PLC-Based Monitoring Control System for Three-Phase Induction Motors
The article presents a monitoring and control system design and implementation for the three-phase induction motor based on programmable logic controller (PLC) technology. the operational parameters of the motor is correlated with the the speed requested by the user by the PLC. This is done in both the during normal operation and under trip conditions. Tests prove that a higher accuracy in speed regulation is provided by the induction motor system driven by inverter and controlled by PLC.

Control System of Induction Motor
PLC’s programming is based on the logic demands of input devices and hence the programs implemented are mostly based on logical rather than numerical computational algorithms. The ladder diagrams are widely used for programming the PLC. The software tools running on a host computer provides the necessary programming tools. As the first step, the high-level program is written in ladder diagrams. It is then translated to binary instruction codes to be stored in RAM or EEPROM to be executed by the CPU.

report:
http://wseas.us/journals/saed/saed-40.pdf