JP5235705B2 - Measuring system - Google Patents

Description

  The present invention relates to a measurement system that performs synchronous measurement of a plurality of powers using a plurality of power measurement devices.

  As this type of measurement system, a system using a power measuring instrument disclosed in Patent Document 1 below is known. This power meter is configured to be selectively set to either the master mode or the slave mode. When synchronous measurement is performed using a plurality of power measuring devices, the measurement start signal output from the internal measurement start signal generating circuit of the power measuring device set to the master mode is set to the plurality of power measuring devices set to the slave mode. The measurement end signal output from the external signal output terminal of the power measuring device set to the master mode is connected to the external signal input terminal of the power measuring device. It connects so that it may be transmitted to the external measurement end signal input terminal in a power meter. As a result, when the power meter in the master mode starts measurement, the measurement start signal generated by this power meter is transmitted to each power meter in the slave mode, and each power meter in the slave mode simultaneously When the power measurement is started and the power meter in the master mode ends the measurement, the measurement end signal generated by this power meter is sent to each power meter in the slave mode, and each power measurement in the slave mode is performed. Simultaneously terminates the power measurement. Therefore, in a measurement system using a plurality of power measuring devices, synchronous measurement with a temporal shift suppressed is possible.

Japanese Patent No. 3896775 (pages 4-5 and 3-4)

  However, the following problems to be solved exist in the measurement system composed of the power measuring device. That is, in this type of wattmeter including the wattmeter, each slave mode power meter measures power directly in synchronization with the measurement start signal and measurement end signal itself transmitted from the master mode power meter. Start and power measurement is finished. However, strictly speaking, a signal delay corresponding to the distance between the master mode power meter and the slave mode power meter always occurs in the measurement start signal and the measurement end signal. For this reason, there is a problem to be solved in the measurement system constituted by these power measuring devices that there is always a time lag between the power measuring devices at both the measurement start timing and the measurement end timing. doing.

  By the way, such a measurement system often employs a configuration in which the measurement time data is stored together with the measurement data for each measuring device. In this configuration, a time generation unit (for example, an RTC) that generates time for each measuring device is employed. ). In the measurement system having this configuration, it is preferable to synchronize the time generated by the time generation unit of each measuring device in order to compare the temporal change of measurement data with high accuracy between the measuring devices. Various methods are known as time synchronization methods. For example, the present applicant has also proposed a measurement system that can synchronize the measurement time of the master side measurement device and the measurement time of the slave side measurement device in Japanese Patent Application Laid-Open No. 2006-292448. According to this measurement system, Measurements generated at each measurement time generator in the master-side measuring device and all slave-side measuring devices by transmitting time data advanced by the time required for the time data to be received by each time generator. It is possible to accurately synchronize the date data indicating the time. As another method, a time synchronization method using GPS (Global Positioning System) is also known. For this reason, the inventors of the present application have determined that the measurement start timing between the master side measurement device and the slave side measurement device under the condition that the internal time of the master side measurement device and the internal time of the slave side measurement device are synchronized. And it was thought that the time lag at the measurement end timing could be further reduced.

  The present invention has been made to solve such a problem, and a main object of the present invention is to provide a measurement system that can significantly reduce the time lag between the measurement start timing and the measurement end timing.

  To achieve the above object, the measurement system according to claim 1 includes a time generation unit that generates time data and a measurement unit that measures an electrical parameter based on an input signal, and the time data indicates the same time. In this measurement system, the time generators are synchronized with each other, and one of the plurality of measurement devices is a master measurement device and the other is a slave measurement device. Then, the measurement units of all the measurement devices execute a process of repeatedly measuring unit periods of the same length synchronized with each other based on the time data, and the measurement units of the master measurement device The nth unit period (n is an integer of 1 or more) measured after the start instruction signal is output to the slave measurement device in synchronization with the beginning and the start instruction signal is output The measurement of the electrical parameter is started in synchronization with the beginning of the period, and the end instruction signal is output to the slave measuring device in synchronization with the beginning of the unit period, and the mth measured after the end instruction signal is output. The measurement of the electrical parameter is finished in synchronization with the beginning of the unit period (m is an integer equal to or greater than 1), and the measurement unit of the slave measurement device measures the n measured after the start instruction signal is input The measurement of the electrical parameter is started in synchronization with the beginning of the unit period of the first unit, and the measurement of the electrical parameter is performed in synchronization with the beginning of the unit period of the mth unit that is measured after the input of the end instruction signal. End measurement.

