JP2008039483A - Electric power measuring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power measuring system equipped with exchangeable electric current detectors and capable of high-accuracy measurement of conversion information specific to respective electric current detectors without any individual manual setting. <P>SOLUTION: An electric power measuring system comprising an electric power measuring system body 100 and exchangeable electric current detectors 120 further includes a memory section 140 in an electric current detector 120 to store conversion information of the electric current detector so that a controller 170 in the electric power measuring system body 100 can detect the conversion information. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power measuring device that measures the amount of power used by a system under measurement.

2. Description of the Related Art Conventionally, power measuring devices that measure the amount of power used and power used by ordinary households, factories, and offices have become widespread. The power measuring apparatus includes a power detection unit that measures the power used and the amount of power used in the system to be measured, a control unit that edits the power used detected by the power detection unit, and data edited by the control unit. And a display unit for displaying. (For example, Patent Document 1)
JP 2004-85413 A (Page 4, FIG. 2)

2. Description of the Related Art Conventionally, power measuring devices that measure the amount of power used and power used by ordinary households, factories, and offices have become widespread. The power measurement device detects the voltage and current of the system under measurement, and multiplies the detected voltage value and current value to create measurement data related to the power amount and power. Usually, a voltage transformer is used for voltage detection, and a current transformer is used for current detection.

In addition, there is a power measuring device capable of exchanging current transformers having different rated currents in accordance with the magnitude of current used in the system to be measured for the purpose of making it possible to measure a wide range of current values.

However, in a power measuring device capable of exchanging the current transformer, it is necessary to input conversion information such as a conversion ratio, a ratio error, and a phase angle error to the power measuring device main body with a key switch or the like. It was. Such an input operation has a problem that it is complicated for the operator and causes an input error.

The present invention provides a power measuring apparatus that can perform high-precision measurement without manually inputting conversion information for each current transformer into the power measuring apparatus body manually even when the current transformer is replaced. The purpose is to provide.

In order to achieve the above object, a power measuring apparatus according to the present invention comprises a current sensor that detects a current of a system under measurement, a semiconductor memory device that stores conversion information of the current sensor, Provided in the current detector, voltage input means for inputting the voltage of the measurement system, power calculating means for calculating a voltage input to the voltage input means and a signal from the current sensor of the current detector, and And a power measuring device main body having a control unit for editing data of the result calculated by the power calculating means in accordance with the conversion information stored in the semiconductor memory device.

According to the present invention, even when the current transformer is replaced, the power that allows the user to perform high-precision measurement without manually inputting conversion information for each current transformer into the power measurement device body. A measuring device can be provided.

  Examples of the present invention will be described below.

  A first embodiment of a measuring instrument according to the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 100 denotes a power measuring device main body, which incorporates internal circuits and the like of each part constituting the power measuring device.

Reference numeral 110 denotes a voltage input line made of a copper wire or the like, and inputs a voltage between lines of the system under measurement to the power measuring apparatus main body 100.

A current detector 120 is used in combination with the power measuring apparatus main body 100. A plurality of different types of current detectors are prepared depending on the maximum measurable current, and a current detector having a rated current corresponding to the current of the system under measurement is selected and attached to the power measuring apparatus main body 100. The configuration is the same even for current detectors with different rated currents.

A current sensor 130 is constituted by a current transformer or the like, and converts the current of the system under measurement into a low level current. Note that current detectors having different rated currents have different numbers of windings of the current sensor.

A storage unit 140 includes a semiconductor memory such as a ROM, and stores various conversion information such as a conversion multiplier, a ratio error, and a phase angle error of the current sensor 130. The storage unit 140 outputs an output code corresponding to the given input code.

Reference numeral 145 denotes a connector portion which is made of a resin or the like with a built-in metallic electrode, and engages with a connector portion 150 on the power measuring device main body 100 side, which will be described later.
0 is electrically connected to the power measuring apparatus main body 100.

Reference numeral 150 denotes a receiving-side connector portion made of a resin or the like with a built-in metallic electrode, and engages with the connector portion 145 to electrically couple the current detector 120 and the power measuring device main body 100.

Reference numeral 160 denotes a power calculation unit which is configured by a circuit combining an analog-digital converter and a multiplication circuit, etc., and converts the voltage of the system under test input from the voltage input line 110 and a low level current from the current detector 120. Is multiplied by the calculated signal and converted into calculation data that is directly proportional to the power used by the system under measurement.

Reference numeral 170 denotes a control unit configured by a microcomputer or the like, which receives calculation data from the used power detection unit 160, edits it as power data, and controls storage and display. Here, the power data refers to data relating to the usage status of the consumer, such as power consumption, total accumulated power consumption, and power consumption for each time period.

A display unit 180 includes a liquid crystal display or the like, and displays the edited power data under the control of the control unit 170.

