GB2312964A - Method for evaluating a remaining life of a rotating machine coil insulating layer - Google Patents
Method for evaluating a remaining life of a rotating machine coil insulating layer Download PDFInfo
- Publication number
- GB2312964A GB2312964A GB9714975A GB9714975A GB2312964A GB 2312964 A GB2312964 A GB 2312964A GB 9714975 A GB9714975 A GB 9714975A GB 9714975 A GB9714975 A GB 9714975A GB 2312964 A GB2312964 A GB 2312964A
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- GB
- United Kingdom
- Prior art keywords
- stator coil
- insulating layer
- remaining life
- wet heat
- water
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
- G01R31/346—Testing of armature or field windings
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Manufacture Of Motors, Generators (AREA)
Abstract
The method disclosed includes the steps of sampling an insulating layer (12-14) of the stator coil finding infrared spectra of the insulating layer (12-l4), comparing the infrared spectra of the insulating layer (12-l4) of the stator coil with infrared spectra of a healthy stator coil's insulating layer (12-l4) not penetrated by water, finding difference spectra of an ester group of an epoxy resin used as a bonding agent of the insulating layer (12-14) and predicting a period of water penetration into the stator coil's insulating layer (12-l4) as a wet heat degeneration period, on the basis of the difference spectra of an ester group, with the use of a relation between the difference spectra of the ester group initially found and an aging time.
Description
"METHOD FOR EVALUATING A REMAINING LIFE OF
A ROTATING MACHINE COIL INSULATING LAYER"
The reader is notified that the applicant has made this divisional application on the basis of the matter disclosed in GB2303458.
The present invention relates to a method for evaluating the remaining life of a coil of an electric rotary machine having a water cooling system. In particular the invention is concerned with evaluating the remaining life of an electrical insulating layer exposed to water leaking from a chamber in the water cooling system.
A known nondestructive testing method for assessing the state of a brazed section (i.e, a covered area joined by brazing between a clip of a stator coil and copper wires) is the coil pressurising test for externally confirming the presence or absence of a clearance in the brazed section.
However, the coil pressurising test cannot quantitatively detect a very fine clearance or space.
Galvanic corrosion occurs at a section of copper wires joined by brazing due to the presence of water which is used as a coolant. As a result, water leaks occur. It has not been possible, by conventional methods, to predict a time when a leak will occur. It is the usual practice to effect repair or maintenance at the time when water leaks.
For this reason it has been difficult to plan preventative measures.
A known method for confirming the dielectric strength of an insulating layer of a generator stator coil is a nondestructive electric test and dielectric strength test which are done by applying an AC commercial frequency voltage across the copper wire unit of a stator coil and an insulating layer surface. However it is not possible to quantitatively detect the wet heat degeneration of the insulating layer of the stator coil.
The copper wires of the conductive section and brazing material for joining them suffer galvanic corrosion.
As a result, a water leak occurs at the brazed section between the clip of the generator stator coil and the copper wires and hence the water penetrates the insulating layer of the stator coil. Because it has not been possible to predict when the water will leak it has not been possible to predict at how fast a rate the dielectric strength of the insulating layer of the stator coil drops due to the wet heat degeneration and how long afterwards the stator coil can still be used. Therefore, it is difficult to plan any preventative measure.
An object of the present invention is to provide a method for evaluating the remaining life of a rotatingmachine coil subject to wet heat degeneration of the insulating layer of the stator coil and accordingly the present invention provides a method for evaluating a remaining life of a rotating machine coil insulating layer, comprising the steps of:
sampling an insulating layer of a stator coil of the rotating machine,
finding infrared spectra of the insulating layer,
comparing the infrared spectra of the insulating layer of the stator coil with infrared spectra of an insulating layer of a healthy stator coil not penetrated by water and finding difference spectra of an ester group in an epoxy resin used as a bonding agent of the insulating layer and,
predicting a period of water penetration into the insulating layer of the stator coil as a wet heat degeneration period, on the basis of the difference spectra of the ester group with the use of a relation between initially found difference spectra of an ester group and an aging time.
