CN114336950A - Method for identifying phase sequence of three-phase static switch - Google Patents
Method for identifying phase sequence of three-phase static switch Download PDFInfo
- Publication number
- CN114336950A CN114336950A CN202210011208.8A CN202210011208A CN114336950A CN 114336950 A CN114336950 A CN 114336950A CN 202210011208 A CN202210011208 A CN 202210011208A CN 114336950 A CN114336950 A CN 114336950A
- Authority
- CN
- China
- Prior art keywords
- voltage
- path voltage
- path
- phase
- 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.)
- Pending
Links
- 238000000819 phase cycle Methods 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 42
- 230000003068 static effect Effects 0.000 title claims abstract description 25
- 238000005070 sampling Methods 0.000 claims abstract description 20
- 230000001360 synchronised effect Effects 0.000 claims abstract description 10
- 230000000630 rising effect Effects 0.000 claims description 24
- 230000002441 reversible effect Effects 0.000 claims description 9
- 230000002238 attenuated effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
Images
Landscapes
- Inverter Devices (AREA)
Abstract
The invention discloses a method for identifying a phase sequence of a three-phase static switch, which relates to the technical field of switch control.A sampling circuit is arranged, alternating voltage is converted into a voltage signal through the sampling circuit, and the input of U-path voltage, V-path voltage and W-path voltage is in a synchronous state with the input of A-path voltage, B-path voltage and C-path voltage, and the U-path voltage, V-path voltage and W-path voltage are consistent with the phase sequences of the A-path voltage, B-path voltage and C-path voltage, so that when the amplitudes of the alternating voltage are consistent, the phase sequence, the frequency, the phase and the amplitude of an alternating current power supply can be consistent, further, the static switch cannot generate a circulating current in the switching process, and the switching process can be quicker and safer.
Description
Technical Field
The invention relates to the technical field of switch control, in particular to a method for identifying a phase sequence of a three-phase static switch.
Background
The static switch is generally applied to an uninterruptible power supply system to realize the quick switching between a mains supply and an inverter power supply; according to the phase relation between the commercial power and the inverter, the two modes of synchronous switching and asynchronous switching are adopted, in a three-phase power supply system, when the output voltages of the commercial power and the inverter are in the conditions of 'same phase sequence, same frequency, same phase and same amplitude', the circulating current cannot be generated during switching, and the safe and quick switching can be met; when any index of 'phase sequence, frequency, phase and amplitude' of the output voltage of the commercial power and the inverter is different, circulation current is generated during switching, and static switch faults are easy to occur during the switching process; in asynchronous switching, the circuit current must be attenuated to a safe value before switching; therefore, the time in the asynchronous handover process is long; therefore, in order to increase the switching speed of the static switch and ensure safety and reliability, the control unit of the static switch must detect the indexes of the commercial power and the inverter power supply, such as phase sequence, frequency, phase, amplitude and the like, and the static switch can be switched quickly and safely only when the indexes of the commercial power and the inverter power supply are consistent, so that a method for identifying the phase sequence by the three-phase static switch is provided.
Disclosure of Invention
The invention aims to provide a method for identifying a phase sequence of a three-phase static switch.
The purpose of the invention can be realized by the following technical scheme: a method for identifying a phase sequence of a three-phase static switch comprises the following steps:
the method comprises the following steps: setting a sampling circuit, and converting the alternating voltage into a voltage signal through the sampling circuit;
step two: performing signal processing and analysis on the voltage signal, and judging the state of the alternating voltage;
step three: and identifying the phase sequence of the alternating voltage according to the state of the alternating voltage.
Further, the sampling circuit is electrically connected with a control circuit, the control circuit comprises 6 paths of alternating-current voltages, and the 6 paths of voltages are respectively marked as A, B, C and U, V, W; when the alternating voltage passes through the sampling point of the A-path voltage, the alternating voltage is changed into a voltage square wave signal, when the alternating voltage passes through the sampling point of the B-path voltage, the alternating voltage is changed into a direct voltage waveform signal, and the obtained voltage signal is sent into a control chip of the control circuit.
