JP2016050913A - Transient current measuring method, method of determining commercial power distribution system capable of measuring transient current, and countermeasure of commercial power distribution system incapable of measuring transient current, and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transient current measuring method, a method of determining a power distribution system capable of measuring transient current, and a countermeasure for enabling a power system that is determined as incapable to be used.SOLUTION: The method includes the steps of: connecting a dummy load to a connection position of an electrical device with the electrical device not connected to a commercial AC power supply shared by a plurality of different power distribution systems; measuring respective values of current through the dummy load when an electronic switch is turned on or off with a phase of 90° or 270°; and determining that a power distribution system is suitable for measuring transient current if each of the current values is equal to or more than a predetermined first current threshold, and determining that the power distribution system is not suitable for measuring the transient current if either one of the current values is not equal to or more than the first current threshold.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a transient current measurement method, a commercial power distribution system determination method capable of measuring a transient current, a countermeasure method for a commercial power distribution system incapable of measuring a transient current, and an apparatus therefor.

  In general, the power supply voltage that can be used for electrical equipment is a nominal value of 100 V or 200 V provided as a commercial AC power supply. In general, an electric device that operates on commercial power is operated by manually operating a power switch when the electric device is used, and then turning off the power after use.

  Although the voltage value of the commercial AC power supply changes at a specific cycle, the voltage value applied to the electric device when connected changes depending on the timing of the power switch operation of the electric device and the phase relationship of the commercial AC power supply, Depending on this, the value of the transient current that flows instantaneously also changes. In particular, it has been found that the maximum transient current value is measured when the power switch is turned on or off at the time when the line voltage is maximum.

  Although it depends on the current supply capacity of the commercial AC power supply, when the power switch is turned on, an instantaneous voltage drop or a transient current flowing in the power system cable generates electromagnetic waves around the cable, and other power distribution systems and Cases that affect the operation of peripheral electrical equipment are assumed. Therefore, measuring the maximum transient current value generated by an electrical device with good reproducibility and evaluating whether or not the electrical device can be introduced affects the operation of other distribution systems and surrounding electrical devices due to the transient current. It is indispensable to reduce the phenomenon.

  FIG. 1 shows a conventional circuit configuration for measuring a transient current for an electric device to be measured. FIG. 1 shows a circuit including a commercial AC power supply 1, a power switch 4, a voltage probe 5 for measuring a power supply voltage waveform, a current probe 6 for measuring a transient current waveform, and an electric device 7. . The commercial AC power source 1, the power switch 4, the current probe 6 and the electric device 7 are connected in series, and the voltage probe 5 is connected in parallel to the electric device 7.

  The voltage probe 5 can record the voltage applied to the electric device 7 at the moment when the switch is operated. The current probe 6 can record the transient current due to the switch operation. Moreover, if the voltage probe 5 and the current probe 6 are connected to an oscilloscope, the time waveform of the change can be recorded. This facilitates reading of the maximum value of the transient current.

  Conventionally, the power switch 4 is manually turned on a plurality of times at an arbitrary timing, the maximum value among the plurality of transient current values is set as the maximum transient current value, and whether this measured value exceeds or exceeds a predetermined current threshold value. Then, whether or not the electrical device 7 to be measured was introduced was evaluated.

"Testing and measurement technology-voltage dip, short-time power failure and voltage immunity test", Japanese Industrial Standards, JIS C61000-4-11, Part 4-11, 2008

  However, each distribution system generally does not have the same impedance, and some distribution systems are not suitable for transient current evaluation. For this reason, when evaluating the worst value of the transient current of the electrical device to be measured, the power distribution system connected at the time of evaluation does not have drive capability, and thus the transient current of the electrical device to be measured may be underestimated. It will be described with reference to FIG. 2 that the distribution system generally does not have the same internal impedance. FIG. 2 shows a circuit configuration of a commercial power distribution system.

