KR101887348B1 - Accurate power measuring method for power delivery system - Google Patents

Abstract

The present invention relates to a method of increasing the measurement accuracy in measurement of voltage, current, and power of a booth bar using a single-pole connection type power measuring apparatus and, more particularly to a circuit for increasing the accuracy of a power factor indicating the efficiency of an active power, a method thereof, and increasing the measurement accuracy of a single-pole connection type power state measuring apparatus including a magnetic shielding material for shielding a magnetic field generated from a current flowing in an adjacent booth bar. The single-pole connection type power measuring apparatus is an apparatus for measuring the power state of each phase of R phase, S phase, T phase and N phase of an AC power source supplied through a booth bar′s main line or branch line in an industrial distribution board and measuring the power of the booth bar using a single-pole connection type sensor capable of indicating the state of the supplied AC power source. Among sensors used to specify the current in a conventional single-pole connection type power measuring apparatus, a hall effect sensor is vulnerable to the influence of a magnetic field introduced from the outside, and the measurement accuracy is changed according to the number of adjacent circuits. Accordingly, an object of the present invention is to reduce the influence of current by adding a filter.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a communication method of a single pole connection type power measuring apparatus and a power measuring apparatus,

The present invention relates to a method for improving measurement accuracy in measurement of voltage, current, and power of a busbar using a single-pole connection type power measuring apparatus, and more particularly to a circuit and method for improving power factor accuracy, And a magnetic field shielding material for shielding a magnetic field generated from a current flowing in the adjacent booth. The present invention is characterized in that the measurement accuracy of a single pole connection type power state measuring apparatus is improved.

The power measuring device for measuring the voltage and the current is generally constituted as one body and must be manufactured variously according to the configuration order according to the current phase of the bus bar. The prior art single-pole connection type power measuring apparatus of the present invention measures a power state by each individual phase of an AC power supplied through a bus bar and uses a single-pole connection type sensor capable of displaying the state of the supplied AC power, .

Prior art to be a background of the present invention is disclosed in Japanese Patent Publication No. JP05885209, which provides various thin film sensor type power measuring devices capable of measuring electric power in a high frequency circuit or a battery in a simple and small configuration. The power measuring apparatus includes a power supply unit having a magnetic film disposed parallel to a primary conductor through which a load current flows, an input / output terminal for supplying a device current to the magnetic film, A bias magnetic field applying unit for applying a direct current magnetic field of an oblique direction and a detecting unit for detecting a voltage between an end portion of the magnetic film in the direction of the device current, A DC voltage component between the DC voltage and the DC voltage is detected,

In addition, in the Japanese Patent Laid-Open Publication No. 10-2012-0047975, it is possible to determine the direction (positive or negative direction), and it is possible to detect the magnetic field with high reliability. The magnetic field sensor includes a ferromagnetic thin film (3), feeding parts (5A, 5B) provided with input / output terminals for supplying device current to the ferromagnetic thin film, and ferromagnetic thin films (5C, 5D) for detecting the voltage of the ferroelectric thin film, and the ferromagnetic film is formed so as to be symmetrical with respect to the direction of the device current to measure the power. -2017-0008584 discloses a power measuring system capable of calculating accurate power information by using a low-voltage meter in a small power system. The power measuring system measures and detects a current and a zero cross point from a power distribution line, And a first meter for generating and outputting current information from the zero cross point to the power distribution line; And a second meter for calculating power information of the distribution line according to the voltage of the distribution line and the current information output from the first meter. However, there is a problem in that the power measurement method using the Hall sensor does not have a method of compensating the power factor, and the influence of the magnetic field of the neighboring bus bar can not be eliminated. In order to solve such a conventional problem, The hall effect sensor is used to calculate the intensity of the current by reading the intensity of the magnetic field. This is because it is easy to make the current measuring device small because of its small size, and its price is lower than other sensors. The Hall effect sensor has the above-described advantages, but is susceptible to influence of a magnetic field introduced from the outside, and thus the accuracy is varied according to the number of circuits in a distribution board composed of a plurality of circuits.

