IJSART - Volume 1
Issue 4 –APRIL 2015
ISSN [ONLINE]: 2395-1052
Auto Power Supply Control From Four
Different Sources: Mains, Solar, Inverter and
Generator To Ensure No Break Power
Garima Pandey1, Khanda Anum2, Waqar Ateeq3, Vivek Tripathi4
Department of Electronics & Instrumentation Engineering
1, 2, 3, 4
Integral University, Lucknow
Abstract- The main objective of this paper is to explain the
uninterrupted power supply to a load, by selecting the supply
from any source out of 4 such as mains, solar, inverter and
generator automatically in the absence of any of the source.
The demand for electricity is increasing every day and
frequent power cuts is causing many problems in various
areas like industries, hospitals and houses. An alternative
arrangement for power source is a must. This arrangement
can be designed by using PLC (Programming Logic
Controller) and relays. When a source, say mains fails the
supply automatically shifts to next priority source generator
and so on. The output could be a lamp of 12 watt. LEDS(Light
emitting diodes) can be used to show that which source is
used to provide the supply.
Keywords- PLC logic, Relays, Supply sources (Inverters, generators,
Solar)
I. INTRODUCTION
An important requirement of electric power
distribution systems is the need for automatic operation. In
particular, the rapid and reliable transfer of the system from
one power source to another during certain system events is
important to achieving the reliability goals for such systems
and the facility serves. However, the design of such an
automatic transfer system is all–too-often considered “less
important” then many other aspects of the overall power
system design. This paper deals with the four switches to
demonstrate the respective failure of that power supply. The
switches used are of “normally open” type switch. When any
of the switches is pressed it shows the absence of that
particular source, switches are connected to PLC as input
signals. A PLC of Allen Bradley Micrologix 1000 is used. The
output of microcontroller is given to the relay driver IC, which
switches appropriate relay to maintain uninterrupted supply to
the load. The output shall be observed using a lamp drawing
power supply from mains initially. On failure of the mains
supply (which is actuated by pressing the appropriate switch)
the load gets supply from the next available source, say a
generator. If the generator also fails it switches over to the
next available source and so on Four LEDS will be used to
demonstrate the source of the power supply.
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Using uninterrupted power supply in an automated
mode, we always have a substitute arrangement as backup to
take place of main power supply in case of power-cut in an
emergency case, where the power cut cannot be avoided. In
many cases load can be changed as per the requirements, it
could be a motor, lamp or anything else which is essentially
required at the time.
II. MODEL DESCRIPTION
Figure 1 explains the working and construction of the
Auto power supply from four different sources. As shown in
the diagram the four sources are Mains, Solar, Inverter and
Generator, four “Normally open” switches are used to show
the failure of each supply, one SMPS to maintain power
supply for PLC(24V dc), PLC is microlgix 1000 Allen
Bradley used, four relays are used to provide protection at
each respective output. This output can be used to drive any
load such as a lamp or motor. LEDs are used to display the
source of supply.When the supply from all the sources (Mains,
Solar, Inverter and generator) are ready, first “Normally open”
switch is pressed it produces mains failure and the supply
automatically shifts to solar. To proceed further, second NO
switch is pressed which produces failure in solar and supply is
provided from inverter and so on. In the PLC ladder logic,
priority is assigned to each power source in the order of
Mains, Solar, Inverter and Generator. In case the mains power
fails, the supply should automatically shift to Solar but if solar
also fails at the moment then the supply will automatically
shift to next priority source.
Other case is when the power switches from one
source to another source, say solar fails and supply shifts to
inverter but the mains comes back then the supply will
automatically reach back to mains power instead of switching
to inverter.
At the output of PLC, each output port is connected
to positive dc voltage as the supply we give is ac and we need
dc output to draw the load. Relays are used in contact with the
output port to provide switching at the output.
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IJSART - Volume 1
Issue 4 –APRIL 2015
ISSN [ONLINE]: 2395-1052
second as the preset value given is 1. After 1 sec delay T4:6
DN provides supply to the main output O0. In this logic
failure and resupply of mains is given by I0 toggle button. If
the main button is OFF that means supply of mains is cutting
down.
