Implementation of Micro Controller Based Electromechanical Over Current Relay for Radial Feeder Protection

Continuous power supply is one of the major concern in modern world and for this purpose protection schemes must be efficient enough to overcome faults with minimum time. This paper presents the design of electromechanical and microcontroller (Arduino) based relay as an educational lab trainer to compare the behavior of both relays in over current protection of radial feeder. The proposed trainer introduces the use of both electromechanical and microcontroller based relays in a single panel in such a way that the system could be switched to either electromechanical or microcontroller based relay setup. It is designed for protection of two sections so that the concept of primary and secondary protection is observed. Microcontroller based relay setup is coded with IDMT characteristics and requires the values of PSM and TMS for the calculation of operational time of relay to clear the fault. This trainer also displays the magnitude of fault current as well as operational time of relay required to clear the fault. The fault is incorporated to the system by the insertion of low resistance path which leads to additional flow of current. Simulations are carried on Proteus and the hardware result shows that microcontroller based relays are fast in operation having less time of operation, more efficient and have very low cost as compared to conventional electromechanical relays. This trainer's idea could be implemented in engineering universities as a compulsory component for electrical power students.