JP7587214B2 - Inspection device, inspection method, and inspection program - Google Patents

Description

The present invention relates to an inspection device, an inspection method, and an inspection program for inspecting or monitoring a three-phase delta power line.

The insulation performance of an electrical system, including the load equipment of electrical equipment, is extremely important in preventing electric shock, fire, etc., but the insulation performance can be impaired due to aging deterioration of electrical equipment or construction work, etc., and leakage current (hereinafter referred to as "Io") can occur in the electric line. It is important to predict the occurrence of Io or detect Io that has actually occurred, and prevent accidents before they occur, or at an early stage.

For this reason, the receiving transformer is provided with an inspection device that inspects Io on the ground wire of the secondary circuit. Here, Io includes leakage current due to capacitance to earth (hereinafter referred to as "Ioc") and leakage current due to insulation resistance to earth, which is directly related to insulation resistance (hereinafter referred to as "Ior").

For example, in Patent Document 1, there is provided a zero-phase current detection means for detecting a zero-phase current in a three-phase electric circuit, a voltage detection means for detecting the voltage of the electric circuit, a specified frequency component extraction means for extracting first and second frequency components from the zero-phase current and voltage, the first frequency component being a harmonic component other than the fundamental wave or a harmonic component of an integer multiple of the third order, and the second frequency component being a harmonic component other than the harmonic component of an integer multiple of the third order and different from the first frequency component, and a specified frequency component extraction means for converting the second frequency component in the zero-phase current into a specified correction current and converting the extracted zero-phase current The present disclosure discloses an insulation monitoring device equipped with a leakage current calculation means that calculates the leakage current due to the earth insulation resistance of two of the three phases based on the first frequency component in the zero-phase current, the correction current, the phase difference between the first and second frequency components in the zero-phase current and the frequency of the first and second frequency components in the zero-phase current relative to the reference voltage, using the voltage of any one of the three phases as a reference voltage, and the predetermined correction current is a current obtained by converting the second frequency component in the zero-phase current to a value when the second frequency component in the voltage is equal to the first frequency component in the voltage.

JP 2004-317466 A

Here, Ior is expressed as the scalar sum of the two phases. However, if it is not known what percentage of Ior is occurring in the two phases, it is difficult to identify the problem area of Ior (such as the location where Ior is occurring), the cause of occurrence, and changes during regular inspections. The two phases are the R phase and T phase, the T phase and S phase, or the S phase and R phase. There is also a demand to be able to also observe changes over time when inspecting or monitoring the electric line under test.

The present disclosure aims to provide an inspection device, inspection method, and inspection program that can calculate the Ior values occurring in each of the two phases in the Ior measurement results, assuming changes in Ioc, and also inspect or monitor a delta-connected electric line under test, including changes over time.