Japanese Patent Publication No. JP05885209 Korean Patent Publication No. 10-2017-0008584 Korean Patent Laid-Open No. 10-2012-0047975

The present invention relates to a method for improving measurement accuracy in measurement of voltage, current, and power of a busbar using a single pole connection type power measuring apparatus, and more particularly, to a method of improving the accuracy of a power factor indicating effective power efficiency Circuit and method, and a magnetic shielding material blocking the magnetic field generated from the current flowing in the adjacent booth.

And a compensation circuit for improving the power factor error caused by the coil and the inductance component of the noise removing filter circuit in the main measuring part and the sub-measuring part of the single pole connection type power measuring device to solve the above problems, And a method of shielding the magnetic field generated from the current flowing in the adjacent booths by surrounding the magnetic field shielding material around the bus bar and the sensor portion to improve the measurement accuracy of the single pole connection type power state measuring device.

According to the present invention, a phase compensation circuit is included in a voltage and current measuring unit to improve errors in the instantaneous value of voltage and current due to the influence of noise. By applying the magnetic shielding material to the sensor unit, The effect of the magnetic field introduced from the two circuits is cut off, thereby improving the accuracy of the current.

1 is a view illustrating a power status measuring apparatus of an industrial distribution board using a single pole connection type sensor according to an embodiment of the present invention.
2 is a block diagram for explaining a main side of a power status measuring apparatus according to an embodiment of the present invention
3 is a block diagram illustrating a sub-measurement unit of the power status measuring apparatus according to an embodiment of the present invention
FIG. 4 is a diagram for explaining a power state of each circuit breaker using a single pole connection type power measuring apparatus according to an embodiment of the present invention
5 is a block diagram of a main measurement module and a sub measurement module of a single pole connection type power measuring apparatus according to an embodiment of the present invention
6 is an application example of a magnetic shielding material in a single pole connection type power measuring apparatus according to an embodiment of the present invention and an application example in which a plurality of circuits are present
7 is a diagram illustrating a configuration of applying a compensation circuit for improving power factor error in a single pole connection type power measuring apparatus according to an embodiment of the present invention
8 is a flowchart for efficiently receiving power status data without data error in serial communication between the status display unit and a plurality of single pole connection type power measuring apparatuses

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. Prior to this, terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms, and the inventor should appropriately interpret the concept of the term appropriately in order to describe its own invention in the best way. The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention. Further, it is to be understood that, unless otherwise defined, technical terms and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Descriptions of known functions and configurations that may be unnecessarily blurred are omitted. The following drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the following drawings, but may be embodied in other forms. In addition, like reference numerals designate like elements throughout the specification. It is to be noted that the same elements among the drawings are denoted by the same reference numerals whenever possible.

In the present invention, a Hall effect sensor is used to calculate the current intensity by reading the intensity of the magnetic field distributed around the sensor. This is because it is easy to make the current measuring device small because of its small size, It has its characteristics. The Hall effect sensor has the above-described advantages, but is susceptible to influence of a magnetic field introduced from the outside, and thus the accuracy is varied according to the number of circuits in a distribution board composed of a plurality of circuits.

Since the current signal and the voltage signal, which are input signals to the measuring unit 201 via the Hall effect sensor, are very weak voltages of less than 1 V and affect the measurement of the accurate signal even by a weak external noise, To remove signal variations due to external noise. However, such a filter circuit is constituted by a coil or a capacitance component and greatly influences the calculation of the power factor indicating the efficiency of the effective power. Therefore, in order to improve the accuracy of the power factor, it is necessary to compensate the power factor error by including a compensation circuit to compensate the power factor error produced by the filter circuit in order to improve the accuracy of the power measuring device.

