CN108390402A - Phase-switching apparatus and system - Google Patents
Phase-switching apparatus and system Download PDFInfo
- Publication number
- CN108390402A CN108390402A CN201810534850.8A CN201810534850A CN108390402A CN 108390402 A CN108390402 A CN 108390402A CN 201810534850 A CN201810534850 A CN 201810534850A CN 108390402 A CN108390402 A CN 108390402A
- Authority
- CN
- China
- Prior art keywords
- phase
- switch
- output
- module
- controlling module
- 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.)
- Pending
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks
Abstract
The present invention provides a kind of Phase-switching apparatus and systems, are related to power supply and distribution technical field.Phase-switching device is for switching over the output phase of three phase mains, Phase-switching device includes input detection module, three handover modules and switch-on controlling module, the power input of three handover modules connects one to one with three phases of three phase mains respectively, the power output end of three handover modules is connect with single-phase output, and switch-on controlling module is electrically connected with input detection module and each handover module respectively；Input detection module is used to detect the instantaneous voltage of the output phase of three phase mains, and switch-on controlling module is used to receive the control signal that the controller for communicating connection is sent, and switches output phase when instantaneous voltage is zero according to control signal.Phase-switching apparatus and system provided by the invention can be switched in load current curve zero crossing, avoided generating electric arc calcination switchgear, reduced switch fault rate.
Description
Technical field
The present invention relates to power supply and distribution technical fields, in particular to a kind of Phase-switching apparatus and system.
Background technology
The low-voltage network in China is with three-phase four-wire system mostly by 10kV/0.4kV transformers to customer power supply, due to
China's low-voltage network area coverage is wide, and running environment is different, power consumer it is numerous and relatively disperse, there are it is a large amount of when
The unbalanced single-phase load of space division cloth, even if three-phase load is evenly distributed on A, B, C three-phase, the consumption habit difference of resident
And the randomness of load is strong, can equally cause larger three-phase imbalance.Power load cannot be evenly distributed in each phase, be
The main reason for three-phase imbalance problem generates, if power grid long-play in the case where three-phase imbalance is more serious, to supplying
Electricity and electricity consumption both sides will have an adverse effect.
Currently, the case where for three-phase imbalance, which mostly uses greatly mechanical switch, carries out commutation, mechanical switch is in commutation process
Present in a serious problem be exactly that mechanical switch will produce electric arc in operation, to the requirement of the arc-rupturing capacity of switch
It is higher, it is susceptible to the failure of short circuit and electric leakage over time.
Invention content
The purpose of the present invention is to provide a kind of Phase-switching apparatus and systems, to improve above-mentioned problem.
The invention is realized in this way：
In a first aspect, an embodiment of the present invention provides a kind of Phase-switching devices, when turning single phase poaer supply for three phase mains
The output phase of three phase mains is switched over, Phase-switching device includes input detection module, three handover modules and combined floodgate
The power input of control module, three handover modules connects one to one with three phases of three phase mains respectively, and three
The power output end of a handover module is connect with single-phase output, and the switch-on controlling module is detected with the input respectively
Module and each handover module are electrically connected；
The input detection module is used to detect the instantaneous voltage of the output phase of the three phase mains, the shutting-brake control
Module is used to receive the control signal that the controller for communicating connection is sent, and according to the control signal in the instantaneous electricity
When pressure is zero, switch the output phase.
Optionally, the handover module includes switching circuit and mechanical switch, and the switching circuit, which includes inverse parallel, two
First igbt of pole pipe and inverse parallel have the second igbt of diode, first insulation
Grid bipolar transistor is in parallel with the mechanical switch after being docked with second igbt, first insulated gate
Bipolar transistor is connected with corresponding phase, and second igbt is connect with single-phase output；
The switch-on controlling module is electrically connected with first igbt and the mechanical switch respectively,
Conduction and cut-off for controlling the switching circuit and the mechanical switch according to the control signal.
Optionally, the switch-on controlling module is connect with the grid of first igbt, and described first
The source electrode of igbt is connect with the source electrode of second igbt, first insulated gate bipolar
The drain electrode of transistor is connected with corresponding phase, and the drain electrode of second igbt is connect with single-phase output.
Optionally, the input detection module is current transformer.
Optionally, the switch-on controlling module is digital signal processor.
Optionally, Phase-switching device further include output detection module, the output detection module respectively with described three
The power output end of handover module and the switch-on controlling module are electrically connected, and the output detection module is single-phase defeated for detecting
The electric current and voltage gone out.
