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AUTOMATIC PHASE CHANGER
IN 3 PHASE SUPPLY
A Project Report
Submitted in partial fulfillment for the award of the degree of
BACHELOR OF TECHNOLOGY
In
Electrical & Electronics Engineering
(IV th SEMESTER)
2014 Batch
UNIVERSITY OF CALICUT
By
ADARSH K SASI (EKAOEEE001)
AMALJO JOJU E (EKAOEEE005)
ATHUL KAMAL (EKAOEEE012)
LINSON PAULSON (EKAOEEE041)
EDUCATION IS DEDICATION
SAHRDAYA COLLEGE OF ENGINEERING AND TECHNOLOGY
KODAKARA, THRISSUR
NOVEMBER 2015
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DEPARTMENT OF ELECTRICAL& ELECTRONICS ENGG.
SAHRDAYA COLLEGE OF ENGINEERING AND TECHNOLOGY
KODAKARA, THRISSUR
EDUCATION IS DEDICATION
BONAFIDE CERTIFICATE
This is to certify that the project report titled “AUTOMATIC PHASE CHANGER
IN 3 PHASE SUPPLY ” is the bonafide work of “ADARSH K SASI
(EKAOEEE001),AMALJO JOJU E(EKAOEEE005),ATHUL KAMAL
(EKAOEEE012),LINSON PAULSON (EKAOEEE041)” during our IV semester
in partial fulfillment of the requirements of the University of Calicut, under our
supervision.
PROJECT GUIDE COORDINATOR HEAD OF THE DEPARTMENT
Mrs. Sreelakshmi Suresh Mr. Madhujith Mrs. Jitha Joseph
Kodakara
15-10-2015
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ACKNOWLEDGEMENT
We hereby acknowledge our sincere gratitude to all persons who have helped us
in completing our project. We are highly grateful to Mr. Madhujith who happens to be
our project coordinator for his constant support and encouragement.
We are greatly indebted to our project guide for her valuable guidance in this
endeavor.
We are thankful to all the nonteaching staff for providing sufficient lab facilities
and our classmates for their encouragement and cooperation without which our project
would not have been possible.
Above all, we thank Lord Almighty for providing us with the courage and confidence to
take up this project.
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ABSTRACT
In most companies, Industrial, commercial and even domestic are dependent on
public power supply which have erratic supply such as phase failure, phase imbalances
or total power failure due to one or more technical problem in power generation,
transmission or distribution. Hence, there is need for automation of phase change during
phase failure or total power failure in order to safe guard consumer appliances from
epileptic power supply.
In most cases, many manufacturing companies, be it domestic or industrial,
which employ single phase equipment for its operation sometimes experience challenges
during unbalance voltages, overloads and under-voltages, in power supply, much time
would be required in the process of manual change over. This means that time and the
process needed for the phase change may cause serious damages to machines and even
the products, hence, there is need for automatic phase switching system.
In a case where a single phase public utility prepaid meter is operated with a
single phase power supply unit and there is phase failure from the public utility power
supply, the prepaid meter will stop reading. At this point if the phase is not manually
changed, the single phase prepaid meter will stop reading. That is to say someone needs
to be present always to make the changes at any point in time. But to overcome these
protocols, automatic systems need to be used.
The system is basically designed to select between the three phases at reasonable
speed, and also address phase imbalances with respect to loads. This means automatic
switching between the three phases and output only singlephase. In other words, the
switching consideration demonstrates the real and practical situation for mainly
domestic, moderate industrial advanced needs.
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CONTENTS
ACKNOWLEDGEMENT..........................................................................................3
ABSTRACT...............................................................................................................4
1. INTRODUCTION................................................................................6
2. BLOCK DIAGRAM............................................................................8
3. HARDWARE DESCRIPTION...........................................................9
3.1 CIRCUIT DIAGRAM...........................................................10
3.2 COMPONENTS AND THEIR DESCRIPTION..................13
3.3 COST ANALYSIS................................................................24
4. CIRCUIT DESIGN............................................................................25
4.1 DESIGN OF ASTABLEMULTIVIBRATOR....................26
5. WORKING..........................................................................................28
6. CONCLUSION...................................................................................30
6.1FEATURES.............................................................................30
6.2 LIMITATIONS......................................................................31
ANNEXURES..........................................................................................................32
BIBLIOGRAPHY....................................................................................................63
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1. 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 circuit will automatically
switch to next phase while one phase is misses.Design and construction of an automatic
change over switch which would solve the problem of manpower and electric hazard.
