JP5855070B2 - Measuring apparatus and current transformer installation state determination method - Google Patents

Description

  The present invention relates to a measuring device that measures current, voltage, power, and the like of a system to be measured, and a current transformer installation state determination method.

  Measuring devices that measure power consumption and power consumption in factories and general households are widespread. This measuring device is installed on the power line of the system to be measured, measures the voltage and current of the power line, and measures the power consumption and the power consumption using the measured voltage value and current value. In general, a voltage dividing circuit is used for voltage measurement, and a current transformer (CT) is used for current measurement.

  Current transformers are classified into "non-split type" and "split type" depending on the difference in structure. The non-divided type is mainly used when a power supply line is newly installed because it is necessary to pass the power supply line to be measured through the center of the core. Since the split type has a structure in which the core of the current transformer can be divided, it can be clamped without removing the power line. For this reason, it can be used also about the power supply line already installed (patent document 1).

  In the split type, the split surfaces of the core are usually brought into full contact with each other and clamped to the power line. This is because if the split surfaces of the cores are incomplete contact, characteristics such as the ratio error and phase error of the current transformer differ from the specifications, and accurate measurement cannot be performed. Further, if the detection coil wound around the core is disconnected, measurement becomes impossible.

  Therefore, the measuring device of Patent Document 1 applies a voltage to the detection coil of the split-type current transformer by the ON / OFF operation of the test power source, and based on the level of the induced voltage generated in the detection coil, The disconnection of the detection coil is detected. That is, the current transformer installation failure is determined only by the induced voltage level generated in the detection coil. For example, when the induced voltage level exceeds a threshold value, it is determined as normal, and when it does not exceed, it is determined as an installation failure.

JP 2003-149275 A

  In the measurement apparatus of Patent Document 1, the detection sensitivity is low because the installation failure of the current transformer is determined only by the output signal level of the detection coil. For example, in the case of an installation failure such as clamping with a small amount of dust attached to the divided surface, the output signal level of the detection coil exceeds the threshold to a slight extent, so the signal level is normal as a result. . As described above, if the change in the output signal level is small, the deterioration of the parameter for obtaining the ratio error is small. However, in this installation failure, the change in the phase of the output signal of the detection coil is large. That is, the parameter for obtaining the phase error is deteriorated. Nevertheless, it cannot be determined as a current transformer installation failure. Even in the case of the non-divided type, there is a possibility that the parameter for obtaining the phase error may be deteriorated due to the surrounding situation where it is installed, aging, and the like.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a measuring device and a current transformer installation state determination method capable of detecting a current transformer installation failure with high accuracy. It is another object of the present invention to provide a measuring device that can be calibrated in the state even if there is a current transformer installation failure and can eliminate the need for re-installation of the current transformer.

In order to achieve the above object, a measuring apparatus according to the present invention includes a current transformer, a test current source, detection means, an acquisition unit, and an installation state determination unit. The current transformer includes a detection coil having a first detection coil and a second detection coil for measuring the current of the power supply line. The test current source supplies a test current signal having the same frequency as the current of the power supply line to the first detection coil. The detecting means detects the induced current signal induced in the second detection coil by the magnetic flux generated in the first detection coil when the test current signal is supplied. The acquisition unit acquires a signal level ratio and a phase difference between the test current signal from the test current source and the induced current signal detected by the detection means. The installation state determination unit determines the installation state of the current transformer based on whether or not the signal level ratio and the phase difference acquired by the acquisition unit are set values.

  According to the present invention, the installation state determination unit has a signal level between the test current signal supplied to the first detection coil and the induced current signal induced in the second detection coil by the magnetic flux generated in the first detection coil. The installation state of the current transformer is determined based on whether the ratio and the phase difference are at the set values. Therefore, it is possible to detect an installation failure that causes the phase error parameter to deteriorate. Therefore, it is possible to provide a measuring device and a current transformer installation state determination method capable of detecting a current transformer installation fault with high accuracy.

