TW201942586A - Insulation measuring apparatus and insulation measuring method - Google Patents

Abstract

Provided is an insulation measurement device and an insulation measurement method which make it possible to accurately determine genuine resistance-component leakage current by appropriately eliminating an error factor during detection. This insulation measurement device (10A) measures resistance-component leakage current of three-phase wiring TRS connected from a power source (1) to a three-phase motor (2). Said measurement device comprises: bus bars (11) which respectively relay the three-phase wiring TRS; a ZCT (12) which has a through-hole (12a), the bus bars (11) passing through and being insulatively fixed/supported in the through-hole (12a), and which detects zero-phase current that is a combination of through-currents flowing through the bus bars (11); a CT (13) which detects the through-current flowing through at least one of the bus bars (11); and a control unit (14) which, using the at least one through-current detected by the CT (13), corrects the detected zero-phase current and measures the resistance-component leakage current.

Description

Insulation measurement device and insulation measurement method

The invention relates to an insulation measuring device and an insulation measuring method, which measure the leakage current of a resistance component of a three-phase wiring connected from a power source to a three-phase motor.

For example, in the wiring to the motor, leakage current is generated due to the deterioration of the insulation resistance of the inductor, and Zero-phase-sequence Current Transformer (ZCT) has been widely used as a detection inductor. .

The zero-phase current transformer (ZCT) is a device that detects the zero-phase current synthesized by the three-phase-divided penetrating current by passing the three-phase divided wires together through the current transformer.

Here, because the zero-phase current transformer (ZCT) uses a through current as the primary winding and the coil inside the zero-phase current transformer (ZCT) is used as the secondary winding transformer, the current corresponding to the winding ratio is output to the zero-phase Specific Current (ZCT) secondary side. Therefore, if the three-phase-divided through-current is passed through the zero-phase current transformer (ZCT) together, the zero-phase current synthesized by the three-phase-divided through-current flows to the secondary side. At this time, because the three-phase alternating current has the same magnitude in each phase and each has a phase difference of 120 °, the zero-phase current synthesized by the three-phase divided through currents of the three-phase alternating current is zero. In other words, under normal conditions, no current flows on the secondary side of the zero-phase current transformer (ZCT).

On the other hand, the zero-phase current flowing on the secondary side of the zero-phase current transformer (ZCT) refers to the state when the balance of the three-phase current is broken, that is, when the current flows from one of the three-phase wires to the ground. In other words, it is when the leakage current is generated. As a result, by using a zero phase current transformer (ZCT), it is possible to detect which of the three-phase phase wirings is below a predetermined insulation resistance.

Examples of such a technique include a ground voltage sensitivity test method disclosed in Patent Document 1.

In the ground voltage sensitivity test method disclosed in Patent Document 1, the ground voltage sensitivity test apparatus 100 used therein is shown in FIG. 9 and includes a zero-phase current transformer 101, a ground direction relay 102, a voltage measuring section 103, Transformer T, residual voltage elimination device 104, power source 105, measurement tester 106, and voltage detector 107.

In this ground voltage sensitivity test method, the residual current voltage is measured in the voltage measurement unit 103, that is, the leakage voltage is measured, and when the residual current voltage is generated, the residual voltage elimination device 104 is connected to the power source 105, and the residual voltage elimination device 104 is The output terminals y1 and y2 are connected to the output terminals y1 and y2 of the voltage measurement unit 103. The phase is adjusted by the phase adjuster 104a and the voltage is adjusted by the voltage adjuster 104b so that the residual current voltage appearing in the voltage detector 107 becomes zero. .

Thereby, since the residual voltage of the voltage measurement unit 103 is removed, it is possible to measure an accurate ground voltage that is not affected by the residual voltage.

[Prior technical literature]
[Patent Literature]
[Patent Document 1] Japanese Published Patent Gazette "Japanese Patent Laid-Open No. 4-48273 (published on September 8, 1998)"
[Patent Document 2] Japanese Patent Laid-Open Publication No. 2010-25743 (published on February 4, 2010)

[Problems to be solved by the invention]
However, in the ground voltage sensitivity test method disclosed in the conventional patent document 1, the residual current is corrected by making the value of the zero-phase current including the residual current zero (zero) on the premise that the motor is not deteriorated. Residual current voltage in Patent Document 1). However, even when the motor is slightly deteriorated in the initial state, it is in a state including an initial error. In addition, if the through position and the through current of the inverter 101 toward the zero phase of the power distribution line are changed, the phase and magnitude of the correction value are changed, and there is a problem that the correction needs to be performed again.

To address these issues, they are described in detail below.

That is, the leakage current (Io) includes two components: a capacitive component leakage current (Ioc) that can flow normally, and a resistance component leakage current (Ior) that is a cause of fire and accident. The resistance component leakage current (Ior) gradually increases with the deterioration of the insulation, and when it becomes equal to or lower than a predetermined insulation resistance, the insulation is broken and the motor is broken. In order to measure the resistance component leakage current (Ior), a method of separating two components is widely used, which is called an Ior method.

In the Ior method, as shown in FIG. 10, the insulation resistance, that is, the voltage applied to the three-phase wiring is measured in the voltage acquisition section (S101). Next, the zero-phase current is measured in a zero-phase current transformer (ZCT) (S102). After that, the zero-phase current is separated into a capacitive component leakage current (Ioc) and a resistive component leakage current (Ior) (S103). Finally, the insulation resistance value is calculated from the resistance component leakage current (Ior) and the voltage (S104).

Here, in order to let the user know the insulation deterioration early, it is necessary to measure a minute resistance component leakage current (Ior) that flows, for example, at an insulation resistance of about 10 MΩ. In the case of a 200V series motor, a resistance component leakage current (Ior) equivalent to 10MΩ is about 20 μA. As mentioned above, the zero-phase current transformer (ZCT) is a transformer that uses the through current of the three-phase wiring as the primary winding and the coil inside the zero-phase current transformer (ZCT) as the secondary winding. The ratio current is output to the secondary side of the zero-phase current transformer (ZCT). Because the zero-phase current output to the secondary side of the zero phase current transformer (ZCT) is usually about 1/1000, it is necessary to be an nA level measurement accuracy. As a result, the zero-phase current output to the secondary side of the zero-phase current transformer (ZCT) is also affected by the induced noise in the surrounding environment. And the current measurement circuit needs sufficient metal shielding.

In addition, the drive current of the motor varies depending on the motor capacity. In the case of a 300 kW high-capacity product of a general low-voltage motor, it flows about 600 A. Therefore, because it is a very severe measurement system capable of measuring from 600A primary current to nA secondary current, it is necessary to take measures to eliminate surrounding noise.

In addition, not only the surrounding noise, but also the measurement accuracy of the ZCT is becoming a problem. When a zero phase current transformer (ZCT) measures zero-phase current on the secondary side, it generates an error current called residual current. This error current, called residual current, is generated because it cannot be accurately shielded because of structural non-uniformities such as manufacturing non-uniformity of the iron core constituting the zero-phase current transformer (ZCT) or winding non-uniformity of the coil. The magnetic flux generated by the through current is interrupted. Because the zero phase current transformer (ZCT) measures the leakage current of the three-phase wiring, that is, the unbalanced component of the three-phase wiring, the unbalanced component of the structural unevenness becomes an error. In terms of such structural non-uniformity, for example, since the magnitude and phase difference of the residual current may change according to the positional relationship between the three-phase wiring and the zero-phase current transformer (ZCT), it is difficult to identify the error factor.