  The measurement system according to claim 2 is the measurement system according to claim 1, wherein the slave measurement device inputs the start instruction signal and the end instruction signal through the instruction signal input unit and inputs the start instruction signal and the end instruction signal. The start instruction signal and the end instruction signal are output to the outside through the instruction signal output unit.

Further, in the measurement system according to claim 3, in the measurement system according to claim 1 or 2, when the measurement unit of the master measurement device inputs an external start instruction signal from the outside, When the start instruction signal is output to the slave measurement device in synchronization with the beginning of the unit period of i-th (i is an integer of 1 or more) measured after input, and the external end instruction signal is input from the outside In addition, the end instruction signal is output to the slave measuring device in synchronization with the beginning of the j-th unit period (j is an integer of 1 or more) measured after the input of the external end instruction signal.

  In the measurement system according to claim 1, the measurement units of all the measurement apparatuses repeatedly measure unit periods of the same length synchronized with each other based on the time data output from the time generation unit. The measurement unit of the master measurement device outputs a start instruction signal to the slave measurement device in synchronization with the beginning of the unit period, and in synchronization with the beginning of the nth unit period measured after the output of the start instruction signal. The measurement of electrical parameters is started, and an end instruction signal is output to the slave measuring device in synchronization with the beginning of the unit period, and at the beginning of the mth unit period measured after the output of the end instruction signal. To complete the measurement of the electrical parameters. The measurement unit of the slave measurement device of the power measurement device starts measuring the electrical parameter in synchronization with the beginning of the nth unit period measured after the start instruction signal is input, and The measurement of the electrical parameter is finished in synchronization with the beginning of the m-th unit period measured after the end instruction signal is input.

  Therefore, according to this measurement system, measurement of electrical parameters is started in synchronization with the beginning of the same unit period (unit period measured at the same timing) in all measurement apparatuses, and measurement of this unit period is performed. Measurement of electrical parameters can be completed in synchronization with the beginning of the same unit period (unit period measured at the same timing) that is measured later (the time difference between the measurement start timing and measurement end timing) Therefore, it is possible to measure the electrical parameters in each measuring device in a state where the measurement periods are matched with high accuracy. As a result, for example, the electrical parameters measured in each measuring device can be measured with high accuracy. Can be compared.

  In the measurement system according to claim 2, the start instruction signal and the end instruction signal input by the slave measurement apparatus via the instruction signal input unit are output to the outside via the instruction signal output unit (the start instruction signal and the end instruction signal). Therefore, a plurality of slave measuring devices can be connected to the master measuring device by a daisy chain method. Therefore, according to this measurement system, it is not necessary to configure the instruction signal output unit of each measurement device using expensive electronic components with a large fan-out capability (current supply capability), so the measurement periods are matched with high accuracy. In addition, the device cost can be reduced.

  In the measurement system according to claim 3, when the measurement unit of the master measurement device inputs an external start instruction signal from the outside, it synchronizes with the beginning of the i-th unit period measured after the input of the external start instruction signal. When the start instruction signal is output to the slave measuring apparatus and the external end instruction signal is input from the outside, in synchronization with the beginning of the jth unit period measured after the input of the external end instruction signal An end instruction signal is output to the slave measuring device. Therefore, according to this measurement system, the master measurement device synchronizes the external instruction signal, which is an asynchronous signal for itself, to the slave measurement device in synchronization with the unit period measured in a synchronized state in all measurement devices. Since it can be output as the instruction signal and the end instruction signal, the measurement periods of the electrical parameters in all the measuring devices can be reliably matched (synchronized).

It is a block diagram which shows the structure of the electric power measurement apparatus 2 used with the measurement system 1. FIG. 1 is a configuration diagram showing a configuration of a measurement system 1. FIG. It is a timing chart for demonstrating operation | movement of the electric power measurement apparatus 2 which functions as a master. It is a timing chart for demonstrating operation | movement of the electric power measurement apparatus 2 which functions as a slave. 3 is a timing chart for explaining the operation of the measurement system 1. It is a block diagram which shows the structure of 1 A of measurement systems.

