DD140185A1 - METHOD AND ARRANGEMENT FOR PREVENTING STORAGE PROBES IN ELECTRICAL MACHINES - Google Patents

Abstract

The aim of the invention is to create an electrical rolling bearing insulation by using high-strength, heat-resistant and electrically well-insulating materials with rational technology, which simultaneously enables constant dimensional accuracy in operating condition and a long service life of the rolling bearings and the bearing seat of the electrical machine. This object is achieved by using windings, release films and shrink tape on the bearing seat made of glass silk webs impregnated with synthetic resin, e.g. epoxy resin. After curing and the insulating bushing has been machined to size, a steel bushing is shrunk on, which serves as the bearing seat. The invention can be used in all electrical machines up to an output of several hundred kW, in particular in frequency converters in the same output range, electrical machines with a small air gap as well as high speeds and elevated bearing temperatures.

Description

Title of the invention

Method and arrangement for preventing bearing currents in electrical machines

Field of application of the invention

The invention relates to a method and an arrangement for producing a mechanically strong and thermally stable electrical insulation at the bearing point of runners of electrical machines to prevent bearing currents, in particular frequency converters to powers of a few 100 kV / and other electrical machines with a small air gap with the same power size and high speed.

Characteristic of the known technical solutions

In an improperly symmetrical design of electrical machines, the circuit, rotor shaft, bearing, housing or base plate may be chained to a time-varying flux of induction which results in electrical currents flowing over journal and bearing and roughening the bearing surfaces of the bearing. The change of this induction flux is in addition to the asymmetries in the structure of the electric machine also dependent on the operating frequency, so that at medium frequency converters having a frequency range up to 10,000 Hz and a very small air gap, particularly high stresses of the bearing caused by bearing currents and thus measures to extend the life of the bearings are required.

The means for this is once the constructive cancellation of the causes of the asymmetries, which are difficult to control, however-especially in frequency converters with asynchronous and high speed and rolling bearings.

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The attachment of shorted windings that wrap around the armature core does not indicate the complete cancellation of the bearing currents. The attachment of grounding brushes, which grind on the shaft or in pillowhouse machines, the attachment of an insulation between the foundation frame and pillow block has proved to be less effective, as subject to subjective conditions, such as monitoring the brushes or the unintentional bridging of the insulation.

, A rolling bearing isolation to prevent bearing currents can be done by a hard paper or hard tissue tube, which is arranged between the shaft and roller bearings. ·. , The disadvantage here is the technological effort.

In the area of the Fälzlagersitzes the wave is on a be-. true fit and the paper or hard tissue tube is shrunk onto the shaft with rotated inside dimension. Subsequently, the outer diameter of the tube is machined so that a steel bushing can be shrunk, which forms the actual seat for the rolling bearing with a turned-fit fit. The superimposed shrink seats must be dimensionally exactly matched to achieve the necessary run quality, especially in the high-speed frequency converters. "The existing in these electric machines higher storage temperature additionally loads the hard paper · * - or hard tissue tube, already by the Aufschrumpfungstemperaturen until was charged to the limit of temperature resistance. _. , ·

d) Object of the invention

The aim of the invention is the elimination of said Wach-. parts through a manufacturing process and arrangement for rolling bearing isolation using high-strength and heat-resistant materials. '

e) Presentation of the invention

The invention has for its object to provide a method and an arrangement that allows by using high-strength, heat-resistant and electrically good insulating materials a rolling bearing isolation electrical machinery with rational technology, constant dimensional accuracy in the operating condition and increased life of the electric machine. This object is achieved in that pre-impregnated glass fabric sheets with curable synthetic resin, for example epoxy resin, as a winding for use and then a shrink band, separated from the winding by a release film, is raised ..

f) embodiment

On the ro'h and manufactured with rough tolerance bearing seat of the rotor shaft is a thermosetting resin, for example, epoxy,. impregnated glass silk sheet evenly applied, surrounded with a release film and covered with shrink tape. Thereafter, the curing takes place at the appropriate curing temperature of the resin. The shrink band shrinks below the curing temperature, so that a compression of the underlying glass silk sheets is formed and a homogeneous, free of trapped air, mechanically and thermally stable Isolieru. of high life is achieved. Wake over the resulting insulating bush, the steel bushing is shrunk.

Claims (1)

Inventive appeal % Method and arrangement for preventing bearing currents in electrical machines, in particular frequency converters with power. · By some 100 kW and other electric machines with a small air gap of the same size and high speed, by an insulating bushing, characterized in that * on the raw processed bearing seat is wound with a thermosetting resin impregnated glass silk sheet, a release film and then a shrink band are applied , then the curing takes place under curing temperature and on the resulting. and custom-made Isolierbuchse a steel bushing is shrunk as a bearing seat.