In order to achieve the above object, the present invention is configured as follows.
(1) A leakage current detection unit that detects a leakage current flowing in a measured electric line having a first phase, a second phase, and a third phase connected in a delta connection; a voltage detection unit that detects a voltage applied to the measured electric line; a phase angle detection unit that detects a phase angle based on the leakage current detected by the leakage current detection unit and the voltage detected by the voltage detection unit; a first calculation unit that calculates a possible range of a capacitive component leakage current caused by earth capacitance included in the leakage current flowing in the measured electric line based on the leakage current detected by the leakage current detection unit and the phase angle detected by the phase angle detection unit; a determination unit that determines a reference capacitive component leakage current as a reference within the possible range of the capacitive component leakage current calculated by the first calculation unit; a second calculation unit that calculates a first resistance component leakage current caused by ground insulation resistance included in the leakage current flowing through the electric line under test, based on the first phase angle detected by the phase angle detection unit and the first leakage current detected by the leakage current detection unit; a third calculation unit that calculates a second resistance component leakage current caused by ground insulation resistance included in the leakage current flowing through the electric line under test, based on the reference capacitive component leakage current identified by the determination unit, the second phase angle detected by the phase angle detection unit, and the second leakage current detected by the leakage current detection unit, at a second measurement time that is a predetermined time after the first measurement time; and a change amount calculation unit that compares the first resistance component leakage current calculated by the second calculation unit with the second resistance component leakage current calculated by the third calculation unit, to calculate an amount of change.
(2) The inspection device according to (1), wherein the determination unit is configured to determine the median value within a range of possible values of the capacitive component leakage current calculated by the first calculation unit as the reference capacitive component leakage current.
(3) The inspection device according to (1), wherein the determination unit is configured to determine an arbitrary value as the reference capacitive component leakage current within a possible range of the capacitive component leakage current calculated by the first calculation unit.
(4) The inspection device described in any one of (1) to (3), wherein the third calculation unit is configured to extend the specified interval and perform the next measurement when there is no difference in the amount of change calculated by the change amount calculation unit in the previous measurement or when the difference is equal to or less than a specified difference.
(5) A leakage current detection step of detecting a leakage current flowing in a measured electric line having a first phase, a second phase, and a third phase connected in a delta connection; a voltage detection step of detecting a voltage applied to the measured electric line; a phase angle detection step of detecting a phase angle based on the leakage current detected by the leakage current detection step and the voltage detected by the voltage detection step; a first calculation step of calculating a possible range of a capacitive component leakage current caused by a capacitance to earth included in the leakage current flowing in the measured electric line based on the leakage current detected by the leakage current detection step and the phase angle detected by the phase angle detection step; a determination step of determining a reference capacitive component leakage current as a reference within the possible range of the capacitive component leakage current calculated by the first calculation step; a second calculation step of calculating a first resistance component leakage current caused by ground insulation resistance included in the leakage current flowing through the electric line under test, based on the first phase angle detected in the phase angle detection step and the first leakage current detected in the leakage current detection step; a third calculation step of calculating a second resistance component leakage current caused by ground insulation resistance included in the leakage current flowing through the electric line under test, based on the reference capacitive component leakage current identified in the determination step, the second phase angle detected in the phase angle detection step, and the second leakage current detected in the leakage current detection step, at a second measurement time a predetermined time after the first measurement time; and a change amount calculation step of comparing the first resistance component leakage current calculated in the second calculation step with the second resistance component leakage current calculated in the third calculation step to calculate an amount of change.
(6) A computer includes a leakage current detection step of detecting a leakage current flowing in a test electric line having a first phase, a second phase, and a third phase connected in a delta connection; a voltage detection step of detecting a voltage applied to the test electric line; a phase angle detection step of detecting a phase angle based on the leakage current detected by the leakage current detection step and the voltage detected by the voltage detection step; a first calculation step of calculating a possible range of a capacitive component leakage current caused by a capacitance to earth included in the leakage current flowing in the test electric line based on the leakage current detected by the leakage current detection step and the phase angle detected by the phase angle detection step; a determination step of determining a reference capacitive component leakage current as a reference within the possible range of the capacitive component leakage current calculated by the first calculation step; a second calculation step of calculating a first resistance component leakage current caused by ground insulation resistance included in the leakage current flowing through the measured electric line based on the first phase angle detected by the phase angle detection step and the first leakage current detected by the leakage current detection step; a third calculation step of calculating a second resistance component leakage current caused by ground insulation resistance included in the leakage current flowing through the measured electric line based on the reference capacitive component leakage current identified by the determination step, the second phase angle detected by the phase angle detection step, and the second leakage current detected by the leakage current detection step, at a second measurement time a predetermined time after the first measurement time; and a change amount calculation step of comparing the first resistance component leakage current calculated by the second calculation step with the second resistance component leakage current calculated by the third calculation step to calculate an amount of change.

According to the present invention, it is possible to calculate the Ior values occurring in each of the two phases in the Ior measurement results, assuming changes in Ioc, and also to inspect or monitor the Δ-connected electric line under test, including changes over time.

FIG. 1 is a diagram showing the configuration of an inspection device. FIG. 2 is a diagram illustrating the possible range of Ioc. FIG. 3 is a diagram showing a schematic diagram of the timing of measurement. FIG. 4 is a diagram showing a schematic diagram of Ior(r), Ior(t), and Ior(rt) calculated at t1, and Ior(r), Ior(t), and Ior(rt) calculated at t2. FIG. 5 is a diagram that illustrates a vector diagram when the expected value of Ioc is set to the median value (Ioc(rt)CEN). FIG. 6 is a flow chart illustrating the procedure of the inspection method. FIG. 7 is a block diagram showing a first configuration example of a computer. FIG. 8 is a block diagram showing a second configuration example of the computer.

