Three-phase digital multifunctional measurement and control instrument

Abstract

The utility model discloses a three-phase digital multifunctional measurement and control instrument, which relates to the technical field of electric power system measurement and monitoring and comprises an instrument body, a liquid crystal display screen and keys, the liquid crystal display screen and the keys are arranged on the side surface of the instrument body, a clock, an alternating current sampling conditioning unit and a CPU (central processing unit) control unit are arranged in the instrument body, and the instrument body is connected with a power supply. The instrument body is internally provided with a metering unit, a clock unit, a data storage unit, an RS485 communication unit, a remote signaling detection unit and a metering pulse output unit which are in communication connection with the CPU control unit. Therefore, the measurement and control instrument can acquire and process a plurality of data points at the same time and provide comprehensive measurement and monitoring functions.

Description

Technical Field

[0001] The utility model relates to the technical field of power system measurement and monitoring, in particular to a three-phase digital multifunctional measurement and control instrument. Background Art

[0002] With the rapid development of the electronics industry, electronic products are being used more and more widely, and power equipment is also being used more and more. Traditional measurement and control instruments have a single power monitoring function and can only monitor the use of electricity. They lack monitoring of multiple data. However, for the requirements of contemporary power development, traditional measurement and control instruments often cannot meet the use needs. Utility Model Content

[0003] 1) Technical issues solved

[0004] The purpose of the utility model is to make up for the deficiencies of the prior art and provide a three-phase digital multifunctional measuring and controlling instrument.

[0005] 2) Technical solution

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a three-phase digital multifunctional measuring and controlling instrument, comprising an instrument body and a liquid crystal display screen and buttons arranged on the side of the instrument body, and the liquid crystal display screen and buttons are located on the same side, the instrument body is internally provided with a clock, an AC sampling conditioning unit and a CPU control unit, and is connected to a power supply, the instrument body is internally provided with a metering unit, a clock unit, a data storage unit, an RS485 communication unit, a remote signal detection unit and a metering pulse output unit, the metering unit is connected between the AC sampling conditioning unit and the CPU control unit, the AC sampling conditioning unit and the metering unit are communicatively connected, and the metering unit, the clock unit, the data storage unit, the RS485 communication unit, the remote signal detection unit and the metering pulse output unit are communicatively connected with the CPU control unit.

[0007] Furthermore, the instrument body is provided with switch input port DI1, switch input port DI2, switch input port DI3 and switch input port DI4, and is also provided with a first relay interface, a second relay interface and an RS485 interface, and the RS485 interface is electrically connected to the RS485 communication unit.

[0008] Furthermore, a DC self-excited power supply is provided inside the instrument body, and the DC self-excited power supply is electrically connected to the switch input port DI1, the switch input port DI2, the switch input port DI3 and the switch input port DI4, and the CPU control unit is communicatively connected to the DC self-excited power supply.

[0009] Furthermore, the AC sampling and conditioning unit includes a sampler, a preamplifier, a digital-to-analog converter and a digital signal processing unit, the sampler is electrically connected to the preamplifier, the preamplifier is communicatively connected to the digital-to-analog converter, the digital-to-analog converter is communicatively connected to the digital signal processing unit, and the digital signal processing unit is communicatively connected to the metering unit.

[0010] Furthermore, a power management unit is provided inside the instrument body, a power source connected to the instrument body is electrically connected to the power management unit, and the CPU control unit is communicatively connected to the power management unit.

[0011] Furthermore, a power failure detection unit is provided inside the instrument body, the power failure detection unit is electrically connected to the input end of the power supply, and the CPU control unit is communicatively connected to the power failure detection unit.

[0012] Furthermore, a liquid crystal display unit is disposed inside the instrument body, the liquid crystal display unit is electrically connected to the liquid crystal display screen, and the CPU control unit is communicatively connected to the liquid crystal display unit.

[0013] Furthermore, a key detection unit is provided inside the instrument body, the key detection unit is electrically connected to the key, and the CPU control unit is communicatively connected to the key detection unit.

[0014] Furthermore, a control output unit and a function expansion unit are provided inside the instrument body, the first relay interface and the second relay interface are electrically connected to the control output unit and the function expansion unit, and the CPU control unit is communicatively connected to the control output unit and the function expansion unit.

