Hossam Guhaish Akram Al-hussaini
Momen Al-qasos Nashwan Malek
Ghamdan Taher Mazen Al-mahbashi
Emirates International University , Sana’a ,Yemen .
Email address:
Hossam424610@gmail.com (H. Guhaish) , momendnn@gmail.com (M. Al-qasos) , ghamdank30@gmail.com (G. Taher),
akram2021@hotmail.com (A. Al-hussaini) , nashwanhashemmalek@yahoo.com (N. Malek) and
mazen.ahmed9@icloud.com (M. Al-mahbashi).
Abstract:
The Automatic Transfer Switch (ATS) is used to transfer the load among several power sources
to ensure continuous operation of load. ATS is required in developing countries where frequent
power failure is an intense issue.Industries, public and private sector organizations Automatic
Transfer Switching system is designed to use three sources namely; public utility supply, solar,
generator to change from one of them to another with priority given. Public utility supply is given
the top priority followed by solar and then generator will run for same hours while checking other
sources, if utility is returned or the level of battery is reach to the required level of charging then
it will be disconnected and switched off, then the load is reconnected to the existing source, In this
project arrangement has been designed by using Siemens PLC (logo! 8) ,contactors and
sensors.
This propsal presents design and implemenation of automatic switching circuits, which is used
in PLC automation for constructing a workable automatic change-over switch with generator
starting/shutdown functions. This switch turns ON the generator automatically in cases of mains
power failure and connects the load to the generator output And will be monitored the level of
diesel in the generator tank to avoid the extinguishing of the instantaneous generator as well as
control the efficiency of battery chargers and the quality of batteries and what distinguishes this
project from others that is monitored and controlled by the system completely by WAN or sms and
will be send a message when happen any problems in the system.
Keywords:-
Switching, PLC, Automation, Sensors, public utility supply, ATS, WAN, SMS.
1
Introduction: control and electrical power systems, such as tap-
Generally organization`s development is dis- changer, substation control, protection and etc.
tracted by intermittent power failure or constant
outage. In countries where there is instability of Practical Considerations
power, investment does not easily succeed, in- Automatic transfer switches are used to serve a contin-
uous power for the load by automatic transferring be-
dustrial transformation cannot be easily sped up,
tween two or more sources when the main source are
however a heavy loss may result when some pro- down or decreased below a certain limit. The ATS
cesses are interrupted such as surgery in health automatically disconnects the faulty source and
care organization and some online financial pro- connects the load to the other healthy source. Some
ceedings in government and private agencies . practical consideration should be taken into account
To avoid these inconveniences, secondary when ATS systems are utilized, such as:
a- Voltage: The voltage regulation of the back up
source of power is mostly introduced to cushion
source should be between the permissible ranges. This
undesirable effect of any unprecedented power could be fulfilled using an automatic voltage regulator
failure. The transition can be achieved by means (AVR) unit to automatically control the excitation of
of an ATS,The poor state of power supply in de- the generator, hence the output voltage. In the UPS, the
veloping countries, calls for alternatives sources DC to AC inverter is controlled to match voltage re-
of power generation and automation of electrical quirements.
b- Frequency: The generator frequency is determined
power generation to back up the utility supply. by the speed of the driving engine, which is provided
Over time, automation of electrical power supply by a closed loop speed control system to supply the
has become so vital as the rate of power outage electrical loads with the standard frequency. The UPS
is predominantly high. normally operated at a fixed output frequency
The main problems of turning it on / off can be (50 Hz or 60 Hz according to the country standards).
removed by installing the auto transfer switch c- Synchronization: In case of the utilization of more
than one backup sources, such as two emergency gen-
(ATS) for industrial generators, Some papers erators or the main it self consists of main transformer
show that automatic switching a challenge to re- and main generator, synchronization conditions (same
searcher's paper presents an economical and voltage, frequency, phase sequence and phase shift)
easy way for switching application of generator should be considered before transferring the power
through PLC incorporated with GSM alerts in in- through the ATS.
dustries. An Automatic Transfer Switch enables
backup enerators. HARDWARE REQUIRED FOR
As new manufacturing technologies become PROTOTYPE MODEL
available and since existing manufacturing tech- a- Sensors and Actuator
nologies become more integrated, industrial en- Sensor: The main and emergency voltage signals
gineering departments must continuously devel- should be monitored by the PLC. Simple relays are
oped their laboratory resources in order to pro- proposed to detect these voltages as their coils are con-
vide their students with effective instructions. Au- nected to the line voltages while their contacts are con-
nected to the control circuit (the inputs of the PLC). R1
tomatic transfer switch (ATS) is an important
component in many electrical power systems. is for main voltage V , R2 is for voltage of Battery
M (R-S)
High voltage ATS ratings and selectively features V and R3 is for generator voltage V .
B, G (R-S)
are discussed in. Currently, many manufacturing Actuators: Two contactors, mechanically and electri-
functions are automated through the use of com- cally interlocked, are proposed (KM and KG). The coils
puters (PC), micro-controllers (μC) and program- of these power contactors are tripped through the con-
mable logic controllers (PLC). PLCs have become trol relays (RM and RG) as outputs of the PLC. Other
at the forefront of manufacturing automation
two PLC output signals (RF and RA) are required to
due to their simple, robust and reliable hardware
start the engine and build up voltage from the genera-
connections and software programming tech-
tor. Two circuit breakers (CBM and CBG) should be
niques. PLCs have been effectively used in process
provided for protection of the power circuits.
Practically, the engine may require ignition signal and
fuel feeding signal. However, in the proposed labora-
tory setup, no engine was valid, and a DC motor with
a DC power electronic speed control unit is utilized to
drive the synchronous generator. Hence the two re-
lays (RF and RA) are now used for the field and arma-
ture of the DC drive unit .
b- Hardware connections
Power circuit: Connections of the power circuit
are shown in figure 1, where the 3-ph loads can
be fed either from the main or the emergency
generator through the contactors (KM and KG)
and circuit breakers (CBM and CBG).
