current transformer, rectification circuit, signal sampling circuit; Current-to-voltage converting circuit, low pressure difference linear voltage regulator, current signal treatment circuit; The ground signalling treatment circuit, microprocessor and peripheral peripheral circuit thereof, trip circuit; Current transformer be series at the electrical network main circuit respectively each mutually in; The output of the current transformer of each phase is connected respectively to the respective input of rectification circuit; The output of rectification circuit connects current-to-voltage converting circuit and low pressure difference linear voltage regulator successively, and the output of low pressure difference linear voltage regulator is system works voltage; The current sample end of each current transformer connects the respective input of signal sampling circuit respectively; The corresponding output end of signal sampling circuit connects the input of current signal treatment circuit and ground signalling treatment circuit respectively; The output of current signal treatment circuit and ground signalling treatment circuit is connected to the input of microprocessor respectively, and the output of microprocessor connects the trigger end of trip circuit; Also comprise zero sequence current mutual inductor; Above-mentioned zero sequence current mutual inductor is series between the input of output end of the same name and above-mentioned rectification circuit of each above-mentioned current transformer, and the secondary side output of above-mentioned zero sequence current mutual inductor is connected to the respective input of above-mentioned signal sampling circuit; Zero sequence current mutual inductor obtains each phase current of electrical network to the vector of each Current Transformer Secondary side current signal and induction vector with, that is, obtain electrical network earth fault signal.
Above-mentioned zero sequence current mutual inductor adopts Weak current vector and induction module; Advantages of small volume; The silica gel embedding, built-in residual current transformer is reserved 4 and is passed from the residual current transformer center by the induced current lead; And all input and output pins adopt the SMT patch design, are convenient to the welding of PCB circuit board.
Above-mentioned ground signalling treatment circuit comprises voltage lifting circuit and ground signalling amplifying circuit; The corresponding output end of above-mentioned signal sampling circuit is connected in the input of above-mentioned ground signalling amplifying circuit, and the output of above-mentioned ground signalling amplifying circuit is connected to the input of above-mentioned microprocessor; Above-mentioned voltage lifting circuit is a reference voltage module; The input of said reference voltage module connects the output of above-mentioned low pressure difference linear voltage regulator; The output of said reference voltage module provides reference voltage, and this reference voltage is the half the of said system operating voltage.
Above-mentioned signal sampling circuit comprises each phase current mutual inductor current sampling resistor and ground signalling sample resistance; One end of above-mentioned each phase current mutual inductor current sampling resistor respectively with corresponding being connected of negative output terminal of above-mentioned rectification circuit; The other end of above-mentioned each phase current mutual inductor current sampling resistor with systematically be connected; Above-mentioned ground signalling sample resistance is parallel to the secondary side output of above-mentioned zero sequence current mutual inductor; And an end of above-mentioned ground signalling sample resistance is connected with the output of said reference voltage module, and the other end is connected to the respective input of above-mentioned ground signalling amplifying circuit.
After adopting such scheme, the utlity model has following beneficial effect:
One, the utility model is on the basis of non-earth fault protection type product circuit structure, to increase zero sequence current mutual inductor, reference voltage and ground signalling treatment circuit; Realize vector and superposition induction through zero sequence current mutual inductor, thereby the secondary conversion obtains electrical network earth fault signal to the secondary side output current of each phase current mutual inductor CT.Its circuit structure is very simple, and electronic devices and components can be accomplished minimized, and the circuit board advantages of small volume promptly needn't design by two CT, also needn't adopt insulating power supply, more needn't adopt expensive difference amplifier, and overall cost is very low, and competitiveness is strong.
Two, further; The product of and if only if ground connection type such as zero sequence current mutual inductor of the utility model and reference voltage and ground signalling treatment circuit just must welding; Fully can short circuit or do not weld and obtain for the product of non-ground connection type, so non-its cost price of ground connection type product of this programme can accomplish to minimize; And the product of ground connection type and non-its PCB circuit board of ground connection type product fully can be shared, are template with non-ground connection type product, revise when customer demand ground connection type product time side and replenish device, can reduce the quantity in stock of circuit board, reduce production costs.
Three, further; The zero sequence current mutual inductor of the utility model adopts modularized design, advantages of small volume, silica gel embedding; Built-in residual current transformer; Reserve 4 and passed from the residual current transformer center, and all input and output pins adopt SMT patch design, can be directly welded in the PCB circuit board by the induced current lead.