[0015] 3) Beneficial effects:

[0016] Compared with the prior art, the utility model has the following beneficial effects:

[0017] The utility model realizes the detection of multiple data through sampling and conversion, multi-channel input, communication interface and multi-function module, so that the measurement and control instrument can obtain and process multiple data points at the same time, and provide comprehensive measurement and monitoring functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a three-dimensional diagram of the utility model;

[0019] Figure 2 It is the front view of the utility model;

[0020] Figure 3 It is a side view of the utility model;

[0021] Figure 4 It is a top view of the utility model;

[0022] Figure 5 It is a three-dimensional diagram of the utility model;

[0023] Figure 6 This is a principle block diagram of the utility model;

[0024] Figure 7 It is the wiring diagram for detecting external contacts of the utility model;

[0025] In the figure: 1. Instrument body; 2. LCD display; 3. Button; 4. Power supply; 5. Clock; 6. DC self-excited power supply; 7. Switch input port DI1; 8. Switch input port DI2; 9. Switch input port DI3; 10. Switch input DI4; 11. First relay interface; 12. Second relay interface; 13. RS485 interface; 14. CPU control unit; 15. AC sampling and conditioning unit; 16. Metering unit; 17. Power management unit; 18. Power failure detection unit; 19. Watchdog; 20. LCD display unit; 21. Button detection unit; 22. Data storage unit; 23. Clock unit; 24. RS485 communication unit; 25. Remote signal detection unit; 26. Metering pulse output unit; 27. Control output unit; 28. Function expansion unit. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0028] Combination Figures 1 to 7The three-phase digital multifunctional measuring and controlling instrument shown in the figure comprises an instrument body 1 and a liquid crystal display screen 2 and a button 3 arranged on the side of the instrument body 1, and the liquid crystal display screen 2 and the button 3 are located on the same side. The liquid crystal display screen 2 can display the parameters measured by the measuring and controlling instrument, such as three-phase voltage, three-phase current, active power, reactive power, apparent power, frequency, power factor, etc., and the user can observe and monitor the relevant parameters of the circuit or power supply 4 in real time; the button 3 is divided into a SET button, a ▲ button, a ▼ button and a Press and hold the SET key for 4 seconds to enter the setting mode and switch the setting options. Press the ▲ key to display the previous screen content, and the cursor value +1. Press the ▼ key to display the next screen content, and the cursor value -1. Move the cursor back and save the program.

[0029] Specifically, such as Figure 6 As shown, the instrument body 1 is internally provided with a clock 5, an AC sampling conditioning unit 15 and a CPU control unit 14, and the instrument body 1 is connected to a power supply 4 to provide electric energy for the measuring and controlling instrument. The instrument body 1 is internally provided with a metering unit 16, a clock unit 23, a data storage unit 22, an RS485 communication unit 24, a remote signal detection unit 25 and a metering pulse output unit 26. The metering unit 16 is connected between the AC sampling conditioning unit 15 and the CPU control unit 14, thereby realizing the functional separation and coordination of electric energy metering and data processing. The AC sampling conditioning unit 15 is responsible for collecting and conditioning voltage and current signals, the metering unit 16 is responsible for electric energy metering, and the CPU control unit 14 is responsible for data processing and management. The AC sampling conditioning unit 15 and the metering unit 16 are communicatively connected, and the metering unit 16, the clock unit 23, the data storage unit 22, the RS485 communication unit 24, the remote signal detection unit 25 and the metering pulse output unit 26 are communicatively connected with the CPU control unit 14.

[0030] In the above structure, the clock 5 connected inside the instrument body 1 provides time information and time functions for the measurement and control instrument. The clock 5 is electrically connected to the clock unit 23, and the clock unit 23 is communicatively connected to the CPU control unit 14, which is used for time marking, data recording and timing control of the measurement data. The function of the clock 5 makes the measurement and control instrument more flexible and intelligent, and can meet the time-related requirements in different application scenarios.

[0031] like Figure 6As shown, the communication connection between the data storage unit 22 and the CPU control unit 14 is used to transmit the measurement data collected by the measurement and control instrument. The collected data is transmitted to the CPU control unit 14 through the data storage unit 22 for subsequent data processing, analysis, storage and management; the CPU control unit 14 can read and process the data stored in the data storage unit 22, including data parsing, calculation, conversion and other operations, and the CPU control unit 14 can send instructions to the data storage unit 22 to control the storage location, storage method, storage format, etc. of the data.