Prior to describing the present invention, the conventional method of measuring the power of the busbar by referring to FIGS. 1 to 3 will be described. The AC power supplied through the three-phase four-wire industrial distribution board includes R, S, And an N-phase AC component, and the industrial distribution panel has connection terminals corresponding to the respective phases. In general, the power status measuring device of an industrial distribution board using a single pole connection type sensor measures the power state of each phase of the three-phase four-wire AC power source, and transmits the measured power state to each phase using communication between the measuring units The apparatus for measuring the power state of an industrial distribution board using a single pole connection type sensor includes a main side portion 10, a sub side portion 20 and a status display portion 30, and the main side portion 10, And the subsidiary measuring unit 20 correspond to the phases of the alternating currents of the bus bars (Phase 1, Phase 2, Phase 3 and Phase 4) And the status display unit 30 communicates with the main unit 10 to measure the values of the current and voltage measured by the main unit 10 and the sub measurement unit 20 and the active power, Apparent power, reactive power, etc., Specifically, the main control unit 10 is a control unit for controlling the operation of one of R-phase, S-phase, T-phase and N-phase of AC power supplied through the main line or branch line of the bus bar in the three- Measure current and voltage for phase. The main unit 10 includes a phase selection unit 11, a bus bar connection terminal 12, a breaker connection terminal 13, a measurement unit 14, a bus communication unit 12, The phase selector 11 selects one of the R phase, the S phase, the T phase, and the N phase of the AC power to a predetermined value or The bus bar connecting terminal 12 is made of a conductive terminal to be connected to a main line or a branch line of the bus bar and the breaker connecting terminal 13 is electrically connected to the bus bar connecting terminal 12 It is a terminal for connection with an external circuit breaker. The measuring unit 14 is connected to the bus bar connecting terminal 12 and the breaker connecting terminal 13 to measure the current and the voltage of the phase selected by the phase selecting unit 11. [ The bus communication unit 15 is connected to the sub-measurement unit 20 and the sub-measurement unit 20. The bus communication unit 15 receives the R phase, S phase, T phase, and N phase of the AC power measured by the sub-measurement unit 20 provided through the bus line from the sub- Current, voltage, apparent power, active power, and reactive power at the time of power-off. The control unit 16 converts the measured value from the measuring unit 14 into a digital signal, and calculates the values of the apparent power, the active power, and the reactive power using the voltage and the current. Here, the control unit 16 may include an analog-to-digital converter for performing the function. The control unit 16 may generate a power anomaly signal for the phase selected by the phase selection unit when the values of the apparent power, the active power, and the reactive power are less than a preset threshold value, Phase, T-phase, and N-phase. The control unit 16 also controls the values of the current and voltage measured from the measuring unit 14 and the values of the apparent power, the effective power and the reactive power calculated therefrom and the values of the R The power state of the AC power source for all the phases supplied through the bus bar based on the current and voltage, the apparent power, the values of the active power and the reactive power in the respective phases of the phases S, S, T and N, Information can be generated. The serial communication unit 17 transmits the power status information of the AC power source to the status display unit 30. The serial communication unit 17 communicates with the status display unit 30 according to RS-485 communication. The RS-485 communication is an extension version of RS 232 and RS 422, and is a kind of serial communication protocol standard supporting a home network. RS-485 communication allows all devices to transmit and receive data on the same line, and supports both half duplex and full duplex communication. The sub-measurement unit 20 is connected to the main unit 10 through a bus line that provides a data transmission / reception path. The sub-measurement unit 20 includes R, S, T, and N phases other than the phase measured by the main unit 10. [ Lt; RTI ID = 0.0 > and / or < / RTI > Here, the sub-measurement unit 20 includes a phase selection unit 21, a bus bar connection terminal 22, a breaker connection terminal 23, a measurement unit 24, a bus communication unit 25, and a control unit 26 . The phase selector 21 selects the phase of any one of the R phase, the S phase, the T phase, and the N phase of the AC power according to a preset value or a user's input. The bus bar connecting terminal 22 is made of a conductive terminal to be connected to a main line or a branch line of the bus bar. The breaker connection terminal 23 is electrically connected to the bus bar connection terminal 22 and is a terminal for connection with the external breaker. The measurement unit 24 is connected to the bus bar connection terminal 22 and the breaker connection terminal 23 to measure the current and voltage of the phase selected by the phase selection unit 21. [ The bus communication unit 25 transmits and receives values relating to the current and voltage of the phase selected by the phase selection unit via the bus line. The control unit 26 converts the measured value from the measuring unit 24 into a digital signal, and calculates the values of the apparent power, the active power, and the reactive power using the voltage and the current. Here, the control unit 26 may include an analog-to-digital converter for performing the function. The controller 26 may generate a power anomaly signal for the phase selected by the phase selection unit when the values of the apparent power, the active power, and the reactive power are less than a preset threshold value, Phase, T-phase, and N-phase. The main unit 10 and the sub-measurement unit 20 may correspond to R phase, S phase, T phase, and N phase, respectively. At this time, a plurality of sub-measurement units 20 may be provided. And can be corresponding to each phase. The main controller 10 is provided with the values of the current and voltage for the phases of the respective R phase, S phase, T phase, and N phases measured by the sub-measurement unit 20, The values of current and voltage for all phases of R phase, S phase, T phase and N phase can be output together with the values of current and voltage. On the other hand, the status display unit 30 displays the current, voltage and the apparent power for each phase, active power, reactive power, power abnormality signal and the like, measured on each of R phase, S phase, T phase and N phase from the main side unit 10 And receives the power status information of the AC power and displays them on a screen or a voice. Here, the status display unit 30 may include communication means for performing the function, control means, and display means. The main control unit 10 or the sub measurement unit 20 can be attached to each branch of the bus bar in different phases (R, S, T, N phases) Sensor modules, A / D converters, communication modules, and busbars for measuring the current, voltage, and temperature of each phase (R, S, T, and N phases) of each branch are compactly integrated into one unit. The power state measuring apparatus has an advantage in that it can be applied without changing the design in either of single-phase 2-wire, 3-phase 3-wire, and 3-phase 4-wire types by differentiating connection and phase selection between the main side and sub- Regardless of whether the order of the phases of the bus bars of the distribution boards is changed.