In night time or during lightning we have not taken care of this system.
In most cases, many manufacturing companies, be it domestic or industrial,
which employ single phase equipment for its operation sometimes experience challenges
during unbalance voltages, overloads and under-voltages, in power supply, much time
would be required in the process of manual change over. This means that time and the
process needed for the phase change may cause serious damages to machines and even
the products, hence, there is need for automatic phase switching system.
In a case where a single phase public utility prepaid meter is operated with a
single phase power supply unit and there is phase failure from the public utility power
supply, the prepaid meter will stop reading. At this point if the phase is not manually
changed, the single phase prepaid meter will stop reading. That is to say someone needs
to be present always to make the changes at any point in time. But to overcome these
protocols, automatic systems need to be used.
Phase Changer
Fig. 1.1 shows the basic circuit of a phase changer. In the supply section we are
connecting the three phases from the transmission line (R,Y,B). There are three switches
available in the system between each phases. There is an option to feed the loads in a
phase by another phase. If any one or two phase is missing we can feed the loads in that
corresponding phase by any of the available phase. In Manuel system the rotatable
switch
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is rotating and make it short. So there is someone required to do it. But in some
conditions it may difficult. So the automatic phase changer will do the work it’s self.
There is a system to check whether the phase is available or not. According to the
conditions it will automatically switches between the phases.
Fig 1.1
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2. BLOCK DIAGRAM
Fig 2.1
Figure 2.1 shows the block diagram representation of the Automatic Phase
changer. There is transformer block consist of 3 transformers in order to step-down the
230V in each phase into 12V. Using rectification block we are rectifying each phase
voltage into DC voltages. Optocoupler is an isolator which is used to isolate the digital
circuit from its left side circuit. There is an anti-shorting system to avoid the shorting
conditions by using delay circuit. There is a 3-contact relay through which the
connection is given to the single phase loads. The phase changing relay system is used to
changing the phases according to the instructions get from the digital circuit.
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3.HARDWARE DESCRIPTION
3.1 CIRCUIT DIAGRAM
Fig. 3.1 circuit diagram
Figure 3.1 shows the circuit diagram of the Automatic Phase changer.
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3.1.1 PCB LAYOUT
A Printed Circuit Board mechanically supports and electrically connects electronic
components using conductive tracks, pads and other features etched from copper sheets
laminated onto a non-conductive substrate. PCBs can be single sided (one copper layer),
double sides (two copper layers) or multi-layer. Conductors on different layers are
connected with plated-through holes called vias. Advanced PCBs may contain
components - capacitors, resistors or active devices - embedded in the substrate.
Printed circuit boards are used in all but the simplest electronic products. Alternatives to
PCBs include wire wrap and point-to-point construction. PCBs require the additional
design effort to lay out the circuit but manufacturing and assembly can be automated.
Manufacturing circuits with PCBs is cheaper and faster than with other wiring methods
as component are mounted and wired with one single part. Furthermore, operator wiring
errors are eliminated.
PCB DESIGN PROCEDURE
Prepare the PCB layout of the circuit using gEDA software
Take the print out of PCB layout
Cut the copper clad sheet in proper dimension and wash it.
Trace the PCB layout on the copper clad sheet
Prepare the ferric chloride solution.
Dip the PCB in to ferric chloride solution for etching non printed surfaces.
Wash cleanly with detergents.
Drill the holes in necessary positions.