[0032] like Figure 6 As shown, the telesignaling detection unit 25 is communicatively connected with the CPU control unit 14. The telesignaling detection unit 25 can detect telesignaling signals in the measuring and controlling instrument, such as switch status, alarm signals, etc., and transmit these signals to the CPU control unit 14. Through the communication connection, the telesignaling detection unit 25 can transmit the detected telesignaling signals to the CPU control unit 14 for subsequent analysis, processing and control; after the telesignaling detection unit 25 transmits the telesignaling signals to the CPU control unit 14, the CPU control unit 14 can analyze and judge these signals to realize monitoring and evaluation of the power system status.

[0033] like Figure 6 As shown, the metering pulse output unit 26 is communicatively connected with the CPU control unit 14. The metering pulse output unit 26 can convert metering data into pulse signals, and transmit the pulse signals to the CPU control unit 14 through the communication connection with the CPU control unit 14, so that the CPU control unit 14 can receive the pulse representation of the metering data for subsequent data processing, analysis and storage; the CPU control unit 14 can collect and record metering data according to the frequency, pulse width and other parameters of the pulse signal, so that real-time monitoring and recording can be achieved. The CPU control unit 14 can process the pulse signal of the metering data through the communication connection with the metering pulse output unit 26, including operations such as counting, frequency measurement and period measurement of the pulse signal. Through the processing of the pulse signal, the CPU control unit 14 can achieve high-precision electric energy metering; the CPU control unit 14 can also calculate parameters such as electric energy consumption and power factor based on the counting and time information of the pulse signal, and generate corresponding data reports to be displayed on the LCD screen 2, so that users can perform energy consumption analysis and evaluation.

[0034] like Figure 5 and Figure 6As shown, the side of the instrument body 1 relative to the liquid crystal display screen 2 is provided with a switch input port DI1 7, a switch input port DI2 8, a switch input port DI3 9 and a switch input port DI4 10, each interface can be used to detect the state of an external passive contact, and the same side is also provided with a first relay interface 11, a second relay interface 12 and an RS485 interface 13, and the RS485 interface 13 is electrically connected to the RS485 communication unit 24 for RS485 communication.

[0035] like Figure 5 and Figure 6 As shown, a DC self-excited power supply 6 is provided inside the instrument body 1, and the DC self-excited power supply 6 is electrically connected to the switch input port DI1 7, the switch input port DI2 8, the switch input port DI3 9 and the switch input port DI4 10. The CPU control unit 14 is communicatively connected to the DC self-excited power supply 6. Through the communication connection with the CPU control unit 14, the contact state of the DC self-excited power supply 6 and the switch input port is monitored in real time and the corresponding state change is recorded for fault diagnosis, state monitoring and event recording.

[0036] like Figure 6 As shown, the AC sampling and conditioning unit 15 includes a sampler, a preamplifier, a digital-to-analog converter and a digital signal processing unit. The sampler is electrically connected to the preamplifier, the preamplifier is communicatively connected to the digital-to-analog converter, the digital-to-analog converter is communicatively connected to the digital signal processing unit, and the digital signal processing unit is communicatively connected to the metering unit 16. The sampler is used to periodically sample the amplitude of the AC signal and convert it into a signal. The preamplifier is used to amplify the signal output by the sampler to improve the amplitude and reliability of the signal. The signal can also be filtered and gain-adjusted to adapt to different measurement ranges and requirements. The analog-to-digital converter converts the analog signal into a digital signal to facilitate digital signal processing and storage. The digital signal processing unit performs operations such as filtering, correction, linearization and data processing on the sampled digital signal. Through the AC sampling and conditioning circuit, the electrical measuring instrument can achieve accurate sampling and processing of the AC signal, thereby improving the accuracy and reliability of the measurement, and is suitable for a variety of electrical measurement scenarios, such as current, voltage, power, frequency and other measurements.