Second aspect, an embodiment of the present invention provides a kind of Phase-switching systems, including multiple phases described above to cut
Changing device further includes controller, and the switch-on controlling module of the controller and each Phase-switching device communicates to connect, institute
Switch-on controlling module is stated for the electric current detected and voltage to be sent to the controller, the controller is used for according to each
The electric current and the voltage that switch-on controlling module detects judge whether the load of three phases of three phase mains is balanced, with
And when the load imbalance of three phases of three phase mains, the combined floodgate control of one or more Phase-switching devices thereto
Molding block sends out control signal, and the switch-on controlling module to receive control signal switches output phase, so that three phase mains
Three phases load balancing.
Optionally, the controller is PLC controller.
Optionally, the controller is server or PC.
Optionally, the controller communicates to connect through wireless communication with each switch-on controlling module.
For the prior art, Phase-switching apparatus and system provided by the invention has following advantageous effect：
Phase-switching apparatus and system provided by the invention can be switched in load current curve zero crossing, be avoided
Electric arc calcination switchgear is generated, switch fault rate is reduced.
Further, phenomena such as electrical equipment can be avoided to shut down, restart during commutation, ensures that power supply is reliable
Property.
To enable the above objects, features and advantages of the present invention to be clearer and more comprehensible, preferred embodiment cited below particularly, and coordinate
Appended attached drawing, is described in detail below.
Description of the drawings
In order to illustrate the technical solution of the embodiments of the present invention more clearly, below will be to needed in the embodiment attached
Figure is briefly described, it should be understood that the following drawings illustrates only certain embodiments of the present invention, therefore is not construed as pair
The restriction of range for those of ordinary skill in the art without creative efforts, can also be according to this
A little attached drawings obtain other relevant attached drawings.
Fig. 1 is the functional block diagram for the Phase-switching device that first embodiment of the invention provides.
Fig. 2 is the structural schematic diagram for the handover module that first embodiment of the invention provides.
Fig. 3 is the functional block diagram for the Phase-switching system that second embodiment of the invention provides.
Icon：10- Phase-switching devices；110- inputs detection module；120- handover modules；121- switching circuits；1211-
First igbt；The second igbts of 1212-；122- mechanical switch；130- switch-on controlling modules；
140- exports detection module；20- controllers.
Specific implementation mode
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.The present invention being usually described and illustrated herein in the accompanying drawings is implemented
The component of example can be arranged and be designed with a variety of different configurations.
Therefore, below the detailed description of the embodiment of the present invention to providing in the accompanying drawings be not intended to limit it is claimed
The scope of the present invention, but be merely representative of the present invention selected embodiment.Based on the embodiments of the present invention, this field is common
The every other embodiment that technical staff is obtained without creative efforts belongs to the model that the present invention protects
It encloses.
It should be noted that：Similar label and letter indicate similar terms in following attached drawing, therefore, once a certain Xiang Yi
It is defined, then it further need not be defined and explained in subsequent attached drawing in a attached drawing.
In the description of the present invention, it should be noted that term "center", "upper", "lower", "left", "right", "vertical",
The orientation or positional relationship of the instructions such as "horizontal", "inner", "outside" is to be based on the orientation or positional relationship shown in the drawings, or be somebody's turn to do
Invention product using when the orientation or positional relationship usually put, be merely for convenience of description of the present invention and simplification of the description, without
It is instruction or implies that signified device or element must have a particular orientation, with specific azimuth configuration and operation, therefore not
It can be interpreted as limitation of the present invention.In addition, term " first ", " second ", " third " etc. are only used for distinguishing description, and cannot manage
Solution is instruction or implies relative importance.
In addition, the terms such as term "horizontal", "vertical", " pendency " are not offered as requiring component abswolute level or pendency, and
It is that can be slightly tilted.It is not to indicate the structure if "horizontal" refers to only that its direction is more horizontal with respect to for "vertical"
It has to fully horizontally, but can be slightly tilted.
In the description of the present invention, it is also necessary to which explanation is unless specifically defined or limited otherwise, term " setting ",
" installation ", " connected ", " connection " shall be understood in a broad sense, for example, it may be fixedly connected, may be a detachable connection or one
Connect to body；It can be mechanical connection, can also be electrical connection；It can be directly connected, it can also be indirect by intermediary
It is connected, can is the connection inside two elements.For the ordinary skill in the art, on being understood with concrete condition
State the concrete meaning of term in the present invention.
First embodiment
Referring to Fig. 1, an embodiment of the present invention provides a kind of Phase-switching device 10, turn single phase poaer supply for three phase mains
When the output phase of three phase mains is switched over, Phase-switching device 10 include input 110, three handover modules of detection module
120, switch-on controlling module 130 and output detection module 140.