In the method for evaluating the remaining life of the rotating machine stator coil, the stator coil insulating layer apparently penetrated by water is sampled and an infrared spectrum analysis is performed on portions of the sampled insulating layer to find difference spectra of its ester group. It is possible to predict the time period over which water penetrates into the insulating layer of the stator coil by means of the difference spectra.
An insulating layer formed of the same material as that used in the stator coil of the machine is initially subjected to forced wet heat degeneration to find a relation between difference spectra of the ester group and an aging time (wet heat degeneration time) with its temperature as a parameter. This makes it possible to predict a period of water penetration into the stator coil insulating layer from the difference spectra of the ester group in that stator coil insulating layer, that is, in that insulating layer penetrated with water, which is measured by the remaining life evaluation method.
After predicting the time period in which water starts penetrating the insulating layer of the stator coil it is possible to find a wet heat degeneration rate (drop rate of the breakdown voltage, kV/year). By doing so it is possible to predict the drop rate of the dielectric strength resulting from the wet heat degeneration of the stator coil insulating layer after a sampling investigation time point and so to predict the remaining life of the insulating layer.
The method may further comprise the steps of: sampling at least one brazed section between a clip of a stator coil and copper wires;
cutting off the sampled section in a copper wire array direction extending parallel to the long axis of the wires;
measuring a portion of the cut-off brazed portion joined with a brazing material in a copper wire array direction and finding an effective sealing length therefrom;
predicting, by statistical processing, a shortest effective sealing length of all clips of the stator coil in one rotating machine on the basis of the effective sealing length of each cut face;
predicting a remaining life of the brazed section resulting from galvanic corrosion on the basis of the shortest effective sealing length and an initially found galvanic corrosion rate;
finding a remaining life of the stator coil from the time of sampling the stator coil on the basis of both the remaining life of the brazed section between clips of the stator coil and the copper wires and the drop rate of the dielectric strength of the insulating layer of the stator coil resulting from the wet heat degeneration.
In the method for evaluating the remaining life of the rotating machine coil, the remaining life of the stator coil from the time of sampling the stator coil can be predicted as a sum of the remaining life of the brazing section resulting from the galvanic corrosion and the remaining life resulting from the wet heat degeneration of the insulating layer. Taking into consideration the remaining life of the brazed section which is provided between the stator coil clip and copper wires and which is predicted by the remaining life prediction method and the drop rate of the dielectric strength resulting from the wet heat degeneration of the insulating layer of the stator coil which is predicted by the remaining life predicting method.
A method of evaluating the remaining life of an electric rotary machine coil insulating layer will now be described, by way of example, with reference to the accompanying illustrative drawings, in which:
FIG. 1 is a diagrammatic view of a brazed section between a clip of a stator coil of the electric machine,
FIG. 2 is a cross-section taken at clip cut off portions 5 and 6
FIG. 3 is a graph of shortest effective sealing length against cumulative defect probability showing including a line of best fit whereby the shortest effective sealing length of all the clip and copper wire junctions in the stator coil can be predicted,
FIG. 4 is a characteristic curve showing one example of a relation between difference spectra of an ester group resulting from the wet heat degeneration of an insulating layer of the stator coil,
FIG. 5 is a characteristic curve showing one example of a relation between aging time (wet heat degeneration time) and the reciprocal of aging temperature with the difference spectra of the ester group (FIG. 4) as a parameter;
FIG. 6 is a diagram of a sample of insulation having six faces prepared for a wet heat degeneration experiment where five faces are sealed;
FIG. 7 is a graph of dielectric strength of the stator coil insulation against age during normal aging and during a wet heat degeneration (aging) period showing the minimum dielectric necessary for stable operation and the breakdown dielectric; and
FIG. 8 is a graph predicting an overall remaining life of the stator coil, taking into consideration both the drop rate of the dielectric strength resulting from the wet heat degeneration of the insulating layer and the remaining life resulting from galvanic corrosion.