It is a block diagram of the measuring device which concerns on Embodiment 1 of this invention. It is a block diagram of CT of the measuring device which concerns on Embodiment 1 of this invention. (A) is a figure which shows a connection structure when a current signal measurement part is a normal measurement mode, (b) is a figure which shows a connection structure when a current signal measurement part is CT installation state determination mode, (c) is a current signal for a test. It is a figure which shows the waveform of an induced current signal. It is a flowchart of CT installation state determination operation | movement of the measuring device which concerns on Embodiment 1 of this invention.

  Hereinafter, a measuring device and a current transformer installation state determination method according to an embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
As shown in FIG. 1, the measuring apparatus 100 according to Embodiment 1 of the present invention measures the power consumption of a load 300 using, for example, a CT (current transformer) 200, and the installation trouble of the CT 200 is reduced. It can be detected, and the deterioration of the parameter due to the installation failure can be corrected. The CT 200 is installed on the power line 400 connected to the load 300.

  As shown in FIG. 2, the CT 200 is a divided CT including a detection coil 210 and a core 220.

  The detection coil 210 is a single-turn coil including two coils of a first detection coil 211 and a second detection coil 212 connected in series. One end of the first detection coil 211 is connected to the terminal Ta, and the other end is connected to the terminal Tb. One end of the second detection coil 212 is connected to the terminal Tb, and the other end is connected to the terminal Tc. In the detection coil 210, an induced current is generated in a direction that obstructs the magnetic flux generated in the core 220 due to the current flowing in the power supply line 400.

  The core 220 includes a first core 221, a second core 222, and a dividing surface 223. The first core 221 and the second core 222 are made of a magnetic material such as ferrite.

  The CT 200 can pass the power supply line 400 into the core 220 by separating the dividing surfaces 223 of the first core 221 and the second core 222. Thereafter, the first core 221 and the second core 222 are brought into close contact with each other at the dividing surface 223 and clamped (joined with a clasp or the like). In this way, the CT 200 is installed on the power line 400.

  As shown in FIG. 1, the load 300 is a load to be measured connected to the power supply line 400, and is an electric product such as a home appliance or a machine tool.

  The measuring apparatus 100 includes a resistance voltage dividing circuit 101 for measuring the voltage of the power line 400, a current signal measuring unit 110 for measuring a current flowing through the power line 400 using the CT 200, and a voltage value of the power line 400. And a power-related amount calculation unit 103 that obtains a current value and power consumption of the load 300, and a storage unit 104 that stores in advance information on the conversion ratio, ratio error, and phase error of the CT 200.

  The resistance voltage dividing circuit 101 divides the voltage of the power supply line 400, converts it to a low voltage electric signal, and outputs it to the A / D converter 102.

  The A / D converter 102 converts the voltage of the electrical signal output from the resistance voltage dividing circuit 101 from an analog value to a digital value, and outputs the converted value to the power related amount calculation unit 103.

  The current signal measurement unit 110 measures the induced current induced in the detection coil 210 of the CT 200 by the current flowing through the power line 400 and outputs a voltage value indicating the measured current to the A / D converter 120.

  The A / D converter 120 converts the voltage value output from the current signal measurement unit 110 from an analog value into a digital value, and outputs the converted value to the power related amount calculation unit 103.

  The power related amount calculation unit 103 obtains the voltage value of the power supply line 400 based on the digital voltage value output from the A / D converter 102. In addition, the power related amount calculation unit 103 converts the CT200 conversion ratio, the ratio error, and the digital voltage value indicating the current flowing through the detection coil 210 output from the A / D converter 120, into the storage unit 104. The current value of the power line 400 is obtained by multiplying, adding and subtracting the information of the phase error. In addition, the power-related amount calculation unit 103 obtains the power used and the amount of power used by the load 300 using the obtained voltage value and current value. In addition, the power-related amount calculation unit 103 controls the communication unit 105 that transmits the obtained voltage value, current value, used power, used power amount, and the like to an external device.

