Detection method and device for high-speed hydraulic generator rotor magnetic pole yoke t-tail groove

Abstract

The invention discloses a detecting method and a detecting device for a T-shaped tail slot of magnetic poles and magnet yokes of a high-speed hydrogenerator rotor. The detecting method comprises the following steps: blocking a magnetic line of force on the surface of the T-shaped tail slot when cracks exist by virtue of the T-shaped tail slot of magnetic poles and magnet yokes of a magnet, thus distorting magnetic flux in a magnetic path to result in the escaping of part of the magnetic flux out of the surface of the T-shaped tail slot and forming of magnetic leakage filed in a space; obtaining a magnetic flux leakage signal by virtue of a magnetic sensitive element, and detecting the magnetic flux leakage signal through a magnetic flux leakage detector. The detecting device comprises a crack probe detecting device, a guide bracket and a magnetic flux leakage detector, wherein the crack probe detecting device is arranged on the guide bracket, and the crack probe detecting device is connected to the magnetic flux leakage detector through a signal transmission line; the crack probe detecting device comprises an inverted U-shaped magnet A and a three-dimensional hall probe fixed on a guide bracket by virtue of an elastic part, wherein the three-dimensional hall probe is connected to the signal transmission line by virtue of a signal terminal through a signal amplifying and digital-to-analog conversion circuit.

Description

technical field [0001] The invention relates to a detection method and a device for a T tail groove, in particular to a detection method and a device for a T tail groove of a magnetic pole yoke of a high-speed hydraulic generator rotor. Background technique [0002] The T-tail slot is a connection structure between the magnetic stage and the yoke of the hydraulic generator. It is made of silicon steel laminations with a thickness of 4mm. It bears a large alternating stress during the start-up and stop process, especially the stress value at the inner corner position. The largest, easy to initiate fatigue cracks, and there have been accidents where all the magnetic yokes of generators were replaced, resulting in huge direct and indirect losses. In order to ensure the safety of the T-tail groove connecting the magnetic pole and the yoke of the high-speed (500r / min) hydro-generator under long-term frequent start-stop conditions, it is necessary to perform crack detection on the...

AI Technical Summary

Problems solved by technology

In the conventional eddy current detection of cracks, although no detection fluid is used and there is no residual problem, the strong "boundary effect" of the laminated silicon steel sheet on the eddy current signal makes the crack eddy current signal submerged in the background eddy current interference, and the signal-to-noise ratio is extremely low , cracks cannot be detected

For conventional magnetic particle testing, water-based or oil-based magnetic suspension fluid must be used. During the testing process, the magnetic suspension fluid will enter the lamination gap and cannot be cleared out after testing. This will not only reduce the insulation of the magnetic grade yoke, but also cause pollution.

In the conventional penetrant detection of cracks, in addition to the problem of penetrant removal after the test cannot be solved, the re-seepage of the residual penetrant in the lamination gap will greatly reduce the detection sensitivity, resulting in missed detection of cracks, which is also unapplicable

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