JP4702726B2 - Display method of vector lines in power meter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for displaying a vector line in a power meter, and more particularly to a method for displaying a vector line in a power meter that measures the power of a three-phase four-wire circuit under test.
[0002]
[Prior art]
FIG. 4 is a block diagram showing a schematic configuration of a power measuring device that measures the power of a three-phase four-wire measured circuit, and includes an input unit 1, a setting unit 2, a CPU 3 as a main controller, and a ROM 4 as storage means. The RAM 5 and the display unit 6 are provided. Each of the input unit 1, setting unit 2, ROM 4, RAM 5, and display unit 6 is connected to the CPU 3 by a bus 7.
[0003]
In this case, for example, three clamp sensors 1 </ b> A to 1 </ b> C and four, for example, shed type clips 1 </ b> D to 1 </ b> G are connected to the input unit 1. Among these, the clamp sensors 1 </ b> A to 1 </ b> C are clamped to three measured electric circuits excluding a neutral wire as a wire penetration type current sensor. Further, the clips 1D to 1G are connected so as to be directly sandwiched between four electric circuits to be measured including a neutral wire. The power meter performs data processing for three channels with one phase as one channel.
[0004]
The input unit 1 includes an A / D converter that converts an alternating current detected by the clamp sensors 1A to 1C and an alternating voltage from the clips 1D to 1G into a digital signal at a predetermined sampling interval. Data and current data are supplied to the CPU 3.
[0005]
Various setting items necessary for measurement are input to the setting unit 2 by a measurement operator, such as selecting an appropriate measurement range according to the AC voltage or AC current value to be measured.
[0006]
The ROM 4 stores in advance processing procedures performed by the CPU 3. In the RAM 5, each data of AC voltage and AC current is written in a readable manner under the control of the CPU 3. A liquid crystal display panel, a plasma display, or the like is used for the display unit 6, and measurement results, determination results, and the like are displayed under the control of the CPU 3.
[0007]
When the CPU 3 receives the digital alternating voltage and alternating current from the input unit 1, the CPU 3 stores these digital signals in the RAM 5 and performs various processes according to the processing procedure stored in the ROM 4.
[0008]
The CPU 3 extracts the fundamental wave of the waveform of the alternating voltage and alternating current by the above processing function, and calculates the effective value and the phase angle. Further, the CPU 3 displays a vector diagram Vec as shown in FIG. 5 on the display unit 6 based on the calculated effective value and phase angle. In the figure, symbol U1 is the first channel AC voltage, I1 is the same AC current, symbol U2 is the second channel AC voltage, I2 is the same AC current, and symbol U3 is the third channel AC. The voltage I3 indicates a vector line of the AC current.
[0009]
Therefore, by displaying the vector diagram Vec shown in FIG. 5 on the display unit 6, the operator can visually determine which of the clamp sensors 1A to 1C and the clips 1D to 1G has a connection error. Can do.
[0010]
[Problems to be solved by the invention]
However, when various loads are connected to the three-phase four-wire electric circuit to be measured, each vector line is not necessarily an ideal vector diagram shifted by 120 degrees. There still remains a problem that it is difficult for an operator to accurately determine whether there is a connection error.
[0011]
The present invention has been made to solve such problems. The purpose of the present invention is to determine whether or not a clip, a clamp sensor, or the like is erroneously connected to a three-phase four-wire electric circuit to be measured, and which clamp sensor. It is an object of the present invention to provide a method for displaying a vector line in a power measuring device capable of accurately confirming whether a misconnection has occurred.