In the line 0002 Solar input I1 is connected in series
with NC(Normally Closed) of mains button. So here when I1
turns ON and I0 turns OFF it activates timer T4:0 and enables
T4:0 DN with a delay of 1 sec as given in preset value ant it
turns ON Solar output O1.
Figure 1.Block diagram of Auto Power supply from four
different sources.
In the line 0004 NC of Solar Output(O1) and NC of
Mains Input(I0) are connected is series with the timer T4:4,
which failure Solar output and turning OFF main input
activates timer T4:4 and enables T4:4 DN with a delay of 3
sec.
III. PLC LOGIC
A programmable(PLC)
logic
controller,
PLC or programmable controller is a digital computer used
for automation of typically industrial
electromechanical
processes, such as control of machinery on factory assembly
lines, amusement rides, or light fixtures. PLCs are used in
many industries and machines. Unlike general-purpose
computers, the PLC is designed for multiple inputs and output
arrangements, extended temperature ranges, immunity to
electrical noise, and resistance to vibration and impact.
Programs to control machine operation are typically stored in
battery-backed-up or non-volatile memory. A PLC is an
example of a hard real-time system since output results must
be produced in response to input conditions within a limited
time, otherwise unintended operation will result. In this
project we are using Micrologix 1000 Allen Bradley PLC for
the uninterruptible power supply.
In Micrologix 1000, it electronically controls your
application. The controllers are available in either 16 I/O
points (10 inputs and 6 outputs) or 32 I/O points (20 inputs
and 12 outputs) in 5 electrical configurations. The I/O options
and electrical configurations make them ideal for almost any
application.
In Figure 2 PLC ladder logic diagram we have four
input toggle buttons, I0 I1, I2, I3 for mains input, solar input,
inverter input and generator input respectively. And in the
same way we have also four different outputs as Mains, Solar,
Inverter, and Generator represented as O1, O2, O3, and O4
respectively for the uninterrupted power supply.
In the above program when mains button I0 turns ON
it activates timer T4:6 and enables T4:6 DN with a delay of 1
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In line 0005 Inverter input button I2 connected in
series with NC of Mains input button I0 as input interlocking.
Here when Inverter input I2 is Turned ON and Mains input
turned OFF it activates timer T4:1 and enables T4:1 DN with
a delay of 1 sec as the preset value is 1.
In line 0006 T4:1 DN is connected in series with
T4:4 DN, here when both the timers get high it turns ON
Inverter output O2. The interlocking of both the timer is
required for the reason that if in case Mains input I0 is fail and
Solar supply is not in working condition and we are not
getting our output through Solar output O1 then automatically
it checks Inverter supply and if it is working properly then it
automatically after a delay of 3 seconds, it switches to Inverter
supply O2.
In line 0007 Generator input I3 is connected in series
with NC of Mains input I0, when the mains input is fail and
Generator Input is turns ON it activates timer T4:2 and
enables T4:2 DN with a delay of 1 sec.
In line 0008 NC of Solar output is connected in series
with NC of Inverter output and both are in series with T4:4
DN. In case of Solar and Inverter failure both the NC’s gets
high and T4:4 DN turns high for failure of Solar output and
for Mains input OFF, all this activates timer T4:5 and enables
T4:5 DN with a delay of 3 sec.
In line 0009 interlocking of T4:2 DN and T4:5 DN
for the reasons that if mains supply, solar output and inverter
output fails then it checks generator supply and if generator is
working correctly then its supply switches to generator supply
and gets our output through generator O3.
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IJSART - Volume 1
Issue 4 –APRIL 2015
ISSN [ONLINE]: 2395-1052
IV. CONCLUSION
The project “Auto power supply from four different
sources: Mains, solar, inverter and generator” has been
explained in this paper with all its features and details. The
significance of this project lies in its various advantages and
wide places of applications where this project can be used
efficiently. It has been developed by integrating features of all
the hardware components used. Presence of every module has
been reasoned out and placed carefully thus contributing to the
best working of the unit.
REFERENCES
[1] http://www.facstaff.bucknell.edu
[2] Rockwell automation SCADA System Selection guide
Allen-Bradley
Figure 2.PLC logicFlow Chart
[3] Knight U. “The power System and its Operational and
Control Infrastructure in emergencies” from contingency
planning to crisis management.
Figure 3. Flow Chart
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