4, a power status monitoring system for monitoring the power status of each circuit breaker in a distribution board using a single pole connection type power measuring apparatus according to an exemplary embodiment of the present invention will be described with reference to FIG. A plurality of single pole connection type power measuring devices 101 connected to the breakers and connected to the single pole connection type power measurement device 101 between the busbars and the breaker 105 in the distribution board or the breaker output terminal are connected to the RS485 communication The power status data is stored in the status display unit 100 through the display unit 106 and the power status such as current, voltage, power, frequency, and power factor is displayed on the screen. The single pole connection type power measuring apparatus 101 is composed of one main measurement module 103 and a plurality of sub measurement modules 104. For example, in a three-phase, four-wire system, it consists of one main measurement module and three sub-measurement modules, each of which consists of one main measurement module and one sub measurement module. More specifically, the main measuring module is connected to the bus bar and includes a plurality of main measuring modules for measuring voltage, current, and power, a plurality of sub-measuring modules, a plurality of hall sensors, A plurality of main measurement modules, a plurality of sub-measurement modules, a status display unit 100 for displaying measured values from the plurality of hall sensors, A main measuring module, a sub measuring module, and a Hall sensor, wherein the main measuring module, the sub measuring module, and the Hall sensor are connected to each other, Further comprising a filter unit for preventing the power factor value generated during the measurement from being changed. The apparatus of claim 1, wherein the filter further comprises: The signal (-) terminal is connected to a resistor and the bead is connected to the negative (+) terminal, and the capacitor (401) is connected to the current signal (+) terminal. A noise filter circuit 402; The beads are connected,

5 is a block diagram of a main measurement module and a sub measurement module of the single pole connection type power measuring apparatus according to an embodiment of the present invention. The main difference between the main measurement module and the sub measurement module is that a control unit (201). The control unit 201 of the main measurement module collects the power status data measured by each sub-measurement module and processes the required power status data to transmit the power status data through the serial communication unit 202 when requested by the status display unit.

FIG. 6 is an application example of a magnetic field shielding material in a single pole connection type power measuring apparatus according to an embodiment of the present invention and a case where there are a plurality of circuits, , And a magnetic shielding material (302) for shielding a magnetic field flowing from the outside from the outside of the sensor main body, unlike the single pole connection type power measuring device, and the sensor part including the magnetic shielding material 303 are required.

7 is a configuration diagram of a compensation circuit applied to improve the power factor error in a single pole connection type power measuring apparatus according to an embodiment of the present invention. In FIG. 7, a capacitance 401 for removing a DC offset component is connected to a sensor output terminal, And a noise filter circuit 402 for removing a high frequency noise component while compensating for a power factor error component generated in the device.