Figure 2 : connection Control circuit
c- The PLC :-
The PLC activates its output terminals in order to
switch things on or off. The decision to activate
an output is based on the status of the system’s
feedback sensors and these are connected to the
input terminals of the PLC. The decisions are
based on the logic programs stored in the RAM
or ROM memory. They have a central processing
unit (CPU), data bus and an address bus. The in-
put instructions are stored in data memory and
the logic control compares the instruction of
data memory with program memory. The out-
put terminals can be connected to loads like
UPS &The load light, motor, control valve, etc. RS232 cable is
used for communication purpose in PLC in mod-
Figure 1 : connection Power circuit
ern PLC programming has been standardized *
Control circuit: Ethernet *
A PLC is utilized to control the system to achieve In this project, PLC system is used to Program-
the requirements. Connections between the PLC mable Logic Controller of Siemens Company.
and all sensors and actuators are shown in fig-
ure 2 .
(LOGO !8)
3
d- Software programming (ladder) Working principle:
This project uses arrangement of three different
sources of supply, which are Channelized, to a load to
have an uninterrupted operation of the load. As it is
not practicable to get three sources of supply such as
solar supply, utility supply and generator supply.
The principle of the work of this project is distin-
guished from other projects, it is considered more
flexible and smooth in terms of control and conver-
sion between sources, where priority is divided into
two periods day and evening so that priority
1- During the daytime:
In the light load of the solar energy and in increasing
the load, the system is examined through the sensors,
which in turn send a reference to a plc device in the
case of the existence of energy to run the solar system
and in case of overload load signals sent signals to the
plc, which in turn check and verify the existence of
public current and Operation of the system in the pub-
lic power In the absence of the general current, the
generator is turned on and the load is connected to it.
2. During the evening:
The priority or priority of the public current and
when the plc device is not receiving signals from the
sensors concerned with the examination of the gen-
eral current, the load is transferred to the solar energy,
which in turn transfers the load to it. In the case of re-
ceiving the plc device signals from the test unit of the
batteries as they are about to enter the sensors, The
plc device, which makes sure to do so, sends the sig-
nals to the special unit and turns on the generator to
transfer the load to it.
In previous systems or used in the event of a problem
in one of the sources or in the system control is to
stop the system in an instant causing many problems,
including: stop working without realizing that, loss of
time when maintenance.
In our project, in the case of any problem in one of
the sources or in the system, plc send SMS messages
and alert to the supervisor and at the same time run-
ning one of the sources according to priority and iso-
late the circle in which the problem occurred to en-
sure that the system does not stop working and avoid
any losses or problems caused by the stop . Plc also
monitors the problems and sends the reports to the su-
pervisor according to the period he wants to see the
system's operation and the possibility of controlling
or modifying the system completely remotely by
phone or through the WAN.
4
ADVANTAGES OF PROJECT: Objectives:
The purpose of the automatic transfer switch
1. Automatic Power Source Selection. (ATS) is to automatically start the generator and
2. Easy to use, Self-explanatory kit. switch from the utility power feed to the power
3. to provide uninterrupted power supply feed from the generator when the normal utility
from any of the available supply. power fails. In order to complete this task, the
4. Flexibility in programming and reprogram- ATS is equipped with electronic circuits that
ming monitor the utility feed, control the starting mech-
5. It insures a constant power supply without anism of the generator and control the switch that
any interruption. transfers the power source from the utility feed to
6. Ideal for automatic switching as changeo- generator feed. Further, when the utility feed
ver happens automatically and mainly con- comes back on-line and is stable, the ATS trans-
trolled by software hence no need to design fers the load back to the utility feed. Due to the
complex hardware electronics involved in the ATS, the ATS is sus-
7. It reduces the stresses on manpower and ceptible to the surge environment that is common
operation is easy to handle. at the service entrance location where the ATS is
8. Improve system stability and reliability installed. Surges from the utility feed due to light-
ning, load switching, etc. can be detrimental to the
Chooseing the system and its operation of or can destroy the ATS rendering the
experience system useless. Also, when the generator starts
It is easy to overlook important details on how up, the voltage may not yet be stabilized at the in-
systems operate in the moments following a loss stant the ATS makes the transfer. This initial
of utility power. There are many considerations to surge of not yet regulated power can damage elec-
tronic systems.
weigh when determining proper ATS settings.
The details must be coordinated and tested to
make sure that staff are not put at risk. This starts Conclusion
with a basic understanding of ATS features and
their importance in the particular appliction. This paper demonstrated steps for designing and
implementing an automatic transfer switch using
The first step in a successful outcome is to deter- a programmable logic controller. Many aspects
mine the system configuration, loads on each of automatic transfer systems for the critical
ATS, and then decide the ATS settings you wish power environment are presented. When
to implement. When working with an existing properly designed and implemented, automatic
system, evaluating the entire system is necessary transfer systems provide a vital function in the
reliable operation of critical power systems.
to ensure the project at hand does not necessitate
Working in conjunction with alternate power
the adjustment of existing system components.
sources , automatic transfer systems help to in-
The final and probably most important step is to sure that critical system loads receive the reliable
test the system thoroughly and often. Running the power they require in order to function.Various
system weekly and loading the system monthly types of switching techniques are also discussed
in this thesis. There are many techniques in auto-
are required. These minimum testing standards
matic switching. Although automatic switching
required by code and AHJ may not be adequate to of load using PLC based system is proposed.
ensure proper operation when called upon to do
so. The more complex the system, the more im-
portant it is to test all its required sequences.
5
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