A communication unit 190 includes an interface circuit such as a current loop, and is connected to a telephone line or a network via an external transmission control device. Control unit 170
Under this control, the edited power data is transmitted to the outside.

  Next, the operation of this embodiment will be described with reference to FIG.

The current sensor 130 converts the current of the system under measurement into a low level current. If the current sensor 130 is a 120A current sensor and the conversion ratio is 1/12000, the current sensor 130 converts the current of the system under measurement into 1/12000.

The storage unit 140 is configured by a semiconductor memory such as a ROM, and stores various conversion information such as a conversion multiplier, a ratio error, and a phase angle error of the current sensor 130. Storage unit 140, when given input code '000', outputs an output code representing a conversion multiplier. Here, the conversion multiplier means the reciprocal of the conversion ratio. In this embodiment, the conversion ratio of the current detector 120 is 1 /
If the conversion multiplier is 12000, the storage unit 140 outputs the corresponding output code '100'. The input code is given from the control unit 170 as will be described later.

Storage unit 140, when given input code '001', outputs an output code representing a ratio error. In this embodiment, if the ratio error of the current detector 120 is −0.6%, the storage unit 140 outputs a corresponding output code “110”.

Storage unit 140, when given input code '010', outputs an output code representing a phase angle error. In this embodiment, when the phase angle error of the current detector 120 is −0.3 °, the storage unit 140 outputs a corresponding output code “011”.

As shown in FIG. 2, the output code is a code corresponding to “conversion multiplier”, “ratio error”, and “phase angle error”, and is stored in the storage unit 140 in the current detector 120 at the time of factory shipment.

The current detector 120 has a connector portion 145. Further, the connector portion 145 is formed of the electrode 1
45 a, 145 b, 145 c, 145 d, 145 e, 145 f, and the electrodes are electrodes 150 a, 150 b, 150 c, 1 of the connector unit 150 on the power measuring device main body 100 side.
50d, 150e, and 150f are electrically engaged with each other.

The electrodes 145a and 145b of the connector unit 145 transmit signals from the current sensor 130 to the electrodes 150a and 150b of the connector unit 150. The current sensor 130 is for measuring the maximum current 120A, and converts the current of the system under measurement into a low level current at a conversion ratio of 1/12000, for example. In addition, for example, the conversion ratio is 1/3000 for the measurement of the maximum current 30A, the maximum current 5
A current detector having a built-in current sensor or the like for measuring A and having a conversion ratio of 1/500 is prepared.

The power usage detector 160 performs analog-to-digital conversion on the voltage of the system under test input from the voltage input line 110 and the low-level current converted by the current detector 120, and further multiplies them to use the system under test. Convert to calculation data that is directly proportional to power.

For example, when the voltage of the system under measurement is AC 100V, the current is AC 120A and the power factor is 1.0, the conversion ratio of the current detector 120 is 1/12000, and the current of the system under measurement 120A is converted to 10 mA. Therefore, the power calculation unit 160 outputs calculation data corresponding to 100 V × 10 mA = 1 W.

The control unit 170 receives the calculation data calculated by the power calculation unit 160 and edits the power data. Here, the power data refers to data relating to the usage status of the consumer, such as used power, total accumulated used power, and used power for each time zone.

In order to obtain the conversion multiplier of the current detector 120, the control unit 170 sends the input code “000” to the storage unit 140 via the electrode 150 c of the connector 150 and the electrode 145 c of the connector 145 using a serial code or the like. Electrode 150e and connector 14
The positive side power supply voltage is output via the fifth electrode 145e, and the negative side voltage is output via the electrode 150f of the connector 150 and the electrode 145f of the connector 145.

Since the current detector 120 is for 120A measurement and the conversion multiplier is “12000”, the storage unit 140 outputs a serial code or the like to the control unit 170 via the electrode 145d of the connector 145 and the electrode 150d of the connector 150. The code “100” is output.

The output code is a code corresponding to the “conversion multiplier” shown in FIG. 2, and “conversion multiplier” data corresponding to the code is stored in the control unit 170 in the power measuring apparatus main body 100 at the time of factory shipment. Thereby, the control unit 170 recognizes that the conversion ratio of the connected current detector 120 is “12000”. However, the control unit 170 performs the conversion multiplier “120
The power data is calculated by multiplying the calculation data from the power calculation unit 160 by “00”.

Next, the control unit 170 obtains the input code '001' using a serial code or the like via the electrode 150c of the connector 150 and the electrode 145c of the connector 145 to the storage unit 140 in order to obtain the ratio error of the current detector 120. Via the electrode 150e of the connector 150 and the electrode 145e of the connector 145, the positive side power supply voltage is changed to the electrode 150f of the connector 150, and
The negative voltage is output via the electrode 145f of the connector 145.

When the ratio error of the current detector 120 is −0.6%, the storage unit 140 is set to the control unit 170 via the electrode 145d of the connector 145 and the electrode 150d of the connector 150 at the time of shipment from the factory. The output code '110' corresponding to the ratio error is output.

