Microcontroller based automatic fault identification in a distribution system

A delta-star transformer connected to distribution system has been analyzed with the approach of generalized theory of electrical machines and expressions for symmetrical and different unsymmetrical faults are derived. The detailed theoretical analysis shows that magnitude and phase angle of fault current varies depending on nature and types of faults. A microcontroller based continuous monitoring unit is developed to detect and identify types of faults in the transformer connected distribution system. Software executed in microcontroller evaluates nature of a fault based on measured magnitudes and phase angles of voltages and currents under faulty condition. Theoretical analysis and experimental results validate acceptability of the developed unit..