Further, the amplitude of the voltage square wave signal is 3V, wherein the voltage square wave signal rises from 0V to 3V, which is called a rising edge; the voltage square wave signal drops from 3V to 0V, called the falling edge.
Further, the control chip includes a signal processing module and a signal analysis module, the signal processing module is configured to process the voltage signal obtained by the sampling circuit, and the specific processing procedure includes:
setting that when the rising edge of a square wave signal of the U-path voltage reaches a chip pin of a control chip, a counter is started, and when the rising edge of a square wave signal of the V-path voltage reaches the chip pin of the control chip, the value of the counter is recorded, wherein the value is the length of a first line segment; when the rising edge of the square wave signal of the W-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of the second line segment; when the rising edge of the square wave signal of the A-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of a third line segment; when the rising edge of the square wave signal of the B-path voltage reaches the chip pin of the control chip, recording the value of the counter, wherein the value is the length of the fourth line segment; when the rising edge of the square wave signal of the C-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of a fifth line segment; when the rising edge of the square wave signal of the U-path voltage reaches the chip pin of the control chip, the value of the counter is recorded, and the counter restarts counting.
Further, the length of the first line segment is a phase difference value between the U-path voltage and the V-path voltage;
the length of the second line segment is a phase difference value between the U-path voltage and the W-path voltage, the phase difference value between the U-path voltage and the V-path voltage is smaller than the phase difference value between the U-path voltage and the W-path voltage, and the U-path voltage, the V-path voltage and the W-path voltage are arranged in sequence; the phase difference value between the U-path voltage and the V-path voltage is larger than that between the U-path voltage and the W-path voltage, and the phase sequence arrangement of the U-path voltage, the V-path voltage and the W-path voltage is a reverse sequence.
Further, the signal analysis module is configured to analyze the voltage signal processed by the signal processing module, and the specific analysis process includes: the input of the U-path voltage, the V-path voltage and the W-path voltage is in a synchronous state with the input of the A-path voltage, the B-path voltage and the C-path voltage;
the U path voltage, the V path voltage and the W path voltage are consistent with the A path voltage, the B path voltage and the C path voltage in phase sequence, namely, the U path voltage, the V path voltage and the W path voltage are in a sequential or reverse state;
when the amplitudes of the alternating-current voltages are consistent, the phase sequence, the frequency, the phase position and the amplitude of the alternating-current power supplies of the U-path voltage, the V-path voltage and the W-path voltage are consistent with those of the A-path voltage, the B-path voltage and the C-path voltage.
Further, when the length of the third line segment is 0, the alternating current of the voltage of the U path and the alternating current of the voltage of the A path are in a synchronous state, and when the length of the third line segment is not 0, the alternating current of the voltage of the U path and the alternating current of the voltage of the A path are in an asynchronous state.
Further, the value obtained by subtracting the length of the third line segment from the length of the fourth line segment is the phase difference value between the voltage of the path A and the voltage of the path B; the value obtained by subtracting the length of the third line segment from the length of the fifth line segment is the phase difference value between the voltage of the A path and the voltage of the C path;
the phase difference value between the A-path voltage and the B-path voltage is smaller than that between the A-path voltage and the C-path voltage, and the A-path voltage, the B-path voltage and the C-path voltage are arranged in sequence; the phase difference value between the A path voltage and the B path voltage is larger than that between the A path voltage and the C path voltage, and the phase sequence arrangement of the A path voltage, the B path voltage and the C path voltage is a reverse sequence.
Compared with the prior art, the invention has the beneficial effects that: the input of the U-path voltage, the V-path voltage, the W-path voltage and the input of the A-path voltage, the B-path voltage and the C-path voltage are regulated to be in a synchronous state, and the phase sequence of the U-path voltage, the V-path voltage, the W-path voltage and the A-path voltage, the B-path voltage and the C-path voltage is consistent, so that when the amplitudes of the alternating-current voltages are consistent, the phase sequence, the frequency, the phase and the amplitude of the alternating-current power supply can be consistent, further, the static switch cannot generate a circulating current in the switching process, and meanwhile, the switching process can be quicker and safer.
