Abstract
This paper describes the problem of overhauling induction motors for enhanced energy efficiency and resource saving. The authors found how to optimise the conventional overhaul procedure and upgrade the current induction motors by retrofitting. The authors developed a technique and built a hardware tool for quick checks of an electric machine’s stator steel. They also developed a mathematical model for a software tool that can analyse the feasibility of the final decision – if a motor should be overhualed, retrofitted or disposed of. The paper provides substantiation for the technique used to analyse the magnetic properties of the stator steel in the motors under repair. The paper also describes a technique and an electric diagram for defining the excitation current and voltage for an experimental analysis of the magnetic properties of the stator core. Stator steel quality assessment criteria are given. The criteria include stator core excitation current and voltage, active power losses in the stator core, excitation current and voltage initial phase shift, unsinusoidality of the excitation current. The paper describes mathematical models for determining the design values of the excitation current, magnetic induction, magnetic voltage, magnetic flux and the number of efficient stator winding turns on the motor under repair. The authors propose to compare the design and actual values characterising the magnetic status of the motor and recalculate the stator winding data in order to maintain or improve the energy efficiency of the electric machine. The paper shows that if the main quality indices characterising the magnetic system of an electrical machine fail to match the criteria obtained as a result of experimental studies, such electric machine is to be disposed of. The authors describe some mathematical models that help evaluate the cost of induction motor disposal through disassembly and sorting of the components. The results of this research could be useful for electrical maintenance personnel.
Keywords
Energy efficiency, resource saving, induction motor, stator core, overhauling and retrofitting of induction motors, disposal, resources, cost efficiency.
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