  The storage unit 104 stores information on the conversion ratio, ratio error, and phase error of the CT 200 in advance. These pieces of information are information necessary for the power-related amount calculation unit 103 to accurately obtain the voltage value, current value, power, and power amount.

  The conversion ratio is a value indicating a current conversion ratio for obtaining a current value, and is determined by the number of turns of CT200. Ratio error is the error that results from the true current ratio not being equal to the nominal current ratio. The phase error is a phase shift between the current actually flowing through the power supply line and the measured current, and is an error caused by the electrical characteristics of the current transformer itself.

  The storage unit 104 also stores in advance setting values (for example, a level ratio setting value Ls and a phase difference setting value θs) used in a CT installation state determination process described later. The level ratio setting value Ls is a value for determining whether or not the signal level ratio Ld acquired in the CT installation state determination process is within the allowable error ± ε1 from the reference value with the level ratio setting value Ls as a reference value. It is. The phase difference set value θs is a value for determining whether or not the phase difference Pd acquired in the CT installation state determination process is within a tolerance ± ε2 from the reference value with the phase difference set value θs as a reference value. is there.

  The communication unit 105 is an I / F (interface) that performs communication with an external device such as a computer. The communication unit 105 transmits the measurement values (such as the voltage value and current value of the power line 400, the power used by the load 300, and the power used) obtained by the power related amount calculation unit 103 to an external device.

  The display unit 106 is, for example, a liquid crystal display, and can display measured values such as a voltage value, a current value, power, and power amount obtained by the power related amount calculation unit 103. A plasma display other than a liquid crystal display or an organic EL display may be used.

  The power supply unit 107 generates a drive power supply voltage from the power supply line 400. The measuring device 100 is operated by the drive power supply voltage from the power supply unit 107. Note that a battery may be used as the power supply unit 107. As the battery, for example, a primary battery, a chemical battery of a secondary battery, a physical battery such as a solar battery, or the like may be used.

  A breaker 500 is disposed on the power line 400. As shown in FIG. 1, the breaker 500 is disposed in the power supply line 400 at a location between the input terminal 101 a of the resistance voltage dividing circuit 101 and the CT 200.

  Furthermore, the measuring apparatus 100 includes a test current source 130 that outputs a test current signal, a CT installation state determination mode switch 140 operated by a user, and a CT installation state determination unit 150 that determines the installation state of the CT 200. .

  The test current source 130 is an AC constant current source used when determining the CT installation state. The alternating current has the same frequency as that applied to the power supply line 400, for example. The test current source 130 switches the output ON / OFF according to the control of the CT installation state determination unit 150 between normal measurement and CT installation state determination. The test current source 130 turns off the output during normal measurement and does not output a test current signal. Further, the test current source 130 turns on the output when the CT installation state is determined, and outputs a test current signal.

  The CT installation state determination mode switch 140 is a switch used by the user to instruct whether the measurement apparatus 100 is in a normal measurement operation mode or a CT installation state determination operation mode. If the CT installation state determination mode switch 140 is OFF, for example, the CT installation state determination unit 150 is instructed to perform a normal measurement operation, and if it is ON, the CT installation state determination unit 150 is instructed to perform a CT installation state determination operation.

  Based on the ON / OFF of the CT installation state determination mode switch 140, the CT installation state determination unit 150 controls the change of the internal circuit configuration of the current signal measurement unit 110 and the ON / OFF switching control of the output of the test current source 130. And do.

  Specifically, if the CT installation state determination mode switch 140 is OFF, the CT installation state determination unit 150 sets the current signal measurement unit 110 to the normal measurement mode connection configuration illustrated in FIG. Set to OFF. Further, if the CT installation state determination mode switch 140 is ON, the CT installation state determination unit 150 sets the current signal measurement unit 110 to the connection configuration of the CT installation state determination mode shown in FIG. Turn on.