[0012]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present invention takes out each fundamental wave by Fourier transforming the measurement voltage and the measurement current taken out for each channel from the circuit to be measured transmitted by three-phase four-wires, and taking these fundamental waves. In a power measuring instrument that displays each vector line obtained by calculating each measurement voltage and each measurement current from the phase and magnitude of each measurement voltage and each measurement current calculated based on In the vector line display method, the vector diagram defines a vector line display direction of the first channel whose angle starting from the reference point is 0 degrees, and a radius obtained by subtracting the effective value variation allowable width from the reference effective value. And two circles centered on the reference point for each of the radius and the radius that has increased the effective value variation allowable width, and are arranged in the vector line display direction of the first channel. A portion surrounded by two circles and two straight lines after two straight lines are drawn from the reference point in an angle obtained by subtracting the phase angle allowable width and the angle direction including the phase angle allowable width. Is used as a fan-shaped permissible area for the first channel, the vector line display direction of the second channel is determined by adding 120 degrees to the vector line display direction of the first channel, and the same processing is performed. The fan-shaped permissible area of the channel is set, the vector line display direction of the third channel is determined by adding 120 degrees to the vector line display direction of the second channel, and the same processing is performed to obtain the fan-shaped allowable area of the third channel. it is, each at a voltage side vector diagram and a current-side vector diagram with three of said fan-shaped allowable area defined by the effective value variation allowable width and phase angle tolerance of the different channels are predetermined respectively Formed in, characterized in that the possible display of confirmation by the respective visual connections in the voltage side and the current side in a positional relationship between corresponding each vector line are for each of the fan-shaped allowable range.
[0013]
For this reason, if a corresponding vector line is included in each sector-shaped allowable area, it can be determined at a glance that the connection is correctly performed.
[0014]
Further, in the present invention, each of the fan-shaped permissible area for each channel and the corresponding vector line displayed separately in the voltage-side vector diagram and the current-side vector diagram is referred to as the fan-shaped permissible area of the other channel. In the case of displaying in a similar color that can be distinguished from the corresponding vector line, this can be easily visually confirmed even when the channels are connected by mistake.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 4, the power measuring device for measuring the power of the three-phase four-wire power circuit to which the method of the present invention is applied includes an input unit 1, a setting unit 2, a CPU 3 as a main controller, A ROM 4 and a RAM 5 as storage means, and a display unit 6 are provided. Incidentally, the details will be omitted in the Ru Oh already mentioned.
[0016]
FIG. 1 is an explanatory diagram showing a display example of a vector diagram realized by being applied to the power meter shown in FIG. 4 on the display unit 6, and is divided into a voltage side vector diagram Vec 1 and a current side vector diagram Vec 2. Is formed.
[0017]
Among them, the voltage-side vector diagram Vec1 is provided with three fan-shaped allowable areas 11 defined by an effective value fluctuation allowable width 12 and a phase angle allowable width 13 that are predetermined for each channel.
[0018]
Similarly, the current-side vector diagram Vec2 is provided with three fan-shaped allowable areas 21 defined by an effective value fluctuation allowable width 22 and a phase angle allowable width 23 that are predetermined for each channel.
[0019]
2 is a flowchart showing an example of a processing procedure for displaying the voltage-side vector diagram Vec1 and the current-side vector diagram Vec2 shown in FIG. 1 on the display unit 6, and FIG. 3 is a process shown in the flowchart of FIG. It is explanatory drawing which shows a corresponding relationship. .
[0020]
According to these figures, when drawing is started, first, a process of determining the vector line display direction α of the first channel whose angle starting from the reference point P set at an arbitrary position is 0 degree is performed.
[0021]
Next, assuming that the reference effective value is β and the effective value variation allowable width is r, two circles having a radius of β ± r and centering on the reference point P are drawn as shown in FIG.
[0022]
When the phase angle allowable width with respect to the vector line display direction α of the first channel is θ, the vector line display direction α draws two straight lines from the reference point P in the direction of α ± θ from the position of the initial angle of 0 degrees.
[0023]
Thereafter, a fan-shaped allowable area 11 (21) for the first channel is drawn by painting a portion surrounded by two circles and two straight lines.
[0024]
Next, after adding 120 degrees to the vector line display direction α of the first channel to determine the vector line display direction (α + 120 degrees) of the second channel, the above-described series of processing is performed, and FIGS. ) To obtain the fan-shaped allowable area 11 (21) of the second channel.