(First Embodiment)
FIG. 1 is a diagrammatic view showing one example of a brazed section between copper wires and clips of a stator coil of a generator having a water cooling system according to the present embodiment. FIG. 2 is a cross-sectional view showing one example of finding a shortest sealing length by investigating a joined portion of the copper wires at the brazed section and holes resulting from galvanic corrosion between different kinds of metals. FIG. 3 is a relation diagram showing one example of the technique of, with the use of Weibull distribution paper, predicting a shortest effective sealing length of the generator stator coil on the basis of the shortest sealing length found from respective clips sampled at the brazed section.
In FIGS. 1 to 3, reference numeral 1 shows copper wires for the generator stator coil; 2, a clip for the generator stator coil clip; 3, a connection pipe coupling; 4, a clip water chamber; 5 and 6, clip cutoff portions; 7, a joined or brazed section; 8, clearances of the brazed section; n, the number of clips investigated or all clips in one generator; and F(t), a cumulative fault probability.
With the present embodiment, a remaining service life of the brazed section between the copper wires 1 and the clip 2 of the generator stator coil is predicted as will be set out below.
First, as shown in FIG. 1, sampling is effected from the brazed section between the copper wires 1 and the clip 2 of the generator stator coil. Then the brazed section is cut off in several places in a direction of the copper wire array and the resultant cut face is polished. Thereafter, the extent to which the brazing material is buried in the direction of the copper wires (those sections 7 joined by the brazing material between the copper wires) is predicted.
That is, at least five or sixth clips 2 are sampled from the generator now being operated and the thus sampled individual clips 2 are cut off at about four places in the copper wire array direction and their cut faces are polished. Then the joined states of the copper wires 1 and size of their corrosion holes are measured in a copper wire array direction (axis direction).
A remaining portion (a joined portion between the copper wires 1) obtained by subtracting a clearance at those unjoined copper wires plus the length of the corrosion hole from a brazed length (fixed) between the copper wires 1 and the clip 2 for water-tight sealing is measured as an effective sealing length.
In this case, the more the clip is cut off, the higher the measuring accuracy of the effective sealing length.
As shown in FIG. 3, the shortest effective sealing length on one generator is estimated by statistical processing.
That is, the shortest effective sealing length of all the cut faces of a single clip 2 is taken as a representative value of the clip 2. The shortest effective sealing length is found with respect to all the clips 2 sampled and, upon being plotted on the Weibull distribution paper, can be regressed with a straight line. From this the shortest effective sealing length of all the stator coils in one generator is estimated through the statistical processing.
Stated in more detail, as shown in FIG. 2, the cut faces of the clips are polished and measurement is made on the joined state 7 between the clip 2 and the copper wires 1, between the copper wires 1 and across the copper wire 1 in a row as well as the size of the corrosion hole resulting from galvanic corrosion between different kinds of metals.
And the shortest effective sealing length of the individual clip 2 is found with the use of the calculation equation given below:
(shortest effective sealing length) = (the
brazed length) - (maximum defect length) (1) where
(maximum defect length) = the maximum value of (clearance length + corrosion hole length).
Regarding the individual clips 2, their shortest effective sealing length is found with the use of the equation (1) above and then the calculated value of the following equation is plotted on the Weibull distribution paper as shown in FIG. 3.
The cumulative defect probability
F(t) = i I (n+l) or (1- 0.3) / (n+0.4) ... (2)
where
n: the number of clips 2 investigated
i: the number of clips 2 of any effective sealing length or below its length.
With respect to the sampled data (shortest sealing lengths of the individual clips) plotted on the Weibull distribution paper the regression line is drawn, as shown in
FIG. 3, with the equation (2) above. The shortest effective sealing length of the generator stator coil is obtained by reading the abscissa's effective sealing length from a intersection between the regression line and the cumulative defect probability F(t) found by inserting n (the number of all the clips in one generator) into the equation (2).
A probable year (remaining life resulting from the galvanic corrosion), that is, a year in which water leaks from the brazed section between the copper wire 1 and the generator stator coil clip 2 due to the development of the galvanic corrosion, is predicted based on the shortest effective sealing length thus found and the galvanic corrosion development rate between different kinds of metal, that is, the rate initially found by experiments.