  The circuit configuration of the commercial power distribution system shown in FIG. 2 includes a first internal impedance 2 and a second internal impedance 3. The first internal impedance 2 is based on the internal impedance of the commercial AC power supply 1 and the internal impedance of the distribution system cable up to the service point S between the area A1 where the user cannot intervene and the area A2 where the user can change. Become. The second internal impedance 3 is composed of an internal impedance by an electric device in another distribution system sharing the commercial AC power supply 1. A general commercial AC power supply 1 is actually connected with a plurality of distribution systems in parallel, and each distribution system has a second internal impedance 3 that is different depending on the plurality of other distribution systems. Therefore, at the service point S, since the voltage divided by the first and second internal impedances 2 and 3 is observed by the voltage probe 5, the observed voltage is lower than the electromotive voltage of the commercial AC power supply 1.

  Further, in a general commercial power distribution system, the first internal impedance 2 differs depending on various main transformer capacities such as the capacity that can be supplied by the commercial AC power supply 1 and the thickness and length of the wiring cable used. Since the second internal impedance 3 is also different depending on the operating conditions of the electrical equipment in other distribution systems sharing the AC power supply 1, the supply voltage and the suppliable current capacity from the commercial AC power supply 1 are different for each distribution system. Therefore, in some distribution systems, the second internal impedance 3 is relatively large, and the transient current is greatly influenced by the second internal impedance 3, so that there are some systems that are not suitable for measuring the transient current. Therefore, there is a need to determine whether the distribution system to be used for transient current measurement is suitable for transient current measurement.

  Furthermore, in the commercial power distribution system to be measured, the impedance in the region A2 also differs depending on the operating status of the electrical equipment 7 connected to the commercial AC power supply 1, that is, the transient current differs for each electrical equipment to be measured. Since the characteristics of the electrical device to be affected affect the determination of whether or not the current distribution system is suitable for the transient current measurement, it may not be possible to accurately determine whether or not the distribution system is suitable for the transient current measurement. Therefore, it is required to determine whether the distribution system to be used for the transient current measurement is suitable for the transient current measurement regardless of the characteristics of the electrical equipment.

  Here, conventionally, the distribution system that is not suitable for transient current measurement is not used, but the transient current of the electrical equipment to be measured is measured using another distribution system that is suitable for transient current measurement. It is assumed that a distribution system that does not have measurement capability must be used. Therefore, a countermeasure is required when using a power distribution system that is not suitable for transient current measurement.

  Conventionally, the power switch 4 is manually operated, and it has been difficult to perform the operation of the power switch 4 in accordance with the power phase of the commercial AC power supply 1. It was practically difficult to obtain with good reproducibility.

  In view of the above circumstances, the present invention provides a transient current measurement method, a distribution system determination method capable of measuring a transient current, and a countermeasure method for enabling use of a power system determined to be unusable.

  In order to solve the above-mentioned problem, the method according to claim 1 is a method in a distribution system having an electric device supplied with a voltage from a commercial AC power source, and the commercial AC power source is shared by a plurality of different power distribution systems. The method includes connecting a pseudo load having a predetermined resistance value to a connection position of the electrical device in the distribution system in a state where the electrical device is not connected to the commercial AC power source; Using an electronic switch that can be set to switch from ON to OFF or OFF to ON when the phase of the voltage supplied from the AC power supply is 90 ° or 270 °, the electronic switch is turned ON when the phase is 90 °. A first current value flowing through the pseudo load when switched off, and the pseudo switch when the electronic switch is switched from off to on when the phase is 90 °. When the electronic switch is switched from ON to OFF when the phase is 270 °, the third current value that flows through the pseudo load when the phase is 270 ° and when the phase is 270 ° A step of measuring a fourth current value flowing in the pseudo load when switching from off to on, respectively, and the distribution system when the first to fourth current values are greater than or equal to a predetermined first current threshold value Determining that the distribution system is not suitable for transient current measurement when any of the first to fourth current values is not equal to or greater than the first current threshold; It is characterized by including.

