A Project reporton INTELLIGENT REAL-TIME AUTOMATIC TRANSFORMER LOAD SHARING AND REMOTE CONTROLLING SYSTEM USING GSM MODEM submitted in partial fulfilment of the requirement for the award ofdegree ofBACHELOR OF TECHNOLOGY in ELECTRICAL & ELECTRONICS ENGINEERING byPRAVEEN DESAI 07BK1A0237 VIKAS VOOTURI 07BK1A0255 PRASHANTH KUMAR CH 07BK1A0236 Under the guidance ofMr. SURESH BABU(M. Tech.) Assistant ProfessorDEPARTMENT OF ELECTRICAL & ELECTRONICS ENGINEERING ST.PETER’S ENGINEERING COLLEGE (Affiliated to Jawaharlal Nehru Technological University, Hyderabad) Opp Forest Academy, Dhulapally, Near Kompally, Medchal Mandal, A.P.
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in partial fulfilment of the requirements for the award of BACHELOR OF
TECHNOLOGY to JNTU, Hyderabad. This record is a bonafide work carried out by them under my guidance and supervision. The result embodied inthis project report has not been submitted to any other university or institute for the award of any degree of diploma.
I would like to express my gratitude to all the people behind thescreen who helped me to transform an idea into a real application.
I would like to express my heart-felt gratitude to my parents withoutwhom I would not have been privileged to achieve and fulfil mydreams. I am grateful to our principal, Mr. K.V.J RAO who mostably run the institution and has had the major hand in enabling me todo my project.
I profoundly thank Mr.GIRI PRASAD, Head of the Department of Electrical & Electronics Engineering who has been an excellent guideand also a great source of inspiration to my work.
I would like to thank my internal guide Mr. SURESH BABU for histechnical guidance, constant encouragement and support in carryingout my project at college.
I would also like to thank my external guide Mr.SANDEEP for histechnical guidance and support in carrying out my project at ORBIT
The satisfaction and euphoria that accompany the successfulcompletion of the taskwould be great but incomplete without themention of the people who made it possible with their constantguidance and encouragement crowns all the efforts with success. In
this context, I would like thank all the other staff members, bothteaching and non-teaching, who have extended their timely help andeased my task.
conversion from "transmission" to "distribution" occurs is in a power
substation. It has transformers that step transmission voltages (in the tens or
hundreds ofthousands of volts range) down to distribution voltages (typically
less than10,000 volts). It has a "bus" that can split the distribution power off
in multiple directions. It often has circuit breakers and switches so that thesubstation can be disconnected from the transmission grid or separate
distribution lines can be disconnected from transmission grid or separate
distribution lines can be disconnected from the substation when necessary.
In this project, a slave transformer in the case of shares the load of master
transformer over load and over temperature. A sensor circuit is designed to
log the data from the master transformer and if it is found to be in over loadcondition, immediately the slave transformer will be connected in parallel to
the master transformer and the load is shared.
1.2 PROBLEM DEFINATION
The existing system presently is done manually, where by which thereare possibilities for the transformer to get easily damaged hence this is a
heavy loss to any grid or industry.
If there’s heavy load suddenly and not spotted out the transformer gets
damaged and there are even chances for the equipment to get damaged.
For home applications to the heavy industries this paper can be a solution
for the protection
1.3 OBJECTIVE OF THE PROJECT
• This paper is a method for the automatic load sharing of the
transformers using a GSM modem
• A message regarding the sharing of the load by the transformers is
The AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8Kbytes of Flash programmable and erasable read only memory (PEROM). The deviceis manufactured using Atmel’s high-density non-volatile memory technology and iscompatible with the industry-standard MCS-51 instruction set and pin out. The on-chip Flashallows the program memory to be reprogrammed in-system or by a conventional non-volatilememory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip,the Atmel AT89C52 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications.
