Measuring and testing – Testing by impact or shock – Specimen impactor detail
Patent
1982-12-07
1985-08-13
Ruehl, Charles A.
Measuring and testing
Testing by impact or shock
Specimen impactor detail
73 82, G01N 330
Patent
active
045342067
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE ART
The present invention relates to a strike diagnosis apparatus for diagnosing insulation of coils or the like of a rotary machine such as a generator and an electric motor, in which only signal waveforms due to a striking force applied to the coil of the rotary machine are processed with respect to a time axis or a frequency axis thereby increasing an efficiency for the insulation diagnosis of the rotary machine's coil or the like.
BACKGROUND OF THE ART
FIG. 1 shows a conventional insulation testing method for a coil of a generator. In FIG. 1 a coil (1) is inserted into a slot (2A) of a core (2). As is apparent from FIG. 2 showing the schematic sectional view of the coil, the coil (1) is composed of a core wire (3) and an insulating member (4) surrounding the core wire (3). In the case where the coil (1) is used for a generator, the insulating member (4) is, in general, fixedly and closely contacted to the core wire (3). Therefore when the coil (1) is applied with striking force by a hammer (5), the coil (1) produces a striked sound "kon, kon" or "karn, karn" in accordance with the amount of the sectional area and the length of the core (1). A tester, using experience and perception obtained on the job, hears the strike sound and estimates the condition of the insulation of the insulating member (4) at each portion thereof.
It is well-known that even an insulating member (4), of the coil (1) which was initially estimated as a good condition is gradually deteriorated in insulation efficiency over years of use. The insulation efficiency of the insulating member (4) is deteriorated because the insulating member (4) covering the core wire (3) is swelled or peeled off.
In this case, upon the application of the striking force to the insulating member (4) by the hammer (5), the insulating member (4) produces a more dull sound such as "boko, boko" than the previously mentioned sounds indicative of good condition.
The tester has estimated hitherto the strike sounds produced for good conditions and inferior conditions by his sense of hearing. However, it is difficult and sometimes misleading to estimate the strike sound at a power-plant or a factory, at which the ambient noise is great. Further if a large striking force is applied to the insulating member (4) by the hammer (5) for the purpose of avoiding the misjudgement of the estimation, the insulation efficiency of the insulating member (4) becomes undesirably deteriorated even when the insulating member (4) is in a good condition. Therefore it is necessary to restrict the amount of strike force due to the hammer (5). Further the standards of estimation for the good or bad conditions is undesirably changed in accordance with the physical condition of the tester during the testing time over the course of a day.
DISCLOSURE OF THE INVENTION
The object of the present invention is to present a strike diagnosis apparatus capable of diagnosing a good or bad condition of an object to be striked on the basis of a detected striking force.
According to the present invention the good or bad condition of the object to be striked is judged or estimated by a peak value holding circuit for holding a signal representing the above striking force (hereinafter referred to as a strike signal), means for detecting the width of the strike signal on the axis of time, and dividing means for obtaining a ratio of the peak value and the width of the strike signal.
Further according to the present invention the good or bad condition of the object is judged by means of comparing the level of the strike signal with a reference level, further the condition is judged by analyzing the frequency of the strike signal and detecting a reduction amount of the level of a high region with respect to the level of a low region of the strike signal.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a conventional method of testing a good or bad condition in insulation, in which coils of a generator are shown;
FIG. 2 is a sectional view taken along the line A--
REFERENCES:
patent: 3421364 (1969-01-01), Moneypenny et al.
patent: 3502983 (1970-03-01), Ingle et al.
patent: 3550434 (1970-12-01), Schroeer et al.
patent: 3744299 (1973-07-01), Bliss
patent: 3759085 (1973-09-01), Wilson et al.
patent: 4157655 (1979-06-01), Campbell et al.
Fukunaga Tokio
Futakawa Akemi
Kiso Mataichiro
Mitsubishi Denki & Kabushiki Kaisha
Ruehl Charles A.
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