  The method according to claim 2 is the method according to claim 1, wherein when it is determined that the power distribution system is suitable for transient current measurement, the pseudo load is removed and the electric device is placed at the connection position. A first transient current value flowing through the electrical device when the electronic switch is switched from on to off when the phase is 90 °, and the electronic switch is switched from off to on when the phase is 90 ° When the electronic switch is switched from ON to OFF when the phase is 270 °, the third transient current value and the phase that flow to the electric device when the phase is 270 ° Measuring a fourth transient current value flowing through the electrical device when the electronic switch is switched from OFF to ON at the time of °, and peak-- of the first to fourth transient current values. determining whether or not a value having the largest to-peak value is equal to or smaller than a predetermined second current threshold value.

  The method according to claim 3 is the method according to claim 2, wherein when it is determined that the power distribution system is not suitable for transient current measurement, a capacitor in which electric charge is accumulated is connected in parallel with the pseudo load. Measuring the first to fourth current values in a state where the capacitor is connected using the electronic switch, and the first to fourth current values in a state where the capacitor is connected. Is greater than or equal to the first current threshold, the pseudo load is removed, the electrical device is connected to the connection position, and the electronic switch is used to connect the first to the first capacitors. A step of measuring each of the fourth transient current values, and a value having the largest peak-to-peak value among the first to fourth transient current values in a state where the capacitor is connected is the second current. Below threshold Determining whether or not, and further comprising a.

  The method according to claim 4 is the method according to claim 1, and when it is determined that the distribution system is not suitable for transient current measurement, a voltage matching the peak voltage of the commercial AC power supply can be supplied. Connecting a battery and the electrical device, measuring a transient current value flowing through the electrical device with the battery connected, and the transient current value flowing through the electrical device with the battery connected Determining whether the peak-to-peak value is less than or equal to a predetermined second current threshold.

  The apparatus according to claim 5 is an apparatus for determining whether or not a distribution system having an electric device supplied with a voltage from a commercial AC power source is suitable for transient current measurement. The apparatus is shared between different power distribution systems, and the device is provided between a pseudo load having a predetermined resistance value provided at a connection position of the electrical device in the power distribution system, and between the commercial AC power source and the pseudo load. And an electronic switch that can be set to switch from on to off or off to on when the phase of the voltage supplied from the commercial AC power supply is 90 ° or 270 °, and a current probe that measures the current flowing through the pseudo load And.

  A device according to a sixth aspect is the device according to the fifth aspect, further comprising a capacitor connected in parallel with the pseudo load and storing charges.

  The apparatus according to claim 7 is an apparatus for measuring a transient current in a power distribution system having an electric device supplied with a voltage from a commercial AC power supply, and the commercial AC power supply is shared by a plurality of different power distribution systems. The apparatus is provided between the commercial AC power supply and the connection position of the electric device, and from on to off or off when the phase of the voltage supplied from the commercial AC power supply is 90 ° or 270 °. An electronic switch that can be set to be turned on, and a current probe that measures a current flowing through the electrical device are provided.

  The device according to claim 8 is a device in a power distribution system having an electric device supplied with a voltage from a commercial AC power source, and the commercial AC power source is shared by a plurality of different power distribution systems. A battery capable of supplying a voltage that matches the peak voltage of the commercial AC power supply, a switch provided between the battery and a connection position of the electrical device, a current probe for measuring a current flowing through the electrical device, It is provided with.

  ADVANTAGE OF THE INVENTION According to this invention, when evaluating the worst value of the transient current of the electric equipment of measurement object, it can prevent underestimating the transient current of the electric equipment of measurement object.

  Further, according to the present invention, by using an electronic switch capable of performing the switch operation timing in accordance with the phase of the AC power supply, it is possible to determine whether or not the transient current measurement is appropriate using the transient current maximum value and the maximum value of the transient current. Measurement can be performed with good reproducibility.

  Further, according to the present invention, even when a distribution system that is determined to be unsuitable for transient current measurement must be used, the measured transient current value can be obtained by placing the distribution system in a state suitable for transient current measurement. Can be obtained.

