AUTOMATIC PHASE CHANGER
Nov 15, 2014
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.