Skewing Impact on Stray Losses of an Induction Machine

The amount of electrical energy consumed by rotating machines comes at around 50% of the total power produced around the world. With all the losses in the transmission and distribution network, the amount of power required to be generated at the power utility are far high. So a small change in the efficiency of an electric machine would mean valuable savings in the energy production. The determination of losses in electric machines and tweaking the design of a machine to achieve more efficiency has been a great challenge to mankind in the last century. Of all the losses, reduction of stray losses in induction machine has been an interesting topic to play with. Studies show that skewing the rotor of an induction machine has changed the stray losses and also the performance of the machine. This article is aimed on analysing the skewing impact on stray losses of an induction machine. Measurement was done on 37 kW induction machine with a skewed and a non-skewed rotor analysing the differences in losses. A locked rotor test was carried out. Simulations were used to predict the behaviour of the machine and mostly direct the analysis to a positive direction. Finite Element Method (FEM) was used to check the plausibility of the measurements and results from analytical models. FEM results were also used to point the direction of the analysis. A rather preliminary investigation on the effect of skewing shows that skew aids the flow of inter-bar current losses in the machine and hence increases the joule losses in the machine. Measurements at higher frequencies showed that the rotor joule losses are significantly reduced in the rotor cage of a skewed induction machine compared to a non-skewed induction machine. These measurements have shown that skewing has a significant effect on the harmonics produced in the air-gap. Therefore the decision to skew a machine depends more on the application where the motor would be used and all motor parameters. Uju, Isidore U. | Asiwe Uchechukwu M."Skewing Impact on Stray Losses of an Induction Machine" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-3 , April 2018, URL: http://www.ijtsrd.com/papers/ijtsrd10808.pdf http://www.ijtsrd.com/engineering/electrical-engineering/10808/skewing-impact-on-stray-losses-of-an-induction-machine/uju-isidore-u