The present embodiment will be described below. Note that the present embodiment described below does not unduly limit the content of the present invention described in the claims. Furthermore, not all of the configurations described in the present embodiment are necessarily essential components of the present invention.

Figure 1 is a diagram showing the configuration of the inspection device 1. The inspection device 1 includes a leakage current detection unit 11, a voltage detection unit 12, a phase angle (phase) detection unit 13, a first calculation unit 14, a determination unit 15, a second calculation unit 16, a third calculation unit 17, and a change amount calculation unit 18.

The leakage current detection unit 11 detects the leakage current flowing in the electric line under test in which the first, second, and third phases are connected in a Δ (delta) configuration. In the following, the first phase is referred to as the R phase, the second phase is referred to as the T phase, and the third phase is referred to as the S phase, but these names are not limited to these. In the following, the leakage current measured by the leakage current detection unit 11 is referred to as "Io", but these names are not limited to these.

In addition, the inspection device 1 is described as having the S phase of the three phases (R phase, S phase, T phase) grounded, but the ground phase may be the R phase or the T phase.

A zero-phase current transformer (ZCT) 10 is connected to the leakage current detection unit 11. The zero-phase current transformer 10 is configured to clamp the electric line all at once. For example, the zero-phase current transformer 10 is configured as a handy type through-hole split type zero-phase current transformer, so that workers can easily install it on the electric line at the site.

The leakage current detection unit 11 detects (calculates) the Io flowing through the measured electric line from the signal measured by the zero-phase current transformer 10.

The voltage detection unit 12 detects the voltage applied to the electric line being measured.

The phase angle detection unit 13 detects a phase angle (θ) based on the leakage current (Io) detected by the leakage current detection unit 11 and the voltage detected by the voltage detection unit 12. Specifically, the phase angle detection unit 13 detects the phase angle (θ) based on the effective value of the leakage current (Io) detected by the leakage current detection unit 11 and the effective value of the voltage (e.g., reference voltage V _T-R ) detected by the voltage detection unit 12. For example, the phase angle detection unit 13 detects the phase angle (θ) between the reference voltage V _T-R and the leakage current (Io) based on the zero crossing points of the reference voltage V _T-R and the zero crossing points of the leakage current (Io).

The first calculation unit 14 calculates the possible range of the capacitive component leakage current (hereinafter referred to as Ioc) caused by the earth capacitance contained in the leakage current flowing through the measured electric line based on the leakage current (Io) detected by the leakage current detection unit 11 and the phase angle (θ) detected by the phase angle detection unit 13.

Here, we explain the possible range of Ioc. Figure 2 is a diagram used to explain the possible range of Ioc.

When the voltage detection unit 12 detects the voltage between the R phase and the T phase and determines the reference point from the detected voltage, as shown in Figure 2, the R phase axis is at a position 60° from the reference point, and the T phase axis is at a position 120° from the reference point. Furthermore, since the phase difference between the R phase Ior (hereinafter referred to as Ior(r)) and the reference point is 60°, Ior(r) appears on the R phase axis. Since the phase difference between the T phase Ior (hereinafter referred to as Ior(t)) and the reference point is 120°, Ior(t) appears on the T phase axis.

In addition, Ior (hereinafter referred to as Ior(rt)), which is the vector synthesis of Ior(r) and Ior(t), occurs between the R-phase axis and the T-phase axis (in the range of 60° to 120° from the reference point).

Furthermore, the Ioc of the R phase (hereinafter referred to as Ioc(r)) occurs at a position 90° from the axis of the R phase. The Ioc of the T phase (hereinafter referred to as Ioc(t)) occurs at a position 90° from the axis of the T phase. When Ioc(r) and Ioc(t) are in equilibrium, the Ioc (hereinafter referred to as Ioc(rt)), which is the combination (vector combination) of Ioc(r) and Ioc(t), occurs in the 180° direction of the reference axis (the "-X" direction in Figure 2).

Io is the composition (vector composition) of Ior(rt) and Ioc(rt). If Io detected by the leakage current detection unit 11 is at the position shown in Figure 2, Ior(rt) will occur on line L (parallel to the reference point line) to which the end point P1 of Io belongs, in the range of 60° to 120° from the reference point (R1 in Figure 2).