Drawings
FIG. 1 is a flow chart of the present invention.
Detailed Description
As shown in fig. 1, a method for identifying a phase sequence of a three-phase static switch includes the following steps:
the method comprises the following steps: setting a sampling circuit, and converting the alternating voltage into a voltage signal through the sampling circuit;
step two: performing signal processing and analysis on the voltage signal, and judging the state of the alternating voltage;
step three: and identifying the phase sequence of the alternating voltage according to the state of the alternating voltage.
It should be further noted that, in a specific implementation process, the alternating voltage is AC220V voltage, the sampling circuit is electrically connected with a control circuit, the control circuit includes 6 paths of alternating voltages, and the 6 paths of alternating voltages are respectively labeled as A, B, C and U, V, W; when the alternating voltage passes through the sampling point of the A-path voltage, the alternating voltage is changed into a voltage square wave signal, when the alternating voltage passes through the sampling point of the B-path voltage, the alternating voltage is changed into a direct voltage waveform signal, and the obtained voltage signal is sent into a control chip of a control circuit; it should be further noted that, in a specific implementation process, the amplitude of the voltage square wave signal is 3V, where the voltage square wave signal rises from 0V to 3V, which is called a rising edge; the voltage square wave signal is reduced from 3V to 0V, called as a falling edge, and the voltage square wave signal is counted by a counter;
the control chip comprises a signal processing module and a signal analysis module, the signal processing module is used for processing the voltage signal obtained by the sampling circuit, and the specific processing process comprises the following steps:
setting that when the rising edge of a square wave signal of the U-path voltage reaches a chip pin of a control chip, a counter is started, and when the rising edge of a square wave signal of the V-path voltage reaches the chip pin of the control chip, the value of the counter is recorded, wherein the value is the length of a first line segment; when the rising edge of the square wave signal of the W-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of the second line segment; when the rising edge of the square wave signal of the A-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of a third line segment; when the rising edge of the square wave signal of the B-path voltage reaches the chip pin of the control chip, recording the value of the counter, wherein the value is the length of the fourth line segment; when the rising edge of the square wave signal of the C-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of a fifth line segment; when the rising edge of the square wave signal of the U-path voltage reaches the chip pin of the control chip, the value of the counter is recorded, and the counter restarts counting.
It should be further noted that, in a specific implementation process, the length of the first line segment is a phase difference value between the U-path voltage and the V-path voltage;
the length of the second line segment is a phase difference value between the U-path voltage and the W-path voltage, the phase difference value between the U-path voltage and the V-path voltage is smaller than the phase difference value between the U-path voltage and the W-path voltage, and the U-path voltage, the V-path voltage and the W-path voltage are arranged in sequence; the phase difference value between the U-path voltage and the V-path voltage is larger than that between the U-path voltage and the W-path voltage, and the phase sequence arrangement of the U-path voltage, the V-path voltage and the W-path voltage is a reverse sequence.
The signal analysis module is used for analyzing the voltage signal processed by the signal processing module, and the specific analysis process comprises the following steps:
when the length of the third line segment is 0, the voltage alternating current of the U path and the voltage alternating current of the A path are in a synchronous state, and when the length of the third line segment is not 0, the voltage alternating current of the U path and the voltage alternating current of the A path are in an asynchronous state;
it should be further noted that, in the specific implementation process, the value obtained by subtracting the length of the third line segment from the length of the fourth line segment is the phase difference value between the voltage of the a path and the voltage of the B path; the value obtained by subtracting the length of the third line segment from the length of the fifth line segment is the phase difference value between the A-path voltage and the C-path voltage.
The phase difference value between the A path voltage and the B path voltage is smaller than that between the A path voltage and the C path voltage, and the A path voltage, the B path voltage and the C path voltage are arranged in sequence; the phase difference value between the A path voltage and the B path voltage is larger than that between the A path voltage and the C path voltage, and the phase sequence arrangement of the A path voltage, the B path voltage and the C path voltage is a reverse sequence.