[0025]
Further, after adding 120 degrees to the vector line display direction (α + 120 degrees) of the second channel to determine the vector line display direction (α + 240 degrees) of the third channel, a series of processes are performed in the same manner as shown in FIG. ), (B), the third channel fan-shaped allowable region 11 (21) is obtained.
[0026]
Thus, as shown in FIGS. 1 (a) and 1 (b), the first channel fan-shaped allowable region 11 (21) and the second channel fan shape are respectively shown in the voltage side vector diagram Vec1 and the current side vector diagram Vec2. After obtaining the tolerance region 11 (21) and the third channel fan-like tolerance region 11 (21), the waveforms of the measurement voltage and the measurement current are sampled for each channel from the circuit to be measured transmitted by three-phase four-wire. And take it out.
[0027]
Each sampled waveform is Fourier-transformed to extract each fundamental wave component, and the effective value and phase angle of these fundamental wave components are calculated.
[0028]
Of the calculated fundamental wave components, on the voltage side, as shown in FIG. 1 (a), vector lines U1, U2 indicating the respective effective values as lengths and phase angles as angles in the voltage side vector diagram Vec1. , U3.
[0029]
Similarly, the fundamental wave components on the current side are also shown in FIG. 1B. In the current side vector diagram Vec2, as shown in FIG. Drawing as I3 ends the processing.
[0030]
In this case, in the voltage-side vector diagram Vec1, the fan-shaped permissible areas 11, 11, 11 for each channel displayed separately and the corresponding vector lines U1, U2, U3 can be distinguished for each channel. It can be displayed with colors.
[0031]
That is, the fan-shaped allowable area 11 of the first channel and the vector line U1 are similar colors that can be distinguished from each other, and the fan-shaped allowable area 11 of the second channel and the vector line U2 are the fan-shaped allowable area of the first channel. 11 and the vector line U1 are different colors and are similar colors that can be distinguished from each other. The third channel fan-shaped allowable area 11 and the vector line U3 are the first channel fan-shaped allowable area 11 and the vector line U1. In addition, the fan-shaped allowable area 11 of the second channel and the vector line U2 can be displayed in different colors and similar colors that can be distinguished from each other.
[0032]
Similarly, the fan-shaped permissible areas 21, 21, 21 for each channel and the corresponding vector lines I1, I2, I3 in the current-side vector diagram Vec2 can be distinguished for each channel. It can be displayed with colors.
[0033]
Therefore, according to the present invention, as shown in FIG. 1 (a), the voltage-side vector diagram Vec1 has a fan-shaped allowable area 11 of the first channel, a fan-shaped allowable area 11 of the second channel, and a fan-shaped allowable of the third channel. After drawing the region 11 separately, the corresponding vector lines U1, U2, U3 can be drawn and displayed on the display unit 6.
[0034]
Further, as shown in FIG. 1B, the current-side vector diagram Vec2 includes a fan-shaped allowable area 21 of the first channel, a fan-shaped allowable area 21 of the second channel, and a fan-shaped allowable area 21 of the third channel. In addition, the corresponding vector lines I1, I2, and I3 can be drawn and displayed on the display unit 6.
[0035]
Therefore, according to the present invention, whether or not the clips 1D to 1G and the clamp sensors 1A to 1C shown in FIG. 4 are erroneously connected to the three-phase four-wire circuit to be measured, and which clamp sensor is causing the erroneous connection. Can be confirmed visually. Note that the same can be applied to the case of direct connection without using a clamp sensor.
[0036]
In particular, the fan-shaped permissible areas 11, 11, 11 and vector lines U1, U2, U3 for each channel depicted in the voltage-side vector diagram Vec1, and the sector-shaped permissible areas 21, 21, 21, and vector lines depicted in the current-side vector diagram Vec2. Each of I1, I2, and I3 is displayed with a color that can be distinguished for each channel as described above, so that the clips 1D to 1G and the clamp sensors 1A to 1C shown in FIG. It is possible to visually check more easily even when connected.
