Protection of Induction Motor Using PLC

Abstract

Abstract: Protection of an induction motor (IM) against possible problems, such as over voltage, over current, overload, over temperature, and under-voltage, occurring during its operation is very important, because it is used intensively in industry as an actuator. IMs can be protected using some components, such as timers, contactors, voltage, and current relays. This method is known as the classical method that is very basic and involves mechanical dynamic parts. Computer and programmable integrated circuit (PIC) based protection methods have eliminated most of the mechanical components. However, the computer-based protection method requires an analog to digital conversion (ADC) card, and the PIC-based protection method does not visualize the electrical parametersmeasured. In this study, for IMs, a new protection method based on a programmable logic controller (PLC) has been introduced. In this method, all contactors, timers, relays, and the conversion card are eliminated. Moreover, the voltages, the currents, the speed, and the temperature values of the motor, and the problems occurring in the system, are monitored and warning indicators are shown using colored LED’s. Experimental results show that the PLC-based protection method costs less, provides higher accuracy as well as a safe and visual environment compared with the classical, the computer, and the PIC-based protection systems. Keywords: programmable logic controller, induction motor, motor protection, ladder diagram, protection system