That is, the remaining life of the generator's brazed section resulting from the galvanic corrosion can be found, by the following calculation equation (3), based on the above-mentioned shortest effective sealing length and the galvanic corrosion development rate (mm/year) initially found by experiment.
(remaining life of the brazed section) =
shortest effective sealing lengths of all the clips
2 in the generator) / (galvanic corrosion
development rate) (mm/year) ... (3) According to the present embodiment, as set out above, upon the prediction of the state of the brazed section between the generator coil clips 2 in the generator having a water cooling system and the copper wires 1 as well as the corrosion development state of the corrosion hole, the clip-to-copper wire-brazed sections are sampled, those sections 7 joined with the brazing material are measured as the copper wire direction lengths to find effective sealing lengths of the brazed sections (joined sections), the shortest effective sealing lengths of all the stator coil clips 2 in one generator are predicted by the statistical processing on the basis of the effective sealing lengths of the respective cut faces, that is, by regressing, with a specific straight line, a relation between the shortest effective sealing lengths of the respective clips 2 and the cumulative defect probability and the remaining life of the brazed section resulting from the galvanic corrosion is predicted based on the shortest effective lengths and initially found galvanic corrosion development rate, in actual practice, by dividing the shortest effective sealing length by the galvanic corrosion development rate.
By finding the effective sealing lengths of the brazed sections between the copper wires 1 and the stator coil clips 2 in the generator having the water cooling system it is possible to predict the shortest effective sealing lengths of all the brazed sections and positively predict and evaluate the remaining life of the brazed section resulting from the galvanic corrosion.
By doing so, it is possible to evaluate the remaining life of the brazed section (joined section) for water leakage so that there arises no leakage of water as a cooling medium.
Further, a planned protective measure can also be properly made through the prediction of the remaining life resulting from the galvanic corrosion. By preventing an unexpected failure, such as a machine stop, it is possible to supply stable power and expect a lowering in the cost of maintenance.
(Second Embodiment)
FIG. 4 is a graph showing a characteristic curve of one example representing a relation between an aging (water penetration) time, that is, the time at which an epoxy resin as a bonding agent for an insulating layer is wet heat aged through the water penetration into the insulating layer of a stator coil in a generator having a water cooling system in accordance with the present embodiment, and difference spectra of an ester group in the epoxy resin. FIG. 5 shows one example representing a relation between the aging time of the insulating layer and the temperature with the difference spectra of the ester group as a parameter on the basis of a graph of FIG. 4. FIG. 6 is a concept diagram showing one example of a specimen insulating layer block of an experimentally aged stator coil with its five faces sealed for finding the relations shown in FIGS. 4 and 5.
FIG. 7 is a graph showing one procedure for predicting, based on the different spectra of an ester group in an insulating layer of a water-penetrated practical stator coil, a water penetration time (wet heat degeneration time) with the use of the relation of the difference spectra of the experimentally found ester group to the aging time and finding a drop rate in the dielectric strength of the wet heat degenerated stator coil from a breakdown voltage of the water-penetrated stator core and usual aged wires. FIG. 8 is a graph showing one example of a procedure for predicting the remaining life of a stator coil from both the remaining life of the stator core clip-to-copper wire brazed section (i.e., the period until the clip-to-copper wire brazed section begins to leak as a result of galvanic corrosion) obtained by the remaining life evaluation method according to the first embodiment and from dielectric failure of the insulation of the stator coil caused by wet heat degeneration and normal degeneration of the dielectric.
It is to be noted that, in FIGS. 4 to 8, al, a2, a3 represent difference spectra of the ester group after the insulating layer of the stator coil has been wet heat degenerated with the aging time b.
Further, reference numeral 11 shows one penetrationdirection face of the insulating layer aged; 12, the side faces of the insulating layer and 14; the penetration direction of the insulating layer.