Wherein, the power input of three handover modules 120 connects one to one with three phases of three phase mains respectively,
The power output end of three handover modules 120 is connect with single-phase output, switch-on controlling module 130 respectively with input detection module
110 and each handover module 120 be electrically connected.Export the power output end with three handover modules 120 respectively of detection module 140
It is electrically connected with switch-on controlling module 130, output detection module 140 is used to detect the electric current and voltage of single-phase output.Input inspection
The instantaneous voltage that module 110 is used to detect the output phase of three phase mains is surveyed, switch-on controlling module 130 is communicated for receiving
The control signal that the controller of connection is sent, and output phase is switched when instantaneous voltage is zero according to control signal.
Specifically, input detection module 110 is connect with the A phase, B phase, C phase of three phase mains and zero curve, wherein a phase is
Output phase, output phase are connected with single-phase output, and to power for unidirectional loads, input detection module 110 is defeated for detecting
Go out the instantaneous voltage of phase, and by the transient voltage feedback detected to switch-on controlling module 130.
The input detection module 110 is used to detect the instantaneous voltage of output phase, and it is mutual can be but not limited to electric current
Sensor, voltage detecting circuit etc., it is current transformer that detection module 110 is inputted described in the embodiment of the present invention.
The power input of three handover modules 120 connects one to one with three phases of three phase mains respectively, three
The power output end of handover module 120 is connect with single-phase output, and one of handover module 120 is connected, thus by three-phase electricity
Source is converted to one-way electric power to power for unidirectional loads.
Fig. 2 is please referred to, handover module 120 includes switching circuit 121 and mechanical switch 122, and switching circuit 121 includes
Inverse parallel has the second insulated gate bipolar transistor that the first igbt 1211 of diode and inverse parallel have diode
Pipe 1212, the source electrode of the first igbt 1211 docked with the source electrode of the second igbt 1212 after with
Mechanical switch 122 is in parallel, and the drain electrode of the first igbt 1211 is connected with corresponding phase, the second insulated gate bipolar
The drain electrode of transistor 1212 is connect with single-phase output.Switch-on controlling module 130 and first igbt 1211
Grid and mechanical switch 122 be electrically connected, for being in the instantaneous voltage of output phase according to the control signal that receives
The conduction and cut-off that switching circuit 121 and the mechanical switch 122 are controlled when zero, to avoid electric arc calcination switchgear, drop is generated
Low switch failure rate.
When powering to unidirectional loads, one of three phase mains phase passes through in handover module 120 three phase mains
Mechanical switch 122 connect conducting with single-phase output, in the process, input detection module 110 detect output phase (with it is single-phase defeated
Go out connection conducting phase) instantaneous voltage, output detection module 140 detect single-phase output electric current and voltage simultaneously will detect
Electric current and voltage be sent to switch-on controlling module 130,130 communication link of switch-on controlling module is connected to a controller, the controller
It is responsible for switching control of the three phase mains to the output phase of unidirectional loads in its compass of competency, switch-on controlling module 130 obtains
After exporting the electric current and voltage that detection module 140 is fed back, by the electric current and the Voltage Feedback to controller, controller according to
The electric current and voltage that all switch-on controlling modules 130 in its compass of competency are fed back carry out three that operation obtains three phase mains
The loading condition of phase, and whether the load for analyzing three phases of three phase mains is balanced.If the load of three phases is uneven
Weighing apparatus, then load one or more Phase-switching devices 10 (switch-on controlling module 130) corresponding to excessive phase thereto
A control signal is sent, the switch-on controlling module 130 for receiving the control signal controls corresponding output according to the control signal
Phase is switched in instantaneous voltage, to avoid generating electric arc calcination switchgear, reduces switch fault rate.
Switch-on controlling module 130 is when controlling output phase switching, first to the switching circuit 121 corresponding to output phase
In the first igbt 1211 grid send a high level signal the first igbt is connected
1211, the conducting of switching circuit 121 at this time, electric current can be along output phase, the first igbt 1211 and second absolutely
The diode in parallel of edge grid bipolar transistor 1212, output detection module 140 enter the single-phase load being connect with single-phase output and set
It is standby.Then switch-on controlling module 130 controls the mechanical switch 122 corresponding to output phase and disconnects.When input detection module 110 is examined
When the instantaneous voltage measured is zero, switch-on controlling module 130 controls the switching circuit 121 corresponding to output phase and disconnects, with this
It controls the switching circuit 121 corresponding to another phase simultaneously to be connected, output phase is another phase by original Phase-switching at this time
Position.Then switch-on controlling module 130 controls the conducting of the mechanical switch 122 corresponding to new output phase again, and controls newly defeated
Go out the corresponding switching circuit 121 of phase to disconnect, to complete the handoff procedure of output phase.In the process, due to the output phase
Position is switched over when instantaneous voltage is zero, to avoid generating electric arc calcination switchgear, reduces switch fault rate.Meanwhile
Since the frequency of igbt is up to this characteristic of 1kHz or more, the moment that can be zero in instantaneous voltage is complete
At the switching of output phase, phenomena such as electrical equipment shuts down, restarts in commutation process is avoided, ensures power supply reliability.
