Development and Deployment of Programmable Logic Controller-Based Switched Capacitor Banks to Enhance Power Factor of Three-Phase Induction Motors

In industries, three-phase inductive loads such as induction motors are widely used due to their low cost, easy maintenance, reliability, and robustness. Due to inductive loads, the power factor is reduced which results in the wastage of power, high billing costs, and penalties from electric power supply companies. In order to resolve this issue, a system has been designed for the power factor improvement of three-phase loads using the programmable logic controller (PLC) which will definitely minimize the operation cost of the plant, and also the demand for electricity supply on utility side will be reduced. The system is implemented by a combination of Hardware and software. The software consists of PLC programming whereas hardware consists of power and control circuits along with the protective devices. The programming of PLC is logic based which controls step by step sequence of operations. When the inductive load adds to the system, PLC will read the signal as an input from the contactor coil of the magnetic contactor connected with the motor and will send the signal as an output to the corresponding contactor coil of the magnetic contactor to switch the appropriate capacitor bank in order to improve the power factor. The experimental results for seven different cases utilized by different combinations of loads, without and with the use of the developed system have been discussed in this paper. So, from the perspective of energy management, we have always a need to improve the power factor of the Load. Due to many industrial control applications, the PLC is used as a power factor controller (PFC).