  Hereinafter, embodiments of a measurement system according to the present invention will be described with reference to the accompanying drawings. Note that, as an example of a measurement apparatus that constitutes the measurement system, a power measurement apparatus will be described as an example.

  As shown in FIG. 2, the measurement system 1 includes a plurality of (four in this example as an example) power measuring devices 2a, 2b, 2c, 2d (hereinafter also referred to as “power measuring device 2” unless otherwise specified). It is prepared for. Each power measuring device 2 has the same configuration as will be described later, but can be selectively set to operate as one of a master and a slave.

  First, the configuration of each power measuring device 2 will be described.

  As shown in FIG. 1, each power measuring device 2 includes a time generation unit 3, a measurement unit 4, an instruction signal input unit 5, a selector 6, an instruction signal output unit 7, a storage unit 8, and an output unit 9. The instantaneous power value W (an example of an electrical parameter in the present invention) is measured based on the input voltage signal Vin and current signal Iin (both examples of the input signal in the present invention). The time generation unit 3 generates and outputs time data Dt. This time data Dt is data indicating the current date and hour, minute, second, and is updated in units of 0.01 seconds (10 milliseconds) as an example.

  As shown in FIG. 1, the measurement unit 4 includes a voltage input unit 11, a current input unit 12, a power calculation unit 13, and a processing unit 14. The voltage input unit 11 samples the input voltage signal Vin with a predetermined sampling clock, converts it to voltage data Dv indicating the amplitude, and outputs the voltage data Dv. The current input unit 12 samples the input current signal Iin with the same sampling clock as that of the voltage input unit 11, converts the current signal Iin into current data Di indicating the amplitude, and outputs the current data Di. The power calculator 13 receives the voltage data Dv and the current data Di, and calculates the instantaneous power value W by multiplying the voltage value indicated by the voltage data Dv and the current value indicated by the current data Di for each input. The calculated instantaneous power value W is output to the processing unit 14.

  The processing unit 14 is constituted by, for example, a CPU, and executes a period measurement process, an instruction signal generation process, a switching control process for the selector 6, and a power integration process. In this period measurement process, the processing unit 14 continuously measures (measures) a unit period Tu having a predetermined time length based on the time indicated by the time data Dt output from the time generation unit 3. In this example, as an example, the processing unit 14 continuously measures a unit period Tu having a time length of 50 milliseconds by this period measurement process.

  When the processing unit 14 functions as a master (when the power measurement device 2 having the processing unit 14 is set as the master measurement device in the present invention), the processing unit 14 performs an instruction signal generation process. In this instruction signal generation process, the processing unit 14 externally instructs the instruction signal Sc1 output to the power measuring device 2 by operating a push button switch (not shown) or the like (via the instruction signal input unit 5), for example. A signal is input as a signal via the instruction signal input unit 5, and an instruction signal Sc 2 synchronized with the unit period Tu is generated based on the instruction signal Sc 1 and output to the selector 6. In this example, as an example, the High level portion of the external instruction signal functions as an external end instruction signal, and the Low level portion functions as an external start instruction signal. Therefore, when the level of the external instruction signal is changed from the High level to the Low level (that is, when the external start instruction signal is input), the processing unit 14 measures i after the input of the external start instruction signal. Synchronously with the beginning of the unit period Tu (where i is an integer equal to or greater than 1) (which means “beginning of period”, but also the end of the previous unit period), the level changes from High level to Low level, In addition, when the level of the external instruction signal is changed from the Low level to the High level (that is, when the external end instruction signal is input), the j-th (j is 1) measured after the input of the external end instruction signal. In synchronization with the beginning of the unit period Tu of the above integer), the instruction signal Sc2 whose level changes from Low level to High level is generated and output to the selector 6. In this case, in the instruction signal Sc2, the High level portion functions as an end instruction signal, and the Low level portion functions as a start instruction signal.