Port 0Port 0 is an 8-bit open-drain bi-directional I/O port. As an output port, each pincan sink eight TTL inputs. When 1s are written to port 0 pins, the pins can beused as highimpedance inputs.Port 0 may also be configured to be the multiplexed loworder address/data busduring accesses to external program and data memory. In this mode P0 hasinternal pullups.Port 0 also receives the code bytes during Flash programming, and outputs thecode bytes during program verification. External pullups are required during
program verification.Port 1Port 1 is an 8-bit bi-directional I/O port with internal pullups. The Port 1 output
buffers can sink/source four TTL inputs.When 1s are written to Port 1 pins they are pulled high by the internal pullupsand can be used as inputs. As inputs, Port 1 pins that are externally being pulledlow will source current (IIL) because of the internal pullups.
Port 1 also receives the low-order address bytes during Flash programming andverification.Port 2Port 2 is an 8-bit bi-directional I/O port with internal pullups. The Port 2 output
buffers can sink/source four TTL inputs. When 1s are written to Port 2 pins theyare pulled high by the internal pullups and can be used as inputs. As inputs,Port 2 pins that are externally being pulled low will source current (IIL) becauseof the internal pullups.Port 2 emits the high-order address byte during fetches from external programmemory and during accesses to external data memory that use 16-bit addresses
(MOVX @ DPTR). In this application, it uses strong internal pull-ups whenemitting 1s. During accesses to external data memory that use 8-bit addresses(MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register.Port 2 also receives the high-order address bits and some control signals duringFlash programming and verification.Port 3Port 3 is an 8-bit bi-directional I/O port with internal pullups. The Port 3 output
buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins theyare pulled high by the internal pullups and can be used as inputs. As inputs,
Port 3 pins that are externally being pulled low will source current (IIL) becauseof the pullups. Port 3 also serves the functions of various special features of the
Port 3 also receives some control signals for Flash programming andverification.RSTReset input. A high on this pin for two machine cycles while the oscillator isrunning resets the device.ALE/PROG
Address Latch Enable output pulse for latching the low byte of the addressduring accesses to external memory. This pin is also the program pulse input(PROG) during Flash programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or clocking purposes. Note,however, that one ALE pulse is skipped during each access to external DataMemory. If desired, ALE operation can be disabled by setting bit 0 of SFR location 8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if the microcontroller is in external execution mode.
PSENProgram Store Enable is the read strobe to external program memory. When theAT89C52 is executing code from external program memory, PSEN is activatedtwice each machine cycle, except that two PSEN activations are skipped duringeach access to external data memory.EA/VPPExternal Access Enable. EA must be strapped to GND in order to enable thedevice to fetch code from external program memory locations starting at 0000Hup to FFFFH. Note, however, that if lock bit 1 is programmed, EA will be
internally latched on reset. EA should be strapped to VCC for internal programexecutions. This pin also receives the 12-volt programming enable voltage
(VPP) during Flash programming, for parts that require 12-volt VPP.XTAL1Input to the inverting oscillator amplifier and input to the internal clock operating circuit.
XTAL2Output from the inverting oscillator amplifier.
The two receivers fully conform to RS232 specifications. They’re
input impedance is between 3K Ω either with or without 5V power applied and
their switching threshold is within the +3V of RS232 specification. To ensure
compatibility with either RS232 IIP or TTL/CMOS input. The MAX232
receivers have VIL of 0.8V and VIH of 2.4V the receivers have 0.5V of
hysterisis to improve noise rejection.
The TTL\CMOS compatible output of receiver will be low whenever the
RS232 input is greater than 2.4V. The receiver output will be high when input is
floating or driven between +0.8V and –30V.
2.3.3 RELAY
A relay is an electrical switch that opens and closes under the controlof another electrical circuit. In the original form, the switch is operated by anelectromagnet to open or close one or many sets of contacts. It was invented byJoseph Henry in 1835. Because a relay is able to control an output circuit of higher power than the input circuit, it can be considered to be, in a broad sense,a form of an electrical amplifier .
