Transformer Fault Detection Using Zigbee and GSM

TRANSFORMER FAULT DETECTION USING ZIGBEE

2011-12

INTRODUCTION In search of our project we plan to do something, which is yet to be established and must be useful to day to day life. We analyzed the current situation and realized that if there may be system that informs the user about various faults in the transformer, we will be able to prevent severe damages. So we decided to develop such a system that detects transformer faults. A system which can detect the voltage of a transformer from normal to danger and to take an initiatives to avoid damage to a transformer. Power transformers are designed to transmit and distribute electrical power. Depending on the size of a transformer, replacement costs can range from a few hundred dollars to millions of dollars. Performing offline and invasive tests also add to the replacement cost. Hence, there is an increasing need to move from traditional schedule-based maintenance programs to conditionbased maintenance. However, a focused approach is required for diagnostics.

Department of ECE,DSCE

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SYSTEM OVERVIEW TRANSMITTER BOCK DIAGRAM


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RECEIVER BLOCK DIAGRAM


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BLOCK DIAGRAM DESCRIPTION : Transformer fault detection includes the following components: 

Power supply



Microcontroller



Buzzer



LCD Display



Relay



Transformer



Mobile



Transmission lines



Zigbee technology


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TRANSFORMER INTRODUCTION The protection system of transformer is inevitable due to the voltage fluctuation, frequent insulation failure, earth fault, over current etc. Thus the following automatic protection systems are incorporated.

1. Buchholz devices: devices: A Buchholz relay, also called a gas relay or a sudden pressure relay, is a safety device mounted on some oil-filled power transformers and reactors, equipped with an external overhead oil reservoir called a conservator. The Buchholz Relay is used as a protective device sensitive to the effects of dielectric failure inside the equipment. It also provides protection against all kind of slowly developed faults such as insulation failure of winding, core heating and fall of oil level.

2. Earth fault relays: An earth fault usually involves a partial breakdown of winding insulation to earth. The resulting leakage current is considerably less than the short circuit current. The earth fault may continue for a long time and creates damage before it ultimately develops into a short circuit and removed from the system. Usually provides protection against earth fault only.

3. Over current relays: An over current relay, also called as overload relay have high current setting and are arranged to operate against faults between phases. Usually provides protection against phase -to-phase faults and overloading faults.

4. Differential system: Differential system, also called as circulating-current system provides protection against short-circuits between turns of a winding and between windings that correspond to phase-to-phase or three phase type short-circuits short-circuit s i.e.

it provides

protection against earth and phase faults. Department of ECE,DSCE

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The complete protection of transformer usually requires the combination of these systems. Most of the transformers are usually connected to the supply system through series fuses instead of circuit breakers. In existing method the transformer does not have automatic protective relays for protecting the transformer.

TRANSFORMER – DEFINITION A device used to transfer electric energy from one circuit to another, especially a pair of multiple wound, inductively coupled wire coils that affect such a transfer with a change in voltage, current, phase, or other electric characteristic.


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Fig 2.1 Basic Transformer

THE UNIVERSAL EMF EQUATION

If the flux in the core is sinusoidal, the relationship for either winding between its number of turns, voltage, magnetic flux density and core cross-sectional area is given by

the universal emf equation (from Faraday’s Law):

 

 √ 

    

…(2.1)

E is the sinusoidal rms or root mean square voltage of the winding,


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TRANSFORMER FAULT DETECTION USING ZIGBEE 

f is the frequency in hertz,



N is the number of turns of wire on the winding,



a is the cross-sectional area of the core in square meters



B is the peak magnetic flux density in Tesla



P is the power in volt amperes or watts,

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NECESSITY FOR PROTECTION Transformers are static devices, totally enclosed and generally oil immersed. Therefore, chances of faults occurring on them are very rare. However, the consequences of even a rare fault may be very serious unless the transformer is quickly disconnected from the system. This necessitates providing adequate automatic protection for transformers against possible faults.