8 is a flowchart for receiving power status data from the total power measuring apparatus as soon as possible without data error in serial communication between the status display unit and a plurality of single pole connection type power measuring apparatuses. More specifically, the method of measuring the power measuring apparatus includes: setting initial data in a communication method of the single pole connection type power measuring apparatus 101 in the status display unit 100; Requesting the data from the status display unit (100) to the single pole connection type power measuring apparatus (101); Waiting until a preset waiting time for each section; If the data is not received and there is no reception or partial reception, the current interval is the maximum interval, and processing is performed as a data reception error; And a step of receiving and processing the data when the data is confirmed and confirming the reception, and setting a maximum waiting time for serial communication between the status display unit 100 and the power measuring apparatus 101, When communication is completed, serial communication with the next power measuring apparatus is performed. If communication is not completed within the maximum waiting time, communication with the next power measuring apparatus is performed after data receiving error processing. After completion of the communication with the power measuring apparatus, communication is performed again. The maximum waiting time is automatically set considering the data rate that can be processed by RS485 communication and the number of data to be processed. When the maximum waiting time is divided by the number of power measuring devices connected to the circuit (maximum interval) A main measurement module in a single pole connection type power state measuring apparatus which improves power factor error in measuring a current and voltage state through a single-phase bus bar, thereby improving the accuracy of the effective power amount; And a correction circuit for removing a DC offset value of an input signal in the main measuring unit and compensating for a phase error of a current signal generated by a filter circuit for removing high frequency and noise components, Connected-type power status measuring device; Further comprising a function of adjusting a time delay amount by software in order to compensate for the amount of phase shift caused by the correction circuit included in order to improve the phase error caused by the noise filter circuit. And 3-phase 3-phase 4-wire of AC power that flows through the main and branch lines of the busbar in the distribution board. A single pole connection type power state measuring device having an effect of reducing a manufacturing cost by using a printed circuit board and dividing the wiring structure only in software; A single pole connection type power state measuring device having a structure that distinguishes the wiring structure only from the software, calculates the phase voltage and line-to-line contact pressure, and easily applies a correction function for correcting errors between measured values and measured values through sampling; A single pole connection type power state measuring device for improving the accuracy of measurement by preventing a voltage measurement error according to a difference in hardware configuration according to the wiring structure; The phase of the R phase, the S phase, the T phase, and the N phase using the sub-measuring unit for three-phase three-wire and three-phase four-wire having the same designed printed circuit board, A plurality of bus bars disposed in the distribution board and configured to detect a current flowing through the plurality of bus bars adjacent to the bus bar and to measure the current more accurately, A single pole connection type power measuring device provided with a magnetic shielding material surrounding a part of a bus bar and storing power state values such as current, voltage, temperature, frequency and power factor measured from the measuring part, It is not only excellent in security, but also has a single pole connection type designed to preserve the accumulated power state when the power is cut off. In order to measure the voltage applied to the booth bar by the measuring unit and to measure the voltage stably and to strengthen the immunity against the external noise signal of surge current, a single pole connection type power measuring device And a plurality of single-pole connection-type power measuring apparatuses connected in series, the single-pole connection-type power measuring apparatus applying an algorithm for receiving power state data from the total power measuring apparatus as soon as possible without data error And the accuracy of the line-to-line voltage measurement on the three-phase three-wire line is improved.

In case of RS-485 communication, serial communication must be implemented in order to perform accurate communication without data error. To this end, in the present invention, a maximum waiting time for serial communication between the status display unit and the power measuring apparatus is set, and when the communication is completed before the maximum waiting time, serial communication with the next power measuring apparatus is performed and communication is completed within the maximum waiting time If it fails, it performs communication with the next power measuring device after data reception error processing. The data reception error-processed power measurement device performs communication again after completing communication with the last power measurement device. The maximum waiting time is automatically set considering the data rate that can be processed by RS485 communication and the number of data to be processed. If the maximum waiting time is divided by the number of power measuring devices connected to the circuit (maximum interval) It becomes.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

10-state government
11 phase selection part, 12 bus bar connection terminal, 13 breaker connection terminal,
14 measurement unit, 15 bus communication unit, 16 control unit, 17 serial communication unit
20 parts measuring part
21 phase selection part, 22 bus bar connection terminal, 23 breaker connection terminal,
24 measuring unit, 25 bus communication unit, 26 control unit
30 status indicator
100 status display 101 Single pole connection type power meter
102 Booth bar 103 Main measuring module
104 parts measuring module 105 breaker
201 control unit 202 serial communication unit
203 bus communication section 204 measuring section
205 Sensor Unit 206 Busbar Connection Terminal
207 Circuit breaker connection terminal 301-303 Sensor section
401 Capacitor 402 Noise Filter Circuit