Obtaining the alternating current states of different circuit voltages by obtaining the counter values of the voltage signals of different circuit voltages, and obtaining the phase sequence arrangement conditions of the circuit A voltage, the circuit B voltage and the circuit C voltage according to the phase difference values of the voltage signals of different circuit voltages;
it should be further noted that, in the specific implementation process, the ac power supply of the V-path voltage, the W-path voltage, the a-path voltage, the B-path voltage, and the C-path voltage satisfies the following conditions:
the input of the U-path voltage, the V-path voltage and the W-path voltage is in a synchronous state with the input of the A-path voltage, the B-path voltage and the C-path voltage;
the U path voltage, the V path voltage and the W path voltage are consistent with the A path voltage, the B path voltage and the C path voltage in phase sequence, namely, the U path voltage, the V path voltage and the W path voltage are in a sequential or reverse state;
when the amplitudes of the alternating-current voltages are consistent, the phase sequence, the frequency, the phase position and the amplitude of the alternating-current power supplies of the U-path voltage, the V-path voltage and the W-path voltage are consistent with those of the A-path voltage, the B-path voltage and the C-path voltage.
It should be further explained that, in the specific implementation process, in the three-phase power supply system, when the commercial power and the output voltage of the inverter are in the conditions of "same phase sequence, same frequency, same phase and same amplitude", no circulating current is generated during switching, and the safe and quick switching can be satisfied; when any index of 'phase sequence, frequency, phase and amplitude' of the output voltage of the commercial power and the inverter is different, circulation current is generated during switching, and static switch faults are easy to occur during the switching process; when asynchronous switching is carried out, circuit current can be switched when the circuit current is attenuated to a safe value, the time of the asynchronous switching process is longer, and the U-path voltage, the V-path voltage, the W-path voltage and the A-path voltage, the B-path voltage and the C-path voltage are in a synchronous state by adjusting the input of the U-path voltage, the V-path voltage and the W-path voltage to be consistent with the phase sequence of the A-path voltage, the B-path voltage and the C-path voltage, so that when the amplitude values of the alternating-current voltages are consistent, the phase sequence, the frequency, the phase and the amplitude value of the alternating-current power supply can be consistent, further, the static switch cannot generate circulation in the switching process, and meanwhile, the switching process can be quicker and safer.
Although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the spirit and scope of the present invention.
Claims (8)
1. A method for identifying a phase sequence of a three-phase static switch is characterized by comprising the following steps:
the method comprises the following steps: setting a sampling circuit, and converting the alternating voltage into a voltage signal through the sampling circuit;
step two: performing signal processing and analysis on the voltage signal, and judging the state of the alternating voltage;
step three: and identifying the phase sequence of the alternating voltage according to the state of the alternating voltage.
2. The method for identifying the phase sequence of the three-phase static switch as claimed in claim 1, wherein the sampling circuit is electrically connected with a control circuit, the control circuit comprises 6 AC voltages, and the 6 AC voltages are respectively labeled as A, B, C and U, V, W; when the alternating voltage passes through the sampling point of the A-path voltage, the alternating voltage is changed into a voltage square wave signal, when the alternating voltage passes through the sampling point of the B-path voltage, the alternating voltage is changed into a direct voltage waveform signal, and the obtained voltage signal is sent into a control chip of the control circuit.
3. The method for identifying the phase sequence of the three-phase static switch as claimed in claim 2, wherein the amplitude of the voltage square wave signal is 3V, wherein the voltage square wave signal rises from 0V to 3V, which is called a rising edge; the voltage square wave signal drops from 3V to 0V, called the falling edge.