Because the residual current including the error due to the resistance component leakage current (Ior) at the insulation resistance of 10MΩ which is necessary for the original measurement is very large, it is impossible to measure the small resistance component leakage current (Ior), and because the insulation is sufficiently deteriorated Later, it becomes measurable when it exceeds 10MΩ. If the insulation is sufficiently deteriorated, the time until the destruction of the insulation is insufficient will be insufficient, and the user must perform maintenance urgently, and cannot be maintained in a planned manner.

As described above, since the residual current includes errors due to non-uniformity in the structure of the zero-phase current transformer (ZCT), the magnitude and phase of the residual current vary depending on the penetration position of the three-phase wiring. In addition, there is a problem in that the current driven by the motor capacity of the motor changes, and the magnitude of the residual current also changes according to the current.

In addition, as a conventional technique using an Ior method of separating two components of a capacitive component leakage current (Ioc) and a resistance component leakage current (Ior), for example, the insulation measuring device disclosed in Patent Document 2 is a Known. However, even in the insulation measuring device disclosed in Patent Document 2, it is impossible to perform analysis to the residual current including such various errors.

The one aspect of the present disclosure is the one completed in view of the conventional problems, and its purpose is to provide an insulation measuring device and an insulation measuring method. The foregoing insulation measuring device and insulation measuring method can reliably remove the error factor during detection. And accurately obtain the true resistance component leakage current.

[Means to solve the problem]
The present inventors found the phase of the residual current by investigating the generation factor of the residual current (current based on the error) of the three-phase motor, and using a conductive member to fix the through position of the zero phase current transformer and the three-phase wiring toward the three-phase motor There is no change in size, and the insulation measurement device and insulation measurement method of the present disclosure are completed.

One specific aspect of the insulation measurement device and insulation measurement method of the present disclosure is as follows.

In order to solve the above-mentioned problem, the present disclosure provides an insulation measuring device for measuring a leakage current of a resistance component connected to a three-phase wiring of a three-phase motor from a power source. Wiring; zero-phase current transformers have through-holes, fixedly support each of the conductive members in an insulating manner, and pass each of the conductive members through the through-holes, and detect each of the through-current sources that will flow through the conductive members. A combined zero-phase current; a through-current ratio detector that detects the through-current flowing through at least one of the conductive members; and a control unit that uses at least one of the through-currents detected by the through-current ratio to Correct the detected zero-phase current, and measure the resistance component leakage current.

In order to solve the above-mentioned problem, the present disclosure provides a method for measuring insulation, which measures the leakage current of a resistance component from a power supply connected to a three-phase wiring of a three-phase motor. The method includes: a setting step of setting up the three phases respectively. Each conductive member of the wiring; a zero-phase current detection step, which is based on a zero-phase current transformer, fixedly supports each of the conductive members in an insulating manner and passes each of the conductive members through the through-holes, and detects that each of the conductive members will flow through The zero-phase current synthesized by each of the through currents of the component; the through current detection step is to detect the through current flowing through at least one of the aforementioned conductive components in a through current ratio meter; and the measurement step is to use the through current ratio At least one of the aforementioned through-currents detected by the current transformer is used to correct the detected zero-phase current, and the leakage current of the resistance component is measured.

[Inventive effect]
According to one aspect of the present disclosure, the following effects can be provided: an insulation measurement device and an insulation measurement method are provided, and the foregoing insulation measurement device and insulation measurement method can reliably remove an error factor during detection and accurately obtain the true accuracy The leakage current of the resistance component.

Hereinafter, an embodiment of one aspect of the present disclosure will be described based on the drawings (hereinafter, also referred to as "this embodiment").

(Application example)
First, an example to which the present disclosure is applied will be described based on FIG. 1. FIG. 1 is a perspective view showing an overall configuration of an insulation measuring device 10A according to an aspect of the present disclosure.

As shown in FIG. 1, an insulation measuring device 10A of the present disclosure measures a resistance component leakage current (Ior) of a three-phase wiring TRS connected from a power source 1 to a three-phase motor 2. Next, it is equipped with: each busbar 11 ･ 11，11, which is connected to the three-phase wiring TRS; zero-phase current transformer (ZCT) 12, which has a through-hole 12a, which is fixed in an insulated manner Support the bus bars 11 汇 11 ･ 11 and let the bus bars 11 ･ 11 贯通 11 pass through the through-holes 12a, and detect the zero-phase current synthesized by the through currents flowing through the bus bars 11 ･ 11 ･ 11; the through-current A current transformer (CT) 13 for detecting a through current flowing through at least one of the bus bars 11 ･ 11 ･ 11; and a control section 14 for using at least one through detected by the through current current transformer (CT) 13 Current to correct the detected zero-phase current and measure the leakage current (Ior) of the resistance component.

In addition, the present invention discloses an insulation measurement method for measuring a leakage current of a resistance component of a three-phase wiring connected from a power source to a three-phase motor. The method includes a setting step of setting each of the three-phase wiring TRSs respectively connected. Bus bars 11 ･ 11 ･ 11; zero-phase current detection step, which is based on the zero phase current transformer (ZCT) 12, and fixedly supports each bus bar 11 ･ 11 ･ 11 in an insulated manner and makes each bus bar 11 ･ 11 ･ 11 through-holes 12a, and detect the zero-phase current synthesized by the through-currents flowing through the bus bars 11 ･ 11 ･ 11; the through-current detection step is based on the through-current current transformer (CT) 13 to detect the current A through current passing through at least one of the bus bars 11 ･ 11 ･ 11; and a measuring step of correcting the detected zero-phase current by measuring at least one through current detected in the through current ratior (CT) 13 and measuring Resistance component leakage current (Ior). The bus bar 11 has a function as a conductive member of the present disclosure.

Thereby, since the zero-phase current to the power line of the three-phase motor 2 is directly detected, it is possible to measure the resistance component leakage current (Ior) that shows only the insulation degradation state of the three-phase motor 2.

In addition, the bus bars 11 具有 11 具有 11 are conductive, and each of the bus bars 11 ･ 11 ･ 11 is fixedly supported and penetrated through the through hole 12 a of the ZCT 12 in an insulated manner. Therefore, since the position of the power line of the three-phase motor 2 is fixed in the through hole 12 a of the ZCT 12, the phase and magnitude of the residual current do not change. As a result, the error factor can be eliminated, and the aforementioned error factor refers to changing the magnitude and phase of the residual current according to the penetration position of each of the three-phase wirings TRS in the through-hole 12 a of the ZCT 12. Therefore, the residual current can be corrected, and a minute resistance component leakage current (Ior) on the order of nA can be measured.

In addition, the insulation measuring device 10A according to the aspect of the present disclosure further includes a control unit 14 that corrects the detected zero-phase current by using at least one of the through currents detected by the through-current ratior (CT) 13. , And measure the leakage current of the resistance component.

This makes it possible to eliminate the error factor based on the motor capacity of the three-phase motor 2 because the zero-phase current is corrected by using at least one through-current detected by the through-current current transformer (CT) 13. In addition, since the resistance component leakage current (Ior) is measured by the control unit 14, the true resistance component leakage current (Ior) can be obtained after the measurement of the zero-phase current is corrected.

Therefore, it is possible to provide an insulation measurement device 10A and an insulation measurement method, which can reliably remove an error factor at the time of detection and accurately obtain a true resistance component leakage current (Ior) with good accuracy. Furthermore, since the deterioration of the insulation of the three-phase motor 2 can be detected early, it can be plannedly maintained.

[Embodiment 1]
An embodiment of the present disclosure will be described based on FIGS. 1 to 5 as follows.

(Configuration example)
The overall configuration of the insulation measuring device 10A of this embodiment will be described based on FIG. 1. FIG. 1 is a perspective view showing an overall configuration of an insulation measuring device according to an embodiment of the present disclosure.