  FIG. 3 is a timing chart when the processing unit 14 executes the instruction signal generation process and generates the instruction signal Sc2 based on the instruction signal Sc1 when i is the numerical value “1” and j is the numerical value “2”. Is shown. In this example, the processing unit 14 synchronizes with the beginning (time t3) of the i (= 1) th unit period Tu after the level of the instruction signal Sc1 (external instruction signal) changes from the High level to the Low level. The level of the instruction signal Sc2 is changed from the high level to the low level, and the beginning of the j (= 2) th unit period Tu (time t6) after the level of the instruction signal Sc1 (external instruction signal) changes from the low level to the high level. ), The instruction signal Sc2 is generated by changing the level of the instruction signal Sc2 from the Low level to the High level.

  In the switching control process for the selector 6, the processing unit 14 outputs a switching signal Scc to the selector 6, thereby inputting the selector 6 when functioning as a master (when set). When the instruction signal Sc2 of the instruction signals Sc1 and Sc2 is output as the instruction signal Sc3 for the slave and functions as a slave (when the power measurement device 2 having the processing unit 14 is set as the slave measurement device in the present invention) ), The selector 6 is controlled to switch so that the instruction signal Sc1 is output as the instruction signal Sc3 to the slave.

  Further, in the power integration process when functioning as the master, the processing unit 14 changes the level of the generated instruction signal Sc2 from the high level to the low level (outputs the start instruction signal) as shown in FIG. An instruction that starts and accumulates the instantaneous power value W (measurement of electrical parameters in the present invention) in synchronization with the beginning of the n-th unit period (n is an integer of 1 or more) unit time Tu to be measured later. The instantaneous power value W is synchronized with the beginning of the m-th unit period (m is an integer of 1 or more) unit period Tu measured after the level of the signal Sc2 is changed from the Low level to the High level (outputting the end instruction signal). End the integration. In FIG. 3, as an example, the execution timing of the power calculation process when n and m are both “2” is shown. For this reason, the processing unit 14 starts the power calculation process in synchronization with the time t5, and ends the power calculation process in synchronization with the time t8.

  On the other hand, in the power integration process when functioning as a slave, the processing unit 14 integrates the instantaneous power value W based on the instruction signal Sc1 input to the power measuring device 2 via the instruction signal input unit 5 (the present invention). The measurement of electrical parameters at (1) is started and the integration of the instantaneous power value W is ended. Specifically, in the case of a slave, for example, in the instruction signal Sc1, the High level portion functions as an end instruction signal, and the Low level portion functions as a start instruction signal. For this reason, in the power integration process when functioning as a slave, the processing unit 14 is measured after changing the level of the instruction signal Sc1 from the High level to the Low level (outputting the start instruction signal) as shown in FIG. The integration of the instantaneous power value W is started in synchronization with the beginning of the n-th unit period (n is an integer equal to or greater than 1), and the level of the generated instruction signal Sc2 is changed from the Low level to the High level ( The integration of the instantaneous power value W is finished in synchronization with the beginning of the m-th unit period (m is an integer of 1 or more) unit period Tu measured after the end instruction signal is output). FIG. 4 shows, as an example, the execution timing of the power calculation process when both n and m are numerical values “2”. For this reason, the processing unit 14 starts the power calculation process in synchronization with the time t5, and ends the power calculation process in synchronization with the time t8. Accordingly, the processing unit 14 calculates the integrated value Ws of the instantaneous power value W in a period that is an integral multiple of the unit period Tu both when functioning as a master and when functioning as a slave.

  As an example, the instruction signal input unit 5 is configured by a buffer, and shapes the instruction signal Sc1 input from the outside of the power measurement apparatus 2 via the input terminal 21 (for example, a rectangular wave) to form a power measurement apparatus. 2 is output. In accordance with the switching signal Scc output from the processing unit 14, the selector 6 selectively selects one of the instruction signal Sc1 output from the instruction signal input unit 5 and the instruction signal Sc2 output from the processing unit 14 as an instruction signal. Output as Sc3. The instruction signal output unit 7 is configured by a buffer, for example, and shapes the instruction signal Sc3 output from the selector 6 (for example, into a rectangular wave) and externally outputs the power measurement device 2 via the output terminal 22. Output to.

  The storage unit 8 is composed of a semiconductor memory such as a ROM and a RAM, stores in advance an operation program that defines the operation content of the processing unit 14, and functions as a work memory for the processing unit 14. The output unit 9 includes a display device as an example, and displays the measurement result (integrated value Ws) on the screen.

