Auto selection of any aviliable phase

AUTO SELECTION OF ANY AVAILABLE PHASE,IN 3 PHASE SUPPLY SYSTEM

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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 NAND 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 .

contentsIntroductionBlock diagramHardware requirements Power supplyGateOpto isolator RelayRelay driverSchematic diagramWorking of the projectAdvantages ApplicationsConclusion

Block diagram

Hardware requirementsTRANSFORMER (230 – 12 V AC)VOLTAGE REGULATOR (LM 7805)FILTERRELAYULN 2003OPTO ISOLATORAND GATE IC 4081INVERTER IC 4069 LED1N4007 RESISTOR CAPACITOR

Hardware Components description 1. 230 V AC 50 Hz 12V step down transformer

2. Using In4007 as Bridge rectifier

3. Capacitors Filter(470µf) 4. 5v Regulator

5. Relay

6. ULN2003 7. OPTO-ISOLATOR

8. AND GATES IC 4081

8. INVERTER IC 40699. LED

10. RESISTOR

11. Capacitor

12. 3c/0 relay

Power supply

Description of power supply

Description of power supply

The circuit uses standard power supply comprising of a step-down transformer from 230v to 12v and 4 diodes forming a Bridge Rectifier that delivers pulsating dc which is then filtered by an electrolytic capacitor of about 470microf to 100microF. The filtered dc being un regulated IC LM7805 is used to get 5v constant at its pin no 3 irrespective of input dc varying from 9v to 14v.The regulated 5volts dc is further filtered by a small electrolytic capacitor of 10 micro f for any noise so generated by the circuit. One LED is connected of this 5v point in series with a resistor of 330ohms to the ground i.e. negative voltage to indicate 5v power supply availability.

And Gate discription {Ic 4081}

The 4000 Series CMOS range, and contains four independent CMOS AND gates each with two inputs.

Pin Description Pin 7 is the negative supplyPin 14 is the positive supply Pins 1&2, 5&6, 8&9, 12&13 are gate inputs Pins 3, 4, 10, 11 are gate outputs

INVERTER IC 4069

The HCC/HCF4069UB consists of six COS/MOS inverter circuits .This device is intended for all general purpose inverter applications where the medium-power TTL-drive and logic-level-conversion capabilities of circuits such as HCC/HCF4049B Hex Inverter/Buffers are not required.Medium-speed operation- tphl, tplh = 30ns (typ.) A 10v. quiescent current specified to 20v for hcc device .standardized symmetrical output characteristics .5v, 10v, and 15v parametric ratings input current of 100na at 18v and 25°c for hcc device .100% tested for quiescent current .

Opto-isolator Opto coupler is a 6 pin IC. It is a combination of 1 LED and a transistorPin 6 of transistor is not generally used and when light falls on the Base-Emitter junction then it switches and pin5 goes to zero.

RelayA 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 two switch positions and have double throw (changeover) switch contacts as shown in the diagram.

Relay driver uln2003

The ULN2003 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.

WORKINGThree 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 combination of inverter and 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 1st phase load automatically changes over to any available phase in the event of the phase failure.