A simple electromagnetic relay, is an adaptation of an electromagnet. It
consists of a coil of wire surrounding a soft iron core, an iron yoke, which provides a low reluctance path for magnetic flux, a moveable iron armature, anda set, or sets, of contacts; two in the relay pictured. The armature is hinged tothe yoke and mechanically linked to a moving contact or contacts. It is held in
place by a spring so that when the relay is de-energised there is an air gap in themagnetic circuit. In this condition, one of the two sets of contacts in the relay
pictured is closed, and the other set is open. Other relays may have more or fewer sets of contacts depending on their function. The relay in the picture alsohas a wire connecting the armature to the yoke. This ensures continuity of the
circuit between the moving contacts on the armature, and the circuit track on thePrinted Circuit Board (PCB) via the yoke, which is soldered to the PCB.
When an electric current is passed through the coil, the resultingmagnetic field attracts the armature, and the consequent movement of themovable contact or contacts either makes or breaks a connection with a fixedcontact. If the set of contacts was closed when the relay was de-energised, thenthe movement opens the contacts and breaks the connection, and vice versa if the contacts were open. When the current to the coil is switched off, thearmature is returned by a force, approximately half as strong as the magneticforce, to its relaxed position. Usually this force is provided by a spring, but
gravity is also used commonly in industrial motor starters. Most relays are
manufactured to operate quickly. In a low voltage application, this is to reducenoise. In a high voltage or high current application, this is to reduce arcing.
If the coil is energized with DC, a diode is frequently installed across the coil, todissipate the energy from the collapsing magnetic field at deactivation, which
would otherwise generate a voltage spike dangerous to circuit components.Some automotive relays already include that diode inside the relay case.Alternatively a contact protection network, consisting of a capacitor and resistor in series, may absorb the surge. If the coil is designed to be energized with AC,a small copper ring can be crimped to the end of the solenoid. This "shadingring" creates a small out-of-phase current, which increases the minimum pull onthe armature during the AC cycle.[1]
By analogy with the functions of the original electromagnetic device, a solid-state relay is made with a thyristor or other solid-state switching device. To
achieve electrical isolation an optocoupler can be used which is a light-emittingdiode (LED) coupled with a photo transistor.
2.3.4 MCT2E (OPTOCOUPLER)
DESCRIPTIONThe MCT2XXX series optoisolators consist of a gallium arsenide
infrared emitting diode driving a silicon phototransistor in a 6-pin dual in-line package.
allows a number of potential threats from eavesdropping the transmissions. It
was soon apparent in the threat analysis that the weakest part of the system was
the radio path, as this can be easily intercepted.
GSM provides a basic range of security features to ensure adequate protectionfor both the operator and customer. Over the lifetime of a system threat and
technology change, and so the security is periodically reviewed and changed.
The technical security features must be properly supported by procedures to
ensure complete security. The security provided by GSM is well in advance of
similar mobile radio systems, and should ensure that it remains at the front of
the field for some time to come.
However, it is vitally important that these capabilities are designed in from the
start, as they will have an impact on the system requirements. Business casesshould show the effect of fraud and the costs of protection.
Encryption of GSM
2.3.6 OTHER COMPONENTS
TRANSFORMERS
The transformer is a static electro-magnetic device that transforms one
alternating voltage (current) into another voltage (current). However, power
remains the same during the transformation. Transformers play a major role in
the transmission and distribution of ac power.
Transformer works on the principle of mutual induction. A transformer consists
of laminated magnetic core forming the magnetic frame. Primary and secondary
coils are wound upon the two cores of the magnetic frame, linked by the
common magnetic flux. When an alternating voltage is applied across the
primary coil, a current flows in the primary coil producing magnetic flux in the
transformer core. This flux induces voltage in secondary coil.