  Next, the operation of the entire measurement system 1 as well as the operation of each power measuring device 2 will be described. In the measurement system 1, the power measurement device 2a functions as a master, and the other three power measurement devices 2b, 2c, and 2d are set in advance so as to function as slaves. The input terminal 21 of the power measuring device 2b is connected to the output terminal 22 of the power measuring device 2a, the input terminal 21 of the power measuring device 2c is connected to the output terminal 22 of the power measuring device 2b, and the output terminal of the power measuring device 2c. 22 is connected to the input terminal 21 of the power measuring device 2d, and the power measuring devices 2a to 2d are connected in a daisy chain manner. Further, in each of the power measuring devices 2a to 2d, n and m are both set to a numerical value “2”, and in the power measuring device 2a functioning as a master, both i and j are set to a numerical value “1”. Shall.

  In the operating state of the measurement system 1, in each power measuring device 2, the voltage input unit 11 of the measurement unit 4 samples the input voltage signal Vin with a predetermined sampling clock, and converts it into voltage data Dv indicating the amplitude. Output. Further, the current input unit 12 samples the input current signal Iin with the same sampling clock as that of the voltage input unit 11, converts the current signal Iin into current data Di indicating the amplitude, and outputs the current data Di. In addition, the power calculation unit 13 receives the voltage data Dv and the current data Di, calculates the instantaneous power value W, and outputs it to the processing unit 14. In addition, the time generation unit 3 of each power measuring device 2 generates time data Dt indicating the same time because the times are synchronized. Each processing unit 14 performs a period measurement process, and continuously measures a unit period Tu having a predetermined time length (for example, 50 milliseconds) based on the time data Dt. In this case, the unit periods Tu measured by the processing unit 14 of each power measuring device 2 are in a state in which the beginnings are synchronized with each other (that is, the beginning times are the same).

  In this operating state, when an external instruction signal is input to the master power measurement device 2a, both i and j are set to the numerical value “1”, so that the processing unit 14 of the power measurement device 2a generates the instruction signal. As shown in FIG. 5, the process is executed, and the beginning of the i (= 1) th unit period Tu (time t3) after the level of the instruction signal Sc1 (external instruction signal) changes from the High level to the Low level. Synchronously with this, the level of the instruction signal Sc2 is changed from the High level to the Low level, and the level of the instruction signal Sc1 (external instruction signal) changes from the Low level to the High level in the j (= 1) th unit period Tu. In synchronization with the beginning (time t5), the level of the instruction signal Sc2 is changed from the Low level to the High level. The selector 6 of the power measuring device 2a selects the instruction signal Sc2 and outputs it to the slave power measuring device 2b as the instruction signal Sc3. In addition, since both n and m are set to the numerical value “2”, the processing unit 14 of the power measuring device 2a is n (= 2) th after the level of the instruction signal Sc2 is changed from the High level to the Low level. The power integration process is started in synchronization with the beginning of the unit period Tu (time t5), and the beginning of the m (= 2) th unit period Tu after the level of the instruction signal Sc2 changes from the Low level to the High level. The power integration process is terminated in synchronization with (time t7). Finally, the processing unit 14 displays the integrated value Ws calculated in the power integrating process on the output unit 9 configured by a display device. This completes the power measurement in the master power measurement device 2a.

  On the other hand, in the slave power measuring apparatus 2b, as shown in FIG. 2, the instruction signal Sc3 output from the power measuring apparatus 2a is input as the instruction signal Sc1, and n and m are both set to the numerical value “2”. Therefore, as shown in FIG. 5, the processing unit 14 synchronizes with the beginning of the n (= 2) th unit period Tu (time t5) after the level of the instruction signal Sc1 changes from the High level to the Low level. The power integration process is started, and the power integration process ends in synchronization with the beginning of the m (= 2) th unit period Tu (time t7) after the level of the instruction signal Sc1 changes from the Low level to the High level. To do. In the power measuring device 2b, the selector 6 outputs the instruction signal Sc1 as the instruction signal Sc3 (through output). The other power measuring devices 2c and 2d set as slaves also operate in the same manner as the power measuring device 2b described above except that the instruction signal Sc3 output from the previous slave is input as the instruction signal Sc1. Execute power integration processing. Finally, each processing unit 14 of the power measuring devices 2b, 2c, and 2d displays the integrated value Ws calculated in the power integrating process on the output unit 9 configured by a display device. This completes the power measurement in each slave power measurement device 2.