Claims (11)

delete delete A plurality of main measurement modules connected to the bus bar 102 for measuring voltage, current and electric power, a plurality of sub-measurement modules, a plurality of Hall sensors; A plurality of main measurement modules, the plurality of sub-measurement modules, a status display unit 100 for displaying measured values from the plurality of hall sensors, A single pole connection type power state measuring device which improves the accuracy of line voltage measurement in a three-phase three-wire system power system in which the load is controlled based on the values measured by the main measuring module, the sub-measuring module and the hall sensor 101)

A filter unit for preventing the power factor value generated at the time of measurement of the main measurement module, the sub measurement module,
A control unit 201 for discriminating the wiring structure in software and measuring the voltage, current, and electric power according to the wiring structure of the AC power flowing through the bus bar 102 and applying a correction function for correcting the error between the measured value and the measured value through sampling ) and a further comprising,

The filter unit includes:
(-) terminal of the filter unit; A capacitor 401 is connected to the current signal (+) terminal of the filter unit; A noise filter circuit 402; Characterized in that beads are connected,
The noise filter circuit (402)
Wherein a DC offset value, a high frequency, and a noise component of the input signal are removed,
The control unit (201)
Characterized in that it is possible to adjust the amount of time delay in software to compensate for the amount of phase shift caused by the compensation circuit,
Further comprising a compensation circuit for compensating for a phase error of the current signal generated by the noise filter circuit (402)
And a sub-measurement module using a resistance to distinguish phases such as R phase, S phase, and T phase using the sub-measurement module for three-phase three-line , corrects the error between the measured measured value and the measured value through sampling,
A Hall effect sensor and a part of the bus bar around the sensor are surrounded to prevent the influence of the current flowing through the plurality of bus bars adjacent to the bus bar other than the current flowing through the bus bar to be measured from among a plurality of bus bars positioned in the distribution board, Has a single-pole connection type power measuring device equipped with a magnetic shielding material,
A single pole connection type power measuring device designed to store power state values such as current, voltage, temperature, frequency, and power factor measured from the main measurement module and the sub measurement module and to preserve accumulated power state during data security and power shutdown Lt; / RTI &
Wherein the main and sub measurement modules measure a voltage applied to the bus bar 102. The main measurement module and the sub measurement module measure a voltage applied to the bus bar 102 , Connected type power measuring device,
There is a single pole connection type power measuring apparatus which applies an algorithm for receiving power state data from the total power measuring apparatus as soon as possible without data error in serial communication between the status display unit and a plurality of single pole connection type power measuring apparatuses A connection method of a single pole connection type power measuring apparatus (101) in a state display (100) of a single pole connection type power state measuring apparatus which improves the accuracy of line voltage measurement in a three phase three wire system power system,
Setting initial data;
Requesting the data from the status display unit (100) to the single pole connection type power measuring apparatus (101);
Waiting until a preset maximum waiting time for each section;
If the data is not received and there is no reception or partial reception, the current interval is the maximum interval, and processing is performed as a data reception error;
And confirming the data and confirming the reception, receiving, processing, and terminating the data
The maximum waiting time per section is obtained by dividing the maximum waiting time automatically set in consideration of the data rate that can be processed by the RS485 communication and the number of data to be processed by the number of power measuring apparatuses connected to the circuit (maximum section) A communication method of a single-pole connection type power state measuring apparatus 101 that improves the accuracy of measurement of a line voltage in a three-phase three-wire system power system
The method of claim 3,
After setting the maximum waiting time for the serial communication between the status display unit 100 and the power measuring apparatus 101, if the communication is completed before the maximum waiting time, serial communication with the next power measuring apparatus is performed and communication is completed within the maximum waiting time And the communication with the next power measuring apparatus is performed after the data reception error process is performed, the communication of the single pole connection type power status measuring apparatus 101 improving the accuracy of the measurement of the line voltage in the power system of the three- Way
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