Design of a Three Phase Induction Motor Protection System
Authors: Igbinoba CK, Ofualagba G
Three-phase induction motors are widely used as industrial drives because they are rugged, reliable and economical. This paper presents the design and construction of a system for the protection of three phase induction motor from external faults such as overvoltage, under voltage and single phasing using operational amplifiers. The operational amplifier used in this work is LM 324 and was configured in the comparator mode by setting one of the inputs at a reference voltage and while varying the other input according to the mains input supply. The mains input voltage from each of the phase was stepped down to 12 VAC, regulated and divided using a potentiometer and fed to the varying input of the operational amplifier. The outputs from the operational amplifier were connected to a three input OR-gate and the output of the OR-gate was connected to the input of a Reset-Set (RS) flip-flop which energizes or de-energizes the three pole double throw relay (3PDT) to power ON or OFF the induction motor. The system was tested using a three phase variac. From the test results, the three phase induction motor only runs when the mains input voltage is between 230 VAC and 240 VAC. Any voltage below or above this from any of the phase will stop the motor from running.
Affiliations: Department of Electrical and Electronics Engineering, College of Technology, Federal University of Petroleum Resources Effurun, Effurun, Nigeria
Keywords: Induction Motor, Operational Amplifier, Overvoltage, Undervoltage, Phase Failure
Published date: 2020/06/30