SU1737627A1 - Stator of electric machine - Google Patents

Description

Fig .. 2

The invention relates to electrical engineering, in particular to the production and operation of large electric machines, such as turbine generators.

The known construction of a hundred-mount turbogenerator, containing a core laminated from electrical steel sheets, is pressed by pressure plates with nuts installed on strapping ribs and ring gaskets arranged under the nuts.

During the operation of such turbine generators, the compaction of the core is often weakened, the clamping ribs are broken, the screws self-unscrew, which leads to emergency shutdowns and forced just m generator.

To prevent these negative effects, a combined probe is used, the state of pressing of the stator core is determined by the depth of which between the sheets of the laminated package.

It is impossible to use a combined probe in the period between capital repairs, since this requires disassembling the generator with a notch in the rotor. In addition, the use of such a device requires a considerable amount of manual labor, is difficult to eutomatise, does not give quantitative estimates of the pressing force, and also does not allow to judge about the presence of edge breaks and unscrewing the nuts.

The stator is the closest to the claimed one. , on which plates are located on an electrically conductive gasket, the distance between which (and, accordingly, the electrical capacitance) varies depending on the pressing force. However, the indications of the capacitance capacitance pressure sensors are affected by the interference in the communication line and the ambient temperature. To reduce the influence of these factors, it is necessary to resort to special methods, for example, to use a differential circuit for switching on a controlled capacitance and an additional one installed outside the zone of application of forces. In addition, to reduce the interference occurring in the communication lines, it is necessary to apply more complex circuit solutions in the meter, which makes it difficult to solve

tasks. The use of non-standard measuring devices causes difficulties in metrological monitoring of the pressing force, therefore, the information obtained does not allow one to formulate an unambiguous conclusion about the state of the object being diagnosed.

The purpose of the invention is to improve the quality of manufacture and repair and increase operational reliability by increasing the accuracy and reliability of monitoring the state of pressing.

This goal is achieved by the fact that in the stator of an electric machine, including a core pressed from electrical steel sheets, pressed by pressure plates with annular gaskets installed on the stubby ribs of nuts and ring gaskets arranged under the nuts. protrusions, with inner and outer cylindrical surfaces having grooves, where at equal distances with respect to one another (for example, at an angle of 120 are attached load cells connected by bridge or half bridge circuit and connected to recording devices with the ability to control the pressing and signaling forces in the absence of pressing forces.

The annular protrusions on the end surface of the gaskets are made with an outer radius smaller than the radius of the outer cylindrical surface of the gaskets, in the form of segments equally spaced from each other, aligned coaxially with strain gauges, and in the middle of the height of the gaskets there are radial through holes (or grooves) equally spaced from the sensors.

The described device makes it possible to obtain quantitative information on the mechanical state of the stator core using a measuring tool, ring gaskets equipped with strain gauges. Making the outer radius of the annular protrusions on the end surface of the gaskets smaller than the radius of the outer cylindrical surface of the gaskets reduces the measurement error in the event of misaligned loading of the gasket. The implementation of radial holes or grooves in the gaskets helps to reduce the error in the case of uneven application of force around the circumference of the gasket; The same purpose is served by the implementation of annular protrusions in the form of segments equally spaced from each other with the axis of symmetry passing in the places where the sensors are pasted.

The proposed device favorably differs from those known for the simplicity and availability of technical solutions, a high degree of accuracy (1-3%) for this class of measurements.

Fig. 1 shows a stator core with fasteners (clamping ribs, O-rings, nuts), a section; Fig. 2 shows an annular gasket along the axis of symmetry with radial holes in the gasket body (node I in Fig. 1), a section; FIG. 3 shows an annular gasket with a continuous annular projection, top view; figure 4 is the same, with annular projections in the form of segments, bottom view.

As an example of implementation, consider the implementation of the proposed device in the manufacture, repair and operation of powerful turbine generators.

In this case, the gasket 1 under the nut 2 of the rigid ribs 3 is made of structural resilient steel (e.g. 40 X). Radial holes 4 are made in the gasket body and grooves on the inner and outer cylindrical surfaces. Annular protrusions 5 and 6 are made on the end surfaces. Thereafter, the blanks are subjected to thermal hardening (for example, up to a 100 kg

mm2

). On the machined cylindrical surfaces at a distance of 120 °, active and compensating strain gauges lean on one another.

The resulting force-measuring elements are subjected to thermal and mechanical aging (105 cycles with a load of 0.8 nominal) and graduated on a calibration stand in the range of 0–300 kN.

The received force-measuring elements are installed after the termination of the stator core is in place (do not remove the pressing force from the pressure plate 8 and do not tighten the nuts 2). Through a gas-tight coupling, the harnesses are taken out for connecting measuring and recording devices, by means of which the readings of each of the load-bearing elements corresponding to zero load are recorded. Do not remove the pressing force from the pressure plate 8, tighten the nuts 2 with an overpressure of 10-20 kN, which is controlled with the help of appropriate measuring elements. After all nuts are tightened, the pressing force is removed.

and record the residual pressure under each nut. Subsequently, all technological operations affecting the pressing (baking, prepressing, winding manufacturing, etc.) are controlled with the help of measuring elements installed under the nuts.

The proposed technical solution in comparison with the prototype makes it possible to improve the quality of manufacture of the stator core of large electric machines, eliminating, at the manufacturing stage, possible omissions in blending and assembly of the stator core.

This technical solution in comparison with the prototype makes it possible to assess the mechanical state of the stator core during the operation of the turbogenerator at the power plant and allows

Claims (1)

thereby optimizing the timing of preventive maintenance, which contributes to improving the reliability of electric machines in operation. Invention Formula The stator of an electric machine, comprising a core laminated from electrical steel sheets, pressed by pressure plates with nuts installed on the stabbing ribs and ring gaskets located under the nuts, characterized in that, in order to improve the quality of manufacture and repair, increase reliability in operation, nuts of the rigid ribs are made of elastic structural steel with end surfaces in the form of annular projections and with internal and external cylindrical surfaces, having and the bore, wherein at equidistant strain gauges connected by a bridge circuit and connected to recording devices with the ability to control the pressing and signaling forces in the absence of pressing forces are attached from another Moreover, the annular protrusions on the end surface of the gaskets are made with an outer radius smaller than the radius of the outer cylindrical surface of the gaskets, in the form of equally spaced segments coaxially with the strain gauges, and in the middle of the height of the gaskets radial through holes equidistant from the strain gauges are made. FIG. one Thebes b Fy