  The current signal measurement unit 110 changes the internal circuit configuration between a normal measurement mode in which normal measurement is performed and a CT installation state determination mode in which a CT installation state is determined in accordance with the control of the CT installation state determination unit 150. Specifically, the current signal measurement unit 110 changes to the connection configuration shown in FIG. 3A at the time of normal measurement and to the connection configuration shown in FIG. 3B at the time of CT installation state determination. In addition, since the breaker 500 is turned off by the user at the time of CT installation state determination, CT200 will be in the state which clamps the power supply line 400 of a non-energized state.

  As shown in FIG. 3, the current signal measurement unit 110 includes a detection resistance element 111 for detecting an induced current induced in the detection coil 210.

  In the normal measurement mode, the current signal measurement unit 110 has terminals Ta and Tc at both ends of a detection coil 210 in which a first detection coil 211 and a second detection coil 212 are connected in series, as shown in FIG. Further, both ends of the detection resistive element 111 are connected. The induced current induced in the detection coil 210 by the current flowing in the power line 400 is converted into a voltage representing the current flowing in the detection coil 210 by the detection resistance element 111. A detection voltage at the detection resistance element 111 is input to the A / D converter 120. The detected voltage is converted from an analog value into a digital value by the A / D converter 120 and input to the power-related amount calculation unit 103.

  In the CT installation state determination mode, the current signal measurement unit 110 connects both terminals of the test current source 130 to the terminals Ta and Tb at both ends of the first detection coil 211 as shown in FIG. 2 Both ends of the detection resistance element 111 are connected to the terminals Tb and Tc at both ends of the detection coil 212. The test current source 130 supplies a test current signal It, which is an alternating constant current, to the first detection coil. As a result, the induced current induced in the second detection coil 212 is converted into a voltage representing the current flowing in the second detection coil 212 by the detection resistance element 111. That is, the induced current signal is detected by the detection resistance element 111. A detection voltage at the detection resistance element 111 is input to the A / D converter 120. The detected voltage is converted from an analog value into a digital value by the A / D converter 120 and input to the CT installation state determination unit 150.

  The CT installation state determination unit 150 includes an acquisition unit 151 that acquires a signal level ratio Ld between the test current signal It and the induced current signal Im and a phase difference Pd between the test current signal It and the induced current signal Im. . The signal level ratio Ld is, for example, a ratio (= Mmax / Tmax) between the maximum value Tmax of the test current signal It and the maximum value Mmax of the induced current signal Im. The phase difference Pd is a phase shift between the test current signal It and the induced current signal Im. Note that the signal level ratio Ld may be acquired using an effective value and an average value in addition to the maximum value. The average value is, for example, a value obtained by averaging either positive or negative half cycles.

  The CT installation state determination unit 150 uses the signal level ratio Ld and the phase difference Pd acquired by the acquisition unit 151 as the set values stored in the storage unit 104 (for example, the level ratio set value Ls ± ε1, the phase difference set value θs). It is determined whether it is within ± ε2), and the CT installation state is determined. If the signal level ratio Ld and the phase difference Pd are at the set values, it is determined that “CT installation is good”, and if it is outside the set values, it is determined that “CT installation failure”.

  Then, CT installation state determination unit 150 outputs the determination result to CT installation state notification unit 170.

  If the CT installation state determination unit 150 determines that there is a CT installation failure, the updated ratio error and phase error are updated based on the signal level ratio Ld and the phase difference Pd acquired by the acquisition unit 151. Find the value.

  Specifically, the difference ΔL between the level ratio set value Ls stored in the storage unit 104 and the acquired signal level ratio Ld is added to the ratio error RE1 before update, and the ratio error RE2 after update (RE2 = RE1 + ΔL). Ask for. This is because the shift ΔL affects only the ratio error.