Reference numeral 15 shows the period (wet heat degeneration period) in which water penetrates the insulting layer; 16, a drop line of the dielectric strength of the stator coil resulting from the wet heat degeneration of the insulating layer; 17, a line (life line) for the dielectric strength necessary for a stable operation; 18, an aging line for the dielectric strength of an ordinary stator coil; 19, the dielectric strength when water starts penetrating the insulating layer resulting from an ordinary aging; 20, the breakdown voltage of the stator coil whose insulating layer is water-penetrated; 21, a remaining life of the clip-tocopper wire brazed section resulting from the galvanic corrosion; 22, a remaining life of the stator core resulting from the wet heat degeneration; and 23, the dielectric strength of the stator coil when water starts penetrating the insulating layer due to the formation of a leak path in the clip-to-copper wire brazed section.
With the present embodiment, the remaining life of the generator stator coil is predicted as will be set out below.
As shown in FIG. 6, except one penetration direction 14 face only, the insulating layer is sealed on five faces, that is, the four side faces 12 and penetration direction 14 bottom face, and aged in pure water at a temperature close to an operation temperature. During a portion of the aging, the insulating layer is sampled, followed by the infrared spectral analysis of an epoxy resin being a bonding agent of the insulating layer. By doing so, the relation between the difference spectra of the ester group and the aging time as shown in FIGS. 4 and 5 is found.
Then the actual-machine stator coil whose insulating layer is water-penetrated is sampled and the infrared spectrum analysis is performed and measurement is made of the difference spectra a of the ester group. Thereafter, the aging time (wet heat degeneration period) b is found from
FIG. 4 or FIG. 5.
Then a commercial frequency voltage is applied to the copper wires 1 of the stator coil and, with the insulating surface of a linear section (corresponding to the stator core slot section) as a ground electrode, measurement is made of a breakdown voltage 20 of the actual stator coil.
In this case, the relation between the breakdown voltage 20 of the above-mentioned actual-machine stator coil and the wet heat degeneration period 15 can be shown on the aging line 18 of the dielectric strength of the stator coil as in FIG. 7.
That is, from FIG. 7 it is found that, through the penetration'of the water into the insulating layer of the stator-coil, the breakdown voltage of the stator coil is dropped, during the wet heat degeneration period, from the line 19-20 in the case of the usual aging.
Thus the drop rate of the dielectric strength over the wet heat degeneration time 15 can be found from the following equation (4).
(drop rate of the dielectric strength resulting
from the wet heat degeneration) = (breakdown
voltage 19 at a wet heat degeneration start
time) - (breakdown voltage 20 after the wet
heat degeneration) / (wet heat degeneration period
15) ... (4) Then a remaining life 21 of the brazed section between the stator coil clips and the copper wires 1 resulting from the galvanic corrosion is found, through sampling investigation of theactual-machine stator coils, as in the case of the remaining life evaluation method of the first embodiment.
With a point 23 on the usual aging line as a starting point in FIG. 8 a drop line 16 for the dielectric strength of the stator coil resulting from the wet heat degeneration is drawn with the use of the drop rate of the dielectric strength resulting from the wet heat generation found from the equation (4) above. From a intersection between the drop line 16 and the dielectric strength line 17 necessary for safe operation it is possible to predict the remaining life 22 of the stator core resulting from the wet heat degeneration in the case where water penetrates the insulating layer of the stator coil.
That is, the remaining life of the stator coil of the generator having the water cooling system can be predicted from the following equation (5).
(remaining life of a water cooling system
stator coil) = (remaining life 21 of the brazed
section between the clips of the stator coil and the
copper wires) + (remaining life 22 of the stator
coil resulting from the wet heat degeneration period
degeneration) ... (5) With the present embodiment, as set out above, the drop line 16 of the dielectric strength 16 is found, with respect to the insulating layer of the same material asthat of the stator coil of a generator having the water cooling system, by predicting the wet heat degeneration characteristic (relation between the difference spectra of the ester group and the aging time - FIG. 4) initially found from the experimental aging, the breakdown voltage 20 of the actual-machine stator coils whose insulating layer is water penetrated, and the aging time :(water penetration period = wet heat'degeneration time) 15 resulting from the difference spectra a of the ester group. Then, in order to evaluate the remaining life with respect'to the sampled stator coils, the remaining life of the coils in the generator having the water cooling system is predicted through the arithmetic addition of both the remaining lives 21 and 22, that is, through the addition of the prediction value of the remaining life 21 of the stator coil clip-to-copper wire brazed section resulting from the galvanic corrosion obtained by the same remaining life evaluation method as that of the first embodiment and the prediction value 22 of the remaining life 22 of the stator coil's insulating layer resulting from the wet heat degeneration through the use of the drop line (drop ratio) 16 of the dielectric strength resulting from the wet heat degeneration as found either experimentally or by the investigation into the actualmachine stator coil penetrated by the water.
