Abstract
This project focused on the construction of 200AMP automatic change over circuit with phase failure indicator and alarming system. The automatic change over circuit with phase failure indicator and alarming is a circuit whose objective is to automatically change over from public power supply to a generator set and vice versa whenever there is power failure. The circuit contains contactors that are used for switching purpose in the circuit. The circuit also contains relays whose contacts were used in the circuit for control purpose. The indicator lamps in the circuit were used to indicate the three phase lines and also when the supply is from P.H.C.N, or from generator sources. This circuit was used in places where power interruption is not needed such as in the hospital for surgical operations, online transfer of money between banks and lots more, and also used in our industries for three phase machines. This automatic change over circuit with phase failure indicator minimizes time wa
CHAPTER ONE
1.0 INTRODUCTION
Electricity plays a major role in economic development of a nation, and that formed the basis of this study, with interests in human, infrastructural and economic development. In most developing and underdeveloped parts of the world, the supply of electricity for industrial, commercial and domestic use is highly unstable. This gave rise to the frequency in the use of alternative sources of power supply to meet up with the energy demands. The introduction of these alternative sources of supply brought forth the challenges of switching smoothly and timely between the main supply and the alternative sources whenever there was a failure on the main sources. There was also the need to reduce drudgery from switching between the two sources on the human side. Therefore, solving these challenges forms the focus of this work. The automatic change-over with phase failure indicator and alarming system, automatically switches over from the man supply to generator set and vice versa when there is a power outage. It equally switches over to the mains supply when power is restored and turns off the generator automatically. The automatic power change over switch is a device that links the load and main supply or the alternative supply together. This enables the use of either the main supply or the alternative sources when there is outage on the main sources. This device which can handle single phase or three phases, maintains constant power supply to the load by automatically activating the generator when there is need. Since the user might not always be in need of the generator, provision has been made to prevent the generator from starting should any outage occur.
Also in the cause of finding solution to switching over to the alternative sources of supply without delay undue wear and tear of the main who effects the change to the alternative sources comes the importance of the research work.
The importance of power supply to our home and industries cannot be over emphasized, but it is worth mentioning that the outage of power supply could bring discomfort in our homes and loss of revenue due to downtime in the industries. Thus, Tony Rudkin, states that the cost and the depreciation associated with breakdown vary from one application to the other, and in some cases, the user has little choice but to ensure that a stand-by unit is available to take over on event of failure of primary system. Also in his book, the author went further to say that the depreciation caused by such instability reduces efficiency of electrical/Electronic gadgets being procured and installed in our homes, hospitals and business premises. There is a justifiable need for a faster and more reliable change-over system in an event of power outage.
1.1 Purpose of the Project
The purpose of this project is to maintain constant power supply to the main circuit that is being supplied by making up for the time lapse or delay that usually accompanies the manual switching from one source to another.