  In addition, since the conversion ratio is determined by the number of turns of the CT 200, it does not change due to a CT installation defect or the like. For this reason, the conversion ratio is not updated based on the deviation ΔL. That is, the conversion ratio remains the same before and after the update.

  Further, the phase error PE2 (PE2 = PE1 + Δθ) after the update is obtained by adding the deviation Δθ between the phase difference set value θs stored in the storage unit 104 and the acquired phase difference Pd to the phase error PE1 before the update. .

  When the CT installation state determination unit 150 obtains the update value, the CT installation state determination unit 150 instructs the correction value update unit 160 to update information stored in the storage unit 104 (CT200 ratio error and phase error information). When the CT installation state determination unit 150 receives a notification of completion of the update operation of the storage information in the storage unit 104 from the correction value update unit 160, the CT installation state determination unit 150 outputs the update completion to the update notification unit 180.

  The correction value update unit 160 updates the storage information in the storage unit 104 to the update value when the CT installation state determination unit 150 determines that there is a CT installation failure. After the update is completed, the correction value update unit 160 notifies the power related amount calculation unit 103 and the CT installation state determination unit 150 of the completion of the update operation.

  The CT installation state notification unit 170 displays the determination result of the CT installation state determination unit 150 on the display unit 106 in accordance with an instruction from the CT installation state determination unit 150. By showing the determination result display to the user, the determination result is notified to the user. In addition, you may make it audio-output with the display of the determination result by the display part 106. FIG. Moreover, as a notification method, LED display and segment display may be used in addition to display by a liquid crystal display, or only sound output may be used.

  When the correction value update unit 160 updates the storage information in the storage unit 104, the update notification unit 180 causes the display unit 106 to display an update operation state such as updating or completion of update. The user is notified by showing this display to the user.

  After the update of the storage unit 104 is completed, the correction value update unit 160 notifies the power related amount calculation unit 103 and the CT installation state determination unit 150 of the update completion. Receiving the notification, the power related amount calculation unit 103 thereafter calculates the voltage value, current value, power used by the load 300, and the like using the conversion ratio and the updated ratio error and phase error. I do. Further, the CT installation state determination unit 150 that has received the notification notifies the update notification unit 180 of the completion of the update.

  Next, the operation of the measuring apparatus 100 having the above configuration will be described. The operation of the measuring apparatus 100 includes a normal measurement mode and a CT installation state determination mode. Hereinafter, it demonstrates according to mode.

<Normal measurement mode>
The measurement apparatus 100 performs a normal measurement operation when the CT installation state determination mode switch 140 is set to OFF by the user. Specifically, the voltage value of the power supply line 400 is obtained by multiplying the output of the A / D converter 102 by the voltage division ratio. Further, the current value of the power line 400 is obtained by multiplying the output of the A / D converter 120 by the conversion ratio. A phase error is added to or subtracted from the obtained current value to obtain the phase of the current flowing through the power supply line 400. The power factor is obtained using the phase, and the power (for example, active power) is obtained using the voltage value, the current value, and the power factor. That is, the voltage value and current value of the power supply line 400, the power consumption of the load 300, the power consumption amount, and the like are measured. The measured value is displayed on the display unit 106.

<CT installation state judgment mode>
Next, the CT installation state determination operation of the measurement apparatus 100 will be described with reference to FIG. The user performs the CT installation state determination operation of the measuring apparatus 100 at the time of initial installation in which the CT 200 is clamped to the power supply line 400, at the time of periodic diagnosis when a predetermined period such as six months or one year has passed.

  Before starting the CT installation state determination of the measuring apparatus 100, the user turns off the breaker 500 shown in FIG. For this reason, the circuit breaker 500 and subsequent parts of the power line 400 are not energized. That is, the power supply line 400 in the CT 200 is not energized. Even when the breaker 500 is turned OFF, the input terminal 101a of the resistance voltage dividing circuit 101 is connected upstream of the breaker 500, so that the power supply unit 107 of the measuring apparatus 100 generates a drive power supply voltage.