[0037] like Figure 6 As shown, a power management unit 17 is provided inside the instrument body 1, the power supply 4 connected to the instrument body 1 is electrically connected to the power management unit 17, the CPU control unit 14 is communicatively connected to the power management unit 17, and the power management unit 17 is responsible for managing and providing the power supply 4 required by the instrument, and ensuring the normal operation of the instrument, measurement accuracy and user safety, and filtering out high-frequency noise and interference in the power supply 4, providing a stable power supply 4 environment, thereby improving the accuracy and reliability of the measurement.

[0038] like Figure 6 As shown, a power failure detection unit 18 is provided inside the meter body 1, and the power failure detection unit 18 is electrically connected to the input end of the power supply 4, and the CPU control unit 14 is in communication connection with the power failure detection unit 18. The power failure detection unit 18 is used to detect and process the power failure of the power supply 4, and can detect the power failure of the power supply 4 in time, and trigger the backup power supply switching, data preservation and recovery and other functions to ensure the continuous operation of the meter and the integrity of the data. In addition, the power failure detection unit 18 can also trigger the alarm and protection mechanism to remind the user or take necessary measures.

[0039] like Figure 1 and Figure 6 As shown, a liquid crystal display unit 20 is provided inside the instrument body 1, and the liquid crystal display unit 20 is electrically connected to the liquid crystal display screen 2. The CPU control unit 14 is in communication connection with the liquid crystal display unit 20. The liquid crystal display unit 20 receives data and processes it for interacting with the user. Through the connection with the liquid crystal display screen 2, the measurement and control instrument can display menus, options, setting parameters and other interfaces on the liquid crystal display screen 2, which is convenient for users to operate and configure.

[0040] like Figure 1 and Figure 6 As shown, a button detection unit 21 is provided inside the instrument body 1, and the button detection unit 21 is electrically connected to the button 3. The CPU control unit 14 is in communication connection with the button detection unit 21. The button 3 is used to select different functions or modes. Through the connection with the button detection unit 21, the measurement and control instrument can switch the measurement mode, adjust parameters, select functions, etc. according to the user's selection, and the user can conveniently operate and configure according to actual needs.

[0041] like Figure 5 and Figure 6 As shown, a control output unit 27 and a function expansion unit 28 are provided inside the instrument body 1, the first relay interface 11 and the second relay interface 12 are electrically connected to the control output unit 27 and the function expansion unit 28, the CPU control unit 14 is communicatively connected to the control output unit 27 and the function expansion unit 28, the control output unit 27 can generate a corresponding control signal according to the measurement result or the user's setting to realize the control of the relay; the function expansion unit 28 is used to expand the function of the measurement and control instrument, and can provide additional measurement channels, data storage capabilities, communication interfaces and other functions to meet the needs of specific applications.

[0042] like Figure 6As shown, a watchdog 19 is provided inside the instrument body 1, and the CPU control unit 14 is in communication connection with the watchdog 19. The watchdog 19 periodically detects the operating status of the measurement and control instrument, and it will send a timing pulse or signal to confirm the normal operation of the system. If the system responds normally and responds to the signal of the watchdog 19 in time, the watchdog 19 will continue to maintain the normal operation of the system. If the signal of the watchdog 19 fails to be responded within a certain period of time, the watchdog 19 will determine that the system fails or stops responding abnormally, and take appropriate measures to minimize system failures and downtime, and improve the reliability and stability of the instrument system.

[0043] Embodiment 1,

[0044] The clock 5 connected inside the meter body 1 provides time information, the clock 5 is electrically connected to the clock unit 23, the clock unit 23 is communicatively connected to the CPU control unit 14, and the measurement data is time-stamped, data recorded and timing controlled. This measurement and control instrument can realize the function of freezing electricity: saving the total positive and reverse active electric energy of the last 96 points; storing the electric energy at zero o'clock every day, and can store the total positive and reverse active and reactive electric energy and electric energy of each rate for the last 7 days; storing the electric energy of the settlement day, and can store the total positive and reverse active and reactive electric energy and electric energy of each rate for the last 12 settlement days.

