Presented by Under the esteemed guidance of D.GANGADHAR REDDY, M. Tech. Asst. Prof., EEE Department UNIVERSAL COLLEGE OF ENGINEERING & TECHNOLOGY AUTO SELECTION OF ANY AVAILABLE PHASE IN 3 PHASE SUPPLY SYSTEM CH.AMALA 13NF1A0207 D.RAJESH 14NF5A0207 I.MAHESH 13NF1A0213 N.ANAND KUMAR 13NF1A0227 0

CONTENTS  Abstract  Introduction  Block diagram  Working  Hardware requirements  Advantages & Applications 1

ABSTRACT It is often noticed that interruption in distribution system is about 70% for single phase faults while other two phases are in normal condition. In this system auto selection is achieved by using a set of relays are interconnected in such way that if one of the relay is feeding to the load remains energized always. Under the phase failure condition the corresponding step down transformer secondary delivers zero voltage which is properly rectified to DC and then fed to the logic gates comprising of AND&OR to switch to the next relay that delivers the power to the load. It also has a provision of connecting to an inverter source which delivers uninterrupted power to the load incase all the three phases go to missing. 2

INTRODUCTION  The basic idea for the development of the project is to provide supply to the single phase load if any of the phases, out of the 3 phases misses.  The three transformers are connected to the 3 phases supply It automatically switch to next phase while one phase is misses.  For monitoring the phase shifting we are using AND gate logics.  The relay driver IC to change the load to the next phase through the contacts those are fed from all the three phases.  At final condition it works on inverter. 3

BLOCK DIAGRAM 4

WORKING  Three phase supply are given to three independent transformers connected in together with another transformers from receiving supply, an inverter.  The secondary of the transformers are used to develop DC by half wave rectification and then deriving four number of opto isolators individually.  The DC supply from all the three phases and inverter supply are combined and then fed to the regulator IC 7805 for the circuit operation power.  One quad inverter is used in combination with a quad AND the o/p of which are fed to relay driver IC ULN2003.  The AND develops a logic of the I/p to the relay driver IC logic high on the event of any source failure for the next available supply.  The relays connected drive the load with interlocking logic from the NO/NC contact such that the 1 st phase load automatically changes over to any available phase in the event of the phase failure. 5

HARDWARE REQUIREMENT  Transformer (230 – 12 V AC)  Voltage Regulator(LM 7805)  Capacitive Filter  Relay  Relay Driver ULN 2003  Opto Isolator  AND Gate IC 4081  Inverter IC

HARDWARE COMPONENTS DESCRIPTION V AC,50 Hz ( 12V step down transformer) 2. Using IN4007 as Bridge rectifier 3. Capacitors Filter(470µf ) 4. 5V Regulator 5. Relay 7

6.Relay Drive ULN Opto-Isolator 8. AND Gate IC

9. Inverter IC LED 11. Resistor 9

12. Capacitor 13. 3c/0 relay 10

AND Gate Description (IC 4081) Truth Table 11 A HIGH output (1) results only if both the inputs to the AND gate are HIGH (1). If neither or only one input to the AND gate is HIGH, a LOW output results. AND Gate IC 4081

OPTO - ISOLATOR  Opto coupler is a 6 pin IC. It is a combination of 1 LED and a transistor  Pin 6 of transistor is not generally used and when light falls on the Base-Emitter junction then it switches and pin5 goes to zero. RELAY  A relay is an electrically operated switch.  Current flowing through the coil of the relay creates a magnetic field which attracts a lever and changes the switch contacts.  The coil current can be on or off so relays have to switch positions and have double throw (changeover) switch contacts as shown in the diagram. 12

RELAY DRIVER ULN 2003  The ULN 2003 is a monolithic high voltage and high current Darlington transistor arrays.  It consists of seven NPN Darlington pairs that features high-voltage outputs with common- cathode clamp diode for switching inductive loads.  The collector-current rating of a single Darlington pair is 500mA.  The ULN functions as an inverter.  If the logic at input 1B is high then the output at its corresponding pin 1C will be low. 13

ADVANTAGES  Automatic switching of the load will decrease human errors.  Controller will see that the load is balanced at every instant of time.  The switching time is less because of which the fault duration on the system is very less. APPLICATIONS  Can be used in industries and commercial complexes.  Can be used near distribution transformers to switch the load between the phases automatically.

THANK YOU 14