The Minimum Circumscribed Circle Based Method for Hydro-turbine Generator Unit Bearing Clearance Adjustment Analysis

摘要

Hydro-turbine generator unit turning test is a key step to check the installation quality of the shafting system. The unit turning data is very important for bearing clearance adjustment. The traditional unit turning test and bearing clearance adjustment are based on a condition of that the spindle turning orbit is an approximate circle. It is simple to be used in the field operation and applicable to the most units. The trajectory of the turning orbit shows irregular shape when the spindle has a certain part of the flaw. If the traditional method is used for the unit turning and adjusting the bearing clearance, this may cause the eccentricity of three guide bearing bushes and uneven of the bearing clearance. The unit may appear a high temperature or large swing phenomenon after its commission. Seriously the unit may be burned and permanent damage. To solve this problem, this paper proposed a new method to calculate a minimum rotation space of the shaft in the bearing for each guide bearing clearance according to a geometric algorithm. Using the new method, according to the minimum circumscribed circle of the turning axis locus and final position of the turning spindle after unit turning, the bearing clearances corresponding to each turning number on the shaft can be calculated precisely. And then the bearing radial position is distributed properly so that the bearing is in the centre of rotation to the centre of the concentric circle. Therefore, the specific value of each bearing clearance adjustment is obtained. Site testing results show that using the new method the high temperature and large adjustment gap caused by using the traditional method can be avoided. Thus, the hydro-turbine generator unit operating stability is improved.