The project aims at the design and the construction of a laboratory replica for a commercial numerical over current relay using microcontroller and micro CT. It will acquire, sample and covert into digital form the analog current signals from a power system in real time. Then it simulates the working principles of a conventional electromechanical over current relay in through a numerical (mathematical) model. Appropriate equations and algorithm have been used. When a current in a part of a power system exceeds a pre-set value either due to a fault or a large overload the relay will isolate the part through sending trip signal to a circuit breaker. In the developed laboratory model, the system is assembled by a lamp board and the circuit breaker is simulated by a hardware solid state (MOSFET) switch. The constructed relay has been tested extensively for various values of load current and two different tripping characteristics (Inverse Definite Minimum Time: IDMT and Definite Time Lag: DTL) have been verified. The project is expected to help students acquire skills in digital logic circuits design and implementation, and applying it in a power system for isolating the faulty part. As commercial numerical relay is expensive, so we have developed for lab demonstration a prototype using cheap and off-the-shelf components to show the working procedures of a numerical over current relay in a power system. The project will also help students develop hands-on skill on numerical relay and enrich their knowledge on the working principle of a relay-breaker combination circuit.
This thesis report is submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Electrical and Electronic Engineering, 2015.
Cataloged from PDF version of thesis report.
Includes bibliographical references (page 37).
Department:
Department of Electrical and Electronic Engineering, BRAC University