ENERGY METER
The energy meter is an electrical measuring device, which is used to recordElectrical Energy Consumed over a specified period of time in terms of units. Inthis project the energy meter acts a s a current sensor for the two transformersEnergy meter is basically an assembly of electrical and mechanical components.The design of energy meter depends upon which rating of current and voltageupon meter has to work. The components like potential coils and current coilsare to be designed in accordance with customer's requirements. Other components like magnets, terminals, Disc and reading registration mechanism
When AC is applied to the primary winding of the power transformer it
can either be stepped down or up depending on the value of DC needed. In our
circuit the transformer of 230v/15-0-15v is used to perform the step down
operation where a 230V AC appears as 15V AC across the secondary winding.
One alteration of input causes the top of the transformer to be positive and the
bottom negative. The next alteration will temporarily cause the reverse. The
current rating of the transformer used in our project is 2A. Apart from stepping
down AC voltages, it gives isolation between the power source and power
supply circuitries.
RECTIFIER UNIT:
In the power supply unit, rectification is normally achieved using a solid
state diode. Diode has the property that will let the electron flow easily in one
direction at proper biasing condition. As AC is applied to the diode, electrons
only flow when the anode and cathode is negative. Reversing the polarity of
voltage will not permit electron flow.
A commonly used circuit for supplying large amounts of DC power is the
bridge rectifier. A bridge rectifier of four diodes (4*IN4007) are used to achieve
full wave rectification. Two diodes will conduct during the negative cycle and
the other two will conduct during the positive half cycle. The DC voltage
appearing across the output terminals of the bridge rectifier will be somewhatlass than 90% of the applied rms value. Normally one alteration of the input
voltage will reverse the polarities. Opposite ends of the transformer will
therefore always be 180 deg out of phase with each other.
For a positive cycle, two diodes are connected to the positive voltage at
the top winding and only one diode conducts. At the same time one of the other
two diodes conducts for the negative voltage that is applied from the bottom
winding due to the forward bias for that diode. In this circuit due to positive half
In this phase we understand the components required for the project andthe block diagram needed to develop the project. Hence we are clear with therequirements thus we will proceed to the design phase followed by the
Now , in this project we look into the designing of the circuit using the
mentioned components in the previous phase
3.2 BASICS
STRIP BOARD
Strip board has parallel strips of copper track on one side. The tracksare 0.1" (2.54mm) apart and there are holes every 0.1" (2.54mm).
Stripboard is used to make up permanent, soldered circuits. It is ideal for smallcircuits with one or two ICs (chips) but with the large number of holes it is veryeasy to connect a component in the wrong place. For large, complex circuits it is
usually best to use a printed circuit board (PCB) if you can buy or make one.Components are placed on the non-copper side, then the stripboard is turnedover to solder the component leads to the copper tracks.
Stripboard layouts are shown from the component side, so the tracks are out of sight under the board. Layouts are normally shown with the tracks runninghorizontally across the diagram.
Placing components on stripboard requires care. The large number of holesmeans it is very easy to make a mistake! For most small circuits the best methodis to very carefully place the IC holder(s) in the correct position and solder in
place. Then you can position all the other components relative to the ICholder(s).
SOLDERING
Soldering is a process in which two or more metal itemsare joined together by melting and flowing a filler metal intothe joint, the filler metal having a relatively low melting point.Soft soldering is characterized by the melting point of the fillermetal, which is below 400 °C (752 °F).[1] The filler metal used inthe process is called solder.
In this way we can design the circuit of the project which is to beimplemented. Thus we have a clear picture of the project before themicrocontroller being coded. Hence any necessary enhancements can be made
• With C the programmer need not know the architecture of the processor.
• Code developed in C will be more portable to other systems rather than in
assembly.
Difference between Conventional C and Embedded C:
• Compliers for conventional C are TC, BC
• Compilers for Embedded C are keil µvision - 2 & 3, PIC C etc.
• Conventional C programs needs complier to compile the program & run it.
• The embedded C program needs a cross compiler to compile & generate HEX
code.