  In addition, according to the present invention, by using a capacitor, it is possible to perform measurement without being affected by the operating status of the electrical equipment connected to the commercial AC power supply in the distribution system to be measured.

  In addition, according to the present invention, by separately preparing a circuit suitable for transient current measurement using a battery, even if it is determined that the distribution system is not suitable for transient current measurement, It is possible to easily obtain the maximum transient current value for the device.

It is a figure which shows the conventional circuit structure for measuring the transient current with respect to a to-be-measured electric equipment. It is a figure for demonstrating that a power distribution system does not have the same impedance in general. It is a figure for demonstrating the method to determine whether the commercial distribution system has a transient current supply capability based on this invention. It is a figure for demonstrating the method to measure the maximum transient electric current with respect to the to-be-measured electric equipment which concerns on this invention. It is a figure for demonstrating the countermeasure method which concerns on this invention when it determines with not being suitable for a transient current measurement. It is a figure which shows the application flow of the method which concerns on Example 1 of this invention. It is a figure which shows the circuit structure for using the method which concerns on Example 2 of this invention. It is a figure which shows the application flow of the method which concerns on Example 2 of this invention.

(Example 1)
A method for determining whether or not the power distribution system is suitable for transient current measurement according to the first embodiment of the present invention will be described with reference to FIG. FIG. 3A shows a circuit including a commercial AC power supply 1, a voltage probe 5 for measuring a power supply voltage, a current probe 6 for measuring a transient current, an electronic switch 8, and a pseudo load 9. Yes. The commercial AC power source 1, the current probe 6, the electronic switch 8 and the pseudo load 9 are connected in series, and the voltage probe 5 is connected in parallel to the pseudo load 9. The circuit configuration of the commercial power distribution system shown in FIG. 3 includes a first internal impedance 2 and a second internal impedance 3.

  The electronic switch 8 has a measurement unit for measuring the phase of the supply voltage from the commercial AC power supply 1. FIG. 3B shows the control timing of the electronic switch 8. The electronic switch 8 measures the phase of the supply voltage from the commercial AC power supply 1 by the measuring unit, and as shown in FIG. 3B, the phase becomes 90 ° or 270 ° at which the absolute value of the voltage value is maximum. Can be set to automatically switch from on to off or off to on. As shown in FIG. 3B, for example, the electronic switch 8 is turned off (1) during a period when the phase φ is 0 ° ≦ φ <90 °, and is turned on during a period when 90 ° ≦ φ <360 °, (2) OFF during the period of 0 ° ≦ φ <270 °, ON during the period of 270 ° ≦ φ <360 °, (3) ON during the period of 0 ° ≦ φ <90 °, and 90 ° ≦ φ < It can be set to turn off the period of 360 °, or (4) turn on the period of 0 ° ≦ φ <270 ° and turn off the period of 270 ° ≦ φ <360 °. Since the transient current is maximized when the absolute value of the voltage value is maximized, the maximum value of the transient current can be used by measuring the current values when the electronic switch 8 is turned on and off, respectively.

  Here, in actuality, the current value differs between the case of phase 90 ° and the case of phase 270 ° depending on the model characteristics of the electrical device 7 to be measured. Therefore, the cases of phase 90 ° and 270 ° are measured respectively. . In addition, since the current value is different between when the phase is 90 ° and when it is 270 °, the current value is different between when the phase is on and when the phase is off. At that time, it may be confirmed whether the switching by the electronic switch 8 is performed at an appropriate timing by confirming the voltage value when the phase becomes 90 ° and 270 ° using the voltage probe 5.

  The pseudo load 9 can be a resistor having a fixed resistance value (for example, 5Ω). In the suitability determination method according to the present invention, an electric device included in a distribution system to be measured is removed and a pseudo load 9 is connected instead.

  It is an application flow of the method which concerns on Example 1 of this invention. Hereinafter, the method according to the first embodiment will be described with reference to the application flow illustrated in FIG.