COMMON TRANSFORMER FAULTS As compared with generators, in which many abnormal conditions may arise, power transformers may suffer only from: 1. Open circuits 2. Overheating 3. Winding short-circuits

Open circuit Faults: An open circuit in one phase of a 3-phase transformer may cause undesirable heating. In practice, relay protection is not provided against open circuits because this condition is relatively harmless. On the occurrence of such a fault, the transformer can be disconnected manually from the system.

Overheating Faults: Overheating of the transformer is usually caused by sustained overloads or short circuits and very occasionally by the failure of the cooling system. The relay protection is also not provided against this contingency and thermal accessories are generally used to sound an alarm or control the banks of fans.


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Winding Short-circuit Faults: Winding short-circuits (also called internal faults) on the transformer arise from deterioration of winding insulation due to overheating or mechanical injury. When an internal fault occurs, the transformer must be disconnected quickly from the system because a prolonged arc in the transformer may cause oil fire. Therefore, relay protection is absolutely necessary for internal faults.


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MICROCONTROLLER

4.1 INTRODUCTION INTRODUCTION Microcontroller is a microprocessor microproc essor designed specifically s pecifically for control applications, applicatio ns, and is equipped with ROM, RAM and facilities I / O on a single chip.AT89S52 is one of the family MCS-51/52 equipped with an internal 8 Kbyte Flash EPROM (Erasable and Programmable Read Only Memory), which allows memory to be reprogrammed.

The AT89S52 is a low-power, high-performance CMOS 8-bit microcomputer with 4Kbytes of Flash programmable and erasable read only memory (PEROM).This device is a Single-chip 8-bit Microcontroller and is a derivative of the 8051 microcontroller family. The instruction set is 100% compatible with the 8051 instruction set. The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89S52 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications.


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FEATURES OF MICROCONTROLLER 

A CPU (central processing unit) 8 bits.



256 bytes of RAM (random access memory) internally.



Four ports of I/O with each consist of 8 bit.



The internal oscillator and timing circuit.



Two timers/counters 16 bits.



Five interrupt lines (two fruits and three external interrupt internal interruptions).



A serial port with full duplex UART (Universal Asynchronous Receiver Transmitter).



Able to conduct the process of multiplication, division, and Boolean.



The size of 8 Kbytes EPROM for program memory.



Maximum speed execution of instructions per cycle is 0.5 s at 24 MHz clock frequency. If the microcontroller clock frequency used is 12 MHz, the speed is 1 s instruction execution.

CPU (central processing unit)

This section serves to control the entire operation on the microcontroller. This unit is divided into two parts, the control unit, or CU (Control Unit) and the arithmetic and logic unit or ALU (Arithmetic Logic Unit) The main function control unit is to take instructions from memory (fetch) and then translate the composition of these instructions into a simple collection of work processes (decode), and implement instruction sequence in accordance with the steps that have been determined the program (execute). Arithmetic and logic unit is the part that deals with arithmetic operations like addition, subtraction, and logical data manipulation operations such as AND, OR, and comparison.

4.2.2 INPUT/OUTPUT (I/O) This section serves as a communication tool with a single chip device outside the system. Consistent with the name, I / O devices can receive and provide data to / from a single chip.


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There are two kinds of devices I / O is used, ie devices for serial connection UART (Universal Asynchronous Receiver Transmitter) and device for so-called parallel relationship with the PIO (Parallel Input Output).Both types of I / O has been available in a single chip AT89S52. SOFTWARE Single flakes MCS-51 family has a special programming language that is not understood by other types of single flakes. This programming language known by the name of the assembler language instruction has 256 devices. However, when this can be done with microcontroller programming using C language. With the C language, microcontroller programming easier, because the C language format will be automatically converted into assembler language with a hex file format. Software on a microcontroller can be divided into five groups as follows:


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PIN CONFIGURATION AT89S52 microcontroller has 40 pins with a single 5 Volt power supply. The pin 40 is illustrated as follows:

4.3.1 THE FUNCTION OF EACH PIN AT89S52 Vcc: Supply Voltage. GND: Ground.


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Port 0:

Port 0 is an 8-bit open drain bi-directional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as high-impedance inputs. Port 0 can also be configured to be the multiplexed low-order address/data bus during accesses to external programmed data memory. In this mode, P0 has internal pull-ups. Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. Port 1:

Port 1 is an 8-bit bi-directional I/O port with internal pull-ups. 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 pull-ups and can be used as inputs. As inputs, port 1 pins that are externally being pulled low will source current (I IL) because of the internal pull-ups. Port 1 also receives the low-order address bytes during Flash programming and verification.

Port 2:

Port 2 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 2 output buffers can sink/ source four TTL inputs. When 1s are written to Port 2 pins, they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current (I IL) because of the internal pull-ups. Port 2 emits the high-order address byte during fetching from external program memory and during access to external data memory that uses 16-bit addresses (MOVX @DPTR). In this application, Port 2 uses strong internal pullups when emitting 1s. During accesses to external data memory that uses 8-bit address (MOVX @R1), Port 2 emits the contents of the P2 Special Function Register. Port 2 also receives the high-order address bits and some control signals during Flash program and verification. Port 3:

Port 3 is an 8-bit bi-directional I/O port with internal pull-ups. The Port 3 output buffers can sink/ source four TTL inputs. When 1s are written to Port 3 pins, they are pulled high by the Department of ECE,DSCE

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internal pull-ups and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (I IL) because of the pull-ups. Port 3 also serves the functions of Port 3 pin alternate Functions: P 3.0 RXD (Serial Input Port) P 3.1 TXD (Serial Output Port) P 3.2 INT0 (External Interrupt 0) P 3.3 INT1 (External Interrupt 1) P 3.4 T0 (Timer 0 External Input) Input) P 3.5 T1 (Timer 1 External Input) Input) P 3.6 WR (External Data Memory Write Strobe) P 3.7 RD (External Data Memory Read Strobe). Port 3 also receives some control signals for Flash programming and programming verification.

RST: Reset Input

A high on this pin for two machine cycles while the oscillator is running resets the device. This pin

drives

High

for

98

oscillator

periods

after

the

Watchdog

times

out.

ALE/PROG:

Address Latch Enable is an output pulse for latching the low byte of the address during 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 data memory. 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.

PSEN: Program Store Enable


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It is the read strobe to external program memory. When the AT89S52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory.

EA/Vpp: External Access Enable/ Programming Enable Voltage

External Access Enable must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up 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 program executions. This pin also receives the 12-volt programming enable voltage (Vpp) during Flash programming.

XTAL1:

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

XTAL2:

It is the output from the inverting oscillator amplifier.


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TIMER 

Timer0: 8-bit timer/counter with 8-bit prescaler



Timer1: 16-bit timer/counter with prescaler



Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler.

Mode 0: 13-Bit Timer Lower byte (TL0/TL1) + 5 bits of upper bytes (TH0/TH1). Backward compatible to the 8048 Not generally used Timer operation in Mode 0

Mode 1: 16-bit All 16 bits of the timer (TH0/TL0, TH1,and TL1) are used. Maximum count is 65,536 At 12 MHz, maximum interval is 65536 microseconds or 65.536 milliseconds TF0 must be reset after each overflow THx/TLx must be manually reloaded after each overflow.

Mode 2: 8-bit Auto Reload Only the lower byte (TLx) is used for counting. Upper byte (THx) holds the value to reload into TLx after and overflow. TFx must be manually cleared. Maximum count is 256 Maximum interval is 256 Microseconds or .256 milliseconds

INTERRUPT Hardware interrupts were introduced as a way to avoid wasting the processor's valuable time in polling loops, waiting for external events. They may be implemented in hardware as a distinct system with control lines, or they may be integrated into the memory subsystem. If implemented in hardware, an interrupt controller circuit such as the IBM PC's Programmable Interrupt Controller (PIC) may be connected between the interrupting device and the processors Department of ECE,DSCE

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interrupt pin to multiplex several sources of interrupt onto the one or two CPU lines typically available. If implemented as part of the memory controller, interrupts are mapped into the system's memory address space. Interrupts can be categorized into: maskable interrupt, non-maskable interrupt (NMI), interprocessor interrupt (IPI), software interrupt, and spurious interrupt. 