Four, further, the ground signalling treatment circuit of the utility model is made up of voltage lifting circuit and common signal amplification circuit, needn't adopt vector and superposition computing circuit; Above-mentioned voltage lifting circuit is a reference voltage module, and above-mentioned signal amplification circuit adopts common operational amplifier, but not accurate difference amplifier, and adopt single power supply, and circuit reduction, cost reduces.
Description of drawings
Fig. 1 is the circuit theory diagrams of non-earth fault protection type electronic trip unit in the prior art;
Fig. 2 is the circuit theory diagrams of the earth fault protection type electronic trip unit of two CT designs in the prior art;
Fig. 3 is the circuit theory diagrams of the earth fault protection type electronic trip unit of single CT design in the prior art;
Fig. 4 is the circuit theory diagrams of 201110112750.4 utility application " earth fault protection type electronic type release " for all application numbers of applicant;
Fig. 5 is the circuit theory diagrams of the utility model;
Fig. 6 is the zero sequence current mutual inductor outline drawing of the utility model.
Embodiment
Existing accompanying drawings and embodiment further specify the utility model.
The utility model novel earthing fault protection electronic type release, as shown in Figure 5, comprise 4 silicon steel core current transformer CT; A zero sequence current mutual inductor ZCT, signal sampling circuit, current signal treatment circuit; The ground signalling treatment circuit, rectification circuit, current-to-voltage converting circuit U1; Low pressure difference linear voltage regulator U2, MCU microprocessor and peripheral peripheral circuit U6 thereof, and trip circuit.
Each current transformer CT is series at respectively among the A, B, C, N phase line of electrical network main circuit, and each phase current of electrical network main circuit is carried out the sensing conversion, realizes induction of signal and circuit energy supply.The secondary side output of current transformer CT is proportional to power network current, and the sense of current of its end output of the same name is consistent with the direction of power network current.
Rectification circuit comprises four diode rectifier bridge D1, D2, D3, D4; The output of each current transformer CT is connected respectively to the input of diode rectifier bridge D1, D2, D3, D4, respectively ac current source A, B, C, the N of each phase current mutual inductor induction is carried out rectification through diode rectifier bridge D1, D2, D3, D4; The positive output end of each rectifier bridge pools together, and is connected to the input of current-to-voltage converting circuit U1, and the negative output terminal of each rectifier bridge meets following each phase current signal sample resistance Ra, Rb, Rc, Rn respectively.
Zero sequence current mutual inductor ZCT is as shown in Figure 6; Comprise input and output totally 10 pins; Its input pin is corresponding a1, a2, b1, b2, c1, c2, n1, n2 respectively; Can be simultaneously to B 4 branch roads carry out zero-sequence current vector and induction, output pin z1, z2 are zero-sequence current induction output.The utility model designs in the application like Fig. 5; Zero sequence current mutual inductor ZCT is connected between the input of output end of the same name and diode rectifier bridge D1, D2, D3, D4 of each current transformer CT; The induction of signal output z1 of zero sequence current mutual inductor ZCT, the then parallelly connected ground signalling sample resistance Rf of z2 (secondary side output) obtain earth fault signal Vf.Zero sequence current mutual inductor ZCT adopts Weak current vector and induction module, realizes vector and superposition to each phase current mutual inductor secondary side current signal.Because of the output of the secondary current signal of current transformer is proportional to power network current; And instrument transformer output current phase place is consistent with power network current; Just can realize indirectly the vector and the superposition of each phase current of electrical network are responded to through the vector and the superposition induction of zero sequence current mutual inductor, thereby obtain electrical network earth fault signal each phase current mutual inductor.
The output of current transformer CT connects zero sequence current mutual inductor ZCT, rectification circuit, current-to-voltage converting circuit U1 and low pressure difference linear voltage regulator U2 successively; Direct current after the rectification circuit rectification converts direct voltage V0 to through current-voltage conversion circuit U1, and this direct voltage V0 is that low pressure difference linear voltage regulator U2 and trip circuit provide power supply; Voltage V0 is transformed into the system works voltage VCC of work such as can supplying microprocessor, signal processing circuit through low pressure difference linear voltage regulator U2.
The ground signalling treatment circuit comprises voltage lifting circuit and as the operational amplification circuit U4 of ground signalling amplifying circuit; Voltage lifting circuit is a reference voltage module U3; The input of this reference voltage module U3 connects the output of low pressure difference linear voltage regulator U2; The output of this reference voltage module U3 provides reference voltage V ref, and this reference voltage V ref is the half the of system works voltage vcc, i.e. Vref=1/2*Vcc.