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3.2 COMPONENTS AND THEIR DESCRIPTIONS
Components used:
Semiconductors
IC1: NE555 TIMER
IC2: 74LS04 NOT GATE
IC3: 74LS11 3 i/p AND GATE
IC4: HCF4075B 3 i/p OR GATE
IC5: ULN2003A RELAY DRIVER IC
IC6: MCT2E OPTOCOUPLER
T1: BC557 PNP transistor
T2: BC547 NPN transistor
D1-D16: 1N4007 Rectifier Diode
LED1: RED LED
LED2: YELLOW LED
LED3: GREEN LED
Resistors (all ¼watt,+/- 5% carbon)
VR1: 15 kilo ohm preset
Capacitors
1000 microfarad, 25V electrolytic
470 microfarad, 25V electrolytic
100 microfarad, 25V electrolytic
10 microfarad, 25V electrolytic
0.01 microfarad ceramic disc
Miscellaneous
230V AC primary to 12V, 500mA secondary transformer
RELAY 1 - 5 : 12V, 200 ohm, 1c/o relay
RELAY 6 : 12V, 250 ohm, 4c/o 5 A relay
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3.2.1 555 Timer IC
Fig. 3.2.1(a) Internal diagram of IC 555 fig 3.2.1(b)
Figure 3.2(a) shows the internal diagram of the NE555 timer IC.The 555 timer
IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and
oscillator applications. The 555 can be used to provide time delays, as an oscillator, and
as a flip-flop element. Derivatives provide up to four timing circuits in one package.
Introduced in 1972 by Signetics, the 555 is still in widespread use, thanks to its ease of
use, low price, and good stability. It is now made by many companies in the original
bipolar and also in low-power CMOS types. As of 2003, it was estimated that 1 billion
units are manufactured every year.
Design
The IC was designed in 1971 by Hans Camenzind under contract to Signetics, which
was later acquired by Philips.
Depending on the manufacturer, the standard 555 package includes 25 transistors, 2
diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package
(DIP-8). Variants available include the 556 (a 14-pin DIP combining two 555s on one
chip), and the two 558 & 559s (both a 16-pin DIP combining four slightly modified 555s
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with DIS & THR connected internally, and TR is falling edge sensitive instead of level
sensitive).
The NE555 parts were commercial temperature range, 0 °C to +70 °C, and the SE555
part number designated the military temperature range, −55 °C to +125 °C. These were
available in both high-reliability metal can (T package) and inexpensive epoxy plastic (V
package) packages. Thus the full part numbers were NE555V, NE555T, SE555V, and
SE555T. It has been hypothesized that the 555 got its name from the three 5 kΩ resistors
used within, but Hans Camenzind has stated that the number was arbitrary.
Low-power versions of the 555 are also available, such as the 7555 and CMOS TLC555.
The 7555 is designed to cause less supply noise than the classic 555 and the
manufacturer claims that it usually does not require a "control" capacitor and in many
cases does not require a decoupling capacitor on the power supply. Such a practice
should nevertheless be avoided, because noise produced by the timer or variation in
power supply voltage might interfere with other parts of a circuit or influence its
threshold voltages. Figure 3.3 shows the pin diagram of NE555 timer IC and table 3.1
gives the pin description.
Fig. 3.3 pin diagram
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Pin Name Purpose
1 GND Ground reference voltage, low level (0 V)
2 TRIG
The OUT pin goes high and a timing interval starts when this input falls
below 1/2 of CTRL voltage (which is typically 1/3 of VCC, when CTRL is
open).
3 OUT This output is driven to approximately 1.7V below +VCC or GND.
4 RESET
A timing interval may be reset by driving this input to GND, but the timing
does not begin again until RESET rises above approximately 0.7 volts.
Overrides TRIG which overrides THR.
5 CTRL
Provides "control" access to the internal voltage divider (by default, 2/3
VCC).
6 THR
The timing (OUT high) interval ends when the voltage at THR is greater
than that at CTRL.
7 DIS
Open collector output which may discharge a capacitor between intervals.
In phase with output.
8 VCC
Positive supply voltage, which is usually between 3 and 15 V depending on
the variation.
Table 3.1
Modes of Operation
The 555 has three operating modes:
Monostable mode: In this mode, the 555 functions as a "one-shot" pulse
generator. Applications include timers, missing pulse detection, bouncefree
switches, touch switches, frequency divider, capacitance measurement, pulse-
width modulation (PWM) and so on.
Astable (free-running) mode: The 555 can operate as an oscillator. Uses include
LED and lamp flashers, pulse generation, logic clocks, tone generation, security
alarms, pulse position modulation and so on. The 555 can be used as a simple
ADC, converting an analog value to a pulse length. Eg: selecting a thermistor as
timing resistor allows the use of the 555 in a temperature sensor: the period of
the output pulse is determined by the temperature. The use of a microprocessor
based circuit can then convert the pulse period to temperature, linearize it and
even provide calibration means.