As shown in FIG. 1, the insulation measuring device 10A of this embodiment measures the insulation resistance value of the three-phase wiring TRS connected from the power source 1 to the three-phase motor 2. The power supply 1 may be a secondary side of an inverter.

The insulation measuring device 10A is provided with three busbars 11 ･ 11 ･ 11 as conductive parts, which are respectively connected to the three-phase wiring TRS, and a zero phase current transformer 12 (hereinafter referred to as ZCT12), which is connected to While having the through holes 12a, the three bus bars 11 ･ 11 ･ 11 are fixedly supported in an insulating manner and the three bus bars 11 ･ 11 ･ 11 pass through the through holes 12a, and the measurement is included in the flow through each of the bus bars 11 ･ The leakage current of the through current of 11 ･ 11; the through-current ratior 13 (hereinafter referred to as CT13) measures the size of the through current flowing through at least one of the three bus bars 11 ･ 11 ･ 11.

The bus bar 11 is made of a plate-shaped metal plate, and has conductivity and rigidity. When the bus bars 11 ･ 11 ･ 11 penetrate the inside of the through hole 12 a of the ZCT 12, the bus bars 11 ･ 11 ･ 11 and between the through holes 12 a and the bus bars 11 ･ 11 ･ 11 are insulated. Specifically, an insulating material (not shown) is installed between these, and the bus bars 11 ･ 11 ･ 11 are fixed and supported so that the bus bars 11 ･ 11 ･ 11 do not move inside the through hole 12 a. Moreover, in this embodiment, although the bus bar 11 is preferably rigid, it does not necessarily need to be rigid, as long as it can be fixed and supported by an insulating material.

One end of each of the bus bars 11 ･ 11 ･ 11 is connected to the three-phase wiring TRS toward the power source 1, and the other end is connected to the three-phase wiring TRS toward the three-phase motor 2.

ZCT12 has coils (not shown). It uses the through current flowing in each of the bus bars 11 ･ 11 一次 11 as the primary winding, and uses the coil inside ZCT12 as the secondary winding, and functions as a transformer. The current corresponding to the winding ratio is output to a control unit 14 described later as the secondary side of the ZCT 12.

The CT13 has a through-hole 13a at the center and is a through-type current generator. In the present embodiment, the through hole 13a is provided so that the through hole 13a of the CT13 penetrates any one of the three bus bars 11 ･ 11 ･ 11. CT13 measures the current value of the through current flowing through one of the three bus bars 11. Although the CT 13 is provided on the side of the three-phase motor 2 of the bus bar 11 in the present embodiment, it is not limited to this, and it may be provided on the power source 1 side of the bus bar 11.

In the insulation measuring device 10A of this embodiment, for example, a control unit 14 is provided above the ZCT 12. The control unit 14 is provided inside a casing formed by a shielding member that shields electricity and magnetism. The reason why the shielding member constitutes the case is that by covering the control unit 14 with the shielding member, the control unit 14 can be isolated from minute noise. Thereby, it is possible to reduce the error of the induced noise, and it is possible to measure a micro-current of nA level.

As shown in FIG. 1, the control unit 14 includes a measurement zero-phase current acquisition unit 14 a as a first measurement zero-phase current acquisition unit, a correction unit 14 b as a first correction unit, and voltage acquisition as a first voltage acquisition unit. Unit 14c; calculation unit 14d as the first calculation unit.

The measurement zero-phase current acquisition unit 14 a measures the magnitude and phase of the zero-phase current from the zero-phase current detected by the ZCT 12 to obtain a measured zero-phase current. The correction unit 14b obtains a residual current correction value corresponding to an arbitrary through current at the time of shipment from the factory. The correction unit 14b also calculates a current correspondence correction value corresponding to the through current detected at CT13, and uses the current correspondence correction value for measuring the zero-phase current to correct the measured zero-phase current and obtain a corrected zero-phase current. The corrected zero-phase current is displayed near the true zero-phase current. The voltage acquisition unit 14c measures the magnitude and phase of the phase-to-phase voltage of at least one of the bus bars 11 and acquires the bus voltage as the voltage of the conductive member. The calculation unit 14d is composed of a CPU, and calculates a resistance component leakage current (Ior) and an insulation resistance value based on the true zero-phase current and the bus voltage. The calculation result can be stored in a storage unit (not shown).

The control operation for determining whether there is a leakage current in the three-phase wiring TRS and the insulation resistance value of the three-phase wiring TRS using the insulation measuring device 10A having the above-mentioned configuration is based on (a) of FIGS. 2 to 5, (b) Explain. FIG. 2 is a flowchart showing a method of correcting the insulation measuring device 10A according to this embodiment when it is shipped from the factory. FIG. 3 is a diagram showing a concept for introducing a correction message. FIG. 4 is a flowchart showing a correction method when the user of the insulation measuring device 10A according to this embodiment is used. (A) of FIG. 5 is a vector diagram in which the residual current is corrected from the zero-phase current measured by the insulation measuring device 10A to obtain a true zero-phase current. FIG. 5 (b) is a vector diagram showing the zero-phase current when the residual current correction is not performed.

As shown in FIGS. 2 and 3, in the insulation measuring device 10A of this embodiment, a residual current correction value corresponding to an arbitrary through current flowing through a bus voltage is obtained at the time of factory shipment. In other words, the magnitude of the through current and the magnitude of the residual current flowing through the bus bars 11 · 11 · 11 have a characteristic of linear change. Therefore, a residual current correction value corresponding to an arbitrary through current is prepared in advance as a correction formula.

Specifically, the correction formula of the residual current correction value corresponding to an arbitrary through current can be expressed as a linear formula of the through current. Thereby, the slope and intercept of the correction formula can be obtained from the first residual current when the first through current flows through the bus bar 11 and the second residual current when the second through current flows through the bus bar 11. As a result, a residual current correction value corresponding to an arbitrary through current can be obtained.

A specific method of calculating the residual current correction value corresponding to an arbitrary through current is as follows.

As shown in FIGS. 2 and 3, first, the magnitude and phase of the first residual current I _R1 (S1) are measured using a first through current I _T1 flowing through the bus 11, and then a second current flowing through the bus 11 is used. The through current I _T2 measures the magnitude of the second residual current I _R2 (S2). Specifically, the first through current I _{T1 is} supplied from the power supply 1 shown in FIG. 1 to the three-phase motor 2 through the three-phase wiring TRS and the bus bars 11 ･ 11 ･ 11, and the CT13 is used to measure the first residual current I _R1 . Size and phase. In addition, the second through-current I _{T2 is} supplied from the power source 1 shown in FIG. 1 to the three-phase motor 2 through the three-phase wiring TRS and the bus bars 11 ･ 11 ･ 11, and the magnitude of the second residual current I _R2 is measured using CT13. In this embodiment, each of the bus bars 11 ･ 11 ･ 11 is fixed so as not to move inside the through hole 12 a of the ZCT 12. Therefore, when the first through current I _T1 and the second through current I _T2 flow through the bus bars 11 ･ 11 ･ 11, the phases of the first residual current I _R1 and the second residual current I _R2 are not changed, and they are mutually the same. Therefore, the phase measurement may be performed only for the first residual current I _R1 or the second residual current I _R2 . Therefore, in this embodiment, for example, only the phase of the first residual current I _R1 is measured.

Accordingly, from the graph shown in FIG. 3, as the residual current correction value, the following relational expression (Expression 1) can be introduced, and specific constants α and β can be obtained.
Residual current I _R = α * through current I _T + β… (Equation 1).