[0045] Embodiment 2:

[0046] Through the AC sampling and conditioning circuit and the metering unit 16, the measurement and control instrument can realize the harmonic analysis function: it can record the 2-21 harmonic content of voltage and current, the waveform distortion rate of voltage and current, and can record data such as harmonic electric energy, fundamental electric energy, and related electric energy. It can evaluate whether the power user's electrical equipment has generated excessive harmonic pollution, accurately measure the harmonic electricity, and determine the location of the harmonic source and the cause of the harmonic generation through the voltage and current harmonic content and distortion rate measured by the electric energy meter.

[0047] Embodiment 3,

[0048] Through the communication connection between the data storage unit 22 and the CPU control unit 14, the measurement and control instrument can realize the maximum demand recording function: the instrument can record the maximum positive and reverse active power demand (kW), the maximum demand in different time periods and the occurrence time for 12 months, and store its data. When the data is transferred on the designated meter reading day, the maximum demand value of the month is automatically reset to zero; for non-designated meter reading days, the data is not transferred when the meter is read, and the data is not reset to zero.

[0049] Embodiment 4:

[0050] Through the communication connection between the data storage unit 22, the power-off detection unit 18 and the CPU control unit 14, the measuring and controlling instrument can realize the function of recording pressure loss and current loss: it can record the total, A, B, and C phase pressure loss cumulative times, time (unit: minute), the start time (year, month, day, hour, and minute) of the most recent 1 to 10 pressure losses, the number of times, and the active power (kWh) during the pressure loss period; it can record the total, A, B, and C phase current loss cumulative times, time (unit: minute), the start time (year, month, day, hour, and minute) of the most recent 1 to 10 current losses, the number of times, and the active power (kWh) during the current loss period.

[0051] Embodiment 5,

[0052] Through the communication connection between the data storage unit 22 and the CPU control unit 14, the measurement and control instrument can realize the event recording function: it has more event records, such as recording the total number of programming times, recording the total number of demand reset times, recording the total number of time calibration times, recording the total number of phase failures, recording the latest 10 current imbalance occurrences, end times and corresponding electric energy data, etc., which can provide users with a good analysis or tracing of various events that occurred during the power supply and use process of the power grid.

[0053] Embodiment 6,

[0054] The DC self-excited power supply 6 is electrically connected to the switch input port DI1 7, the switch input port DI2 8, the switch input port DI3 9 and the switch input port DI4 10, and the CPU control unit 14 is communicatively connected to the DC self-excited power supply 6. The measurement and control instrument can realize the switch monitoring function: the switch input DI17~DI4, each channel can detect the state of the external passive contact, and the real-time state of the switch input can be observed through the LCD display 2.

[0055] Embodiment 7,

[0056] The first relay interface 11 and the second relay interface 12 are electrically connected to the control output unit 27 and the function expansion unit 28, and the CPU control unit 14 is communicatively connected to the control output unit 27 and the function expansion unit 28. The measurement and control instrument can realize the relay function and support the remote control function.

[0057] Embodiment 7,

[0058] By means of the RS485 interface 13 being electrically connected to the RS485 communication unit 24 , the CPU control unit 14 is communicatively connected to the RS485 communication unit 24 , and the measurement and control instrument can realize the communication function.

[0059] Embodiment 8,

[0060] Through the communication connection between the CPU control unit 14, the control output unit 27 and the function expansion unit 28, the measurement and control instrument can realize the communication function: various expansion functions such as analog input (output), switch input (output), CAN bus interface, Ethernet communication interface, etc. can be configured according to user needs.

[0061] Embodiment 9,

[0062] Through the communication connection between the CPU control unit 14 and the metering pulse output unit 26, the CPU control unit 14 processes the pulse signal of the metering data according to the frequency, pulse width and other parameters of the pulse signal of the metering pulse output unit 26. The present measuring and control instrument can achieve high-precision measurement: the voltage accuracy measurement range is 0 to 1.2 times the rated phase voltage; the current accuracy measurement range is the rated current 5A: 0 to 6A.

[0063] During specific use, the DC working power supply is rated at 220V and 110V, with an allowable voltage deviation of -40% to +40%, the AC working power supply is rated at 220V, with an allowable voltage deviation of -40% to +60%, the rated phase voltage input is rated 57.7V, rated 220V or rated 400V, the current loop is rated 5A or 1A, the frequency is 50Hz, 12V DC excitation self-excitation is adopted, the reference temperature is 23℃, the reference humidity is 40% to 60%, the normal operating temperature is -25℃ to +70℃, the extreme operating temperature is -40℃ to +75℃, the relative humidity is 5% to 95% (no condensation), and the maximum absolute humidity is 29g / m3.