Bistable mode or Schmitt trigger: The 555 can operate as a flip-flop, if the DIS
pin is not connected and no capacitor is used. Uses include bounce-free latched
switches.
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3.2.2 74LS04 NOT GATE
Fig 3.2.2(a) Fig 3.2.2(b)
This device contains six independent gates each of whichperforms the logic INVERT
function. It is used in the circuit to produce R’, Y’ and B’.Figure 3.2.2(a) shows the
internal diagram of the 74LS04. An inverter circuit outputs a voltage representing the
opposite logic-level to its input. Its main function is to invert the input signal applied. If
the applied input is low then the output becomes high and vice versa.The hex inverter is
an integrated circuit that contains six (hexa-) inverters. For example, the 7404 TTL chip
which has 14 pins and the 4049 CMOS chip which has 16 pins, 2 of which are used for
power/referencing, and 12 of which are used by the inputs and outputs of the six
inverters (the 4049 has 2 pins with no connection)NOT gates are simply inverters. They
simply invert the input logic for the output. Here we are going to use 74LS04 IC for
demonstration. This IC has 6 NOT gates in it.
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3.2.3 74LS11 AND GATE IC
Fig 3.2.3(a) Fig 3.2.3(b)
This IC consists of 3 independent AND gates. A Logic AND Gate is a type of digital
logic gate that has an output which is normally at logic level “0” and only goes “HIGH”
to a logic level “1” when ALL of its inputs are at logic level “1”. The output state of a
“Logic AND Gate” only returns “LOW” again when ANY of its inputs are at a logic
level “0”. In other words for a logic AND gate, any LOW input will give a LOW output.
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3.2.4 HCF4075B OR GATE IC
Fig 3.2.4(a) Fig 3.2.4(b)
The HCF4075B is a monolithic integrated circuit fabricated in Metal Oxide
Semiconductor technology available in DIP and SOP packages. The HCF4075B
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TRIPLE 3 INPUT OR GATE provides the system designer with direct implementation
of the positive logic OR functions and supplements the existing family of CMOS gates.
3.2.5 MCT2e OPTOCOUPLERS IC
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Opto-isolators or Opto-couplers, are made up of a light emitting device, and a light
sensitive device, all wrapped up in one package, but with no electrical connection
between the two, just a beam of light. The standard opt coupler circuits design uses a
LED shining on a phototransistor-usually it is an npn transistor and not pnp. The signal
is applied to the LED, which then shines on the transistor in the IC. The MCT2E series
of opto-coupler devices each consist of gallium arsenide infrared LED and a silicon
NPN phototransistor. They are packaged in a 6-pin DIP package and available in wide-
lead spacing. 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.
3.2.6 ULN2003A IC
Fig 3.2.6(a) Fig 3.2.6(b)
Ideally suited for interfacing between low-level logic circuitry and multiple peripheral
power loads, the Series ULN20xxA/L high-voltage, high-current Darlington arrays
feature continuous load current ratings to 500 mA for each of the seven drivers. At an
appropriate duty cycle depending on ambient temperature and number of drivers turned
ON simultaneously, typical power loads totalling over 230 W (350 mA x 7,95 V) can be
controlled. Typical loads include relays, solenoids, stepping motors, magnetic print
hammers, multiplexed LED and incandescent displays, and heaters. All devices feature
open-collector outputs with integral clamp diodes.
The ULN2003A/L and ULN2023A/L have series input resistors selected for operation
directly with 5 V TTL or CMOS. These devices will handle numerous interface needs
— particularly those beyond the capabilities of standard logic buffers. The
ULN2004A/L and ULN2024A/L have series input resistors for operation directly from 6
to 15 V CMOS or PMOS logic outputs. The ULN2003A/L and ULN2004A/L are the
standard Darlington arrays. The outputs are capable of sinking 500 mA and will
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withstand at least 50 V in the OFF state. Outputs may be paralleled for higher load
current capability. The ULN2023A/L and ULN2024A/L will withstand 95 V in the OFF
state.
3.2.7 12V 250 OHM 4C/O RELAY
Fig 3.2.7(a) Fig 3.2.7(b)
Figure 3.2.7 shows a 12V 4 C/O relay. A relay is an electrically operated switch.