• The programs in C are basically processor dependent whereas Embedded C
programs are micro controller dependent.
•The C program is used for developing an application and not suitable for
embedded systems.
• The embedded C is an extension of the conventional C. i.e Embedded C has
all the features of normal C, but has some extra added features which are not
available in C.
• Many functions in C do not support Reentrant concept of functions.
•C is not memory specific. i.e variables cannot be put in the desired memorylocation but the location of variable can be found out.• In embedded C this can be done using specific inbuilt instructions.
The implementation part is the most important phase of the project. In this
phase, we code the entire project in the chosen software according to the designlaid during the previous phases.The code should be efficient in all terms like space, easy to update, etc. In thismanner, we can complete the coding part of the project and later it can be tested
#include <string.h>sbit rs=P1^0;//selecting cmd or display modesbit en=P1^2; //make lcd to excue a cmd or display a charactrer sbit relay=P1^3;
sfr lcd=0xa0; //a0 is ram address of port 2
void lcd_init();//initialize ur lcdvoid lcdcmd(unsigned char);//execute any cmdvoid lcddis(unsigned char);//display an ASCII chrcter void lcdstr(unsigned char *);//display a stringvoid del();//generate a delayvoid ser_ini();//initalize serial commvoid serstr(unsigned char *);//transmit a string to GSMvoid ser(unsigned char);//transmit a char to gsm
void msgsnd();//send the msg
unsigned int val=0;unsigned long res=0,cnt=0;float result=0;
void main()unsigned char current[5];TMOD=0x21;//timer 1 in serial comm timer 0 in interruptlcd_init();IT0=1;//level triggering interruptIE=0x83;// enable global interrupt timer interrupt xerternal
interrupt
ser_ini();while (1)for (i=0;i<5;i++)current[i]=0;lcdcmd(0x01);sprintf(current,"%lu",res);EA=1;lcdstr("Current:-");while (!first);lcdstr(current);lcdstr("mA");static bit msg=0;if (res>1400)relay=1;
if(msg==0)msgsnd();msg=1;elserelay=0;msg=0;// if ((msg==1)&&(res>1400))// msgsnd();msg=0;
void lcd_init()lcdcmd(0x38);//activate 5x8 matrixlcdcmd(0x01);//clear the screen
lcdcmd(0x06);//increment the cursor lcdcmd(0x0e);//dipslay the cursor void lcdcmd(unsigned char cmd)lcd=cmd;//port2 is equal to cmdrs=0;//cmd modeen=1;//enabledel();en=0;
void msgsnd()serstr("AT+CMGS=\"9703456607\"\r");del();del();serstr("The supply has been shared by two transformers");ser(0x1a);del();del();del();del();del();del();del();while (!RI);while(RI)RI=0;del();del();
Testing is a critical element for any project to be successful. Now the codeinterfaced into the Microcontroller is in the circuit this has to be tested so that
the load is shared by the transformer when it is high
6.2 STEPS
• Check that the whole setup is in OFF condition first
• Now turn on the supply and see that only one bulb is turned ON thisindicates that the load is low and the current is displayed on the LCD
• Now for this condition only one LED of Master transformer has to beturned on, this shows that the load is only through master transformer
• After this , turn on the second bulb too , this indicates that the load is highand the current is displayed on the LCD
• Now as the load is high the microcontroller trips on the relay and the loadis shared by the two transformers
• Now both the LED’s of transformers start glowing which indicates theload is being shared by both the transformers
• A message has to be sent to the mobile number saved in the programthrough GSM
• Thus the project is tested if the results satisfy the conditions
6.3 Testing Results
A good test has a high probability of finding an as yet undiscovered error.
A successful test is one that uncovers an as yet undiscovered error.
6.4 CONCLUSION
In this way we also completed the testing phase of the project and ensured thatthe system is ready to go live.Thus we developed a system which automaticallyshares the load with two transformers when the load is high by which manyindustries and companies can run safely