The current signal treatment circuit adopts see-saw circuit U5.
Signal sampling circuit comprises current sampling resistor Ra, Rb, Rc, Rn and the ground signalling sample resistance Rf of each phase current mutual inductor; The end of current sampling resistor Ra, Rb, Rc, Rn is connected with the negative output terminal of diode rectifier bridge D1, D2, D3, D4 respectively; And being connected to the inverting input of see-saw circuit U5 respectively, the other end of current sampling resistor Ra, Rb, Rc, Rn then with systematically is connected; The end of ground signalling sample resistance Rf is connected with the output of reference voltage module U3, and the other end of ground signalling sample resistance Rf is connected to the in-phase input end of operational amplification circuit U4.
In the utility model; The current sampling signal Va that current sampling resistor Ra, Rb, Rc, Rn obtain, Vb, Vc, Vn are negative full-wave rectified voltage signal; Can not satisfy the requirement of MCU microprocessor AD conversion, must passing through see-saw circuit U5, to carry out signal processing be can input microprocessor AD input port behind the positive full-wave rectified voltage signal.Earth fault signal Vf is an ac voltage signal, can not satisfy the requirement of microprocessor AD conversion, converts the voltage signal of these alternations into positive direct current alternating signal through voltage lifting circuit; This voltage lifting circuit directly is connected the end of sample resistance Rf and obtains with system voltage benchmark Vref; Earth fault sampled signal Vf after voltage promotes, after operational amplification circuit U4 signal processing, with respect to alternation about the voltage reference Vref, but its amplitude limitation is between 0-Vcc.
Trip circuit is made up of tripping coil RELAY, transistor Q1 and circuits for triggering etc.; When fault took place, earth fault signal Vf got into the MCU microprocessor after operational amplification circuit U4 signal processing, send a triggering signal by the MCU microprocessor again; Trigger transistor Q1 conducting; Tripping coil RELAY snap action drives circuit breaker operation mechanism, the disjunction main circuit.
Claims (4)
1. novel earthing fault protection electronic type release comprises current transformer, rectification circuit, signal sampling circuit; Current-to-voltage converting circuit, low pressure difference linear voltage regulator, current signal treatment circuit; The ground signalling treatment circuit, microprocessor and peripheral peripheral circuit thereof, trip circuit; Current transformer be series at the electrical network main circuit respectively each mutually in; The output of the current transformer of each phase is connected respectively to the respective input of rectification circuit; The output of rectification circuit connects current-to-voltage converting circuit and low pressure difference linear voltage regulator successively, and the output of low pressure difference linear voltage regulator is system works voltage; The current sample end of each current transformer connects the respective input of signal sampling circuit respectively; The corresponding output end of signal sampling circuit connects the input of current signal treatment circuit and ground signalling treatment circuit respectively; The output of current signal treatment circuit and ground signalling treatment circuit is connected to the input of microprocessor respectively, and the output of microprocessor connects the trigger end of trip circuit; It is characterized in that: also comprise zero sequence current mutual inductor; Above-mentioned zero sequence current mutual inductor is series between the input of output end of the same name and above-mentioned rectification circuit of each above-mentioned current transformer, and the secondary side output of above-mentioned zero sequence current mutual inductor is connected to the respective input of above-mentioned signal sampling circuit; Zero sequence current mutual inductor obtains each phase current of electrical network to the vector of each Current Transformer Secondary side current signal and induction vector with, that is, obtain electrical network earth fault signal.
2. novel earthing fault protection electronic type release according to claim 1; It is characterized in that: above-mentioned zero sequence current mutual inductor adopts Weak current vector and induction module, advantages of small volume, silica gel embedding; Built-in residual current transformer; Reserve 4 and passed from the residual current transformer center, and all input and output pins adopt SMT patch design, be convenient to the welding of PCB circuit board by the induced current lead.
3. novel earthing fault protection electronic type release according to claim 1; It is characterized in that: above-mentioned ground signalling treatment circuit comprises voltage lifting circuit and ground signalling amplifying circuit; The corresponding output end of above-mentioned signal sampling circuit is connected in the input of above-mentioned ground signalling amplifying circuit, and the output of above-mentioned ground signalling amplifying circuit is connected to the input of above-mentioned microprocessor; Above-mentioned voltage lifting circuit is a reference voltage module; The input of said reference voltage module connects the output of above-mentioned low pressure difference linear voltage regulator; The output of said reference voltage module provides reference voltage, and this reference voltage is the half the of said system operating voltage.