If a perpendicular line is dropped from the end point P1 of Io to the line on which Ioc(rt) is generated and the intersection point is "P2", then the point P3 from the origin 0 is the maximum value of Ioc(rt) (hereinafter referred to as Ioc(rt)MAX). The angle between points P1, P3, and P2 is 60°. The point P4 from the origin 0 is the minimum value of Ioc(rt) (hereinafter referred to as Ioc(rt)MIN). The angle between points P1, P4, and P2 is 60°.

Note that Ioc(rt)MAX and Ioc(rt)MIN occur in the 180° direction (-X direction) of the reference axis, but are shown in different positions in Figure 2 for the sake of explanation.

When Ioc(rt)MIN, "Ior(rt) = Ior(t)" (Ior(r) = 0). When Ioc(rt)MAX, "Ior(rt) = Ior(r)" (Ior(t) = 0).

The first calculation unit 14 therefore calculates Ioc(rt)MIN and Ioc(rt)MAX based on Io detected by the leakage current detection unit 11 and the phase angle (θ) detected by the phase angle detection unit 13. The range of Ioc(rt) is the range between Ioc(rt)MIN and Ioc(rt)MAX (R2 in FIG. 2).

The determination unit 15 determines a reference capacitive component leakage current (hereinafter referred to as reference Ioc) that serves as a reference within the possible range of Ioc calculated by the first calculation unit 14.

Specifically, the determination unit 15 may be configured to determine the median value within the range of possible Ioc values calculated by the first calculation unit 14 as the reference Ioc.

The determination unit 15 may be configured to determine an arbitrary value as the reference Ioc within the possible range of the Ioc calculated by the first calculation unit 14. For example, the inspection device 1 includes a display unit that displays information and an operation unit that accepts operations by the user. The user selects an arbitrary value from the range of Ioc displayed on the display unit and inputs it by operating the operation unit.

The second calculation unit 16 calculates the first resistance component leakage current caused by the earth insulation resistance contained in the leakage current flowing through the measured electric line based on the reference Ioc identified by the determination unit 15, the first phase angle detected by the phase angle detection unit 13, and the first leakage current detected by the leakage current detection unit 11 during the first measurement.

The first resistive component leakage current is Ior(r), Ior(t), and Ior(rt), which are calculated based on the reference Ioc, the first phase angle, and the first leakage current.

The third calculation unit 17 calculates the second resistance component leakage current caused by the earth insulation resistance contained in the leakage current flowing through the measured electric line at the time of the second measurement, which is a predetermined time after the time of the first measurement, based on the reference Ioc identified by the determination unit 15, the second phase angle detected by the phase angle detection unit 13, and the second leakage current detected by the leakage current detection unit 11.

The second resistive component leakage current is Ior(r), Ior(t), and Ior(rt), which are calculated based on the reference Ioc, the second phase angle, and the second leakage current.

The change amount calculation unit 18 compares the first resistance component leakage current calculated by the second calculation unit 16 with the second resistance component leakage current calculated by the third calculation unit 17 to calculate the change amount.

Here, the operation of the second calculation unit 16, the third calculation unit 17, and the change amount calculation unit 18 will be described. FIG. 3 is a diagram that shows a schematic diagram of the timing at which measurements are performed. In FIG. 3, four timings, t1, t2, t3, and t4, are shown as the timings at which measurements are performed, but the timings are not limited to four. FIG. 4 is a diagram that shows a schematic diagram of Ior(r), Ior(t), and Ior(rt) (hereinafter, sometimes referred to as various Iors) calculated at t1, and various Iors calculated at t2. In FIG. 4, various Iors calculated at t3 and t4 are not shown.

At t1 (first measurement), the second calculation unit 16 calculates Ior1(r), Ior1(t), and Ior1(rt) based on the reference Ioc (Ioc(rt)CEN) and the first phase angle (θ1) and first leakage current (Io1) measured at t1.

At t2 (second measurement), the third calculation unit 17 calculates Ior2(r), Ior2(t), and Ior2(rt) based on the reference Ioc (Ioc(rt)CEN) and the second phase angle (θ2) and second leakage current (Io2) measured at t2.

The change amount calculation unit 18 calculates the difference between Ior1(r) and Ior2(r), the difference between Ior1(t) and Ior2(t), and the difference between Ior1(rt) and Ior2(rt).

Also, at t3, the second calculation unit 16 calculates Ior3(r), Ior3(t), and Ior3(rt) based on the reference Ioc (Ioc(rt)CEN) and the third phase angle (θ3) and third leakage current (Io3) measured at t3.