The output code is a code corresponding to the “ratio error” shown in FIG. 2, and “ratio error” data corresponding to the code is stored in the control unit 170 in the power measuring apparatus main body 100 at the time of factory shipment. Here, the ratio error refers to an error related to the current conversion ratio of the current sensor 130. For example, when the current of the system under measurement is 120A, the current sensor 130 outputs only 9.9mA even though it is designed to output 10mA. If not, the ratio error is -1%.
The current detector 120 is inspected at the time of factory shipment, and an output code corresponding to the ratio error of the current sensor 130 is stored in the storage unit 140. For example, the ratio error is -0.6%
In this case, the output code is “110”, and when the ratio error is −0.2%, the output code is “0”.
10 ′.

The controller 170 that has detected the output code “110” recognizes that the ratio error is “−0.6%”. However, taking into account that the ratio error of the current sensor 130 is “−0.6%”, the control unit 170 calculates the power data by dividing the calculation data from the power calculation unit 160 by “0.994”.

Next, in order to obtain the phase angle error of the current detector 120, the control unit 170 inputs an input code “010” to the storage unit 140 via a serial code or the like via the electrode 150 c of the connector 150 and the electrode 145 c of the connector 145. The positive power supply voltage is output via the electrode 150e of the connector 150 and the electrode 145e of the connector 145, and the negative voltage is output via the electrode 150f of the connector 150 and the electrode 145f of the connector 145.

When the current detector 120 has a phase angle error of −0.3 °, the storage unit 140 stores the connector 145.
Output code '011' corresponding to the phase angle error set at the time of shipment from the factory to the control unit 170 via the electrode 145d of the connector 150 and the electrode 150d of the connector 150
Is output.

The output code is a code corresponding to the “phase angle error” shown in FIG. 2, and the “phase angle error” data corresponding to the code is stored in the control unit 170 in the power measuring apparatus main body 100 at the time of factory shipment. Yes. Here, the phase angle error means an error related to the phase angle generated during current conversion of the current sensor 130. For example, when the phase angle of the output current of the current sensor 130 matches the current of the system under measurement, the phase angle error is When the angle is 0 ° but is advanced by 0.5 °, the phase angle error is −0.5 °. The current detector 120 is inspected at the time of shipment from the factory, and an output code corresponding to the phase angle error of the current sensor 130 is stored in the storage unit 170. For example, when the phase angle error is −0.3 °, the output code is “011” and the ratio error is −
In the case of 0.7 °, the output code is “111”.

The controller 170 that has detected the output code “011” recognizes that the phase angle error is “−0.3 °”. However, the control unit 170 calculates the power data based on the calculation data from the power calculation unit 160 in consideration that the phase angle error of the current sensor 131 is “−0.3 °”.

In this way, even when the current detector is replaced with respect to the power measuring instrument main body, the controller 170
In order to obtain conversion information from the storage unit 140 in the current detector 120, the “conversion multiplier”, “
It is not necessary for the user to manually input data such as “ratio error” and “phase angle error” to the main body of the power measuring apparatus. In addition, since the control unit 170 can automatically acquire conversion information such as “ratio error” and “phase angle error”, a highly accurate power measurement device can be provided.

As described above, by using this embodiment, it is possible to provide a high-accuracy power measurement device that does not require the user to manually input conversion information to the power measurement device main body.

The internal block diagram which shows the structure of Example 1 of the electric power measuring apparatus by this invention Storage contents of the storage unit according to the first embodiment of the power measuring apparatus of the present invention

Explanation of symbols

100 Power measuring device main body 110 Voltage input line 120 Current detector 130 Current sensor 140 Storage unit 145 Connector unit 145a Electrode 145b Electrode 145c Electrode 145d Electrode 145e Electrode 145f Electrode 150 Connector unit 150a Electrode 150b Electrode 150c Electrode 150d Electrode 150e Electrode 150f Electrode 160 Power calculation unit 170 Control unit 180 Display unit 190 Communication unit

Claims (4)

A current sensor for detecting the current of the system under measurement;
A current detector comprising a semiconductor memory device storing conversion information of the current sensor;
Voltage input means for inputting the voltage of the system under measurement;
Power calculating means for calculating a voltage input to the voltage input means and a signal from the current sensor of the current detector;
A power measuring device main body including a control unit that edits data of a result calculated by the power calculating unit in accordance with conversion information stored in the semiconductor memory device provided in the current detector. A power measuring device characterized by the above. The power measurement apparatus according to claim 1, wherein the conversion information is a conversion multiplier of the current sensor. The power measurement apparatus according to claim 1, wherein the conversion information is a ratio error of the current sensor. The power measurement apparatus according to claim 1, wherein the conversion information is a phase angle error of the current sensor.

Images