25-09-2013, 12:54 PM
DESIGN OF AUTOMATIC CHANGE OVER SWITCH WITH GENERATOR CONTROL MECHANISM
DESIGN OF AUTOMATIC CHANGE.pdf (Size: 128.65 KB / Downloads: 214)
ABSTRACT
Power supply in Nigeria and most developing countries of the world is anything but stable.
This has adverse effects on the consumers of the electricity and the equipments that are
operated from the mains sources of electricity supply in these parts of the world. In this paper,
we provide an automatic switching mechanism that transfers the consumer loads to a power
source from a generator in the case of power failure in the mains supply. It automatically
detects when power has been restored to the mains supply and returns the loads to this source
while turning off the power from the generator set. This mechanism has been tested and we
recorded a great result. It thus holds an important key in the provision of a continuous power
supply through a near seamless switching between the mains supply and an alternative standby
source like the generator set.
INTRODUCTION
Electricity (energy), which plays a major role in economic development of a nation, forms 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 gives rise to the frequent use of alternative sources of power supply to
meet up with the energy demands. The introduction of these alternative sources of supply brings forth
the challenge of switching smoothly and timely between the mains supply and the alternative sources
whenever there is a failure on the mains source. There is also the need to reduce drudgery from
switching between the two sources on the human side. Solving these challenges forms the focus of this
work. The Automatic Change-over switch, automatically switches over to the alternative source of
power supply (generator) 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 mains supply or the alternative supply together. This enables
the use of either the mains supply or an alternative source when there is outage on the mains source.
This can either come in with three phase or single phase. This device 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 an outage occur.
THE STAND-BY POWER UNIT (GENERATOR)
The stand-by generator set is commonly used to supply emergency power to most of the power
consumers where the mains supply is unstable. For best performance of the system, we must put into
consideration the type of generator, engine type, its cooling system and fuel, the load capacity and the
operating environment. Whatever cooling system is used to cool the generator, it is recommended that
the heated air be channeled outside through an exhaust pipe while provision should be made to bring
in fresh air so that the generating room, where the generator is installed, can be kept from becoming
excessively hot, as this might cause damage to the engine of the generating set. Furthermore, the
lubrication of the set is much important; the recommended lubricant should be used in order to
maintain smooth and prolonged life span of the set by reducing wear and tear of the engine and other
parts due to friction. Finally, it is important to determine the correct rating of the mechanical engine to
drive a given generator so that it has the minimum capacity necessary to supply the selected load.
DESIGN CONSIDERATION
In designing and construction of this change-over switch, a generator with the capacity of 12KVA was
used and its rating determines the ratings of the components and circuit elements to be used. It does
not function with a faulty generating set and the generator must have a manual starter and engine
stopper which is a sine quo non to the function of the automatic change-over. This automatic change-
over switch is designed and constructed with the aim of achieving the following automatic actions.
CONCLUSION
Automatic change over switch with generator starting/shut down facility has been designed to help
man reduce the stress and loss of time associated with the starting and shutting down of the alternative
sources of supply (generator). It is worthy to note that this project is subject to scrutiny and further
development. I recommend that for future development an overload protection system be included. I
also recommend this project to the entire field where electricity is highly needed and even to the small
and medium entrepreneur that the automatic change over switch with generator starting/shut down
facility will help them. To the government, I recommend they encourage the mass production of this
project.