ABSTRACT
This project work deals on the design and construction of an automatic power changeover that will change/transfer control from MAINS to Gen set and can switch ON/OFF the Gen automatically. The system integrates phase selector in MAINS and changeover to Gen. It is designed in several blocks all combined to from one functional unit. A +5v regulated DC power supply unit forms the first block whose output is fed to priority encoder and decoder block. The output of the BCD – Decimal decoder is used to select the phase in priority through a transistor driver stage and electromagnetic relay that activates contactors. The least prioritized phase is the Gen set which contains a circuitry that automatically starts and stops the Gen set. The system is realized with TTL chips market. LEDs and AC panel lamps are used to indicate the status of the system while a manual switch is used to demonstrate the mode of operation of the system.
CHAPTER ONE
INTRODUCTION
Industrial automation and control has contributed immensely to the high rate of the world’s technological growth. Power control and automation is a part of this field which is applied in virtually anywhere electrical power is used, generated or transmitted. Manual power change-over switches have been in existence and in different forms and shapes. 1959, the advent of microelectronics has paved way to modify the manually operated change-over switches. This project deals with the design and construction of automatic change-over switch with indicator. It eliminates the time and energy spent in operating the manual change – over and starting of Gen. Set. It is fully automated. It can be used in residential houses, offices and most importantly, in factories that required constant power supply. It has so many advantages over the existing ones/types.
1.1. BACKGROUND OF THE STUDY
This project work is embarked upon to eliminate nearly every shortcomings associated with the manually operated type to ensuring that it is fully automated.This system is realized in several functional blocks all combined to form one functional system. The first block is a 3-phase MAINS regulated dc power supply unit that powers the overall circuit and acts as the input. The output of thin block is fed into a priority encoder (74147) which selects the most prioritized phase at a time. The third block is a BCD – to – DECIMAL Decoder (7442) used to decode the prioritized phase.