  Then, when the user turns on the CT installation state determination mode switch 140, the CT installation state determination of the measurement apparatus 100 starts.

  The CT installation state determination unit 150 instructs the current signal measurement unit 110 to enter the CT installation state determination mode and instructs the test current source 130 to turn on. The current signal measurement unit 110 changes to the connection configuration in the CT installation state determination mode shown in FIG. The test current source 130 starts supplying the test current signal It to the first detection coil 211 shown in FIG. 3B (step S101).

  The CT installation state determination unit 150 outputs an output signal from the test current source 130 (test current signal It) and an output signal from the A / D converter 120 (inducted current obtained by detecting the induced current by the detection resistance element 111). CT installation state processing for determining the CT installation state based on the signal Im) is performed (step S102).

  In the CT installation state determination process, if the output signal of the A / D converter 120 is “0”, the CT installation state determination unit 150 is disconnected from the first detection coil 211 or the second detection coil 212. Judged as “disconnected”.

  Further, as shown in FIG. 3C, the acquisition unit 151 obtains the signal level ratio Ld between the test current signal It and the induced current signal Im and the phase difference Pd between the test current signal It and the induced current signal Im. get. If the signal level ratio Ld and the phase difference Pd are set values (for example, the level ratio set value Ls and the phase difference set value θs) stored in advance in the storage unit 104, the CT installation state determination unit 150 determines “normal”. If it deviates from the set value, it is determined as “installation failure”.

  The CT installation state determination unit 150 outputs the determination result in step S102 to the CT installation state notification unit 170. The CT installation state notifying unit 170 displays the determination result on the display unit 106 and notifies the user (step S103).

  When the determination result is “installation failure”, the CT installation state determination unit 150 instructs the correction value update unit 160 to update the information (ratio error and phase error) stored in the storage unit 104. Further, the signal level ratio Ld and the phase difference Pd between the output signal of the test current source 130 (test current signal It) and the output signal of the A / D converter 120 (inductive current signal Im) acquired in step S102 are expressed as follows: It transmits to the correction value update part 160 (step S104).

  The correction value update unit 160 updates the information stored in the storage unit 104 (CT200 ratio error and phase error information) (step S105).

  Specifically, the CT installation state determination unit 150 determines the difference ΔL between the level ratio set value Ls stored in the storage unit 104 and the signal level ratio Ld between the test current signal It and the induced current signal Im acquired in step S102. To the ratio error RE1 before update, and the ratio error RE2 after update (RE2 = RE1 + ΔL) is obtained. As described above, since the shift ΔL affects only the ratio error, the conversion ratio is not updated.

  Further, the CT installation state determination unit 150 calculates a difference Δθ between the phase difference setting value θs stored in the storage unit 104 and the phase difference Pd between the test current signal It and the induced current signal Im acquired in step S102. In addition to the phase error PE1 before update, a phase error PE2 after update (PE2 = PE1 + Δθ) is obtained. The correction value update unit 160 updates the storage information in the storage unit 104 to the updated ratio error and phase error obtained by the CT installation state determination unit 150.

  When the update of the information stored in the storage unit 104 is completed, the correction value update unit 160 notifies the power related amount calculation unit 103 and the CT installation state determination unit 150 of the completion of the update (step S106).

  Receiving the update completion notification, the power-related amount calculation unit 103 acquires update values (updated ratio error RE2 and phase error PE2) from the storage unit 104, and uses the acquired update values in the subsequent normal measurement mode to perform CT200. The calculation processing for obtaining the voltage value, current value, power consumption of the load 300, and the like is performed. Further, the CT installation state determination unit 150 that has received the update completion notification notifies the update notification unit 180 of the completion of the update. The update notification unit 180 displays the update completion on the display unit 106 and notifies the user that the information update of the storage unit 104 has been completed.