Thus, the remaining life of the stator coil as a whole is integrally predicted by both the remaining life 21 of the stator coil clip-to-copper coil brazed section in the generator having the water cooling system and the remaining life 22 of the insulating layer of the stator coil penetrated by the water, that is, both the remaining lives 21 and 22 not understandable from a nondestructive test from a surface and an electric test.
Further, a planned protective measure can be taken at a proper time through the prediction of the remaining lives. By preventing occurrence of an unexpected machine fault stop and it is possible to supply stable electric power and expect a lowering in maintenance cost.
(Other embodiments)
(a) Although, in the first embodiment, the shortest effective sealing lengths of the individual clips have been explained as being used as the statistical data, the present invention is not restricted thereto. As many cut faces as practical can be made in the individual clips in a way as shown in FIG. 2. in this case, the shortest effective sealing lengths of the cut faces can be used as the statistical processing data, these lengths be plotted on the
Weibull distribution paper and the shortest effective sealing lengths of all the clips in the generator be read out with the use of the equation (6) below.
(cumulative defect probability) F(t) 9
= i / (n x m+ 1)
or
= (i - 0.3)/(n x m + 0.4) ............ (6)
Here
n: the number of the clips 2 in one generator;
m: the number of cut faces investigated per clip;
and
i: the number of any effective sealing length or
below.
(b) In the second embodiment it is possible to find the relation of difference spectra of an ester group to an aging time, as well as the drop rate of dielectric strength, by, instead of the aging of the insulating layer initially effected experimentally, forcibly creating a leak path between the clip 2 and the copper wires 1 in a plurality of stator coils of an actual machine, effecting aging in a simulated state of operation through the penetration of cooling water into the stator coil and perform a sampling investigation during a portion of the aging.
Claims (6)
1. A method for evaluating a remaining life of a rotating machine coil, comprising the steps of
sampling an insulating iayer of a stator coil of the rotating machine;
finding infrared spectra of the insulating layer;
comparing the infrared spectra of the insulating layer of the stator coil with infrared spectra of an insulating layer of a healthy stator coil not penetrated by water and finding difference spectra of an ester group in an epoxy resin used as a bonding agent of the insulating layer and,
predicting a period of water penetration into the insulating layer of the stator coil as a wet heat degeneration period, on the basis of the difference spectra of the ester group with the use of a relation between initially found difference spectra of an ester group and an aging time.
2. A method according to claim 1, wherein the relation between the difference spectra of the ester group and the aging time is initially found by causing the insulating layer of a specimen stator coil made of the same material as that of the stator coil to be wet heat degenerated through experimental aging in pure water with temperature as a parameter and performing infrared spectrum analysis.
3. A method according to claim 2, wherein the experimental aging of the insulating layer in pure water is effected a through a path such that water penetrates directly into only one water penetration face of a cut-off six faced block-like portion of the specimen stator coil with five faces thereof sealed.
4. A method according to any one of claims 1 to 3 further comprising measuring a breakdown voltage of the stator coil; and
predicting a drop rate-of a dielectric strength resulting from a wet heat degeneration of the insulating layer of the stator coil on the basis of a period of water penetration into the insulating layer of the stator coil and breakdown voltage of the stator coil.