The change amount calculation unit 18 uses Ior2(r), Ior2(t), and Ior2(rt) calculated by the third calculation unit 17 at t2 to calculate the difference between Ior2(r) and Ior3(r), the difference between Ior2(t) and Ior3(t), and the difference between Ior2(rt) and Ior3(rt).

Furthermore, at t4, the third calculation unit 17 calculates Ior4(r), Ior4(t), and Ior4(rt) based on the reference Ioc (Ioc(rt)CEN) and the fourth phase angle (θ4) and fourth leakage current (Io4) measured at t4.

The change amount calculation unit 18 uses Ior3(r), Ior3(t), and Ior3(rt) calculated by the second calculation unit 16 at t3 to calculate the difference between Ior3(r) and Ior4(r), the difference between Ior3(t) and Ior4(t), and the difference between Ior3(rt) and Ior4(rt).

The inspection device 1 repeats the same process as described above from t4 onwards. The reference Ioc is fixed and not changed for each measurement. This is based on the assumption that Ioc does not change much. The reference Ioc does not have to be fixed and may be changed periodically.

In this way, the inspection device 1 calculates the possible range of Ioc, determines a reference Ioc, calculates various Ior using this reference Ioc, calculates the amount of change between the various Ior calculated last time and the various Ior calculated this time, and uses this amount of change to inspect or monitor the delta-connected electric line under test.

Although the above description has been given with the measurement intervals (predetermined time) being equal, the intervals do not have to be equal. Specifically, the third calculation unit 17 may be configured to extend the timing of the next measurement beyond the predetermined interval when there is no difference in the amount of change calculated by the change amount calculation unit 18 in the previous measurement or when the difference is equal to or less than the predetermined difference. With this configuration, the inspection device 1 can extend the timing of the measurement when there is no difference or is small between the first resistance component leakage current and the second resistance component leakage current, thereby reducing the processing burden on the second calculation unit 16, the third calculation unit 17, and the change amount calculation unit 18.

(Regarding the calculation formula)
Next, a description will be given of a specific procedure for calculating Ior(r), Ior(t), and Ior(rt) in the second calculation unit 16 and the third calculation unit 17. Note that the formulas for calculating Ior(r), Ior(t), and Ior(rt) are not limited to the following.

In this embodiment, by assuming an Ioc value within the possible range of Ioc calculated by the first calculation unit 14, the composite vector of Ior (Ior(rt)) is determined, and Ior(r) and Ior(t), which are elements of Ior(rt), can be calculated.

Specifically, in a delta-connected circuit, Ior(rt) can be calculated using (1).
Ior(rt)=Io×sin(θ)/cos30°...(1)

Ior(t) can be calculated by equation (2).
Ior(t)=Ior(rt)-Ioc-(Io×sin(120°-θ/cos30°)...(2)

Moreover, Ior(r) can be calculated by the formula (3).
Ior(r)=Ior(rt)-Ior(t)...(3)

For example, let us take the case where the leakage current (Io) detected by the leakage current detection unit 11 is "50.00 (mA)" and the phase angle (θ) detected by the phase angle detection unit 13 is "110°". Here, Ior in a delta-connected circuit can be calculated using formula (1).

Ior is calculated by substituting Io and θ into equation (1).
Ior(rt)=50× ^10-3 ×sin110°/cos30°=54.253(mA)

In addition, when "Io = 50.00 (mA)" and "θ = 110°", the minimum value of Ioc(rt) (Ioc(rt)MIN) is "-10.026 (mA)", the maximum value of Ioc(rt) (Ioc(rt)MAX) is "44.228 (mA)", and the median value of Ioc(rt) (Ioc(rt)CEN) is "((-10.026 + 44.228)/2 =) 17.101 (mA)".

If Ioc(rt) is a negative value, Ioc(rt)MIN is set to "0 (mA)."

Next, we consider the case where the expected value of Ioc is set to the median value (Ioc(rt)CEN). Figure 5 is a schematic diagram showing a vector diagram when the expected value of Ioc is set to the median value (Ioc(rt)CEN). As mentioned above, Ioc(rt)CEN is "17.101 (mA)".