Many relays use an electromagnet to mechanically operate a switch, but other operating
principles are also used, such as solid-state relays. Relays are used where it is necessary
to control a circuit by a low-power signal (with complete electrical isolation between
control and controlled circuits), or where several circuits must be controlled by one
signal. The first relays were used in long distance telegraph circuits as amplifiers: they
repeated the signal coming in from one circuit and re-transmitted it on another circuit.
Relays were used extensively in telephone exchanges and early computers to perform
logical operations.
A type of relay that can handle the high power required to directly control an
electric motor or other loads is called a contactor. Solid-state relays control power
circuits with no moving parts, instead using a semiconductor device to perform
switching. Relays with calibrated operating characteristics and sometimes multiple
operating coils are used to protect electrical circuits from overload or faults; in modern
electric power systems these functions are performed by digital instruments still called
"protective relays".
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3.2.8 230V AC PRIMARY TO 12V, 500mA SECONDARY TRANSFORMER
Fig 3.2.8
Figure 3.2.8 shows a 230V AC primary to 12V, 500mA secondary transformer.
Three single phase transformers are used to step down the three phase supply separately.
Phases R, Y and B are stepped down by transformers X1,X2and X3 to deliver the
secondary output of 12V at 500 mA.
3.2.9 BC547 NPN TRANSISTOR
Fig 3.2.9
Figure 3.2.9 shows a BC547 NPN transistor. BC547 is an NPN bi-polar junction
transistor. A transistor, stands for transfer of resistance, is commonly used to amplify
current. A small current at its base controls a larger current at collector & emitter
terminals.
BC547 is mainly used for amplification and switching purposes. It has a maximum
current gain of 800. Its equivalent transistors are BC548 and BC549.
The transistor terminals require a fixed DC voltage to operate in the desired region of its
characteristic curves. This is known as the biasing. For amplification applications, the
transistor is biased such that it is partly on for all input conditions. The input signal at
base is amplified and taken at the emitter.
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3.3 COST ANALYSIS
The cost analysis of the components are shown in the table 3.3
COMPONENT QUANTITY COST
NE555 TIMER 3 30.00
IC 74LS04 1 10.00
IC 74LS11 3 2 20.00
IC HCF4075B 1 14.00
IC ULN2003A 1 12.00
IC MCT2E 3 36.00
DIODES 24 12.00
TRANSISTORS 3 9.00
RESISTORS 15 7.00
CAPACITORS 7 20.00
LEDS 10 10.00
PRESET 3 30.00
TRANSFORMERS 4 320.00
RELAYS 6 280.00
JUMPER WIRES 10 50.00
CONNECTING WIRES 100.00
Table 3.3
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4) DESIGN
4.1 DESIGN OFANTY SHORTING SYSTEM:
We have the relation for the pulse width of mono stable multi vibrator using IC 555 as,
tp = R* C* ln (3)
Let C= 100µF.
For tp= 1.5 s,
R = tp/(C* ln(3) ) = 1.5s / (100µF * ln(3) )
R = 1.5/(100*10-6*ln(3))
R = 13653.58 Ω = 13.65 KΩ (Using 15KΩ preset)
4.2 DESIGN OF LOGIC CIRCUIT
Design of this digital circuit is done using various steps of k map. By using k map
we found the digital logic high and low in order to operate our phase changer relay
combinations automatically
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5. WORKING
In case of 3 phase connections, if any phase cut off
the supply, we have to manually connect the missing phase to any available phase.
Usually we are using 3 phase supplies in buildings including offices, houses, industrial
buildings ...etc. where heavy duty is required. We cannot operate any devices if in case
all the three phases in 3 phase supply is missing.
Initially an external DC source of 18V is used for the supply and later supply is provided
from the load side for the section having three transformers with rectifier blocks and
optocoupler which is used to check whether the phase is available or not. Here
optocoupler acts as switch which acts at different voltage levels; it contains an infrared
LED on input side and a photo detector on the outside side. The left source voltage and
the series resistors set up a current through the LED. Then the light from LED falls on
the photodiode which sets up a common reverse current in the output circuit. When the
input voltage is varied the amount of light fluctuates, this means that output voltage
varies in step with input voltage.