In the embodiment of the present invention, the switch-on controlling module 130 is used for according to control signal when instantaneous voltage is zero, is cut
Change output phase.It may be, but not limited to, digital signal processor (Digital Signal Processing, DSP), PLC
Controller etc..
The output detection module 140 is used to detect the electric current and voltage of single-phase output, may be, but not limited to, ammeter
Or the circuit being made of current detection circuit and voltage detecting circuit.
In conclusion Phase-switching device 10 provided in an embodiment of the present invention can be carried out in output phase in instantaneous voltage
Switching reduces switch fault rate to avoid generating electric arc calcination switchgear.Simultaneously as can be zero in instantaneous voltage
Phenomena such as completing the switching of output phase, electrical equipment is avoided in commutation process to shut down, restart moment, avoid to user terminal
Load equipment damage, ensure power supply reliability.
Second embodiment
Referring to Fig. 3, present embodiments providing a kind of Phase-switching system, which includes multiple first real
The Phase-switching device 10 described in example is applied, further includes controller 20, the controller 20 and each Phase-switching device 10
Switch-on controlling module 130 communicate to connect, the switch-on controlling module 130 is used to the electric current detected and voltage being sent to institute
Controller 20 is stated, the electric current and the voltage that the controller 20 is used to detect according to each switch-on controlling module 130
Judge whether the load of three phases of three phase mains is balanced, and when the load imbalance of three phases of three phase mains,
The switch-on controlling module 130 of one or more Phase-switching devices 10 sends out control signal thereto, to receive control
The switch-on controlling module 130 of signal processed switches output phase, so that the load balancing of three phases of three phase mains.
In the embodiment of the present invention, the electricity of the controller 20 for being detected according to each switch-on controlling module 130
Stream and the voltage judge whether the load of three phases of three phase mains balanced, and when three phase mains three phases bear
When carrying unbalanced, the switch-on controlling module 130 of one or more Phase-switching devices 10 sends out control signal thereto.Its
It may be, but not limited to, PLC controller, server or PC etc..
The controller and each switch-on controlling module 130 can by way of wired or wireless communication communication link
It connects.
In conclusion Phase-switching system provided in an embodiment of the present invention can be cut in output phase in instantaneous voltage
It changes, to avoid generating electric arc calcination switchgear, reduces switch fault rate.Simultaneously as can be zero in instantaneous voltage
Moment completes the switching of output phase, avoids phenomena such as electrical equipment shuts down, restarts in commutation process, avoids to user terminal
Load equipment damages, and ensures power supply reliability.
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, for the skill of this field
For art personnel, the invention may be variously modified and varied.All within the spirits and principles of the present invention, any made by repair
Change, equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.It should be noted that：Similar label and letter exist
Similar terms are indicated in following attached drawing, therefore, once being defined in a certain Xiang Yi attached drawing, are then not required in subsequent attached drawing
It is further defined and is explained.
The above description is merely a specific embodiment, but scope of protection of the present invention is not limited thereto, any
Those familiar with the art in the technical scope disclosed by the present invention, can easily think of the change or the replacement, and should all contain
Lid is within protection scope of the present invention.Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. a kind of Phase-switching device, switches over the output phase of three phase mains when turning single phase poaer supply for three phase mains,
It is characterised in that it includes input detection module, three handover modules and switch-on controlling module, the power supply of three handover modules
Input terminal connects one to one with three phases of three phase mains respectively, the power output ends of three handover modules with list
Mutually output connection, the switch-on controlling module are electrically connected with the input detection module and each handover module respectively；
The input detection module is used to detect the instantaneous voltage of the output phase of the three phase mains, the switch-on controlling module
It is in the instantaneous voltage for receiving the control signal for communicating the controller of connection and sending, and according to the control signal
When zero, switch the output phase.
