Metal working – Method of mechanical manufacture – Electrical device making
Patent
1992-04-08
1994-08-30
Hall, Carl E.
Metal working
Method of mechanical manufacture
Electrical device making
29598, 29606, 310 43, 310215, H02K 1506
Patent
active
053415612
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL DOMAIN
The invention relates to a process for manufacturing the electrical insulation of the winding of an electrical machine which has winding sections, particularly subconductor bundles, which are placed with play in the grooves of the rotor or stator.
STATE OF THE ART
The quality of the electrical insulation of the windings of electrical machines, i.e., motors and generators, can be impaired to a considerable degree by the occurrence of air gaps between the individual layers of the insulating, and in particular, by air gaps between the outer insulating layers of the winding and the inner walls of the grooves in the laminate housing of the rotor or stator of the machine in which the winding is placed. Such air gaps have a detrimental effect on the discharge of the Joule heat occurring in the winding during operation into the laminate housing.
Air inclusions and air gaps inside the insulation itself can be largely prevented by other known technologies. However, this applies only to a limited degree to the prevention of air gaps between the outermost layer of the insulation and the inner walls of the groove. For manufacturing reasons, it is generally not possible to make both side walls of the groove in the laminate housing fully uniform and plane-parallel. Even if a subconductor bundle to be placed in the groove had a perfected prismatic cross-section, it would only be possible to place it in the groove with a more or less large degree of play between the surface of the insulated subconductor bundle and the two side walls of the groove.
According to the so-called "resin-rich" process for the manufacture of insulation of windings of electrical machines, a technique is known in which the insulation is composed of insulating materials which have such a high content of binders in the form of thermosetting synthetic resin that because the synthetic resin becomes fluid during manufacturing, air inclusions can be avoided. In this process, following the application of the insulating materials, the winding is heat-treated in an expansive device and brought into a pressing process involving hardening of the synthetic resins contained in the insulation down to a precisely predetermined size, which makes it possible to achieve a relatively low degree of play between the winding and the inner walls of the groove.
According to another process, referred to as the vacuum pressure impregnation process, the insulation of the winding consists at least to a large extent of absorbent, porous insulating materials. After placement of the winding in the grooves, however, there is initially a larger play between the winding and the inner walls of the groove. The rotor or stator having the winding is then impregnated with a thermosetting impregnating resin in a vessel. In this process, in an initial step, the rotor or stator is placed under a vacuum in the impregnation vessel, which removes the air from the pores and/or gaps, after which it is placed in the impregnation resin bath. The subsequent production of excessive pressure in the impregnation vessel makes penetration of the impregnation resin into the pores and gaps easier. In subsequent heat treatment under elevated temperature, the impregnation resin absorbed by the rotor or stator and the binders and synthetic resins in the insulation are hardened.
However, experience shows that in the case of conventional vacuum pressure impregnation processes as well, the occurrence of air gaps between the subconductor insulation and the inner walls of the groove cannot be reliably prevented.
In order to remedy this, the applicant of the older international patent application, PCT/AT91/00021, suggested that, for the manufacture of the electrical insulation of the winding of an electrical machine according to the vacuum pressure impregnation process, the grooves be fitted with a laminate prior to laying the winding into the grooves of the stator or rotor, which laminate would contain at least one laminate layer made of an elastically compressed, highly elastic, electrically
REFERENCES:
patent: 4037312 (1977-07-01), Deis
patent: 4484024 (1984-11-01), Bentley, Jr.
patent: 4643940 (1987-02-01), Shaw et al.
Deutschmann Gottfried
Schorm Josef
Zych Otakar
CKD Trakce A.S.
Hall Carl E.
Isovolta Osterreichische Isolierstoffwerke Aktiengesellschaft
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