SUBMITTED BY
K.MADHU KIRAN
SATHISH.BOLLI

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ABSTRACT
Power instability in developing countries creates the need for automation of phase selection or alternative sources of power to back-up the utility supply. Most industrial and commercial applications are dependent on power supply and if the process of change over is manual ,not only considerable time is wasted but also the device or machine may get damaged from human error during the change over connections, incurring massive losses.
Here is a digital phase selector that can be installed in residential and office premises where single-phase equipment is used. When any of the mains phase lines fails, it automatically selects the available phase line (out of three phase lines or backup lines)
INTRODUCTION
1.1 Importance of electrical energy:
Electrical energy is the only form of energy which is easily available. The main advantage of this form of energy is we can easily convert any form of energy into electrical energy and vice-versa.
The usage of this electrical energy is increasing day-by-day. The best example is in India in 1950 the generation of electrical energy was 150MW and now the generation has been increased to a very large extent. To meet this load demand many power stations were build across the country.
1.2 Objective of the project:
The load demand is increasing day by day and we are able to generate power to the requirement and we are able to transmit power to the load centers with maximum efficiency and minimum losses.
The major problem a consumer facing now a days is power interruption. Due to this power interruption lot of damage is caused in terms of money and sometimes to life. Due to this power interruption lot of time is wasted.
But the major problem of power interruption is in distribution system and more over 70% faults are single phase faults, in this case power is available in other two phases.
But all the domestic loads are connected to single phase supply and if the fault occurs, even then power is available in other phases we can not utilize that power. If we want to utilize that power manual operation is required which results in fire accidents and also not reliable.
For this we need automatic switching from one phase to other automatically which is made possible by this “DIGITAL PHASE SELECTOR”.
1.3 Need For Automation:
In order to change from one phase to other manual operation is not possible as we are dealing with 3-Φ 415V supply which causes fire accidents during change over and leads to 3-Φ faults which is dangerous to electrical equipment. And more over manual changing is not possible at every time as identifying the phase of power interruption is difficult.
To avoid all this we need automation which is done by “DIGITAL PHASE SELECTOR”. Here we do not need any manual work and we are no way concerned with the phase of fault as the digital phase selector automatically switches to the phase where the power is available.
1.4 High frequency switching technology:
High frequency switching technology is the latest technique which uses infra red radiation for switching purpose.
For this we use IC MCT2E opto coupler. The main advantage of this technique is, mechanical switching is reliable for single phase supply, but for three phase supply sudden mechanical switching causes arching. This can be avoided by using this technology as it uses infrared radiation to trigger transistors, MOSFETS, IGBTs etc...
1.5 INVERTER:
The digital phase selector has capability to take power from inverter also. Even if the power failure is in all the three phases the availability of inverter makes this more reliable. And more over this inverter need not me manually operated just by connecting it to digital phase selector it can be operated. During normal conditions the inverter is charged i.e.., the battery is charged and during fault conditions it gives back up.
CHAPTER-2
DIGITAL PHASE SELECTOR
2.1 INTRODUCTION:
Power instability in developing countries creates the need for automation of phase selection or alternative sources of power to back-up the utility supply. Most industrial and commercial applications are dependent on power supply and if the process of change over is manual ,not only considerable time is wasted but also the device or machine may get damaged from human error during the change over connections, incurring massive losses.
Here is a digital phase selector that can be installed in residential and office premises where single-phase equipment is used. When any of the mains phase lines fails, it automatically selects the available phase line (out of three phase lines or backup lines).
2.2 BLOCK DIAGRAM OF DIGITAL PHASE SELECTOR:
The figure below is the block diagram of digital phase selector. This has mainly four blocks they are
• Phase sensing and switching block.
• Control logic block.
• Relay driver section.
• Power supply unit.
All the four blocks are inter connected to each other and are independent of load connected to it. All the blocks get signals simultaneously and we can not decide which block is operating first physically.