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Design And Construction Of Automatic Change Over Switch With Indicator
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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.
The fourth is the driver stage which comprises of
NPN transistor that energizes the electromagnetic relay which switches
the phase in priority. The Gen set switching section is achieved using
the least prioritized phase. This section switches ON the Gen set when
all the NEPA phases are low, OFF or faulty. Once the Gen set phase is
selected, a switching transistor fires an SCR which conducts large
battering current to the ignition coil of the Gen set. Panel indicators
are used to show the status of the system.
CHAPTER ONE -- [Total Page(s) 2]
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ABSRACT - [ Total Page(s): 1 ]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 ... Continue reading---