  In this case, as described above, each of the slave power measurement devices 2b and 2c outputs the input instruction signal Sc1 as the instruction signal Sc3, so that the instruction signal input unit 5, the selector 6 and the instruction of each power measurement device 2 are output. Although a slight signal delay occurs when passing through each component of the signal output unit 7, the delay time is extremely short (several tens of microseconds) compared to the length of the unit period Tu (50 milliseconds). is there. Therefore, the instruction signal Sc1 is also input to the power measuring devices 2c and 2d at almost the same timing as the input timing of the instruction signal Sc1 to the power measuring device 2b shown in FIG. For this reason, in each of the power measuring devices 2c and 2d, similarly to the power measuring device 2b, the processing unit 14 starts the power integration process in synchronization with the time t5, and also synchronizes with the time t7. Exit.

  As described above, in the measurement system 1, the processing units 14 included in the measurement units 4 of all the power measurement devices 2 have the same length synchronized with each other based on the time data Dt output from the time generation unit 3. The processing unit 14 of the power measurement device 2 that repeatedly measures the unit period Tu and functions as a master among these power measurement devices 2 sends an instruction signal to the slave power measurement device 2 in synchronization with the beginning of the unit period Tu. Sc2 is output as the instruction signal Sc3 and is synchronized with the beginning of the n-th unit period Tu measured after the level of the instruction signal Sc2 changes from the High level to the Low level (after the start instruction signal is output). Then, the integration of the instantaneous power value W is started and the m-th measured after the level of the instruction signal Sc2 changes from the Low level to the High level (after the end instruction signal is output). Place in synchronization with the beginning of the period Tu ends the calculation of instantaneous power values W. In addition, the processing unit 14 of each power measuring device 2 that functions as a slave of the power measuring devices 2 has changed the level of the instruction signal Sc3 input as the instruction signal Sc1 from the High level to the Low level (the start instruction signal (After output), the integration of the instantaneous power value W is started in synchronization with the beginning of the n-th unit period Tu measured, and the level of the instruction signal Sc3 changes from the Low level to the High level (end instruction signal) The calculation of the instantaneous power value W is finished in synchronization with the beginning of the m-th unit period Tu measured after the output of (1).

  Therefore, according to the measurement system 1, in all the power measurement devices 2, the integration of the instantaneous power value W is started in synchronization with the beginning of the same unit period Tu and is measured after the measurement of the unit period Tu. Since the calculation of the instantaneous power value W can be completed in synchronization with the beginning of the same unit period Tu (the time lag between the measurement start timing and the measurement end timing can be greatly reduced), the integration period (measurement period ) Can be measured at each power measuring device 2 in a state where they are matched with high accuracy. As a result, for example, the integrated value Ws of power measured at each power measuring device 2 can be measured with high accuracy. Can be compared.

  In the measurement system 1, the slave power measuring devices 2b and 2c output through the instruction signal Sc1 input through the instruction signal input unit 5 as the instruction signal Sc3. Thus, the slave power measuring devices 2b, 2c, and 2d can be connected in a daisy chain manner. Therefore, according to this measurement system 1, it is not necessary to configure the instruction signal output unit 7 of each power measurement device 2 using expensive electronic components having a large fan-out capability (current supply capability). The device cost can be reduced while matching with high accuracy.

  Further, in this measurement system 1, the master power measurement device 2a synchronizes with the beginning of the i-th unit period Tu after the level of the instruction signal Sc1 as the external instruction signal changes from the High level to the Low level, The instruction signal Sc2 output to the slave power measuring apparatus 2b as the instruction signal Sc3 is changed from the high level to the low level, and the jth unit period from when the instruction signal Sc1 changes from the low level to the high level. In synchronization with the beginning of Tu, the level of the instruction signal Sc2 is changed from the Low level to the High level. Therefore, according to this measurement system 1, the master power measurement device 2a synchronizes the external instruction signal, which is an asynchronous signal to itself, with the unit period Tu measured in a synchronized state in all the power measurement devices 2. Thus, since the instruction signal Sc3 can be output to the slave power measurement device 2, the integration periods of the instantaneous power values W in all the power measurement devices 2 can be reliably matched.