As a result, the residual current correction value for the actual through current, that is, the current corresponding correction value can be expressed by (Expression 2).
Residual current correction value =-(α * penetration current + β) ... (Equation 2).
The through current of (Expression 2) is a through current that can be obtained by a user when actually measuring. The negative sign is added to (Expression 2) because the residual current correction value =-(residual current I _R ), and the correction for the measured zero-phase current is operated on the negative sign side. These calculations are performed by the correction unit 14B.

In addition, the residual current shown in FIG. 3 shows that when the first through current I _T1 flows through the bus bar 11, a first residual current I _{R1 is} generated in response to the first through current I _T1 ; When I _T2 flows through the busbar 11, a second residual current I _{R2 is} generated in response to the second through current I _T2 . The magnitude of the first through current I _T1 is preferably a through current of the smallest motor capacity of the three-phase motor 2 used, and the magnitude of the second through current I _T2 is preferably a three-phase motor 2 used. The maximum motor capacity of the through current.

As a result, as shown in FIG amended message calculating the residual current I _R in the (α, β) is kept in a storage-based portion (S3) of calculating portion 14d 2.

As shown in FIG. 4, on the other hand, when a user who purchases the insulation measuring device 10A uses it, first, the through current is obtained at CT 13 (S11). Specifically, the third through-current I _{T3 is} supplied from the power source 1 shown in FIG. 1 to the three-phase motor 2 through the three-phase wiring TRS and the bus bars 11 ･ 11 ･ 11. Thereby, the magnitude of the third through current I _T3 is measured in the CT 13 and the correction unit 14 b. Next, the correction unit 14b is used to determine a current corresponding correction value from the obtained third through current I _T3 (Equation 1), that is, a residual current correction value corresponding to the third through current I _T3 (S12).

Next, while the voltage obtaining section 14c measures the voltage and phase of the phase-to-phase wiring between the bus bars 11 ･ 11 ･ 11 applied to the insulation resistance (S13), the ZCT12 and the measuring zero-phase current obtaining section 14a measure the zero-phase current and phase (S14).

Here, as shown in FIG. 5 (a), the measured zero-phase current includes the error of the residual current of the capacitive component (Ioc) and the leakage current of the resistive component (Ior), and also includes the error of the residual current. Therefore, the residual current correction value is synthesized from the measured zero-phase current vector. Thereby, a true zero-phase current is obtained (S15).

Next, as shown in FIG. 4 and FIG. 5A, the true zero-phase current is separated into a capacitive component leakage current (Ioc) and a resistive component leakage current (Ior) (S16). In the case of separation, the phase difference between the phase of the measured zero-phase current and the phase of the voltage applied to the insulation resistance is separated into a capacitive component leakage current (Ioc) and a resistance component leakage current (Ior).

Next, the calculation unit 14d calculates the insulation resistance value based on the resistance component leakage current (Ior) and the phase-to-phase voltage applied to the insulation resistance obtained by the voltage acquisition unit 14c (S17). The insulation resistance value can be obtained by dividing the voltage applied to the insulation resistance obtained by the voltage acquisition unit 14c by the resistance component leakage current (Ior).

When such a correction is not performed, as shown in FIG. 5 (b), the resistance component leakage current (Ior) is calculated based on the measured zero-phase current, so an error including the residual current is calculated. The resistance component leakage current (Ior).

In this way, the insulation measuring device 10A of this embodiment measures the resistance component leakage current (Ior) of the three-phase motor 2 connected from the power source 1 through the three-phase wiring TRS. It is equipped with: bus bars 11 ･ 11 ･ 11 as conductive parts, which are connected to the three-phase wiring TRS; zero-phase current transformer (ZCT) 12, which has through-holes 12a, which are fixed and supported in an insulated manner Each of the bus bars 11 ･ 11 并使 11 passes each of the bus bars 11 ･ 11 ･ 11 through the through hole 12a, and detects a zero-phase current synthesized by each of the through currents flowing through the bus bars 11 ･ 11 ･ 11; the through-current ratio A current transformer (CT) 13 detects a through current flowing through at least one busbar 11 ･ 11 ･ 11; and a control unit 14 uses at least one through current detected by CT13 to correct the detected zero Phase current and measure the leakage current (Ior) of the resistance component.

The insulation measurement method of this embodiment measures the leakage current (Ior) of the resistance component of the three-phase wiring TRS connected from the power source 1 through the three-phase wiring TRS. It includes a setting step of setting the bus bars 11 设置 11 ･ 11 as the conductive parts of the three-phase wiring TRS respectively, and a zero-phase current detection step of the zero phase current transformer (ZCT) 12. The bus bars 11 固定 11 ･ 11 are fixedly supported in an insulating manner, and the bus bars 11 ･ 11 ･ 11 are penetrated through the through holes 12a, and a zero obtained by combining the through currents flowing through the bus bars 11 ･ 11 ･ 11 is detected. Phase current; a through-current detection step for detecting a through-current flowing through at least one busbar 11 ･ 11 ･ 11 in a through-current ratior (CT) 13; and a measuring step for using at least the current detected by CT13 A through current to correct the detected zero-phase current and measure the leakage current (Ior) of the resistance component.

Thereby, since the zero-phase current to the power line of the three-phase motor 2 can be directly detected, it is possible to measure the resistance component leakage current (Ior) that shows only the insulation degradation state of the three-phase motor 2.

In addition, the bus bars 11 具有 11 具有 11 are conductive, and each of the bus bars 11 ･ 11 ･ 11 is fixedly supported and penetrated through the through hole 12 a of the ZCT 12 in an insulated manner. Therefore, since the position of the power line of the three-phase motor 2 is fixed in the through hole 12 a of the ZCT 12, the phase and magnitude of the residual current do not change. As a result, the error factor can be eliminated, and the aforementioned error factor refers to changing the magnitude and phase of the residual current according to the penetration position of each of the three-phase wirings TRS in the through-hole 12 a of the ZCT 12. Therefore, the residual current can be corrected, and a minute resistance component leakage current (Ior) on the order of nA can be measured.

In addition, the insulation measuring device 10A of this embodiment further includes a control unit 14 that corrects the detected zero-phase current by using at least one through current detected by the CT 13 and measures the resistance component leakage current (Ior). .

Thereby, since at least one through current detected by CT13 is used to correct the measured zero-phase current, an error factor based on the motor capacity of the three-phase motor 2 can be eliminated. In addition, since the resistance component leakage current (Ior) is measured by the control unit 14, the true resistance component leakage current (Ior) can be obtained after the measurement of the zero-phase current is corrected.

Therefore, it is possible to provide an insulation measurement device 10A and an insulation measurement method, which can reliably remove an error factor at the time of detection and accurately obtain a true resistance component leakage current (Ior) with good accuracy. Furthermore, since the deterioration of the insulation of the three-phase motor 2 can be detected early, it can be plannedly maintained.

In the insulation measuring device 10A of the present embodiment, the bus bar 11 has rigidity. Thereby, when the bus bars 11 ･ 11 ･ 11 are fixedly supported inside the through holes 12a of the ZCT12, a simple supporting member can be used and the bus bars 11 汇 11 ･ 11 cannot be easily moved.

In addition, in the insulation measuring device 10A of this embodiment, the control unit 14 includes a measured zero-phase current acquisition unit 14a as a first measured zero-phase current acquisition unit, which is derived from the zero-phase current detected by the ZCT 12. The magnitude and phase of the zero-phase current are measured to obtain the measured zero-phase current. As the correction section 14b of the first correction section, the correction value of the residual current corresponding to an arbitrary through-current is obtained in advance, and the corresponding response is calculated. The correction value of the current corresponding to the through current detected by CT13, and for measuring the zero-phase current, the current corresponding correction value is used to correct the measured zero-phase current and obtain the corrected zero-phase current; as a voltage acquisition section of the first voltage acquisition section 14c, which measures the magnitude and phase of the phase-to-phase voltage of at least one of the bus bars 11 ･ 11 ， 11 and obtains the bus bar voltage as the voltage of the conductive member; the calculation section 14 d, which is the first calculation section, uses the The corrected zero-phase current and the bus voltage calculate the resistance component leakage current (Ior).