  In the determination method according to the present invention, after the electric device is removed in the area A2 that can be changed by the user and is not connected to the commercial AC power source 1, the resistance value is fixed at the connection position of the removed electric device. The load 9 is connected to the commercial AC power source 1. In step S101 of FIG. 6, as described in FIG. 3B, the phase of the supply voltage from the commercial AC power supply 1 is 90 ° or 270 °, and the electronic switch 8 is switched from on to off or from off to on. Then, the current value is measured using the current probe 6. As a result of the measurement, when each current value exceeds a predetermined first current threshold value (for example, 25 A) after the electronic switch 8 is turned on and before a predetermined period elapses (for example, approximately 0.01 s), the commercial distribution system Is determined to be suitable for transient current measurement, and if any of the current values does not exceed the first current threshold, it is determined that the commercial distribution system is not suitable for transient current measurement. When the first current threshold is exceeded after a predetermined period has elapsed since the electronic switch 8 is turned on, the current value rises gently after the electronic switch 8 is turned on, and the transient current at the gently rising stage has less energy. In this case as well, it is determined that the power distribution system is not suitable for transient current measurement.

  With reference to FIG. 4, a method for measuring the maximum transient current for the electrical equipment under test according to the present invention will be described. If it is determined by the determination method according to the present invention shown in FIG. 3 that the distribution system is suitable for transient current measurement, the pseudo load 9 is removed in step S102 of FIG. The electrical device 7 to be measured that has been connected to the power distribution system is connected again, and the electronic switch 8 is turned on or off at the timing described with reference to FIG. 3B, and each transient current value at that time is measured.

  The countermeasure method according to the present invention when it is determined that the distribution system is not suitable for the transient current measurement will be described with reference to FIG. In the circuit shown in FIG. 5, a capacitive element (capacitor) 10 charged with electric charge is connected between the lines on the power source side of the electronic switch 8 in the region A2. For example, a capacitor having a capacity of 30 μF to 100 μF can be used as the capacitor 10.

  If it is determined that the power distribution system is not suitable for the transient current measurement, the capacitor 10 in which the charge is accumulated is connected in parallel with the pseudo load 9 as shown in FIG. By connecting the capacitor 10 in which charges are accumulated in this way, it is possible to improve the transient current supply capability of the distribution system determined to be unsuitable for transient current measurement and to make the distribution system suitable for transient current measurement. it can. Thereafter, the process proceeds to step S101 in FIG. 6, and the electronic switch 8 is turned on at the timing described with reference to FIG. 3B, and the appropriateness determination of the transient current measurement is performed again with the capacitor 10 connected. As a result of the suitability determination, when it is determined that it is suitable for the transient current measurement, the process proceeds to step S102 in FIG. 6, the pseudo load 9 is removed and the electric device 7 is connected as shown in FIG. Measure the transient current value when is connected. If it is determined that it is not suitable for the transient current measurement, it is possible to remove the capacitor 10 used in step S103 in FIG. 6 and connect a capacitor 10 having a different capacity, and determine whether or not it is appropriate in step S101 in FIG.

  When four transient current values (when turned on and off at phases 90 ° and 270 °) are obtained in step S102 of FIG. 6, the peak-to-peak value of the four transient current values is obtained in step S104 of FIG. It is determined whether or not the largest value is equal to or less than a predetermined second current threshold value (for example, 5 A p-p). If it is less than or equal to the second current threshold, it is determined that the electrical device 7 to be measured can be introduced, and if it is greater than or equal to the second current threshold, it is determined that the electrical device 7 to be measured cannot be introduced.

  As described above, when the switch operation is performed manually as in the prior art, the suitability determination result and the maximum transient current value in the transient current measurement cannot be obtained with good reproducibility, but according to the measurement method of the present invention, By performing on / off control of the switch 8 automatically in accordance with the phase of the commercial AC power supply 1, it is possible to stably obtain the suitability determination result and the maximum transient current value in the transient current measurement for each switch operation.

