JPH09163685A - Insulation diagnoser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To quantitatively diagnose the deterioration of insulation of the insulating film of a winding of a motor in a non-destructive way, by sticking a probe for measurement of impedance fast to the surface of electric winding, and measuring the impedance of the insulating film for diagnosis. SOLUTION: A cable 10b led out of a probe 10 and a cable 10a connected to the lead wire of the winding of a motor are connected to a preamplifier 12, and a voltage signal according to the current flowing through an insulating film 9 when voltage is applied between the probe 10 and the lead wire 11 is given to the I/F board 8 of a diagnoser 1. That is, the preamplifier 12 measures the current flowing through the probe 10 and the insulating film 9, and this measurement is equivalent to measuring the impedance of the insulating film 9, and the measurement range of the preamplifier 12 is changed over, according to the degree of deterioration of the insulating film 9. Hereby, the insulation deterioration of the insulating film of the winding of the motor can be diagnosed quantitatively in a non-destruction way.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impedance measuring probe for a deterioration diagnosis device for an insulating film of a motor electric winding.

[0002]

2. Description of the Related Art Generally, when diagnosing insulation of a motor electric winding, non-destructive tests such as insulation resistance, polarization index, leakage current measurement, humidity resistance characteristic, winding resistance measurement, and residual breakdown voltage Measurement, material analysis, sheet mechanical strength measurement, wire abrasion resistance test, winding test, and other destructive tests are used for evaluation. Other than this, there is a method of monitoring insulation resistance, capacitance, tan δ, partial discharge, etc. using an automatic measuring device.

Many of these test methods are used for determining deterioration and estimating the remaining life based on the correlation of the measured value with the residual breakdown voltage, operating time, and the like. In particular, it is known that the ratio of insulation resistance between wet and dry, tan δ, polarization index, and the like show changes corresponding to deterioration caused by environmental pollution. Even at this time, the remaining life is correlated with the residual breakdown voltage and the operating time, rather than being considered as a change that corresponds specifically to the deterioration behavior occurring inside the insulating material, such as the occurrence of pinholes and the penetration of water and electrolyte. It is often used for estimation.

[0004]

By the way, as a method for nondestructively diagnosing deterioration of a coating film having an insulating effect such as an insulating film of an electric wire, for example, Japanese Patent Laid-Open No. 4-19014.
No. 9 proposes a coating film diagnostic device by impedance measurement. What we want to pay attention to in this diagnostic method by impedance measurement is that the measurement is performed at a very low voltage and a low current. Therefore, this method can diagnose the deterioration of the coating film nondestructively. As an example of applying the deterioration diagnosis by impedance measurement to the insulation film of the covered electric wire, Japanese Patent Application No. 7-
No. 17580 can be mentioned, but it has been clarified here that the measured value of impedance shows frequency characteristics corresponding to permeation of water and electrolyte into the insulating film, surface crazing, and generation of pinholes. However, this method can be measured in the state where the coated conductor is used alone such as an overhead wire, and cannot be measured in the case where the coated conductor is assembled and fixedly molded like the motor winding. However,
It is possible to estimate the permeation of water and electrolyte into the insulating film, the occurrence of surface crazing and the occurrence of pinholes by the change of the frequency characteristic of the impedance value, which can provide very effective information for the deterioration diagnosis of the motor winding. It is a thing.

The object of the present invention is suitable for the deterioration diagnosis device which cannot be achieved by the above-mentioned conventional method and which quantitatively determines the insulation deterioration of the insulation film of the motor winding by impedance measurement and the measurement of the motor winding. It is to provide a measuring probe.

[0006]

In order to achieve such an object, the present invention aims to provide a pinhole in an insulating film of a covered electric wire, a crack or void which is not a pinhole, a penetration of water and an electrolyte into the insulating film, and the like. The present invention proposes a diagnostic device for estimating the insulation deterioration of a film and its precursor state by measuring the frequency characteristic of the impedance of the insulating film, and a probe for the measurement.

First, in measuring the impedance of the insulating film, a measuring voltage of various frequencies is applied between the lead wire of the motor winding and the measuring electrode which is in close contact with the coil end surface, and the insulation is measured based on the flowing current. The impedance of the film is read from the instrument and recorded.

Then, it is checked whether the resistance / capacitive impedance value and the dielectric loss at various frequencies correspond to the deterioration criterion prepared in advance, and the insulation deterioration state of the insulating film is judged based on this.

Further, in measuring the impedance of the insulating film at the coil end portion of the above-mentioned electric motor winding, a conductive gel or electrolyte solution is held on the surface of the measuring electrode which has flexibility to cope with irregularities of the measuring portion. A measurement probe is used, which is characterized in that the measurement is performed in a state where the electrode is in close contact with the measurement site by a probe provided with a layer (sheet of sponge, fiber, pulp, etc.).

When a measuring voltage is applied between the lead wire of the motor winding and the probe, a current flows through the probe through the insulating film, and the impedance is derived from the magnitude and phase of the current. It is known that the frequency characteristics of the resistance component, dielectric loss, and capacitance component of the measured impedance show changes corresponding to the deterioration state of the insulating film. Therefore, by analyzing the measured impedance value recorded from the instrument by means of determining the deterioration state, not only physical defects such as pinholes and cracks in the insulating film, but also electrochemical reactions due to water and electrolyte permeation, etc. Defects
It becomes possible to detect nondestructively.

Here, the impedance measuring probe of this deterioration diagnosing device has a flexible flat electrode that can be arbitrarily deformed according to the unevenness of the exposed surface of the motor winding.
By filling the space between the electrode and the measurement site with a conductive fluid,
It is characterized in that the electrode is brought into close contact with the measurement site. As the conductive fluid, it is possible to use a conductive gel, an aqueous electrolyte solution, etc. alone or by impregnating a sheet of sponge, fiber, pulp or the like. In addition, for the measurement site where conductive fouling substance is expected to adhere, the influence of fouling substance can be directly measured using the above-mentioned sheet impregnated with ultrapure water. It is also possible to wipe off and collect fouling substances with a pure water impregnated sheet.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described with reference to FIGS. In the figure, reference numeral 1 is a diagnostic device of the present invention, which has a structure in which a CPU 2, ROM 3, RAM 4, FDD 5, etc. are built in a main body case (not shown), and a liquid crystal type display 6 and a keyboard 7 are aligned. An I / F having a D / A conversion function and an A / D conversion function is provided in the expansion slot of the diagnostic device 1.
The board 8 is inserted.

On the other hand, the impedance is measured by bringing the probe 10 into close contact with the insulating film 9 of the motor winding to be subjected to the deterioration diagnosis. This probe 10
Is basically a flexible flat electrode that can be arbitrarily deformed according to the unevenness of the measurement site, and a sponge-like electrode impregnated with conductive gel in a cylindrical body, and is installed at the center of the sponge-like electrode. By inserting the measurement electric wire between the slits, the insulating film 9 of the covered electric wire is brought into close contact with the sponge electrode.

A cable 10 derived from the probe 10.
a and the cable 10 connected to the lead wire 11 of the motor winding
b is connected to the preamplifier 12 and is connected to the probe 1
Insulating film 9 when voltage is applied between 0 and lead wire 11
The voltage signal corresponding to the current flowing through the diagnostic device 1
I / F board 8 of the above. That is, the preamplifier 12 functions as a current measuring unit for measuring the current flowing through the insulating coating 9 to the probe 10.
This current measurement corresponds to measuring the impedance of the insulating film 9, and the preamplifier 12 can switch the measurement range according to the degree of deterioration of the insulating film 9.

Next, a procedure for diagnosing the insulating film 9 by the coated wire deterioration diagnosing device having the above-mentioned configuration will be described. First,
The diagnostic device 1, the preamplifier 12, and the probe 10 are brought to the site where the deterioration diagnosis is performed, the covered electric wire is inserted in the center of the probe 10, and the probe 10 and the preamplifier 12 are connected as shown in FIG. When the diagnostic device 1 executes the measurement program, a voltage is applied between the probe 10 and the conductor of the output line 11 as a result of the execution, and the current flowing through the insulating film 9 at that time is detected by the preamplifier 12 and I / F board 8
Thus, the electric signal obtained by the current measurement is input to the diagnostic device 1. The procedure of such impedance measurement is described in detail in JP-A-4-190149.
It is characterized by the deterioration determination method described below.

The electrical signal input to the diagnostic device 1 is converted into impedance data by the measurement program,
Thereby, the frequency characteristic of the impedance of the insulating film 9 is obtained. Here, FIGS. 2A, 2 </ b> B, and 2 </ b> C are measurement examples of frequency characteristics of impedance according to the state of the insulating film.

FIG. 2 (a) is an example of measurement of a sound insulating film, and almost the same curve can be obtained even if the type of insulating film is different. However, if there are cracks or pinholes in the insulating film that reach the wire conductor, the frequency characteristics of the impedance are reduced by a few digits as shown in FIG. 2 (b), and the capacitance component Cx is particularly in the range of 0-10 Hz. Increase with. FIG.
(B) is an impedance characteristic characteristically seen when a crack or a pinhole that penetrates to the conductor is generated.

FIG. 2c) shows an example of measurement of frequency characteristics observed when surface crazing occurs due to water or an electrolyte penetrating the insulating film, or when cracks or voids that do not reach the conductor are generated. However, what is characteristic here is that the dielectric loss factor tan δ increases in the region of 0 to 2 Hz. Due to the increase of tan δ in the low frequency region, it is possible to estimate the occurrence of surface crazing, which is a state in which the entanglement of the molecular chains is loosened and the voids are expanded, rather than the crack in which the molecular chains of the insulating film are physically broken. .

The deterioration state of the insulating film according to the present invention is judged by comparing the capacitance component Cx of the impedance with the change of the dielectric loss factor tan δ as shown in FIGS. 2 (b) and 2 (c). . The judgment can be performed while displaying the frequency characteristic graph on the display 6 and confirming it on the screen at the time of measurement. Alternatively, the measurement data can be temporarily recorded on a floppy disk and analyzed at any time, and connected to the diagnostic device 1. It is also possible to output by a printer. In addition, the impedance measuring means of the insulating film described above has a configuration in which the probe 10 and the preamplifier 12 are connected to each other by mounting the microcomputer for executing the frequency characteristic analysis and the deterioration state judgment program on the measuring instrument having the impedance measuring function. It's okay to have it.

Further, FIG. 3 shows the structure of the impedance measuring probe 10 according to the present invention. The probe 10 is an impedance measurement probe including a flexible flat electrode 13 that can be arbitrarily deformed according to the unevenness of the measurement site and a data cable. A sheet 15a obtained by impregnating a sheet 15 made of sponge, fiber or pulp alone with the conductive gel 14a is attached to the surface of the flat electrode 13 to improve the adhesion. For the same purpose as the sheet 15a, the sheet 15b impregnated with the aqueous electrolyte solution 14b may be used. When the electrolyte solution 14b is used, it is possible to reflect the influence of changing the type or concentration of the electrolyte in the measurement result.

Here, as a result, the impedance measuring probe of the diagnostic device has a flexible flat electrode that can be arbitrarily deformed according to the unevenness of the exposed surface of the motor winding.
It is characterized in that the gap between the electrode and the measurement site is filled with a conductive fluid to bring the electrode into close contact with the measurement site. As the conductive fluid, a conductive gel 14a, an electrolyte aqueous solution 14b, or the like may be used alone, or the gel 14a and the electrolyte aqueous solution 14b may be used by impregnating a sheet 15 such as sponge or fiber / pulp. It is possible.

Further, FIG. 4 shows a conductive fouling substance 1
6 is an application example of the impedance measuring probe of this deterioration diagnosing device to a measurement site where 6 is expected to be attached. In this case, it is possible to directly measure the influence of the fouling substance 16 by using the sheet 15c impregnated with the ultrapure water 14c. Furthermore, if the sheet 15c impregnated with ultrapure water is removed from the probe 10 after measurement, the contaminant 16 at the measurement site can be wiped off as it is, and it can be used as a smear sample for contamination analysis.

[0023]

As described above, according to the apparatus for diagnosing the deterioration of the insulation coating of the coated electric wire of the present invention, the operator can bring the probe into close contact with the motor coil end portion and cause the determining means to determine the degree of deterioration. It is possible to nondestructively estimate the deterioration degree of the covered electric wire from the very early precursory phenomena such as water and electrolyte permeation to the occurrence of pinholes, simply by performing an operation.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention;

FIG. 2 is a graph of frequency characteristics of impedance according to changes in the state of the insulating film,

FIG. 3 is a diagram showing an embodiment of a probe of the deterioration diagnostic device of the present invention,

FIG. 4 is a diagram showing another embodiment of the probe of the deterioration diagnostic device of the present invention.

[Explanation of symbols]

In the drawing, 1 is a diagnostic device, 2 is a CPU
(Determination means), 6 is a display (output means), 8 is I
/ F board (voltage applying means, A / D converting means), 9 is an insulating film of the rotary electric wire winding, 10 is a probe, 11 is a lead wire of the rotary electric wire winding, 12 is a preamplifier (current measuring means), 13 Is a plane electrode of the probe 10, 14a is a conductive gel, 14b is an electrolyte solution, 14c is ultrapure water, 15 is a sponge or fiber or pulp sheet, 15a is a sheet impregnated with conductive gel, and 15b is an electrolyte solution. The impregnated sheet, 15c is a sheet impregnated with ultrapure water, and 16 is a pollutant attached to the surface of the rotary electric wire winding.

Claims (4)

[Claims] 1. An insulation diagnostic device for diagnosing a coil end insulating film of a motor electric winding by impedance measurement, wherein an impedance measuring probe comprises a flexible electrode and a conductive gel alone provided on the electrode, or An insulation diagnosis device, which is formed of a sheet impregnated with a conductive gel, and is made by closely contacting the impedance measurement probe with the surface of the electric winding to measure the impedance of the insulation film for diagnosis. 2. The insulation diagnosis apparatus according to claim 1, wherein the sheet is made of sponge, fiber, or pulp, and a flat electrode is impregnated with and holds an aqueous electrolyte solution. 3. The insulation diagnosis apparatus according to claim 1, wherein the electrolyte aqueous solution is simply ultrapure water or distilled water, and the impedance change of the insulation film due to the electrolyte adhering to the surface of the electric winding is measured. 4. The insulation diagnosis apparatus according to claim 1, wherein the holding layer of the ultrapure water or distilled water is replaceable, and after the measurement, the sheet is removed so that dust at the measurement site can be wiped and collected.