Thereby, the measurement zero-phase current acquisition unit 14a measures the magnitude and phase of the zero-phase current from the zero-phase current detected by the ZCT 12, and obtains the measured zero-phase current. In addition, the correction unit 14b calculates a current corresponding correction value corresponding to the through current detected by CT13 using a residual current correction value corresponding to an arbitrary through current, and uses the current corresponding correction value to measure the zero phase current to correct the measurement zero. Phase current, and find the true zero-phase current as the corrected zero-phase current.

Next, the voltage acquisition unit 14c measures the magnitude and phase of the phase-to-phase voltage of at least one of the bus bars 11 ･ 11 ･ 11, and obtains the bus voltage. The calculation unit 14d calculates the resistance component leakage current (Ior) based on the true zero-phase current and the bus voltage.

As a result, specifically, it is possible to provide an insulation measuring device 10A that can reliably remove an error factor at the time of detection and accurately obtain a true resistance component leakage current (Ior) with good accuracy.

In the insulation measuring device 10A of this embodiment, the correction unit 14b obtains a residual current correction value corresponding to an arbitrary through current from the first residual current I _R1 and the second residual current I _R2 . The residual current I _R1 includes an error, which corresponds to the magnitude of the first through current I _T1 detected at CT13 when the first through current I _T1 flows through the bus bars 11 ･ 11 ･ 11; the second residual current I _R2 is An error is included, which corresponds to the magnitude of the second through current I _T2 detected at CT13 when the second through current I _T2 flows through the bus bars 11 ･ 11 ･ 11.

Specifically, the correction formula corresponding to the residual current correction value of an arbitrary through current can be expressed in a linear form of the through current, and the first residual current I _R1 and the second through current when the first through current I _T1 flows When the current I _T2 flows, the second residual current I _R2 can obtain the slope and intercept of the correction formula. As a result, a residual current correction value corresponding to an arbitrary through current can be obtained.

Therefore, since the correction formula can be used to determine the correction value of the residual current that changes depending on the magnitude of the through current, the time for the user to correct can be saved, and a convenient insulation measuring device 10A can be provided.

Moreover, in the insulation measuring device 10A of this embodiment, the control unit 14 is provided inside a casing made of a shielding material that shields electricity and magnetism. Thereby, by covering the control unit 14 with a housing made of a shielding material, the control unit 14 can be isolated from minute noise. Thereby, it is possible to reduce the error of the induced noise, and it is possible to measure a micro-current of nA level.

[Embodiment 2]
The following description will discuss other embodiments of the present invention with reference to FIGS. 6 to 8. Configurations other than those described in this embodiment are the same as those in the first embodiment. For convenience of explanation, members having the same functions as those shown in the drawings of the first embodiment are given the same reference numerals, and descriptions thereof are omitted.

In addition to the insulation measuring device 10A according to the first embodiment, the insulation measuring device 10B of this embodiment includes the following differences as shown in FIG. 6: The three busbars 11 ･ 11 ･ 11 are respectively provided at CT 23a. ･ 23b ･ 23c.

The overall configuration of the insulation measuring device 10B according to this embodiment will be described with reference to FIG. 6. FIG. 6 is a perspective view of the overall configuration of an insulation measuring device 10B according to this embodiment.

As shown in FIG. 6, the insulation measuring device 10B of this embodiment is provided with three bus bars 11 ･ 11 ･ 11 at CT 23 a ･ 23 b ･ 23 c. The CT 23a, 23b, and 23c are the same members as the CT13 of the first embodiment.

As shown in FIG. 6, the control unit 24 is provided with a measurement zero-phase current acquisition unit 24 a as a second measurement zero-phase current acquisition unit, a correction unit 24 b as a second correction unit, and voltage acquisition as a second voltage acquisition unit. Unit 24c; calculation unit 24d as the second calculation unit.

The measurement zero-phase current acquisition unit 24a measures the magnitude and phase of the zero-phase current from the zero-phase current detected by the ZCT 12 to obtain a measured zero-phase current. The correction unit 24b uses a residual current correction value corresponding to an arbitrary through current, and calculates a correction value corresponding to the current corresponding to the through current flowing through each of the bus bars 11 ･ 11 ･ 11 detected in CT 13 ･ 13 ･ 13, and uses For the current corresponding correction value of the measured zero-phase current, the measured zero-phase current is corrected and the corrected zero-phase current is obtained. The voltage acquisition unit 24c measures the magnitude and phase of the phase-to-phase voltage of at least one of the bus bars 11 ･ 11 ･ 11, and obtains the bus bar voltage. The calculation unit 24d calculates a resistance component leakage current (Ior) by using a true zero-phase current and at least one bus voltage.

The control operation for determining whether there is a leakage current in the three-phase wiring TRS and the insulation resistance value of the three-phase wiring TRS using the insulation measuring device 10B having the above-mentioned configuration is based on (a) of FIG. 7 and FIG. 8, (b) Explain. FIG. 7 is a diagram showing a concept of introducing a correction message for an unbalanced state of the insulation measuring device 10B. FIG. 8A is a diagram for calculating a correction message γ that is an unbalanced state of the insulation measuring device 10B. FIG. 8B is a diagram for calculating the correction information δ as an unbalanced state.

First, in the insulation measuring device 10B of the present embodiment, it is assumed that, in a factory or the like, a current imbalance occurs due to a deterioration of the power supply environment, and the through current changes in each phase of the three-phase wiring TRS. In other words, although the through currents of the three-phase wiring TRS are generally the same, in the three-phase motor 3 installed in a factory or the like, the through-currents of the three-phase wiring TRS may be different from each other. As a result, the correction value of the residual current is changed according to the current imbalance of the through current in each phase.

Therefore, in the insulation measuring device 10B of this embodiment, three CTs 23a, 23b, and 23c are provided to detect the through currents flowing through the respective bus bars 11, 11 and 11. Next, in each of the CTs 23a, 23b, and 23c, it is possible to continuously monitor the unbalanced state of the through current by measuring the through current of each phase. Therefore, it is possible to correct the imbalance of the combined current.

A method for correcting the zero-phase current measured by the insulation measuring device 10B of this embodiment will be described below.

As shown in FIG. 7, in the insulation measurement device 10B, when the factory shipment is corrected, the magnitude of the first residual current I _R1 is measured using the first through current I _T1 , and the measurement is performed using the second through current I _T2. The magnitude of the second residual current I _R2 . Specifically, the first through current I _{T1 is} supplied from the power source 1 shown in FIG. 6 to the three-phase motor 3 through the three-phase wiring TRS and each of the bus bars 11 ･ 11 ･ 11, and the ones in the CT 23a ･ 23b ･ 23c are used. Either one or the correction unit 24b measures the magnitude of the first residual current I _R1 . In addition, the second through current I _{T2 is} supplied from the power source 1 shown in FIG. 6 to the three-phase motor 2 through the three-phase wiring TRS and each of the bus bars 11 ･ 11 ･ 11, and any one of CT 23a ･ 23b ･ 23c is used. The correction unit 24b measures the magnitude of the second residual current I _R2 .