Ior(t) is calculated from equation (2) as follows:
Ior(t)=27.13 (mA)

Moreover, Ior(r) is calculated from equation (3) as follows:
Ior(r)=27.13 (mA)

(Inspection method)
Here, a description will be given of an inspection method using the inspection device 1. Fig. 6 is a flow chart illustrating the procedure of the inspection method.

In step ST1, the leakage current detection unit 11 detects the leakage current flowing in the measured electric line in which the first, second, and third phases are delta-connected (leakage current detection process).

In step ST2, the voltage detection unit 12 detects the voltage applied to the electric line to be measured (voltage detection process).

In step ST3, the phase angle detection unit 13 detects the phase angle based on the leakage current detected by the leakage current detection process and the voltage detected by the voltage detection process (phase angle detection process).

In step ST4, the first calculation unit 14 calculates the possible range of the capacitive leakage current caused by the earth capacitance contained in the leakage current flowing through the measured electric line based on the leakage current detected by the leakage current detection process and the phase angle detected by the phase angle detection process (first calculation process).

In step ST5, the determination unit 15 determines a reference capacitive component leakage current that serves as a reference within the possible range of the capacitive component leakage current calculated in the first calculation process (determination process).

In step ST6, the second calculation unit 16 calculates the first resistive component leakage current caused by the earth insulation resistance contained in the leakage current flowing through the measured electric line during the first measurement based on the reference capacitive component leakage current identified in the determination process, the first phase angle detected in the phase angle detection process, and the first leakage current detected in the leakage current detection process (second calculation process).

In step ST7, the third calculation unit 17 calculates the second resistance component leakage current caused by the earth insulation resistance contained in the leakage current flowing through the measured electric line at the time of the second measurement, which is a predetermined time after the time of the first measurement, based on the reference capacitive component leakage current identified in the determination process, the second phase angle detected in the phase angle detection process, and the second leakage current detected in the leakage current detection process (third calculation process).

In step ST8, the change amount calculation unit 18 compares the first resistance component leakage current calculated in the second calculation process with the second resistance component leakage current calculated in the third calculation process to calculate the change amount (change amount calculation process).

In this way, the inspection method calculates the possible range of Ioc, determines a reference Ioc, calculates various Ior using this reference Ioc, calculates the amount of change between the various Ior calculated last time and the various Ior calculated this time, and uses this amount of change to inspect or monitor the delta-connected electric line under test.

(About the inspection program)
An inspection program that calculates the possible range of Ioc, determines a reference Ioc, calculates various Ior using this reference Ioc, calculates the amount of change between the various Ior calculated last time and the various Ior calculated this time, and uses this amount of change to inspect or monitor a Δ-connected electric line under test is mainly composed of the following steps and is executed by a computer 500 (hardware).

Step 1: Detecting leakage current flowing through a test line in which the first, second, and third phases are delta-connected (leakage current detection step).
Step 2: Detecting the voltage applied to the electric line to be measured (voltage detection step)
Step 3: Detecting a phase angle based on the leakage current detected in the leakage current detection step and the voltage detected in the voltage detection step (phase angle detection step).
Step 4: Based on the leakage current detected in the leakage current detection step and the phase angle detected in the phase angle detection step, a possible range of the capacitive leakage current caused by the earth capacitance included in the leakage current flowing through the electric line under test is calculated (first calculation step).
Step 5: A reference capacitive component leakage current is determined within the possible range of the capacitive component leakage current calculated in the first calculation step (determination step).
Step 6: During the first measurement, a first resistive component leakage current caused by the insulation resistance to ground, which is included in the leakage current flowing through the electric line under test, is calculated based on the reference capacitive component leakage current identified in the determination step, the first phase angle detected in the phase angle detection step, and the first leakage current detected in the leakage current detection step (second calculation step).
Step 7: At the time of a second measurement that is a predetermined time after the time of the first measurement, a second resistive component leakage current caused by the insulation resistance to ground, which is included in the leakage current flowing through the electric line under test, is calculated based on the reference capacitive component leakage current identified in the determination step, the second phase angle detected in the phase angle detection step, and the second leakage current detected in the leakage current detection step (third calculation step).
Step 8: Calculate the amount of change by comparing the first resistance component leakage current calculated in the second calculation step with the second resistance component leakage current calculated in the third calculation step (amount of change calculation step).