  As described above, according to the measuring apparatus 100 according to Embodiment 1 of the present invention, the CT installation state determination unit 150 uses the acquisition unit 151 to obtain the acquired value (the signal of the test current signal It and the induced current signal Im). Since the installation state of the CT 200 is determined based on whether or not the level ratio Ld and the phase difference Pd) are at the set values, in addition to detection of an installation failure that causes deterioration of parameters for obtaining the CT 200 ratio error. Therefore, it is possible to detect an installation failure that causes deterioration of parameters for obtaining the phase error of the CT 200, and it is possible to improve detection sensitivity. Therefore, it is possible to provide the measuring apparatus 100 that can detect the installation failure of the CT 200 with high accuracy. For example, in the case of the split type CT, it is possible to detect an installation failure such as clamping with a small amount of dust attached to the split surface 223 of the core 220. Further, even in the case of non-divided CT, the installation state can be determined with high accuracy.

  Further, the correction value update unit 160 performs processing for updating the information on the ratio error and the phase error stored in the storage unit 104 based on the signal level ratio and the phase difference of the CT 200 acquired by the acquisition unit 151. Therefore, the CT 200 can be calibrated after being installed on the power line 400. Even if a CT200 installation failure occurs, the voltage value and current value of the power supply line 400, the power consumption of the load 300, the usage of the power supply line 400 using the new information after calibration (the updated ratio error RE2 and phase error PE2). The amount of power can be determined. That is, since CT200 can be measured in a calibrated state, the user does not need to re-install CT200.

  In addition, the CT installation state notification unit 170 notifies the user of the determination result of the CT installation state determination unit 150. Therefore, the installation state of CT200 can be known. The update notification unit 180 notifies the user of the update operation state when the correction value update unit 160 updates the storage unit 104. Therefore, when the correction value update unit 160 updates the storage unit 104, it is possible to notify the user of an update operation state such as updating or completion of update.

  Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  In the measurement apparatus 100 of the above-described embodiment, the split type CT 200 is used, but the present invention is not limited to this. For example, non-divided CT may be used.

  Further, the CT installation state determination unit 150 may acquire the signal level ratio Ld and the phase difference Pd between the analog signal test current signal It and the analog signal induced current signal Im.

  In step S102 of the above-described embodiment, the test current source 130 sequentially outputs a plurality of output signals (test current signals It) having different output levels and periods. For each output signal, the CT installation state determination unit 150 compares the signal level ratio Ld between the output signal of the test current source 130 (test current signal It) and the output signal of the A / D converter 120 (inductive current signal Im). And the phase difference Pd between the two output signals. The CT installation state determination unit 150 obtains one signal level ratio Ld and phase difference Pd by analysis such as averaging and normalizing a plurality of signal level ratios Ld and phase differences Pd. You may make it determine the installation malfunction of CT200 based on phase difference Pd. In this case, the installation failure can be detected with higher accuracy. In step S105, the updated value of the storage unit 104 can be obtained more accurately.

  In the present embodiment, the measurement apparatus 100 includes the display unit 106, but the display unit 106 may be configured to be included in an external device. By adopting a configuration in which an external device communicates with the CT installation state determination unit 150 using the communication unit 105, the measurement device 100 does not have to include the display unit 106 such as a liquid crystal display, and the measurement device 100 can be downsized. Can do. Furthermore, the user can determine the CT installation state even at a place away from the measuring apparatus 100, and usability is improved.

  In the embodiment, the power-related amount calculation unit 103 acquires all of the voltage value and current value of the power supply line 400, the power consumption of the load 300, and the power consumption amount. At least one of these values is obtained. May be obtained.

  In the embodiment, as shown in FIGS. 3A and 3B, the detection resistance element 111 is commonly used for both normal measurement and CT connection determination. Different detection resistance elements may be used for the CT connection determination.

  The detection coil 210 of the above-described embodiment is a single-turn coil in which the first detection coil 211 and the second detection coil 212 are connected in series, but is not limited to this. For example, a compound coil may be used.