In addition, since the unbalanced state does not occur at the time of factory shipment, the first through current I _T1 and the second through current I _T2 can be caused to flow through one bus bar 11. As a result, this processing is the same as the processing in the first embodiment.

Thereby, as shown in FIG. 3 described above, as a general residual current correction value, the following (Expression 1) shown in Embodiment 1 can be obtained.

Residual current I _R = α * through current I _T + β …… (Equation 1)
Then, using Equation (1) and the first through current I _T1 , the first residual current I _R1 , the second through current I _T2, and the second residual current I _R2 , a specific constant α and a constant β can be obtained. . The calculation unit 24d performs this calculation.

Here, since there are three CTs 23a, 23b, and 23c in total, the following (Equation 3) is obtained as (Equation 1) as shown in FIG. 7 as the individual residual current correction value, that is, the current corresponding correction value. Relation:
Residual current correction value =-(α '* penetration current + β') ... (Equation 3).
At this time, α 'and β' can be expressed as the following (Expression 4) and (Expression 5):
α '= α * γ (unbalance coefficient) …… (Equation 4);
β '= β * δ (unbalance coefficient) ... (Equation 5).

These imbalance coefficients γ · δ can be obtained from the imbalance coefficient γ calculation table shown in FIG. 8 (a) and the imbalance coefficient δ calculation table shown in FIG. 8 (b).

Specifically, the vertical axis of FIG. 8A shows whether the through current of the S-phase wiring is 0.7 times, 0.8 times, 0.9 times, 1.0 times, 1.1 times, or 1.2 times that of the R-phase wiring in the three-phase wiring TRS. Any of 1.3 times is shown on the horizontal axis of FIG. 8 (a), whether the through current of the T-phase wiring is 0.7 times, 0.8 times, 0.9 times, 1.0 times of the R-phase wiring in the three-phase wiring TRS, Any of 1.1 times, 1.2 times, and 1.3 times. Next, the imbalance coefficients γ are shown at the intersections of each other.

By this, for example, when the through-current of the S-phase wiring is 0.8 times that of the R-phase wiring and the through-current of the T-phase wiring is 0.9 times that of the R-phase wiring, the imbalance coefficient γ is 0.9. As a result, α '= α * γ (imbalance coefficient) = 0.9 * α.

In addition, the vertical axis of (b) in FIG. 8 shows whether the through current of the S-phase wiring is 0.7 times, 0.8 times, 0.9 times, 1.0 times, 1.1 times, 1.2 times, 1.3 times of the R-phase wiring in the three-phase wiring TRS. The horizontal axis of FIG. 8 (b) shows whether the through current of the T-phase wiring is 0.7 times, 0.8 times, 0.9 times, 1.0 times, or 1.1 times the R-phase wiring of the three-phase wiring TRS. , 1.2 times, 1.3 times. Next, the imbalance coefficients δ are shown at the intersections of each other.

Thus, for example, when the through current of the S-phase wiring is 0.8 times that of the R-phase wiring and the through-current of the T-phase wiring is 0.9 times that of the R-phase wiring, the imbalance coefficient δ is 0.9. As a result, β '= β * δ (imbalance coefficient) = 0.9 * β.

Therefore, by substituting these α 'and β' into (Expression 3) and inserting the through current of the R-phase wiring, the measured zero-phase current can be corrected and the true zero-phase current can be obtained.

Then, while obtaining the resistance component leakage current (Ior) from the true zero-phase current, the voltage between the phase wirings obtained by the voltage acquisition unit 14c is divided by the resistance component leakage current (Ior). In addition, the insulation resistance value of the three-phase wiring TRS can be obtained. At this time, even if the through currents flowing through the three-phase wirings TRS and the bus bars 11 ･ 11 ･ 11 are different from each other, the voltage between the wirings of the respective phases hardly changes. Therefore, it is sufficient to use one phase wiring voltage measurement for each phase wiring voltage.

The tables shown in (a) and (b) of FIG. 8 focus on those in which the magnitude of the current value as an unbalanced state differs among the three-phase wiring TRS systems, and show the unbalanced coefficients γ · δ. However, since the phases, which are unbalanced states, change individually, it is necessary to correct the phases. Therefore, it is preferable to prepare a table for obtaining a phase imbalance coefficient with respect to the phase and calculate a residual current correction value.

In this way, in the insulation measuring device 10B of this embodiment, three CTs 23a, 23b, and 23c are provided to detect the through currents flowing through the respective busbars 11 to 11 and 11. Thereby, by measuring the through current of each phase in the three-phase wiring TRS, it is possible to continuously monitor the unbalanced state of the through current. Therefore, it is possible to correct the imbalance of the combined current.

In addition, in the insulation measuring device 10B of the present embodiment, the control unit 24 includes a measurement zero-phase current acquisition unit 24a as a second measurement zero-phase current acquisition unit, which is derived from the zero-phase current detected by the ZCT 12. Measure the magnitude and phase of the zero-phase current to obtain the measured zero-phase current. As the correction section 24b of the second correction section, it uses a residual current correction value corresponding to an arbitrary through current, and calculates the response in CT 23a ･ The corresponding correction values of the currents flowing through the busbars 11 ･ 11 ･ 11 detected by 23b ･ 23c, and the corresponding correction values of the current are used to measure the zero-phase current to correct the measured zero-phase current and obtain it as a correction The true zero-phase current of the subsequent zero-phase current; the voltage obtaining section 24c as the second voltage obtaining section measures the magnitude and phase of the phase-to-phase voltage of the bus bars 11 ･ 11 ･ 11, and obtains the bus bar voltage; The calculation unit 24d as the second calculation unit calculates a resistance component leakage current (Ior) by using a true zero-phase current and a bus voltage.

As a result, when an unbalanced through-current flows through each of the bus bars 11 ･ 11 ･ 11, an insulation measuring device 10B can be specifically provided, which can reliably remove an error factor at the time of detection and obtain it with good accuracy. True resistance component leakage current (Ior).

As described above, the present disclosure provides an insulation measuring device for measuring a leakage current of a resistance component of a three-phase wiring connected from a power source to a three-phase electric motor. ; The zero phase current transformer has a through hole, fixedly supports each of the conductive members in an insulating manner, and passes each of the conductive members through the through holes, and detects a combination of each through current flowing through each of the conductive members. Zero-phase current; a through-current ratio detector that detects the through-current flowing through at least one of the conductive members; and a control unit that uses at least one of the through-currents detected by the through-current ratio to correct the current The aforementioned zero-phase current is detected, and the aforementioned leakage current of the resistance component is measured.

One aspect of the present disclosure is a method for measuring insulation, which measures the leakage current of the resistance component of a three-phase wiring connected from a power source to a three-phase motor. The method includes: a setting step of setting each conductive member that is connected to the three-phase wiring. ; A zero-phase current detection step, which is based on a zero-phase current converter, fixedly supports each of the conductive members in an insulating manner and passes each of the conductive members through the through-holes, and detects each through-current that will flow through each of the conductive members The synthesized zero-phase current; a through-current detection step for detecting a through-current flowing through at least one of the aforementioned conductive members in a through-current ratio current device; and a measurement step for using the through-current ratio device for detecting the through-current current. At least one of the through currents is used to correct the detected zero-phase current, and the leakage current of the resistance component is measured.

In general, if a zero-phase current detector is used to detect the zero-phase current of the three-phase wiring, the residual current as an error will become a problem. Therefore, the user measures the zero-phase current of the ground wire and sets the measured zero-phase current. The current is separated into a capacitive component leakage current (Ioc) and a resistive component leakage current (Ior) to measure the resistive component leakage current (Ior). However, since only the leakage current (Io) flows in the ground line and a large current does not flow, the effect of the residual current as an error does not become a problem. On the other hand, the measurement of the zero-phase current on the ground line of the system refers to measuring the leakage current of multiple loads including the motor and other loads connected to the system, so it is impossible to monitor the insulation degradation state of the load of one motor.

Therefore, in the insulation measuring device of one aspect of the present disclosure, each conductive member is provided, and each of the three-phase wiring is connected. Next, each conductive member is fixed and supported in an insulating manner so that each conductive member passes through the through hole of the zero-phase current transformer, and the zero-phase current is used to detect the zero-phase current synthesized by the through-currents flowing through the conductive members. . As a result, in one aspect of the present disclosure, since the zero-phase current of the power line toward the three-phase motor is directly detected, it is possible to measure the resistance component leakage current (Ior) that shows only the insulation degradation state of the three-phase motor.

In addition, the conductive member has conductivity, and each of the conductive members is fixed and supported through the through-hole of the zero-phase current transformer in an insulated manner. Therefore, because the position of the power line of the three-phase motor is fixed in the through-hole of the zero phase current transformer, the phase and magnitude of the residual current will not change. As a result, the error factor can be eliminated, and the aforementioned error factor means that the magnitude and phase of the residual current are changed according to the penetration positions of the three-phase wirings in the through-holes of the zero-phase current transformer. Therefore, the residual current can be corrected, and the leakage current of the minute resistance component of the nA level can be measured.

In addition, the insulation measuring device according to one aspect of the present disclosure further includes a control unit that corrects the detected zero-phase current by using at least one of the through currents detected by the through current ratio meter, and measures the leakage of the resistance component. Current.

Thereby, because at least one through current detected by the through current converter is used to correct the measured zero-phase current, an error factor based on the motor capacity of the three-phase motor can be eliminated. In addition, since the resistance component leakage current is measured by the control unit, the true resistance component leakage current (Ior) can be obtained after the measurement of the zero-phase current is corrected.

Therefore, it is possible to provide an insulation measurement device and an insulation measurement method, which can reliably remove the error factor at the time of detection and accurately obtain the true resistance component leakage current. What's more, because the insulation deterioration of the three-phase motor can be detected early, it can be planned for maintenance.

In one aspect of the insulation measuring device of the present disclosure, the conductive member is preferably rigid.

Thereby, in a case where each conductive member is fixedly supported inside the through-hole of the zero phase current transformer, a simple supporting member can be used and the conductive member cannot be easily moved.

In the insulation measuring device of this embodiment, the control unit may include a first measurement zero-phase current acquisition unit that measures the zero-phase current from the zero-phase current detected by the zero-phase current transformer. The magnitude and phase of the current are used to obtain the measured zero-phase current. The first correction unit uses the residual current correction value corresponding to an arbitrary through current to calculate the current corresponding correction corresponding to the through current detected by the through current ratior. And use the current corresponding correction value for the aforementioned measured zero-phase current to correct the measured zero-phase current and obtain the corrected zero-phase current; the first voltage obtaining section measures the phase of at least one of the conductive members. The magnitude and phase of the voltage between the wirings and obtain the voltage of the conductive component; the first calculation unit calculates the resistance component leakage current by using the aforementioned zero-phase current after correction and the voltage of the conductive component.

Thereby, the first measurement zero-phase current acquisition unit measures the magnitude and phase of the zero-phase current from the zero-phase current detected by the zero-phase current converter, and obtains the measured zero-phase current.

The first correction unit calculates a current corresponding correction value corresponding to the through current detected by the through current ratior by using a residual current correction value corresponding to an arbitrary through current, and uses the current corresponding correction for measuring a zero-phase current. Value, the measured zero-phase current is corrected, and the corrected zero-phase current is obtained. The corrected zero-phase current is displayed near the true zero-phase current.

Next, the first voltage acquisition unit measures the magnitude and phase of the phase-to-phase voltage of at least one of the conductive members, and obtains the conductive member voltage. The first calculation unit calculates the leakage current of the resistance component based on the corrected zero-phase current and the voltage of the conductive member.

As a result, specifically, it is possible to provide an insulation measuring device capable of reliably removing an error factor at the time of detection and accurately obtaining a true resistance component leakage current.

In the insulation measuring device according to one aspect of the present disclosure, the first correction unit obtains a residual current correction value corresponding to an arbitrary through current from the first residual current and the second residual current, wherein the first residual The current includes an error, which corresponds to the magnitude of the first through current detected by the first through-current ratior when the first through-current flows through the conductive member; the second residual current includes an error, which corresponds to the second The magnitude of the second through-current detected by the through-current converter when the through-current flows through the conductive member.

In other words, the applicant was able to determine the characteristic that the magnitude of the through current and the magnitude of the residual current changed linearly. Therefore, a residual current correction value corresponding to an arbitrary through current is prepared in advance as a correction formula.

Specifically, the correction formula corresponding to the residual current correction value of an arbitrary through current can be expressed in a linear form of the through current, and the ratio between the first residual current when the first through current flows and the second through current when the first through current flows The second residual current can obtain the slope and intercept of the correction formula. As a result, a residual current correction value corresponding to an arbitrary through current can be obtained.

Therefore, since the correction formula can be used to determine the correction value of the residual current that changes depending on the magnitude of the through current, the time for the user to correct can be saved, and a convenient insulation measuring device can be provided.

In the insulation measuring device according to one aspect of the present disclosure, it is possible to provide three of the above-mentioned through-current current transformers, and each of them detects the through-current flowing through each of the conductive members.

In other words, there is a case where the current imbalance occurs due to the deterioration of the power supply environment and the through current changes in each phase. That is, the through currents having three-phase wirings are different from each other. As a result, the correction value of the residual current is changed according to the current imbalance of the through current in each phase.

However, in the insulation measuring device of one aspect of the present disclosure, since three through-current ratios are provided to separately detect the through-currents flowing through the conductive members, it is possible to continuously monitor by measuring the through-currents of each phase. Unbalanced through-current. Therefore, it is possible to correct the imbalance of the combined current.

In the insulation measuring device according to one aspect of the present disclosure, the control unit may include a second measurement zero-phase current acquisition unit that measures the zero-phase current detected by the zero-phase current transformer. The magnitude and phase of the zero-phase current in order to obtain the measured zero-phase current; the second correction unit calculates the residual current correction value corresponding to any through current in advance, and calculates The corresponding correction value of the current of each of the through currents flowing through each of the conductive members is detected, and the current corresponding correction value is used for the measured zero-phase current to correct the measured zero-phase current and obtain the corrected zero-phase current; The second voltage acquisition unit measures the magnitude and phase of the phase-to-phase voltage of the conductive member and obtains the voltage of the conductive member; and the second calculation unit calculates by using the aforementioned modified zero-phase current and the voltage of the conductive member. The aforementioned resistance component leaks current.

Thereby, the second measurement zero-phase current acquisition unit measures the magnitude and phase of the zero-phase current from the zero-phase current detected by the zero-phase current converter, and obtains the measured zero-phase current.

In addition, the second correction unit calculates a current corresponding correction value corresponding to each of the through currents detected by the above-mentioned through-current converter, and calculates a correction value corresponding to each of the through-currents detected by the above-mentioned through-current converter, while calculating a residual current correction value corresponding to an arbitrary through-current in advance, and The current uses the current corresponding correction value to correct the measured zero-phase current and obtain the corrected zero-phase current. The corrected zero-phase current is displayed near the true zero-phase current.

Next, the second voltage acquisition unit measures the magnitude and phase of the phase-to-phase voltage of the conductive member, and obtains the voltage of the conductive member. The second calculation unit calculates the leakage current of the resistance component based on the corrected zero-phase current and the voltage of the conductive member.

As a result, in particular, when an imbalanced through current flows through each conductive member, an insulation measuring device can be provided, which can reliably remove the error factor at the time of detection and accurately obtain the true Resistance component leakage current.

In one aspect of the insulation measuring device of the present disclosure, the aforementioned control unit can be provided inside a casing made of a shielding material that shields electricity and magnetism.

Thereby, by covering the control portion with a housing made of a shielding material, the control portion can be isolated from minute noise. Thereby, it is possible to reduce the error of the induced noise, and it is possible to perform a small current measurement at the level of nA.

In addition, this disclosure is not limited to the above-mentioned embodiments, and various changes can be made within the scope shown in the claims, and the embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in Within the technical scope of this disclosure. In addition, new technical features can be formed by combining the technical means disclosed in the respective embodiments.

1‧‧‧ Power

2‧‧‧Three-phase motor

3‧‧‧Three-phase motor

10A, 10B‧‧‧Insulation measuring device

11‧‧‧Bus (conductive parts)

12‧‧‧Zero Comparator (ZCT)

12a, 13a‧‧‧through hole

13‧‧‧Through Current Comparator (CT)

23a, 23b, 23c ‧‧‧through current ratio (CT)

14‧‧‧Control Department

14a‧‧‧ Measurement zero-phase current acquisition unit (first measurement zero-phase current acquisition unit)

14b‧‧‧Amendment Division (First Amendment Division)

14c‧‧‧Voltage acquisition unit (first voltage acquisition unit)

14d‧‧‧Calculation Department (First Calculation Department)

24‧‧‧Control Department

24a‧‧‧ Measurement zero-phase current acquisition unit (second measurement zero-phase current acquisition unit)

24b‧‧‧ Correction Division (Second Correction Division)

24c‧‧‧Voltage acquisition unit (second voltage acquisition unit)

24d‧‧‧Calculation Department (Second Calculation Department)

I _R1 ‧‧‧ the first residual current

I _R2 ‧‧‧Second residual current

I _T1 ‧‧‧ first through current

I _T2 ‧‧‧second through current

I _T3 ‧‧‧ third through current

TRS‧‧‧Three-phase wiring

α, β‧‧‧ constant

γ, δ‧‧‧ imbalance coefficient

101‧‧‧Zero Phase Comparator

102‧‧‧ Ground Direction Relay

103‧‧‧Voltage Measurement Department

104‧‧‧Residual voltage elimination device

104a‧‧‧Phase Adjuster

104b‧‧‧Voltage Regulator

105‧‧‧ Power

106‧‧‧Measurement tester

107‧‧‧Voltage Detector

FIG. 1 is a perspective view showing the overall configuration of an insulation measuring device according to a first embodiment of the present disclosure.

[Fig. 2] Fig. 2 is a flowchart showing a method of correcting the insulation measurement device when it is shipped from the factory.

[Fig. 3] Fig. 3 is a diagram showing a concept of introducing a correction message for the insulation measurement device.

[FIG. 4] A flowchart showing a correction method when the user of the insulation measuring device is used.

[Fig. 5] (a) is a vector diagram of correcting the residual current from the zero-phase current measured by the aforementioned insulation measuring device to obtain the true zero-phase current; (b) is the zero-phase current when there is no residual current correction Vector illustration.

6 is a perspective view of the overall configuration of an insulation measuring device according to a second embodiment of the present disclosure.

[Fig. 7] Fig. 7 is a diagram showing a concept of introducing a correction message for an unbalanced state of the insulation measuring device.

[Fig. 8] (a) is a diagram for calculating a correction message? Which is an unbalanced state of the insulation measuring device; (b) is a diagram for calculating a correction message?

FIG. 9 is a circuit diagram showing a configuration of a conventional ground voltage sensitivity test device.

FIG. 10 is a flowchart showing a measurement flow when a conventional insulation measuring device is not corrected.

Claims (8)

An insulation measuring device for measuring the leakage current of a resistance component of a three-phase wiring connected from a power source to a three-phase motor, and includes: Each conductive component is connected to the aforementioned three-phase wiring, respectively; The zero-phase current transformer has a through-hole, fixedly supports each of the conductive members in an insulating manner, and passes each of the conductive members through the through-holes, and detects a zero formed by each of the through-currents flowing through the conductive members. Phase current A through-current ratio detector that detects a through-current flowing through at least one of the aforementioned conductive members; and The control unit corrects the detected zero-phase current by using at least one of the through currents detected by the through-current converter, and measures the resistance component leakage current. The insulation measuring device according to claim 1, wherein the conductive member is rigid. The insulation measuring device according to claim 1 or 2, wherein the aforementioned control unit includes: A first measurement zero-phase current obtaining unit, which measures the magnitude and phase of the zero-phase current from the zero-phase current detected by the aforementioned zero-phase current converter, and obtains a measured zero-phase current; The first correction unit uses a residual current correction value corresponding to an arbitrary through current, calculates a current corresponding correction value corresponding to the through current detected by the through current ratior, and uses the correction value corresponding to the measured zero-phase current. This current corresponds to the correction value to modify the aforementioned measured zero-phase current, and obtain the corrected zero-phase current; The first voltage obtaining unit measures the magnitude and phase of the phase-to-phase voltage of at least one of the conductive members, and obtains the voltage of the conductive member; The first calculation unit calculates the leakage current of the resistance component based on the corrected zero-phase current and the voltage of the conductive member. The insulation measuring device according to claim 3, wherein the first correction unit obtains a residual current correction value corresponding to an arbitrary through current in advance from the first residual current and the second residual current; and the first residual The current includes when the first through current flows through the conductive member, the error detected by the through current ratio should be based on the magnitude of the first through current; and the second residual current includes the second through current. In the case of the conductive member, the error detected by the through-current ratio responds to the magnitude of the second through-current. The insulation measuring device according to claim 1 or 2, wherein three of the through-current ratios are provided to detect the through-currents flowing through the conductive members, respectively. The insulation measuring device according to claim 5, wherein the control unit includes: A second measuring zero-phase current obtaining unit, which measures the magnitude and phase of the zero-phase current from the zero-phase current detected by the aforementioned zero-phase current converter, and obtains a measured zero-phase current; The second correction unit uses a residual current correction value corresponding to an arbitrary through current, calculates a current corresponding correction value corresponding to the through current detected by the through current ratior, and uses the correction value corresponding to the measured zero-phase current. This current corresponds to the correction value to modify the aforementioned measured zero-phase current, and obtain the corrected zero-phase current; The second voltage obtaining unit measures the magnitude and phase of the phase-to-phase voltage of the conductive member, and obtains the voltage of the conductive member; The second calculation unit calculates the leakage current of the resistance component based on the corrected zero-phase current and the voltage of the conductive member. The insulation measuring device according to claim 1 or 2, wherein the control unit is provided inside a housing made of a shielding material that shields electricity and magnetics. An insulation measurement method that measures the leakage current of the resistance component of a three-phase wiring connected from a power source to a three-phase motor. It includes: The setting step is to set each conductive component of the three-phase wiring separately; The zero-phase current detection step is based on a zero-phase current transformer, fixedly supports each of the conductive members in an insulating manner, passes each of the conductive members through the through-holes, and detects each through-current current flowing through each of the conductive members. Synthesized zero-phase current A through-current detection step for detecting a through-current that flows through at least one of the aforementioned conductive members in a through-current ratio; and The measuring step is to correct at least one of the detected zero-phase currents by using at least one of the foregoing through-currents detected by the through-current ratio meter, and measure the resistance component leakage current.