AUTOMATIC PHASE CHANGER

Aim:The main aim of this system is to provide

uninterruptable power supply for single phase loads even in the failure of one or two phases in a three phase system.

Introduction:

If any one or two phases in a 3-phase supply interrupted/goes low and you want equipment to work on normal voltages then this circuit will give solution .

This system is designed to monitor the presence of supply to the three phases and to display condition of each phase on an LCD.

Hardware Requirements:Power Supply 5V.Microcontroller AT89C51.Step Down Transformers.Comparators.Switching Devices.Other Hardware Components

Power supply to all sections

Step down

T/F

Bridge Rectifier

Filter Circuit Regulator

Block Diagram of power supply:

D13

R15

P U S H P A K T E C H N O L O G I E S

D16C11

D15

V C CU531

2

V O U TV I NG

ND

C12

POW ER SUPPL Y<R e v C o d e >

3 P HAS E DRIV E S AFTY S YS TEM

C u s t o m

2 2S a t u rd a y , M a rc h 1 3 , 2 0 1 0

Tit le

S ize D o c u m e n t N u m b e r R e v

D a t e : S h e e t o f

PST V IN

D14 C13

GND IN

LED1

Relay Relay Relay

Output Output Output

Transformer1 (R-phase) Transformer2 (Y-phase) Transformer3 (B-phase)

Rectifier & Filter circuit

Rectifier & Filter circuit

Rectifier & Filter circuit

Comparator Comparator Comparator

Relay Relay Relay

Output Output Output

Transformer1 (R-phase) Transformer2 (Y-phase) Transformer3 (B-phase)

Rectifier & Filter circuit

Rectifier & Filter circuit

Rectifier & Filter circuit

Comparator Comparator Comparator

Transformer1 (R-phase) Transformer2 (Y-phase) Transformer3 (B-phase)

Rectifier & Filter circuit

Rectifier & Filter circuit

Rectifier & Filter circuit

Comparator Comparator Comparator

Sensing Module:

Working:It monitors the presence of three phases and to

display condition of each phase on an LCD. It monitors the voltage condition of each phase. If the

voltage level of any phase is under the rated / specified voltage rating, immediately this phase is connected to a healthy phase thus, supplies to the load.

The phase voltage is stepped down 230 V to 12 V,300 mA.

These 12v is rectified through a rectifier circuit and filtered through a capacitor.

The voltage at inverting terminal of Op-Amp is taken from voltage divider circuit of resistor R1 and preset resistor VR1, at non inverting terminal 5.1 V will be set through zener diode.

When the line voltage is below 200 V, the voltage at the inverting terminal is less than the voltage at the non-inverting terminal. Thus the output of the operational amplifier now goes low.

As a result transistor conducts and output is fed to microcontroller and output microcontroller is fed to electromagnetic relay through a transistor.

Consequently, the AC supply is shifted to absence phase and electrical appliances turn ON.

Thus the appliances are protected against under-voltage.

Circuit Diagram:

R8R5

GND IN

P H A S E I N 2

R18

L3

-

+ U23

26

7 14 5

D6

R9

Q4

S W 31 2

R1

V C C

R2

R L 3

C7D11

R17

R12

-

+ U33

26

7 14 5

D7

C2

R11

R7

S W 11 2

R6

V C C

V C C

S W 41 2

P H A S E I N 1

R10

Q1

LS 1

35

412

C1

Q2

R L 1Q5

P H 1

P H A S E I N 3

PST V IN

R4

P H 2

D8

V C C

R3

T2

156

48

C6D9

LS 2

35

412

P U S H P A K T E C H N O L O G I E S

C4

Q6

Q3

D3D2

V C C

D1

L2

V C C

V C C

D10

D4

LS 3

35

412

C3

-

+ U13

26

7 14 5

C5D12

L1

D5

V C C

SENSING M ODUL E <R e v C o d e >

3 P HAS E DRIV E S AFTY S YS TEM

A 4

1 2S a t u rd a y , M a rc h 1 3 , 2 0 1 0

Tit le

S ize D o c u m e n t N u m b e r R e v

D a t e : S h e e t o f

V C C

R L 2

S W 21 2

N E U TR A L

R16

T3

156

48

P H 3

T1

156

48

Sensing Module

D21

L E D 2

D20

R L 3

D19

S W 5O K

D17

C ONT ROL M ODUL E <R e v C o d e >

3 P HAS E DRIV E S AFTY S YS TEM

C u s t o m

2 2Tu e s d a y , J u ly 1 9 , 2 0 1 1

Tit le

S ize D o c u m e n t N u m b e r R e v

D a t e : S h e e t o f

R L 1

BZ1

P O T

R13

3

1

2

V C C

A P P L I A N C E

P U S H P A K T E C H N O L O G I E S

Y1

U4AT89S 52

29

3 0

40

20

31

191 8

9

3 93 83 73 63 53 43 33 2

12345678

2 12 22 32 42 52 62 72 8

1 01 11 21 31 41 51 61 7

PSEN

A L E

VCC

GN

D

EA

X1X2

R S T

P 0 . 0 / A D 0P 0 . 1 / A D 1P 0 . 2 / A D 2P 0 . 3 / A D 3P 0 . 4 / A D 4P 0 . 5 / A D 5P 0 . 6 / A D 6P 0 . 7 / A D 7

P 1 . 0 / T2P 1 . 1 / T2 E XP 1 . 2P 1 . 3P 1 . 4P 1 . 5 / M O S IP 1 . 6 / M I S OP 1 . 7 / S C K

P 2 . 0 / A 8P 2 . 1 / A 9

P 2 . 2 / A 1 0P 2 . 3 / A 1 1P 2 . 4 / A 1 2P 2 . 5 / A 1 3P 2 . 6 / A 1 4P 2 . 7 / A 1 5

P 3 . 0 / R XDP 3 . 1 / TXDP 3 . 2 / I N T0P 3 . 3 / I N T1P 3 . 4 / T0P 3 . 5 / T1P 3 . 6 / W RP 3 . 7 / R D

C8

L E D 1

P H 3

D18

P H 2

R22

C10

L E D 3

R21

V C C

O K

R19

V C C

J1

12345678910111213141516

P H 1

R20V C C

L E D 3

B U Z Z E R

R23

A P P L I A N C EB U Z Z E R

R14

V C C

R L 2

L E D 2

C9

L E D 1

Control Module

Programming modules:LCD module.Phase sensing Module.Control Module.

Advantages:Revenue Collection EfficiencyTransparency in distributionBetter customer ServiceZero man-made errorsContinuous running of single phase loads

Applications:Small and Medium Scale IndustriesResidential Apartments. Offices.ATM.

REFERENCES1. Electron Devices and Circuits by P. Ramesh

Babu, T.R. Ganesh Babu,Scitech Publications(INDIA) Pvt. Ltd. Chennai.

2.http://www.circuitstoday.com/wpcontent/uploads/ 2009/09/741ic-inverting- comparator-circuit.jpg

3.IEEE Standard , Standard Inverse-Time Characteristic Equations for Overcurrent Relays.

4. http://www.en.wikipedia.org/wiki/tansformer#mw-head.