  In the measurement apparatus 100 of the above-described embodiment, the resistance voltage dividing circuit 101 is used as shown in FIG. 1 in order to measure the voltage. However, the present invention is not limited to this. For example, a voltage transformer may be used.

  DESCRIPTION OF SYMBOLS 100 Measuring apparatus, 101 Resistance voltage dividing circuit, 102 A / D converter, 103 Electric power related quantity calculating part, 104 Memory | storage part, 105 Communication part, 106 Display part, 110 Current signal measuring part, 111 Detection resistive element (detection means) ), 120 A / D converter (detection means), 130 test current source, 140 CT installation state determination mode switch, 150 CT installation state determination unit (installation state determination unit), 151 acquisition unit, 160 correction value update unit, 170 CT installation state notification unit (installation state notification unit), 200 CT, 210 detection coil, 211 first detection coil, 212 second detection coil, 221, 222 core, 223 division plane, 400 power supply line, 500 breaker

Claims (7)

A current transformer comprising a detection coil having a first detection coil and a second detection coil for measuring the current of the power line;
A test current source for supplying a test current signal having the same frequency as the current of the power supply line to the first detection coil;
Detecting means for detecting an induced current signal induced in the second detection coil by a magnetic flux generated in the first detection coil by being supplied with a test current signal;
An acquisition unit for acquiring a signal level ratio and a phase difference between a test current signal from the test current source and an induced current signal detected by the detection unit;
An installation state determination unit that determines an installation state of the current transformer based on whether the signal level ratio and the phase difference acquired by the acquisition unit are set values;
A measuring device comprising: The current transformer is a split type current transformer including a core having a split surface,
The detection coil is a single coil in which the first detection coil and the second detection coil are wound around the core, and outputs an electric signal corresponding to a change in magnetic flux generated by a current flowing through the power line. is there,
The measuring apparatus according to claim 1. A storage unit for storing information on a ratio error and a phase error of the current transformer;
A correction value update unit that performs a process of updating the information stored in the storage unit based on a signal level ratio and a phase difference of the current transformer acquired by the acquisition unit;
Comprising
The measuring apparatus according to claim 1, wherein: A power-related amount calculation unit that obtains at least one of voltage, current, power, and energy by using the conversion ratio, ratio error, and phase error information of the current transformer;
When the information stored in the storage unit is updated, the power-related amount calculation unit acquires at least one of voltage, current, power amount, and power using the updated information.
The measuring device according to claim 3. An installation state notification unit for notifying the user of the determination result of the installation state determination unit;
An update notification unit that notifies the user of an update operation state when the correction value update unit updates the storage unit;
Comprising
The measuring apparatus according to claim 3 or 4, wherein The test current source supplies a plurality of test current signals to the first detection coil,
The acquisition unit includes a plurality of signal level ratios and a plurality of levels of a plurality of test current signals from the test current source and a plurality of induced current signals detected by the detection unit for each of the plurality of test current signals. Obtain a phase difference, analyze the multiple signal level ratios and multiple phase differences to obtain a single signal level ratio and phase difference,
The installation state determination unit determines the installation state of the current transformer based on whether the one signal level ratio and the phase difference acquired by the acquisition unit are at a set value,
The measuring apparatus according to claim 1, wherein An installation state determination method for determining an installation state of a current transformer to a power line,
Supplying a test current signal having the same frequency as the current of the power supply line to the first detection coil of the detection coil having a first detection coil and a second detection coil in a non-energized state of the power supply line ; ,
A detection step of detecting an induced current signal induced in the second detection coil by a magnetic flux generated in the first detection coil by being supplied with a test current signal;
Obtaining a signal level ratio and phase difference between the test current signal and the induced current signal;
A determination step of determining the installation state of the current transformer based on whether or not the acquired signal level ratio and phase difference are set values;
An installation state determination method for a current transformer, comprising:

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