2. Phase-switching device according to claim 1, which is characterized in that the handover module includes switching circuit and machine
Tool switchs, and the switching circuit, which includes inverse parallel, has the first igbt of diode and inverse parallel to have diode
Second igbt, after first igbt is docked with second igbt
In parallel with the mechanical switch, first igbt is connected with corresponding phase, and second insulated gate is double
Gated transistors are connect with single-phase output；
The switch-on controlling module is electrically connected with first igbt and the mechanical switch respectively, is used for
The conduction and cut-off of the switching circuit and the mechanical switch is controlled according to the control signal.
3. Phase-switching device according to claim 2, which is characterized in that the switch-on controlling module is exhausted with described first
The grid of edge grid bipolar transistor connects, and the source electrode of first igbt is brilliant with second insulated gate bipolar
The source electrode of body pipe connects, and the drain electrode of first igbt is connected with corresponding phase, second insulated gate
The drain electrode of bipolar transistor is connect with single-phase output.
4. Phase-switching device according to claim 1, which is characterized in that the input detection module is Current Mutual Inductance
Device.
5. Phase-switching device according to claim 1, which is characterized in that the switch-on controlling module is at digital signal
Manage device.
6. Phase-switching device according to claim 1, which is characterized in that further include output detection module, the output
Detection module is electrically connected with the power output end of three handover modules and the switch-on controlling module respectively, the output
Detection module is used to detect the electric current and voltage of single-phase output.
7. a kind of Phase-switching system, which is characterized in that including the Phase-switching device described in multiple claims 6, further include
The switch-on controlling module of controller, the controller and each Phase-switching device communicates to connect, the shutting-brake control mould
Block is used to the electric current detected and voltage being sent to the controller, and the controller is used for according to each switch-on controlling module
The electric current and the voltage detected judges whether the load of three phases of three phase mains is balanced, and works as three phase mains
Three phases load imbalance when, the switch-on controlling module of one or more Phase-switching devices sends out control thereto
Signal processed, the switch-on controlling module to receive control signal switch output phase, so that three phases of three phase mains
Load balancing.
8. Phase-switching system according to claim 7, which is characterized in that the controller is PLC controller.
9. Phase-switching system according to claim 7, which is characterized in that the controller is server or personal electricity
Brain.
10. Phase-switching system according to claim 7, which is characterized in that the controller is controlled with each combined floodgate
Molding block communicates to connect through wireless communication.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810534850.8A CN108390402A (en) | 2018-05-29 | 2018-05-29 | Phase-switching apparatus and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810534850.8A CN108390402A (en) | 2018-05-29 | 2018-05-29 | Phase-switching apparatus and system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN108390402A true CN108390402A (en) | 2018-08-10 |
Family
ID=63072030
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810534850.8A Pending CN108390402A (en) | 2018-05-29 | 2018-05-29 | Phase-switching apparatus and system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN108390402A (en) |
-
2018
- 2018-05-29 CN CN201810534850.8A patent/CN108390402A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Nuutinen et al. | Short-circuit protection in a converter-fed low-voltage distribution network | |
| KR101837742B1 (en) | Grid-connected inverter system with seamless transfer function | |
| US9876390B2 (en) | Techniques for improving operation of static transfer switches during voltage disturbances | |
| CN106655470B (en) | A kind of uninterruptible power supply and its control method | |
| CN105720595A (en) | Three-phase load unbalance adjustment apparatus | |
| CN105305470A (en) | Low-voltage load balance adjustment device for power distribution network, and automatic phase-change switch | |
| CN105453363B (en) | For the method and apparatus of power back-off | |
| JP2000228826A (en) | Power supply device according to quality | |
| CN109687569B (en) | Data center power supply system | |
| CN205583705U (en) | Three -phase unbalanced load adjusting device's major loop | |
| CN107769367B (en) | Distribution network medium-voltage load seamless switching device based on solid-state switch | |
| CN207399040U (en) | A kind of three-phase stable-pressure device | |
| CN104319815A (en) | Grid connection/disconnection seamless switching method for micro-grid converter | |
| CN106772128B (en) | A kind of energy consumption type alternating current electronic load and its method of work | |
| CN208285016U (en) | Phase-switching apparatus and system | |
| CN108390402A (en) | Phase-switching apparatus and system | |
| CN208079434U (en) | Electromagnetic heater | |
| CN207098628U (en) | A kind of low pressure administers automatic control switch | |
| CN207502591U (en) | Current sensing means | |
| CN204732875U (en) | A kind of phase-lacking protective device | |
| CN205583706U (en) | Three -phase unbalanced load adjusting device | |
| CN104242326A (en) | Three-phase load balancer | |
| CN209419233U (en) | A kind of commutation device and system | |
| CN208112223U (en) | Power of alterating and direct current multi-function test stand distribution system | |
| CN206313524U (en) | Avoid the automatic change-over of neutral pole dangerous voltage |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |