JPH02147971A - Method for diagnosing insulation - Google Patents

Abstract

PURPOSE:To improve accuracy of diagnosing insulation of a main electric motor for railway by humidifying an object to be measured. CONSTITUTION:An object to be measured which has been subjected to test 3 after being cleaned and dried is placed in a box having a humidifier and is subjected to humidification test 5. The object is stored in a state of almost 100% RH at 30 to 40 deg.C during daytime, and from evening to next morning the object is continuously kept in the box with the humidifier stopped and its MEG R0, R1, R2 are calculated. This cycle of humidification and leaving is performed one cycle/day, and if the need arises, cycles can be repeated. After measurement, recovery rate of MEG Rr6 is calculated to estimate moisture proofness of the object. With this result and the result of intermediate determination 7 mentioned above are combined and estimated together to perform general determination 8.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to insulation diagnosis of electrical equipment transported to factories for the purpose of periodic inspection, etc., such as a main motor for a railway (hereinafter referred to as MM). The present invention relates to an insulation diagnosis method for determining insulation deterioration in electrical equipment that uses high voltages.

[Conventional technology]

In general, suspension of operation due to failure of electrical equipment for railways, especially MM, causes inconvenience to many users and may also cause great economic damage. Therefore, to ensure safe operation, railway operators regularly stop trains for inspection and repair to ensure safety until the next regular inspection.

It is desirable to quickly manufacture a new MM whose insulation has deteriorated as it approaches the end of its service life, but manufacturing a new one costs a huge amount of money. Therefore, it is desired to diagnose the degree of insulation deterioration with a high degree of certainty and to take measures depending on the degree of insulation deterioration, such as finishing varnish treatment, re-impregnation with varnish, insulation renewal, etc.

By the way, conventionally, properties before cleaning and after cleaning and drying obtained from three tests (tan δ test method, DC component test method, and DC high voltage test method, which will be described later) are used to evaluate MM insulating insulation surface fouling, moisture absorption, heat, and The deterioration of each wound has been distinguished and diagnosed.

The tan δ test method is based on the AC voltage applied to the object to be measured and the tan δ test method.
The respective deterioration states of surface contamination, moisture absorption, and heat are determined from the relationship of nδ. If one of the above-mentioned conditions occurs, that is, surface contamination deterioration or moisture absorption deterioration, tanJo (normally AOlk
When the value of tan δ of v) becomes larger than that of characteristic A before deterioration and thermal deterioration occurs, Δ
tan δ (usually 3 kv tan δ - 1 kv tan δ)
The value of is also larger than that of A before deterioration.

In the DC component test method, an AC voltage is applied to the object under test, and the minute DC current flowing there is measured through a filter circuit.

Although it is difficult to understand the mechanism of DC component generation in actual equipment, DC components may be generated if iron powder, carbon powder, or other debris gets stuck in cracks or dents in the insulation layer due to thermal deterioration. Therefore, the DC component can detect flaws in the insulating layer caused by electrical, mechanical, or chemical factors. Normally, it is not possible to predict whether the denomination is deteriorating or not.

In the DC high voltage test method, a DC voltage is applied to the object to be measured, the value of the minute current flowing there is measured after 1 minute using a minute current measuring device, and the insulation resistance is determined by dividing the applied voltage by this measured current. Alternatively, measure with a direct-readable super wire resistance measuring device. This insulation resistance (hereinafter referred to as MEG) decreases in value due to deterioration due to contamination and moisture absorption.

If the MM is disassembled into the stator and rotor and the characteristics are determined in a dirty state, i.e., before cleaning, and the characteristics are found to be poor, it is possible to determine whether the MM is due to surface fouling, moisture absorption, or thermal deterioration. Difficult to distinguish.

Therefore, after disassembling and cleaning and drying, the same characteristics as above were measured, and the value of tanJo was smaller than the value before cleaning, and Δt
If an δ becomes larger than the characteristics after MMfi fabrication (initial characteristics) or the previous regular inspection, and MEG becomes larger than the value before cleaning, it can be diagnosed that blistering or peeling of the insulating layer has occurred due to thermal deterioration.

[Problem that the invention seeks to solve]

However, if Δtanδ remains unchanged from the initial characteristic under the above conditions, it is difficult to distinguish between surface staining deterioration and moisture absorption deterioration. That is, if the surface of the insulation is contaminated with conductive substances such as carbon powder or iron powder, it will easily absorb moisture, and jan5g will become large, while meg will become small. Cleaning and drying this removes dirt and moisture,
tana6 becomes smaller, and meg becomes larger. Both characteristics deteriorate or improve at the same time, so it is difficult to distinguish between staining and moisture absorption. In order to distinguish this point, it is necessary to add one more measurement condition and measure after cleaning and after drying, but this increases both the man-hours and the construction period.

Furthermore, even if the measurement conditions are increased midway through and it is determined that moisture absorption deterioration has occurred, it is difficult to determine the degree of moisture resistance of the insulation.

The present invention was devised in view of the above-mentioned points, and its purpose is to improve the above-mentioned drawbacks, to perform judgment with a high degree of certainty, and to economically carry out maintenance according to the degree of insulation deterioration. An object of the present invention is to provide an insulation diagnosis method that can be implemented.

[Means for solving problems]

In other words, the means to achieve this purpose is to use (1) tanao and Δt obtained from the tanδ test method as parameters that indicate the insulation deterioration of the electrical equipment as the object to be measured.
anδ (4 DC components from the DC component test method (3) Insulation resistance of the measured object from the DC high voltage test method

Characteristics before cleaning with iron powder etc. attached, after cleaning/drying with air blowing or steam spraying, and after cleaning the object to be measured (2) Forced moisture absorption for a certain period of time, then leaving it for a certain period of time. Using the MEG characteristics of In this method, the results are combined with the results of performing predetermined arithmetic processing on MEG, which has been made to absorb moisture in the same way as described above, to make a comprehensive judgment of insulation deterioration.

That is, in addition to measuring the characteristics before and after cleaning, the object to be measured is forced to absorb moisture in a humidifying box for a certain period of time, and then left in the same box for a certain period of time. During this time, the deterioration characteristics of MEG with respect to time and the recovery property of MEG are measured.

These characteristics are calculated and processed according to certain standards, and each characteristic is judged as good or fair.

This is a method of diagnosing insulation based on the characteristics before and after cleaning.

The reason for adding a humidification test is to check the moisture resistance of the insulation layer.
The degree of moisture absorption can be seen to some extent from the data before cleaning, but in the case of natural moisture absorption, the moisture absorption state of the measured object varies depending on the rainy season, dry season, high humidity days and low humidity days, so comparisons should be made under the same conditions. There is a need to. The above-mentioned MEG recovery properties are also useful in determining moisture resistance.

Next, its effect will be explained.

[For production]

For example, if the object to be measured is placed in a box with a humidity generator and a person manually performs measurements, the humidity is forcibly humidified during the day, and the object to be measured continues to be placed in the box at night with the humidity generator turned off. Keep it inside, and measure Meg during that time to see how Meg recovers.

In the case of automatic measurement, there is no need to distinguish between day and night as long as the humidification and leaving times are determined.

As a result of MEG measurement, if the insulating layer of the object to be measured is still healthy, it has deteriorated on the surface, if the inside is healthy, or if the inside has deteriorated extremely. If the Meg (horse) and the Meg recovery rate (Rr) during neglect are classified, the Meg-time characteristics shown in FIG. 2 and the data shown in Table 1 will be obtained.

By humidifying the object to be measured as described above, the MEG drop 2 recovery properties vary depending on the degree of deterioration of the insulating layer, which is useful for insulation diagnosis. By taking such measures,
Insulation diagnosis of railway traction motors can be performed with high accuracy.

Hereinafter, one embodiment of the insulation diagnosis method of the present invention will be described based on the drawings.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the insulation diagnosis method of the present invention. In FIG. 1, a MM brought in for insulation diagnosis is disassembled into a stator side and a rotor side, and each is cleaned. As pre-test 1, tan δ-voltage characteristics, DC component-voltage characteristics, and MEG are measured. From the tan δ-voltage characteristics, jtan δ2 (overhead line'1 pressure 15
In the case of 00V MM, the tanδ-voltage characteristics are usually AO3k.
(up to v is applied) is calculated. Then, the insulation properties before cleaning are evaluated.