  In addition, even when a distribution system determined to be unsuitable for transient current measurement by necessity according to the countermeasures according to the present invention must be used, the transient current measurement is performed with the distribution system in a state suitable for transient current measurement. A value can be obtained.

(Example 2)
A second embodiment of the present invention will be described with reference to FIGS. FIG. 7 shows a circuit when the battery 11 such as a storage battery is used without using the commercial AC power supply 1. FIG. 8 shows an application flow of the method according to the second embodiment of the present invention.

  In step S201 of FIG. 8, a determination is made as to whether or not the transient current measurement of the distribution system is appropriate using the circuit shown in FIG. As a result of the suitability determination, if it is determined that the distribution system is suitable for the transient current measurement, in step S202, the transient current value is measured by the transient current measurement described above with reference to FIG. Thereafter, in step S204, it is determined whether or not the measurement-target electrical device can be introduced in the same manner as in step 104 in FIG.

  As a result of the suitability determination in step S201, if it is determined that the distribution system is not suitable for the transient current measurement, the transient current measurement of the electrical device 7 to be measured is performed in step S203 by the circuit using the battery 11 shown in FIG. Do.

  Here, in the transient current measurement, the measurement time of the transient current is very short, and if the instantaneous peak voltage can be applied to the electrical device 7 to be measured, the maximum transient current can be measured. A battery 11 capable of supplying a voltage in accordance with the peak voltage of the power source 1 can be substituted. Further, since it is not necessary to perform the on / off operation of the switch in accordance with the power supply phase of the commercial AC power supply 1, as shown in FIG. 7, the power switch 4 is used instead of the electronic switch 8 that performs the on / off control according to the phase. It can be turned on and off manually.

  Further, when the commercial AC power supply 1 is used, since the commercial AC power supply 1 is shared by a plurality of different power distribution systems, the second internal impedance 3 greatly affects the determination of whether or not the transient current measurement is appropriate. In some cases, the distribution system was determined to be unsuitable for transient current measurements. However, when the battery 11 is used in this way, a plurality of different power distribution systems are not connected to the battery 11, and the circuit shown in FIG. 7 does not have the second internal impedance 3 as shown in FIG. Therefore, the circuit using the battery 11 shown in FIG. 7 is suitable for transient current measurement.

  After performing the transient current measurement in step S203, it is determined in step S205 whether or not the electrical device 7 to be measured can be introduced. In step S205, it is determined whether or not the transient current value obtained in step S203 is equal to or less than a predetermined second current threshold value (for example, 5A p-p). If it is less than or equal to the second current threshold, it is determined that the electrical device 7 to be measured can be introduced, and if it is greater than or equal to the second current threshold, it is determined that the electrical device 7 to be measured cannot be introduced.

  In this manner, by separately preparing a circuit suitable for transient current measurement using the battery 11 capable of supplying a voltage that matches the peak voltage of the commercial AC power supply 1, the distribution system can be determined by determining whether the transient current measurement is appropriate in step S201. Even when it is determined that is not suitable for transient current measurement, it is possible to easily obtain the maximum transient current value for the electrical device to be measured.

Commercial AC power supply 1
First internal impedance 2
Second internal impedance 3
Power switch 4
Voltage probe 5
Current probe 6
Electrical equipment 7
Electronic switch 8
Pseudo load 9
Capacitor 10
Battery 11

Claims (8)