4. The method for identifying the phase sequence of the three-phase static switch according to claim 3, wherein the control chip comprises a signal processing module and a signal analysis module, the signal processing module is used for processing the voltage signal obtained by the sampling circuit, and the specific processing procedure includes:
setting that when the rising edge of a square wave signal of the U-path voltage reaches a chip pin of a control chip, a counter is started, and when the rising edge of a square wave signal of the V-path voltage reaches the chip pin of the control chip, the value of the counter is recorded, wherein the value is the length of a first line segment; when the rising edge of the square wave signal of the W-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of the second line segment; when the rising edge of the square wave signal of the A-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of a third line segment; when the rising edge of the square wave signal of the B-path voltage reaches the chip pin of the control chip, recording the value of the counter, wherein the value is the length of the fourth line segment; when the rising edge of the square wave signal of the C-path voltage reaches a chip pin of the control chip, recording the value of the counter, wherein the value is the length of a fifth line segment; when the rising edge of the square wave signal of the U-path voltage reaches the chip pin of the control chip, the value of the counter is recorded, and the counter restarts counting.
5. The method for identifying the phase sequence of the three-phase static switch as claimed in claim 4, wherein the first line segment length is a phase difference value between a U-path voltage and a V-path voltage;
the length of the second line segment is a phase difference value between the U-path voltage and the W-path voltage, the phase difference value between the U-path voltage and the V-path voltage is smaller than the phase difference value between the U-path voltage and the W-path voltage, and the U-path voltage, the V-path voltage and the W-path voltage are arranged in sequence; the phase difference value between the U-path voltage and the V-path voltage is larger than that between the U-path voltage and the W-path voltage, and the phase sequence arrangement of the U-path voltage, the V-path voltage and the W-path voltage is a reverse sequence.
6. The method for identifying the phase sequence of the three-phase static switch according to claim 5, wherein the signal analysis module is configured to analyze the voltage signal processed by the signal processing module, and the specific analysis process includes: the input of the U-path voltage, the V-path voltage and the W-path voltage is in a synchronous state with the input of the A-path voltage, the B-path voltage and the C-path voltage;
the U path voltage, the V path voltage and the W path voltage are consistent with the A path voltage, the B path voltage and the C path voltage in phase sequence, namely, the U path voltage, the V path voltage and the W path voltage are in a sequential or reverse state;
when the amplitudes of the alternating-current voltages are consistent, the phase sequence, the frequency, the phase position and the amplitude of the alternating-current power supplies of the U-path voltage, the V-path voltage and the W-path voltage are consistent with those of the A-path voltage, the B-path voltage and the C-path voltage.
7. The method for identifying the phase sequence of the three-phase static switch as claimed in claim 6, wherein when the length of the third line segment is 0, the U-path voltage and the a-path voltage alternating current are in a synchronous state, and when the length of the third line segment is not 0, the U-path voltage and the a-path voltage alternating current are in an asynchronous state.
8. The method for identifying the phase sequence of the three-phase static switch as claimed in claim 7, wherein the value obtained by subtracting the length of the third line segment from the length of the fourth line segment is the phase difference value between the voltage of the A path and the voltage of the B path; the value obtained by subtracting the length of the third line segment from the length of the fifth line segment is the phase difference value between the voltage of the A path and the voltage of the C path;
the phase difference value between the A-path voltage and the B-path voltage is smaller than that between the A-path voltage and the C-path voltage, and the A-path voltage, the B-path voltage and the C-path voltage are arranged in sequence; the phase difference value between the A path voltage and the B path voltage is larger than that between the A path voltage and the C path voltage, and the phase sequence arrangement of the A path voltage, the B path voltage and the C path voltage is a reverse sequence.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210011208.8A CN114336950A (en) | 2022-01-06 | 2022-01-06 | Method for identifying phase sequence of three-phase static switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210011208.8A CN114336950A (en) | 2022-01-06 | 2022-01-06 | Method for identifying phase sequence of three-phase static switch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114336950A true CN114336950A (en) | 2022-04-12 |