The external dc supply of 18V is dividing into 2 supplies using the Regulator IC. By
using a regulator IC, we are dividing this external supply to 5V and 15V. Where this
15V supply is used for the anti-shorting delay system. This system stops when the
missing phase arrives or it delays the arrival of the missing phase in order to avoid the
shorting of 2 phases due to mechanical time lag of the circuit and the relay. The other
5V supply is used for power up the digital circuit
Digital Circuit
For a 3 phase connection there are 8 combinations of RYB supplies with 0s and 1s,
ranging from 000 to 111.Except in case of 000 we can feed the missing phase using the
available phase. The conditions for missing any one of the phase are 110,011,101 and in
all of these conditions the phase changing relay system is energized. Similarly two
phases missing conditions are denoted by 100,010,001 and here both relays are
energized. In all the cases i.e. 001 to 111, 3 contact relays are energized.
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Relays are electrically operated switches. It consist iron core surrounded by a control
coil. When current starts flowing through control coil the electromagnets starts
energizing and thus intensifies the magnetic field. Since relays are mechanical devices
which are operated on the basis of electromagnetic induction there will be some lagging
in ON/OFF conditions. So during phase sharing conditions the presence of missing
phase leads to the shorting of the two phases which can lead to serious errors and
damages. To take care of this condition an anti-shorting delay system is introduced
which brings the 3phase supply to phase changing portion, thereby missing phase
approaches only after the degeneration of phase changing relay and anti-shorting relay
will pass the missing phase. Anti-shorting relay system is controlled by means of a 555
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CONCLUSION
In three phase application if low voltage is available in any one
phase, and you want your equipment to work on normal voltage, this automatic phase
changer will solve your problem. This device is more reliable, is of less cost and
maintenance free. Automatic phase changer finds wide application in modem world.
During earlier days, if there is a power failure in any one of three phases, we have to
manually switch to the available phase. By implementing automatic phase changer it
automatically shifts to the phase where correct voltage is available. It can be used in
residences, small offices, buildings etc.
Features:
For low- to high-power three-phase motors.
Reduced starting current
Six connection cables
Reduced starting torque
Advantages :
High switching speed
Low power consumption
Low cost
Small in size
Easy to install
Less switching noice
There is an option to take three phase connection.
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Disadvantages:
Switching happen only if there is total power failure.
Three phase loads cannot attach to this system.
There is an external supply required.
Application of Automatic Phase Changer:
Small and medium scale industries
Residential Apartments
Office
ATM
Factories operating with 1 phase machineries.
Hospitals/Banks/Institutions.
It automatically supplies voltage in case of power failure or low voltage in up to
2 of the 3 incoming phases.
Automatic Phase Changer automatically cuts supply during low voltage thus,
protects equipment from the harmful effects of unhealthily low voltage.
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ANNEXURE 6(12V 3C/O RELAY DATASHEET)
COIL DATA (AT 25 C)
Nominal
Coil
voltage
(VDC)
Coil
resistance
ohms
(+/-10%)
Nominal
Coil power
approx.
(W)
Pick up
voltage
max.
(VDC)
Drop out
voltage
min. (VDC)
NO
12V 75
1.9W
80% of
nominal
voltage
10% of
nominal
voltage
18V
24V
• Non Plastic high temp. withstanding base
• Insert moulded terminals
• Screw / Solder type terminals
• Suitable for motor starters & controllers
• Configuration : 3 NO (3 Form A)
3 CO (3 Form C)
• Contact Rating : 30A at 240 VAC / 24 VDC
(Resistive) (Higher AC voltage Contact rating Model
also available)
• Contact Resistance : 100 mohm max (initial)
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Various coil voltages available.
AC coils also available
pick up Voltage for AC coil relays 85% max. Of nominal coil voltage
GENERAL PERFORMANCES
• Operate time 30 msec max
Fast Switching version 10 msec max
• Release time 10 msec max
• Life Expectancy
Electrical 5x104 Operations at rated load
Mechanical 106 Operations
• Dielectric Strength
Between Open Contacts 1000 VAC
Between Coil & Contact 2000 VAC
Between Any terminal & earth 2000 VAC
• Insulation Resistance 1000 Mohm min @ 500 VDC, 25°C & RH 50
• Temp. Range -40°C to + 70°C
• Weight 200 gms (approx.)
• Mounting Chassis mounting