Maskable interrupt (IRQ) is a hardware interrupt that may be ignored by setting a bit in

an interrupt mask register's (IMR) bit-mask. 

Non-maskable interrupt (NMI) is a hardware interrupt that lacks an associated bit-mask, so

that it can never be ignored. NMIs are often used for timers, especially watchdog timers. 

Inter-processor interrupt (IPI) is a special case of interrupt that is generated by one

processor to interrupt another processor in a multiprocessor system. 

Software interrupt is an interrupt generated within a processor by executing an instruction.

Software interrupts are often used to implement system calls because they implement a subroutine call with a CPU ring level change. 

Spurious interrupt is a hardware interrupt that is unwanted. They are typically generated by

system conditions such as electrical interference on an interrupt line or through incorrectly designed hardware. Processors typically have an internal interrupt mask which allows software to ignore all external hardware interrupts while it is set. This mask may offer faster access than accessing an interrupt mask register (IMR) in a PIC, or disabling interrupts in the device itself. In some cases, such as the x86 architecture, disabling and enabling interrupts on the processor itself act as a memory barrier, however it may actually be slower. An interrupt that leaves the machine in a well-defined state is called a precise interrupt. Such an interrupt has four properties: 

The Program Counter (PC) is saved in a known place.



All instructions before the one pointed to by the PC have fully executed.



No instruction beyond the one pointed to by the PC has been executed (that is no prohibition on instruction beyond that in PC, it is just that any changes they make to registers or memory must be undone before the interrupt happens).


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The execution state of the instruction pointed to by the PC is known.

An interrupt that does not meet these requirements is called an imprecise interrupt. The phenomenon where the overall system performance is severely hindered by excessive amounts of processing time spent handling interrupts is called an interrupt storm.

TYPES OF INTERRUPT 

LEVEL-TRIGGERED



EDGE-TRIGGERED



HYBRID



MESSAGE SIGNALED



DOORBELL

USES OF INTERRUPT Typical uses of interrupts include the following: system timers, disks I/O, power-off signals, and traps. Other interrupts exist to transfer data bytes using UARTs or Ethernet; sense keypresses; control motors; or anything else the equipment must do. A classic system timer generates interrupts periodically from a counter or the power-line. The interrupt handler counts the interrupts to keep time. The timer interrupt may also be used by the OS's task scheduler to reschedule the priorities of running processes. Counters are popular, but some older computers used the power line frequency instead, because power companies in most Western countries control the power-line frequency with a very accurate atomic clock. A disk interrupt signals the completion of a data transfer from or to the disk peripheral. A process waiting to read or write a file starts up again. A power-off interrupt predicts or requests a loss of power. It allows the computer equipment to perform an orderly shut-down. Interrupts are also used in type ahead features for buffering events like keystrokes . Department of ECE,DSCE

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NEED OF MICROCONTROLLER 

Microcontroller is a general-purpose device which has in-built CPU memory and peripherals to make it act as a mini-computer



Microcontroller has one or two operational codes for moving data from external to CPU



Microcontroller has many bit handling instructions



Microcontroller works faster than microprocessor because of rapid movement of bits within the chip



Microcontroller can function as a computer with the addition of no external parts


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POWER SUPPLY INTRODUCTION A power supply is a device that supplies electrical energy to one or more electric loads. The term is most commonly applied to devices that convert one form of electrical energy to another, though it may also refer to devices that convert another form of energy (e.g., mechanical, chemical, solar) to electrical energy. A regulated power supply is one that controls the output voltage or current to a specific value; the controlled value is held nearly constant despite variations in either load current or the voltage supplied by the power supply's energy source. Every power supply must obtain the energy it supplies to its load, as well as any energy it consumes while performing that task, from an energy source. Depending on its design, a power supply may obtain energy from: 

Electrical energy transmission systems. Common examples of this include power supplies that convert AC line voltage to DC voltage.