Family
ID=81023998
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210011208.8A Pending CN114336950A (en) | 2022-01-06 | 2022-01-06 | Method for identifying phase sequence of three-phase static switch |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114336950A (en) |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1114429A (en) * | 1964-09-30 | 1968-05-22 | Siemens Ag | Apparatus for producing monophase and polyphase alternating currents from direct current |
| GB1436851A (en) * | 1972-06-21 | 1976-05-26 | Gen Electric | Analog-to-digital-converter |
| US4159513A (en) * | 1977-09-30 | 1979-06-26 | Westinghouse Electric Corp. | Static controlled AC motor drive having plug reversal capability |
| JPH1189217A (en) * | 1997-09-03 | 1999-03-30 | Mitsubishi Electric Corp | Method and device for controlling synchronization and uninterruptible power unit |
| CN206117299U (en) * | 2016-09-30 | 2017-04-19 | 中国电子科技集团公司第二十七研究所 | Modularization high reliability UPS |
| CN209043980U (en) * | 2018-09-29 | 2019-06-28 | 江苏银佳电子设备有限公司 | A kind of digital synchronous and phase sequence identification circuit |
-
2022
- 2022-01-06 CN CN202210011208.8A patent/CN114336950A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1114429A (en) * | 1964-09-30 | 1968-05-22 | Siemens Ag | Apparatus for producing monophase and polyphase alternating currents from direct current |
| GB1436851A (en) * | 1972-06-21 | 1976-05-26 | Gen Electric | Analog-to-digital-converter |
| US4159513A (en) * | 1977-09-30 | 1979-06-26 | Westinghouse Electric Corp. | Static controlled AC motor drive having plug reversal capability |
| JPH1189217A (en) * | 1997-09-03 | 1999-03-30 | Mitsubishi Electric Corp | Method and device for controlling synchronization and uninterruptible power unit |
| CN206117299U (en) * | 2016-09-30 | 2017-04-19 | 中国电子科技集团公司第二十七研究所 | Modularization high reliability UPS |
| CN209043980U (en) * | 2018-09-29 | 2019-06-28 | 江苏银佳电子设备有限公司 | A kind of digital synchronous and phase sequence identification circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Caseiro et al. | Real-time IGBT open-circuit fault diagnosis in three-level neutral-point-clamped voltage-source rectifiers based on instant voltage error | |
| US9797955B2 (en) | Insulation inspection device for motors and insulation inspection method for motors | |
| JP2006054933A (en) | Inverter device | |
| CN103091587A (en) | Energy-saving inverter test circuit and control method | |
| Sui et al. | The post-fault current model of voltage source converter and its application in fault diagnosis | |
| CN112067912B (en) | Open-phase detection method, electronic equipment and storage medium | |
| CN105353261B (en) | Open phase fault detection method, device and a kind of automatic change-over | |
| EP2863536A1 (en) | Motion and control system | |
| US11644506B2 (en) | Power switch fault detection method and power switch fault detection circuit | |
| JP2020076710A (en) | Arc detection circuit, breaker, power conditioner, solar panel, solar panel accessory module, junction box, arc detection method, and program | |
| CN114336950A (en) | Method for identifying phase sequence of three-phase static switch | |
| CN204361909U (en) | Power inverter | |
| EP3393033A1 (en) | Matrix converter and method for determining constants of alternating-current motor | |
| Raj et al. | A novel open-transistor fault detection method in symmetric cascaded H-bridge multilevel inverter | |
| Ibem et al. | Multiple open switch fault diagnosis of three phase voltage source inverter using ensemble bagged tree machine learning technique | |
| CN110927548A (en) | System and method for detecting surge current bearing capacity of power semiconductor device | |
| CN203025291U (en) | Energy-saving inverter test circuit | |
| CN211785910U (en) | Power semiconductor device heavy current turn-off capability detection circuitry | |
| CN102540023B (en) | Device for detecting partial discharge signal of insulating structure | |
| EP4243288A1 (en) | A controller | |
| CN110323834A (en) | Line switching control system, method and apparatus | |
| CN112398107B (en) | Voltage sampling circuit in overvoltage suppression device of three-phase variable-frequency alternating-current power generation system | |
| CN217360245U (en) | Equipment for testing three-phase inverter and three-phase inverter | |
| CN220043218U (en) | Self-energy-taking and current sampling circuit and device for current transformer | |
| CN216144919U (en) | Microcomputer relay protection testing arrangement |
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 |