Here, the configuration and operation of computer 500 will be described with reference to the diagram. As shown in FIG. 7, computer 500 is configured with processor 501, memory 502, storage 503, input/output I/F 504, and communication I/F 505 connected on bus A, and these components work together to realize the functions and/or methods described in this disclosure.

The input/output I/F 504 is connected to, for example, a display that displays various information, and a touch panel that accepts user operations. The touch panel is located in front of the display. Thus, the user can perform intuitive operations by touching icons displayed on the display with his/her finger. The touch panel does not have to be located in front of the display. Also, instead of or together with the touch panel, a keyboard and a pointing device such as a mouse may be connected to the input/output I/F 504. Also, a speaker that outputs sound to the outside and a microphone that inputs sound from the outside may be connected to the input/output I/F 504.

The display is configured with a liquid crystal display or an organic EL (Electro Luminescence) display, and displays various information under the control of the processor 501.

Memory 502 is composed of RAM (Random Access Memory). The RAM is composed of volatile memory or non-volatile memory.

Storage 503 is composed of ROM (Read Only Memory). ROM is composed of non-volatile memory, and is realized, for example, by HDD (Hard Disc Drive) or SSD (Solid State Drive). Storage 503 stores various programs such as the inspection programs realized in steps 1 to 8 described above.

For example, the processor 501 controls the overall operation of the computer 500. The processor 501 is an arithmetic device that loads an operating system and various programs that realize various functions from the storage 503 into the memory 502 and executes the instructions contained in the loaded programs.

Specifically, when processor 501 receives a user operation, it reads a program (e.g., an inspection program) stored in storage 503, expands the read program in memory 502, and executes the program. In addition, by processor 501 executing the inspection program, the functions of leakage current detection unit 11, voltage detection unit 12, phase angle detection unit 13, first calculation unit 14, determination unit 15, second calculation unit 16, third calculation unit 17, and change amount calculation unit 18 are realized.

Here, the configuration of the processor 501 will be described. The processor 501 is realized, for example, by a CPU (Central Processing Unit), an MPU (Micro Processing Unit), a GPU (Graphics Processing Unit), various other arithmetic devices, or a combination of these.

Furthermore, in order to realize the functions and/or methods described in this disclosure, some or all of the functions of the processor 501, memory 502, storage 503, etc. may be configured in a processing circuit 601, which is dedicated hardware, as shown in FIG. 8. The processing circuit 601 is, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination of these.

Although the processor 501 has been described as a single component, the present invention is not limited to this and may be configured as a collection of multiple physically separate processors. In this specification, a program or instructions included in the program described as being executed by the processor 501 may be executed by a single processor 501, or may be distributed and executed by multiple processors. Furthermore, a program or instructions included in the program executed by the processor 501 may be executed by multiple virtual processors.

The communication I/F 505 is an interface that complies with a specific communication standard and communicates with external devices via wired or wireless communication.

In this way, the inspection program is executed by the computer 500 to calculate the possible range of Ioc, determine a reference Ioc, calculate various Ior's using this reference Ioc, calculate the amount of change between the various Ior's calculated last time and the various Ior's calculated this time, and use this amount of change to inspect or monitor the delta-connected electric line under test.

REFERENCE SIGNS LIST 1 Inspection device 10 Zero-phase current transformer 11 Leakage current detection unit 12 Voltage detection unit 13 Phase angle detection unit 14 First calculation unit 15 Determination unit 16 Second calculation unit 17 Third calculation unit 18 Change amount calculation unit

Claims (5)