5. A method according to any one of the preceding claims comprising the steps of:
sampling at least one brazed section between a clip of a stator coil and copper wires;
cutting off the sampled section in a copper wire array direction extending parallel to the long axis of the wires;
measuring a portion of the cut-off brazed portion joined with a brazing material in a copper wire array direction and finding an effective sealing length therefrom;
predicting, by statistical processing, a shortest effective sealing length of all clips of the stator coil in one rotating machine on the basis of the effective sealing length of each cut face;
predicting a remaining life of the brazed section resulting from galvanic corrosion on the basis of the shortest effective sealing length and an initially found galvanic corrosion rate;
finding a remaining life of the stator coil from the time of sampling the stator coil on the basis of both the remaining life of the brazed section between clips of the stator coil and the copper wires and the drop rate of the dielectric strength of the insulating layer of the stator coil resulting from the wet heat degeneration.
6. A method as herein described with reference to the accompanying figures.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP17899295 | 1995-07-14 | ||
| JP01271596A JP3272933B2 (en) | 1995-07-14 | 1996-01-29 | Remaining life evaluation method for rotating electrical machine windings |
| GB9613029A GB2303458B (en) | 1995-07-14 | 1996-06-21 | Method for evaluating a remaining life of a rotating machine coil |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9714975D0 GB9714975D0 (en) | 1997-09-24 |
| GB2312964A true GB2312964A (en) | 1997-11-12 |
| GB2312964B GB2312964B (en) | 1998-07-29 |
Family
ID=27268342
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9714975A Expired - Fee Related GB2312964B (en) | 1995-07-14 | 1996-06-21 | Method for evaluating a remaining life of a rotating machine coil insulating layer |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2312964B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103760480A (en) * | 2014-01-10 | 2014-04-30 | 国家电网公司 | Method for judging composite insulator fault by utilization of infrared temperature measurement technology |
| CN105445625A (en) * | 2015-10-26 | 2016-03-30 | 西南交通大学 | Method for classifying alternating-current conductivity frequency domain spectrums of transformer oil clearance under difference temperatures into same reference temperature |
| CN110672954A (en) * | 2019-10-14 | 2020-01-10 | 华北电力大学 | Composite insulator core rod aging characterization method |
| CN111505459A (en) * | 2020-05-09 | 2020-08-07 | 东方电气集团东方电机有限公司 | Insulation aging evaluation method for generator stator winding |
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| CN113299355B (en) * | 2021-05-07 | 2024-05-24 | 中国电子产品可靠性与环境试验研究所（（工业和信息化部电子第五研究所）（中国赛宝实验室）） | Reliability evaluation method for high-frequency substrate |
| CN114167234B (en) * | 2021-11-29 | 2024-05-28 | 海南电网有限责任公司电力科学研究院 | Insulator aging detection method based on hyperspectrum of unmanned aerial vehicle |
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-
1996
- 1996-06-21 GB GB9714975A patent/GB2312964B/en not_active Expired - Fee Related
Non-Patent Citations (1)
| Title |
|---|
| Tecnica Italiana Vol. 36 No. 4 April 1971, pages 73-82 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103760480A (en) * | 2014-01-10 | 2014-04-30 | 国家电网公司 | Method for judging composite insulator fault by utilization of infrared temperature measurement technology |
| CN103760480B (en) * | 2014-01-10 | 2016-08-17 | 国家电网公司 | Utilize the method that infrared temperature-test technology judges composite insulator fault |
| CN105445625A (en) * | 2015-10-26 | 2016-03-30 | 西南交通大学 | Method for classifying alternating-current conductivity frequency domain spectrums of transformer oil clearance under difference temperatures into same reference temperature |
| CN105445625B (en) * | 2015-10-26 | 2018-03-20 | 西南交通大学 | Transformer oil clearance AC conductivity frequency domain spectra is incorporated into the method for reference temperature under different temperatures |
| CN110672954A (en) * | 2019-10-14 | 2020-01-10 | 华北电力大学 | Composite insulator core rod aging characterization method |
| CN111505459A (en) * | 2020-05-09 | 2020-08-07 | 东方电气集团东方电机有限公司 | Insulation aging evaluation method for generator stator winding |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9714975D0 (en) | 1997-09-24 |
| GB2312964B (en) | 1998-07-29 |
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Effective date: 20140621 |