  In addition, this invention is not limited to said structure. For example, the configuration has been described above in which an external instruction signal asynchronous with each signal in the measurement system 1 is input to the master power measurement device 2a, and the integration of the instantaneous power value W is executed in each power measurement device 2. A configuration in which the instruction signal Sc1 to be input to the instruction signal input unit 5 of the power measurement device 2a is generated in the master power measurement device 2a may be employed. As an example of this configuration, the processing unit 14 of the power measuring device 2a generates the instruction signal Sc1 when the time indicated by the time data Dt output from the time generation unit 3 matches the time programmed in advance. Thus, a configuration in which the instruction signal input unit 5 outputs the signal can be employed.

  In addition, the measurement system 1 that connects the power measurement devices 2 in a daisy chain manner and transmits the instruction signal Sc3 to the subsequent power measurement device 2 has been described above. However, as in the measurement system 1A illustrated in FIG. The input terminals 21 of all the slave power measurement devices 2 are directly connected to the output terminal 22 of the power measurement device 2a, and the instruction signal Sc3 output from the master power measurement device 2a is sent to each of the power measurement devices 2b and 2c. Of course, it is also possible to adopt a configuration for transmitting directly to 2d. Further, as to the polarities of the instruction signals Sc1, Sc2, and Sc3, as described above, for example, an “end instruction signal” is indicated when in a high level state, and a “start instruction signal” is indicated when in a low level state. However, it may be specified to indicate a “start instruction signal” when in a high level state and an “end instruction signal” when in a low level state. Furthermore, it is possible to adopt a configuration in which the start instruction signal and the end instruction signal are separately transmitted to different lines as separate signals. Moreover, although the measurement system comprised by the power measurement apparatus 2 was mentioned as an example as an example of a measurement apparatus, the measurement comprised by the measurement apparatus which measures electric parameters (electric current, voltage, resistance, etc.) other than electric power was demonstrated. Of course, the present invention can also be applied to a system.

DESCRIPTION OF SYMBOLS 1 Measurement system 2 Electric power measurement apparatus 3 Time generation part 4 Measurement part Dt Time data Iin Current signal Vin Voltage signal W Instantaneous electric power value Ws Integrated value

Claims (3)

A measuring device including a time generating unit that generates time data and a measuring unit that measures an electrical parameter based on an input signal, and the time generating units are synchronized so that the time data indicates the same time A measurement system in which one of the plurality of measurement devices is a master measurement device and all the others are slave measurement devices,
The measuring units of all the measuring devices perform a process of repeatedly measuring unit periods of the same length synchronized with each other based on the time data,
The measurement unit of the master measurement device outputs a start instruction signal to the slave measurement device in synchronization with the beginning of the unit period and is measured after the start instruction signal is output (n is 1 or more). The measurement of the electrical parameter is started in synchronization with the beginning of the unit period, and an end instruction signal is output to the slave measuring device in synchronization with the beginning of the unit period and the end instruction signal is output. The measurement of the electrical parameter is finished in synchronization with the beginning of the unit period of the m-th (m is an integer of 1 or more) measured later,
The measurement unit of the slave measurement device starts measuring the electrical parameter in synchronization with the beginning of the n-th unit period measured after the start instruction signal is input, and inputs the end instruction signal. A measurement system that ends the measurement of the electrical parameter in synchronization with the beginning of the m-th unit period to be measured later.   The slave measuring device inputs the start instruction signal and the end instruction signal through an instruction signal input unit, and outputs the input start instruction signal and the end instruction signal to the outside through an instruction signal output unit. The measurement system according to claim 1. The measurement unit of the master measuring apparatus starts the i-th unit period (i is an integer of 1 or more) of the unit period measured after the external start instruction signal is input when the external start instruction signal is input from the outside. The j-th measurement (j is 1 or more) measured after the external end instruction signal is input when the start instruction signal is output to the slave measuring apparatus in synchronization with the external end instruction signal. The measurement system according to claim 1, wherein the end instruction signal is output to the slave measurement device in synchronization with the beginning of the unit period.

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