a leakage current detection unit for detecting a leakage current flowing through a test electric line having a first phase, a second phase, and a third phase connected in a delta configuration;
A voltage detection unit that detects a voltage applied to the electric line under test;
a phase angle detection unit that detects a phase angle based on the leakage current detected by the leakage current detection unit and the voltage detected by the voltage detection unit;
a first calculation unit that calculates a possible range of a capacitive leakage current caused by an earth capacitance included in the leakage current flowing through the electric line under test, based on the leakage current detected by the leakage current detection unit and the phase angle detected by the phase angle detection unit;
a determination unit that determines a reference capacitive component leakage current as a reference within a possible range of the capacitive component leakage current calculated by the first calculation unit;
a second calculation unit that calculates a first resistance component leakage current caused by an insulation resistance to ground, which is included in the leakage current flowing through the electric line under measurement, based on the reference capacitive component leakage current specified by the determination unit, the first phase angle detected by the phase angle detection unit, and the first leakage current detected by the leakage current detection unit during a first measurement;
a third calculation unit that calculates a second resistance component leakage current caused by an insulation resistance to ground, which is included in the leakage current flowing through the electric line under test, based on the reference capacitive component leakage current identified by the determination unit, the second phase angle detected by the phase angle detection unit, and the second leakage current detected by the leakage current detection unit, at a second measurement time that is a predetermined time after the first measurement time;
a change amount calculation unit that calculates a change amount by comparing the first resistance component leakage current calculated by the second calculation unit with the second resistance component leakage current calculated by the third calculation unit ,
The inspection device, wherein the determination unit is configured to determine a median value within a range of possible values of the capacitive component leakage current calculated by the first calculation unit as the reference capacitive component leakage current . The inspection device according to claim 1, wherein the determination unit is configured to determine an arbitrary value as the reference capacitive component leakage current within a possible range of the capacitive component leakage current calculated by the first calculation unit. 3. The inspection device according to claim 1, wherein the third calculation unit is configured to extend the predetermined time and perform a next measurement when there is no difference in the amount of change calculated by the change amount calculation unit in the previous measurement or when the difference is equal to or smaller than a predetermined difference. a leakage current detection step of detecting a leakage current flowing in a test electric line in which a first phase, a second phase, and a third phase are delta-connected;
a voltage detection step of detecting a voltage applied to the electric line to be measured;
a phase angle detection step of detecting a phase angle based on the leakage current detected by the leakage current detection step and the voltage detected by the voltage detection step;
a first calculation step of calculating a possible range of a capacitive leakage current caused by an earth capacitance included in the leakage current flowing through the electric line under test, based on the leakage current detected in the leakage current detection step and the phase angle detected in the phase angle detection step;
a determination step of determining a median value of a reference capacitive component leakage current as a reference within a range of possible values of the capacitive component leakage current calculated in the first calculation step;
a second calculation step of calculating a first resistance component leakage current caused by an insulation resistance to ground, which is included in the leakage current flowing through the electric line under test, based on the reference capacitive component leakage current determined in the determination step, the first phase angle detected in the phase angle detection step, and the first leakage current detected in the leakage current detection step during the first measurement;
a third calculation step of calculating a second resistance component leakage current caused by insulation resistance to ground, which is included in the leakage current flowing through the electric line under test, based on the reference capacitive component leakage current determined in the determination step, the second phase angle detected in the phase angle detection step, and the second leakage current detected in the leakage current detection step, at a second measurement time that is a predetermined time after the first measurement time;
An inspection method comprising: a change amount calculation process for calculating an amount of change by comparing the first resistance component leakage current calculated in the second calculation process with the second resistance component leakage current calculated in the third calculation process. On the computer,
a leakage current detection step of detecting a leakage current flowing in a test electric line in which a first phase, a second phase, and a third phase are delta-connected;
a voltage detection step of detecting a voltage applied to the electric line to be measured;
a phase angle detection step of detecting a phase angle based on the leakage current detected by the leakage current detection step and the voltage detected by the voltage detection step;
a first calculation step of calculating a possible range of a capacitive leakage current caused by an earth capacitance included in the leakage current flowing through the electric line under test, based on the leakage current detected in the leakage current detection step and the phase angle detected in the phase angle detection step;
a determination step of determining a median value of a reference capacitive component leakage current as a reference within a range of possible values of the capacitive component leakage current calculated in the first calculation step;
a second calculation step of calculating a first resistance component leakage current caused by an insulation resistance to ground, which is included in the leakage current flowing through the electric line under test, based on the reference capacitive component leakage current determined in the determination step, the first phase angle detected in the phase angle detection step, and the first leakage current detected in the leakage current detection step during the first measurement;
a third calculation step of calculating a second resistance component leakage current caused by insulation resistance to ground, which is included in the leakage current flowing through the electric line under test, based on the reference capacitive component leakage current determined in the determination step, the second phase angle detected in the phase angle detection step, and the second leakage current detected in the leakage current detection step, at a second measurement time that is a predetermined time after the first measurement time;
and a change amount calculation process for calculating a change amount by comparing the first resistance component leakage current calculated by the second calculation process with the second resistance component leakage current calculated by the third calculation process.

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