Next, after cleaning and drying, test the object to be measured! Remove dirt using compressed air or steam cleaning depending on the degree of dirt.
Remove dust and dry further. After cooling, measure the same items as before cleaning. After calculating Δtanδ4,
Intermediate judgment 7 of the insulation state of the object to be measured is performed while comparing the characteristics before and after cleaning or comparing with the new product. On the other hand, the object to be measured, which has been cleaned and dried and has undergone Test 3, is placed in a box equipped with a humidity generator and subjected to Humidification Test 5. 30 during the day
The specimen was maintained at ~40°C and approximately 100 S RH, and humidified 5. From the evening until the next morning, the object to be measured was kept in the box with the humidity generator turned off, as shown in Figure 2. MegRO+ R1*
Let each R2 be determined. This humidification/leaving may be repeated once per day as necessary.

After the measurement, the MEG recovery rate Rr6 is calculated according to the definition in FIG. 2, and the moisture resistance of the object to be measured is evaluated. This result and the result of the previous intermediate judgment 7 are evaluated again, and a comprehensive judgment 8 is made.

Diagnostic analysis is also possible by adding PI (polarization index) obtained from the DC high voltage method to the parameters of insulation deterioration, but the diagnostic function overlaps with tanJg and has a negative correlation with tanJg. There is a relationship.

In other words, when the janδ0 value is small, the PI becomes large,
As the jan90 value increases, the PI decreases, but the PI
is the ratio of the insulation resistance after 10 minutes of application to the insulation resistance after 1 minute of application, so it generally does not become smaller than 1.

〔Effect of the invention〕

As detailed above, the present invention uses data from tests before cleaning, after cleaning/drying, and humidification to diagnose insulation deterioration due to staining, moisture absorption deterioration, thermal deterioration, and damage including cracks, pinholes, etc. For staining and deterioration, finish varnish treatment is applied, moisture absorption deterioration is treated with finish varnish treatment or varnish re-impregnation treatment depending on the moisture resistance, and thermal deterioration is treated with varnish re-impregnation treatment or insulation renewal depending on the degree. It is possible to judge with a high degree of certainty whether to apply finishing varnish, varnish re-impregnation, or insulation renewal depending on the degree of damage, and to economically carry out maintenance according to the degree of insulation deterioration. A method for diagnosing insulation can be provided.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a characteristic diagram showing a typical example of MEG characteristics in a humidification test of an embodiment of the present invention, and Fig. 3 is a typical tan δ-voltage characteristic. shows,
FIG. 2 is a characteristic diagram showing the definitions of tana□ and atanδ. 1... Pre-cleaning test, 2... Δtanδ
, 3...Test after cleaning and drying, 4...Δ
tan δ, 5...humidification test, 6...Y
Lrs 7...Intermediate judgment, 8...Overall judgment, A...Normal characteristics, Mouth...Characteristics subjected to thermal deterioration, C... ...Characteristics subjected to moisture absorption, staining and deterioration, a...Definition of tanJg, b...
...Definition of Δtanδ, A... Normal example, B.
...Example where the surface is deteriorated and the inside is normal, C...
・Example of deterioration both on the surface and inside.

Claims (1)

[Scope of Claims] In the insulation diagnosis of electrical equipment transported to a factory for the purpose of periodic inspection, etc., as a parameter indicating insulation deterioration of the electrical equipment as an object to be measured, (1) determined from the tan δ test method. tanδ_0 and Δtanδ (2) DC component from the DC component test method (3) Insulation resistance of the measured object from the DC high voltage test method Using the characteristics before cleaning and after cleaning and drying by blowing with air or steam, and the MEG characteristics after cleaning the object to be measured, forcing it to absorb moisture for a certain period of time, and then leaving it for a certain period of time, Calculate the required value by performing prescribed arithmetic processing on the insulation properties of An insulation diagnosis method comprising performing a comprehensive judgment of insulation deterioration by combining the results of predetermined arithmetic processing on MEG that has absorbed moisture in the same manner as described above.