[0064] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The patent protection scope of the present invention shall be based on the claims. All equivalent structural changes made using the description and drawings of the present invention shall be included in the protection scope of the present invention.

Claims

1. A three-phase digital multifunctional measuring and controlling instrument, comprising an instrument body (1) and a liquid crystal display screen (2) and a key (3) arranged on the side of the instrument body (1), wherein the liquid crystal display screen (2) and the key (3) are located on the same side, and the instrument body (1) is internally provided with a clock (5), an AC sampling conditioning unit (15) and a CPU control unit (14), and is connected to a power supply (4), characterized in that: The meter body (1) is provided with a metering unit (16), a clock unit (23), a data storage unit (22), an RS485 communication unit (24), a remote signal detection unit (25) and a metering pulse output unit (26); the metering unit (16) is connected between the AC sampling and conditioning unit (15) and the CPU control unit (14); the AC sampling and conditioning unit (15) and the metering unit (16) are in communication connection; the metering unit (16), the clock unit (23), the data storage unit (22), the RS485 communication unit (24), the remote signal detection unit (25) and the metering pulse output unit (26) are in communication connection with the CPU control unit (14).

2. A three-phase digital multifunctional measuring and controlling instrument according to claim 1, characterized in that: The instrument body (1) is provided with a switch input port DI1 (7), a switch input port DI2 (8), a switch input port DI3 (9) and a switch input port DI4 (10), and is also provided with a first relay interface (11), a second relay interface (12) and an RS485 interface (13), and the RS485 interface (13) is electrically connected to the RS485 communication unit (24).

3. A three-phase digital multifunctional measuring and controlling instrument according to claim 2, characterized in that: A DC self-excited power supply (6) is provided inside the instrument body (1); the DC self-excited power supply (6) is electrically connected to the switch input port DI1 (7), the switch input port DI2 (8), the switch input port DI3 (9) and the switch input port DI4 (10); and the CPU control unit (14) is communicatively connected to the DC self-excited power supply (6).

4. A three-phase digital multifunctional measuring and controlling instrument according to claim 3, characterized in that: The AC sampling and conditioning unit (15) comprises a sampler, a preamplifier, a digital-to-analog converter and a digital signal processing unit, wherein the sampler is electrically connected to the preamplifier, the preamplifier is communicatively connected to the digital-to-analog converter, the digital-to-analog converter is communicatively connected to the digital signal processing unit, and the digital signal processing unit is communicatively connected to the metering unit (16).

5. A three-phase digital multifunctional measuring and controlling instrument according to claim 4, characterized in that: A power management unit (17) is provided inside the instrument body (1); a power source (4) connected to the instrument body (1) is electrically connected to the power management unit (17); and the CPU control unit (14) is communicatively connected to the power management unit (17).

6. A three-phase digital multifunctional measuring and controlling instrument according to claim 5, characterized in that: A power failure detection unit (18) is provided inside the meter body (1), the power failure detection unit (18) is electrically connected to the input end of the power supply (4), and the CPU control unit (14) is communicatively connected to the power failure detection unit (18).

7. A three-phase digital multifunctional measuring and controlling instrument according to claim 6, characterized in that: A liquid crystal display unit (20) is arranged inside the instrument body (1); the liquid crystal display unit (20) is electrically connected to the liquid crystal display screen (2); and the CPU control unit (14) is communicatively connected to the liquid crystal display unit (20).

8. A three-phase digital multifunctional measuring and controlling instrument according to claim 7, characterized in that: A key detection unit (21) is provided inside the instrument body (1); the key detection unit (21) is electrically connected to the key (3); and the CPU control unit (14) is communicatively connected to the key detection unit (21).

9. A three-phase digital multifunctional measuring and controlling instrument according to claim 2, characterized in that: The instrument body (1) is provided with a control output unit (27) and a function expansion unit (28); the first relay interface (11) and the second relay interface (12) are electrically connected to the control output unit (27) and the function expansion unit (28); and the CPU control unit (14) is communicatively connected to the control output unit (27) and the function expansion unit (28).

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