4. novel earthing fault protection electronic type release according to claim 3; It is characterized in that: above-mentioned signal sampling circuit comprises each phase current mutual inductor current sampling resistor and ground signalling sample resistance; One end of above-mentioned each phase current mutual inductor current sampling resistor respectively with corresponding being connected of negative output terminal of above-mentioned rectification circuit; The other end of above-mentioned each phase current mutual inductor current sampling resistor with systematically be connected; Above-mentioned ground signalling sample resistance is parallel to the secondary side output of above-mentioned zero sequence current mutual inductor; And an end of above-mentioned ground signalling sample resistance is connected with the output of said reference voltage module, and the other end is connected to the respective input of above-mentioned signal amplification circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120382144XU CN202276131U (en) | 2011-10-10 | 2011-10-10 | Novel electronic ground fault protection release |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120382144XU CN202276131U (en) | 2011-10-10 | 2011-10-10 | Novel electronic ground fault protection release |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202276131U true CN202276131U (en) | 2012-06-13 |
Family
ID=46196469
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201120382144XU Expired - Lifetime CN202276131U (en) | 2011-10-10 | 2011-10-10 | Novel electronic ground fault protection release |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202276131U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102412555A (en) * | 2011-10-10 | 2012-04-11 | 厦门士林电机有限公司 | Novel grounding fault protection electrical apparatus release |
| CN102914683A (en) * | 2012-11-01 | 2013-02-06 | 天津市电力公司 | Method for acquiring single-phase grounding current of three-phase single cable |
| CN107271763A (en) * | 2017-06-20 | 2017-10-20 | 常熟开关制造有限公司(原常熟开关厂） | Current sampling circuit, electronic trip unit, breaker |
-
2011
- 2011-10-10 CN CN201120382144XU patent/CN202276131U/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102412555A (en) * | 2011-10-10 | 2012-04-11 | 厦门士林电机有限公司 | Novel grounding fault protection electrical apparatus release |
| CN102914683A (en) * | 2012-11-01 | 2013-02-06 | 天津市电力公司 | Method for acquiring single-phase grounding current of three-phase single cable |
| CN107271763A (en) * | 2017-06-20 | 2017-10-20 | 常熟开关制造有限公司(原常熟开关厂） | Current sampling circuit, electronic trip unit, breaker |
| CN107271763B (en) * | 2017-06-20 | 2019-07-23 | 常熟开关制造有限公司(原常熟开关厂） | Current sampling circuit, electronic trip unit, breaker |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN207354054U (en) | The electric power system of online power equipment monitoring system | |
| CN202276131U (en) | Novel electronic ground fault protection release | |
| CN102170105A (en) | Ground fault protection type electronic tripper tripping device | |
| CN102412555A (en) | Novel grounding fault protection electrical apparatus release | |
| CN202856305U (en) | Low-voltage intelligent circuit breaker | |
| CN1975957A (en) | Portable analog circuit breaker | |
| CN201909807U (en) | On-line direct-current measuring device for transformer neutral point | |
| CN103236679A (en) | Electronic type backup protection device for AC (alternating current) circuit breaker | |
| CN206339637U (en) | A kind of power detecting system | |
| CN202084916U (en) | Ground fault protection type electronic electrical apparatus release | |
| CN202696482U (en) | Power supply circuit for leakage circuit breaker | |
| CN205104445U (en) | Anti -electricity -theft circuit breaker | |
| CN201733211U (en) | Multi-input power adapter | |
| CN201352253Y (en) | Testing box for electrical protection tests | |
| CN206834725U (en) | Protection device for arc faults circuit structure | |
| CN202362371U (en) | Anti-electricity-theft electric energy meter | |
| CN108776252B (en) | Metering secondary current loop of main transformer | |
| CN104620455B (en) | Power supply and measuring apparatus for intelligent electronic device | |
| US9384928B2 (en) | Electrical switching apparatus including transductor circuit and alternating current electronic trip circuit | |
| CN206977324U (en) | Power circuit for low-voltage circuit breaker | |
| CN110780255A (en) | Secondary electrical measurement system for circuit breaker on primary and secondary fusion complete set of column | |
| CN110034536A (en) | A kind of middle school teaching experiment power supply protection system | |
| CN208656482U (en) | A kind of low-loss electric toothbrush charging circuit | |
| CN110048516A (en) | A kind of electric current electricity getting system of wide scope high current protection | |
| CN211790004U (en) | Power plant service grounding structure containing diesel generator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term |
Granted publication date: 20120613 |
|
| CX01 | Expiry of patent term |