Energy storage devices such as batteries and fuel cells.



Electromechanical systems such as generators and alternators.



Solar power.

A power supply may be implemented as a discrete, stand-alone device or as an integral device that is hardwired to its load. Examples of the latter case include the low voltage DC power supplies that are part of desktop computers and consumer electronics devices. 

The amount of voltage and current it can supply to its load.



How stable its output voltage or current is under varying line and load conditions.



How long it can supply energy without refueling or recharging (applies to power supplies that employ portable energy sources)

.


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EXPLAINATION AND BLOCK DIAGRAM The ac voltage, typically 220V rms, is connected to a transformer, which steps that ac voltage down to the level of the desired dc output. A diode rectifier then provides a fullwave rectified voltage that is initially filtered by a simple capacitor filter to produce a dc voltage. This resulting dc voltage usually has some ripple or ac voltage variation. A regulator circuit removes the ripples and also remains the same dc value even if the input dc voltage varies, or the load connected to the output dc voltage changes. This voltage regulation is usually obtained using one of the popular voltage regulator IC units.

D.C Output

230V AC

Step down transformer

Bridge Rectifier

Filter Regulator

POWER SUPPLY


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CIRCUIT DIAGRAM OF POWER SUPPLY


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WORKING OF POWER SUPLLY

TRANSFORMER: Usually, DC voltages are required to operate various electronic equipment and these voltages are 5V, 9V or 12V. But these voltages cannot be obtained directly. Thus the a.c input available at the mains supply i.e., 230V is to be brought down to the required voltage level. This is done by a transformer. Thus, a step down transformer is employed to decrease the voltage to a required level.

RECTIFIER: The output from the transformer is fed to the rectifier. It converts A.C. into pulsating D.C. The rectifier may be a half wave or a full wave rectifier. In this project, a bridge rectifier is used because of its merits like good stability and full wave rectification.

FILTER: Capacitive filter is used in this project. It removes the ripples from the output of rectifier and smoothens the D.C. Output received from this filter is constant until the mains voltage and load is maintained constant. However, if either of the two is varied, D.C. voltage received at this point changes. Therefore a regulator is applied at the output stage.

VOLTAGE REGULATOR: As the name itself implies, it regulates the input applied to it. A voltage regulator is an electrical regulator designed to automatically maintain a constant voltage level. In this project, power supply of 5V and 12V are required. In order to obtain these voltage levels, 7805 and 7812 voltage regulators are to be used. The first number 78 represents positive supply and the numbers 05, 12 represent the required output voltage levels.


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5.5 POWER SUPPLY APPLICATION 5.5.1 Computer power supply A modern computer power supply is a switch-mode power supply that converts AC power from the mains supply, to several DC voltages. Switch-mode supplies replaced linear supplies due to cost, weight, and size improvement. The diverse collection of output voltages also has widely varying current draw requirements.

5.5.2 Welding power supply Arc welding uses electricity to melt the surfaces of the metals in order to join them together through coalescence. The electricity is provided by a welding power supply, and can either be AC or DC. Arc welding typically requires high currents typically between 100 and 350 amps. Some types of welding can use as few as 10 amps, while some applications of spot welding employ currents as high as 60,000 amps for an extremely short time. Older welding power supplies consisted of transformers or engines driving generators. More recent supplies use semiconductors and microprocessors reducing their size and weight.

5.5.3 AC Adapter A power supply that is built into an AC mains power plug is known as a "plug pack" or "plug-in adapter", or by slang terms such as "wall wart". They are even more diverse than their names; often with either the same kind of DC plug offering different voltage or polarity, or a different plug offering the same voltage. "Universal" adapters attempt to replace missing or damaged ones, using multiple plugs and selectors for different voltages and polarities. Re5lacement power supplies must match the voltage of, and supply at least as much current as, the original power supply.


