Method for locally tempering rotor tooth head of turbogenerator

Abstract

The invention relates to a method for locally tempering a rotor tooth head of a turbogenerator, which is used for tempering a generator rotor whose heating temperature is higher than Ac1 and lower than Ac2. The method has the following beneficial effects that after the technical scheme of the invention is adopted, the temperature and cooling rate of the generator rotor which is abnormally heated can be determined quickly, a correct local tempering process is developed to successfully eliminate the martensite structure at the burnt position and take into account the softened over-tempering zoneas to prevent further over-tempering during tempering from reducing the strength and reduce the thermal impact on the normal matrix, thus avoiding the introduction of large thermal stress on the rotor teeth.

Description

technical field [0001] The invention relates to a method for locally heat-treating the tooth head of a generator rotor. Background technique [0002] According to the incomplete statistics of domestic generator accidents since 1960, the accidents causing generator rotor burns are mainly divided into electrical faults (excessive negative sequence current, rotor winding grounding fault) and mechanical faults (mechanical grinding), see Table 1. Judging from the previous treatment, burnt generator rotors are simply polished based on experience, and put into use again after passing the penetration test. [0003] Table 1 Cases of Generator Rotor Burns [0004] [0005] After the rotor burns out during the operation of the generator, subject to the limit of on-site technical conditions and the needs of actual production, according to the degree of rotor burnt out, the ones that are only overheated and bluish are generally put into use without treatment, and the ones that are pa...

AI Technical Summary

Problems solved by technology

If the tempering temperature is too high or the time is too long, the strength of the over-tempered area on the edge of the burn will be further reduced; if the tempering temperature is too low or the time is too short, the strength of the hardened zone in the center of the burn will not be reduced.

Although local heat treatment can eliminate the structural stress caused by quenching, it will introduce relatively large thermal stress. If the size of the tempering area is determined arbitrarily without calculation, the safety margin of rotor operation will be reduced.

Images