[0037]
【The invention's effect】
As described above, according to the present invention, each of the fan-shaped permissible area and vector line for each channel of the voltage-side vector diagram and the fan-shaped permissible area and vector line for each channel of the current-side vector diagram are mutually viewed. Since it can be displayed easily, it is possible to display the clip to the measured circuit of the three-phase four-wire circuit, for example, whether there is an incorrect connection of the clamp sensor, and which clamp sensor has the incorrect connection. it can.
[0038]
In addition, each of the fan-shaped permissible area and vector line for each channel drawn in the voltage-side vector diagram and the fan-shaped permissible area and vector line drawn in the current-side vector diagram are colored so that they can be distinguished from each other. In the case of display, even when a clip or a clamp sensor, for example, is connected with a wrong channel, it can be visually confirmed more easily.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a display example of a vector diagram on a display unit according to the present invention.
FIG. 2 is a flowchart showing an example of a processing procedure for displaying the voltage side vector diagram and the current side vector diagram shown in FIG. 1 on a display unit;
FIG. 3 is an explanatory diagram showing a correspondence relationship with the processing shown in the flowchart of FIG. 2;
FIG. 4 is a block diagram showing a schematic configuration of a power measuring device for measuring the power of a three-phase four-wire circuit under measurement.
5 is a vector diagram as a conventional example obtained by applying to the power measuring device shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Input part 1A-1C Clamp sensor 1D-1G Clip 2 Setting part 3 CPU
4 ROM
5 RAM
6 Display Unit Vec1 Voltage Side Vector Diagram 11 Fan-shaped Allowable Area 12 RMS Value Allowable Width 13 Phase Angle Allowable Width U1, U2, U3 Vector Line (Voltage Side)
Vec2 Current side vector diagram 21 Fan-shaped allowable area 22 RMS fluctuation allowable width 23 Phase angle allowable width I1, I2, I3 Vector line (current side)

Claims (2)

Each measured voltage and each measurement calculated based on these fundamental waves are obtained by Fourier transforming the measured voltage and measured current taken for each channel from the circuit to be measured transmitted by three-phase four-wire, respectively. In the method of displaying a vector line in a power meter that displays each vector line obtained by calculating each measurement voltage and each measurement current from the phase and magnitude of the current as a vector diagram on the display unit,
The vector diagram defines the vector line display direction of the first channel whose angle starting from the reference point is 0 degrees, the radius obtained by subtracting the effective value variation allowable range from the reference effective value, and the effective value variation allowable range. Draw two circles centered on the reference point for each of the increased radii, an angle obtained by subtracting the phase angle tolerance with respect to the vector line display direction of the first channel, and an angle direction adding the phase angle tolerance After drawing two straight lines from the reference point, the portion surrounded by the two circles and the two straight lines is painted to form a fan-shaped allowable area for the first channel, and the vector line of the first channel After the 120 degree is added to the display direction to determine the vector line display direction of the second channel, the same processing is performed to make the sector allowable area of the second channel, and 120 degrees in the vector line display direction of the second channel. In addition in terms of defining the vector line display direction of the third channel by performing the same processing by a fan-shaped allowable range of the third channel,
Formed in each separate predetermined effective value variation allowable width are the three that are defined by the phase angle tolerance of the fan-shaped allowable range in the voltage side vector diagram and a current-side vector diagram, each having a separate channel, respectively A method for displaying a vector line in a power meter, wherein the connection state between the voltage side and the current side is displayed in a positional relationship with each corresponding vector line with respect to the sector-shaped permissible region so as to allow visual confirmation.  The fan-shaped permissible area for each channel and the corresponding vector line displayed in the voltage-side vector diagram and the current-side vector diagram are respectively distinguished from the fan-shaped permissible area of the other channel and the corresponding vector line. 2. The method of displaying a vector line in a power meter according to claim 1, wherein the vector line is displayed in a similar color.

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