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LIQUID CRYSTAL DISPLAY LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. A 16x2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred over seven segment and other multi segment LEDs. LEDs. The reasons being: LCDs are economical; easily programmable; have no limitation of displaying special & even custom characters (unlike in seven segments), animations and so on.

A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each character is displayed in 5x7 pixel matrix. This LCD has two registers, namely, Command and Data. The command register stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing it, clearing its screen, setting the cursor position, controlling display etc. The data register stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD.

LCDs are used in a wide range of applications, including computer monitors, television, instrument panels, aircraft cockpit displays, signage, etc. They are common in consumer devices such as video players, gaming devices, clocks, watches, calculators, and telephones. LCDs have replaced cathode ray tube (CRT) displays in most applications. They are available in a wider range of screen sizes than CRT and plasma displays, and since they do not use phosphors, they cannot suffer image burn-in. LCDs are, however, susceptible to image persistence. The LCD is more energy efficient and offers safer disposal than a CRT. Its low electrical power consumption enables it to be used in battery-powered electronic equipment. It is an electronically modulated optical device made up of any number of segments filled with liquid crystals and arrayed in front of a light source (backlight) or reflector to produce images in color or monochrome. The most flexible ones use an array of small pixels. The earliest discovery leading to the development of LCD technology, the discovery of liquid crystals, dates from 1888. By 2008, worldwide sales of televisions with LCD screens had surpassed the sale of CRT units.


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6.2 FEATURES 

5 x 8 dots with cursor



Built-in controller (KS 0066 or equivalent)



+5V power supply (also available for +3V)



1/16 duty cycle



B/L to be driven 1,pin 2 or pin 15,pin 16



N.V. optional optional for +3V +3V power supply supply

LCD can display a character successfully by placing the

1.

Data in Data Register

2. Command in Command Register of LCD 3. Data corresponds to the ASCII value of the character to be printed. This can be done by placing the ASCII value on the LCD Data lines and selecting the Data Register of the LCD by selecting the RS (Register Select) pin. 4.

Each and every display location is accessed and controlled by placing respective command on the data lines and selecting the Command Register of LCD by selecting the (Register Select) RS pin.

TABLE 1: Pin description for LCD

Pin

symbol

I/O

Description

1

Vss

--

Ground

2

Vcc

--

+5V power supply

3

VEE

--

Power

supply

to

control contrast


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TRANSFORMER FAULT DETECTION USING ZIGBEE 4

RS

I

RS=0

to

select

command register RS=1 to select data register 5

R/W

I

R/W=0 for write R/W=1 for read

6

E

I/O

Enable

7

DB0

I/O

The 8-bit data bus

8

DB1

I/O

The 8-bit data bus

9

DB2

I/O

The 8-bit data bus

10

DB3

I/O

The 8-bit data bus

11

DB4

I/O

The 8-bit data bus

12

DB5

I/O

The 8-bit data bus

13

DB6

I/O

The 8-bit data bus

14

DB7

I/O

The 8-bit data bus

TYPES OF DISPLAY LCD: 

Segment (or alphanumeric)



Dot matrix (or character)



Graphic LCD.


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Advantages and disadvantages of LCDs In spite of LCDs being a well proven and still viable technology, as display devices LCDs are not perfect for all applications.

6.5.1 Advantages 

Very compact and light.



Low power consumption.



No geometric distortion.



Little or no flicker depending on backlight technology.



Not affected by screen burn-in.



Can be made in almost any size or shape.



No theoretical resolution limit.

6.5.2 Disadvantages Disadvantages 

Limited viewing angle, causing color, saturation, contrast and brightness to vary, even within the intended viewing angle, by variations in posture.



Bleeding and uneven backlighting in some monitors, causing brightness distortion, especially toward the edges.



Smearing and ghosting artifacts caused by slow response times (>8 ms) and "sample and hold" operation.