A method in a power distribution system having an electrical device supplied with voltage from a commercial AC power source, wherein the commercial AC power source is shared by a plurality of different power distribution systems,
Connecting a pseudo load having a predetermined resistance value to a connection position of the electrical device in the distribution system in a state where the electrical device is not connected to the commercial AC power source;
Using an electronic switch that can be set to switch from on to off or off to on when the phase of the voltage supplied from the commercial AC power supply is 90 ° or 270 °, the electronic switch is turned on when the phase is 90 °. A first current value that flows through the pseudo load when switched from on to off, a second current value that flows through the pseudo load when the electronic switch is switched from off to on when the phase is 90 °, When the electronic switch is switched from on to off when the phase is 270 °, a third current value flowing in the pseudo load and when the electronic switch is switched from off to on when the phase is 270 ° Measuring each of the fourth current values flowing through the load;
When the first to fourth current values are greater than or equal to a predetermined first current threshold, it is determined that the power distribution system is suitable for transient current measurement, and any one of the first to fourth current values is the first Determining that the distribution system is not suitable for transient current measurement when not greater than a current threshold of 1;
A method comprising the steps of: If it is determined that the distribution system is suitable for transient current measurement,
The pseudo load is removed, the electrical device is connected to the connection position, and the electronic switch is used to flow to the electrical device when the electronic switch is switched from on to off when the phase is 90 °. When the electronic switch is switched from OFF to ON when the phase is 90 °, the second transient current value that flows through the electrical device when the phase is 90 °, and when the phase is 270 ° A third transient current value that flows through the electrical device when switched off and a fourth transient current value that flows through the electrical device when the electronic switch is switched from off to on when the phase is 270 °, respectively. Measuring step;
Determining whether the peak-to-peak value of the first to fourth transient current values is equal to or less than a predetermined second current threshold;
The method of claim 1 further comprising: If it is determined that the power distribution system is not suitable for transient current measurement, a capacitor in which electric charge is stored is connected in parallel with the pseudo load, and the first to the state in which the capacitor is connected using the electronic switch. Measuring each of the fourth current values;
When the first to fourth current values with the capacitor connected are equal to or greater than the first current threshold, the pseudo load is removed, the electrical device is connected to the connection position, and the electronic Measuring each of the first to fourth transient current values in a state where the capacitor is connected using a switch;
Determining whether a value having the largest peak-to-peak value among the first to fourth transient current values in a state where the capacitor is connected is equal to or less than the second current threshold;
The method of claim 2, further comprising: If it is determined that the distribution system is not suitable for transient current measurement,
Connecting a battery capable of supplying a voltage that matches a peak voltage of the commercial AC power supply and the electric device, and measuring a transient current value flowing in the electric device in a state where the battery is connected;
Determining whether a peak-to-peak value of the transient current value flowing through the electrical device in a state where the battery is connected is equal to or lower than a predetermined second current threshold;
The method of claim 1 further comprising: An apparatus for determining whether or not a power distribution system having electrical equipment supplied with voltage from a commercial AC power source is suitable for transient current measurement, the commercial AC power source is shared by a plurality of different power distribution systems, The device is
A pseudo load having a predetermined resistance value provided at a connection position of the electrical device in the power distribution system;
An electronic switch that is provided between the commercial AC power supply and the pseudo load and can be set to switch from on to off or from off to on when the phase of the voltage supplied from the commercial AC power supply is 90 ° or 270 ° When,
A current probe for measuring a current flowing through the pseudo load;
A device characterized by comprising:   The apparatus according to claim 5, further comprising a capacitor connected in parallel with the pseudo load and storing electric charges. A device for measuring a transient current in a distribution system having an electric device supplied with voltage from a commercial AC power source, wherein the commercial AC power source is shared by a plurality of different power distribution systems,
Provided between the commercial AC power supply and the connection position of the electrical device, and can be set to switch from on to off or off to on when the phase of the voltage supplied from the commercial AC power supply is 90 ° or 270 ° An electronic switch,
A current probe for measuring a current flowing through the electrical device;
A device characterized by comprising: A device for measuring a transient current in a distribution system having an electric device supplied with voltage from a commercial AC power source, wherein the commercial AC power source is shared by a plurality of different power distribution systems,
A battery capable of supplying a voltage that matches the peak voltage of the commercial AC power supply;
A switch provided between the battery and the connection position of the electrical device;
A current probe for measuring a current flowing through the electrical device;
A device characterized by comprising:

Images