Only one native resolution. Displaying resolutions either requires a video scaler, lowering perceptual quality, or display at 1:1 pixel mapping, in which images will be physically too large or won't fill the whole screen.



Fixed bit depth, many cheaper LCDs are only able to display 262,000 colors. 8-bit S-IPS panels can display 16 million colors and have significantly better black level, but are expensive and have slower response time.



Low bit depth results in images with unnatural or excessive contrast.



Input lag



Dead or stuck pixels may occur during manufacturing or through use.


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In a constant-on situation, thermalization may occur, which is when only part of the screen has overheated and looks discolored compared to the rest of the screen.



Not all LCDs are designed to allow easy replacement of the backlight.



Cannot be used with light guns/pens.



Loss of contrast in high temperature environments.

6.6 MAX 232

max 232 circuit diagram

Since the RS232 (Recommended Standard) is not compatible with today’s microprocessor and microcontrollers, we need a line driver to convert the RS232’s signal to TTL voltage levels that will be acceptable to the AT89C51 TXD and RXD pins.


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One example of such a converter is MAX 232. MAX 232 converts from Rs232 voltage levels to TTL voltage levels, and vice versa. One advantages of the MAX232 chip is that it uses a +5v power source which ,is the same as the source voltages for the 89C52. In other words with a single +5v power supply we can power both the AT89C51 and MAX232, with no need for the dual power supply that are common in many older systems. The MAX232 has 2 sets of line drivers for transferring and receiving data, as shown the line drivers used for TXD are called T1 and T2, while the line drives for RXD are designated as R1 and R2. The MAX232 is an integrated circuit that converts signals from an RS-232 serial port to signals suitable for use in TTL compatible digital logic circuits. The MAX232 is a dual driver/receiver and typically converts the RX, TX, CTS and RTS signals. The drivers provide RS-232 voltage level outputs (approx. ± 7.5 V) from a single + 5 V supply via on-chip charge pumps and external capacitors. This makes it useful for implementing RS-232 in devices that otherwise do not need any voltages outside the 0 V to + 5 V range, as power supply design does not need to be made more complicated just for driving the RS-232 in this case. The receivers re ceivers reduce RS-232 inputs (which may be as high hi gh as ± 25 V), to standard 5 V TTL levels. These receivers have a typical threshold of 1.3 V, and a typical hysteresis of 0.5 V. The later MAX232A is backwards compatible with the original MAX232 but may operate at higher baud rates and can use smaller external capacitors – 0.1 μF in place of the 1.0 μF capacitors used with the original device. The newer MAX3232 is also backwards compatible, but operates at a broader voltage range, from 3 to 5.5 V.


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GSM

7.1 INTRODUCTION INTRODUCTION GSM (Global System for Mobile Communications: originally from Groupe Special Mobile) is the world's most popular standard for mobile telephony systems. The GSM Association estimates that 80% of the global mobile market uses the standard. GSM is used by over 1.5 billion people across more than 212 countries and territories. territori es. This ubiquity means that subscribers

can

use

their

phones

throughout

the

world,

enabled

by

international roaming arrangements between mobile network operators. GSM differs from its predecessor technologies in that both signalling and speech channels are digital, and thus GSM is considered a second generation (2G) mobile phone system. This also facilitates the wide-spread implementation of data communication applications into the system. The GSM standard has been an advantage to both consumers, who may benefit from the ability to roam and switch carriers without replacing phones, and also to network operators, who can choose equipment from many GSM equipment vendors. GSM also pioneered low-cost implementation of the short message service (SMS), also called text messaging, which has since been supported on other mobile phone standards as well. The standard includes a worldwide emergency telephone number feature. Newer versions of the standard were backward-compatible with the original GSM system. For example, Release '97 of the standard added packet data capabilities by means of General Packet Radio Service (GPRS). Release '99 introduced higher speed data transmission using Enhanced Data Rates for GSM Evolution (EDGE).


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7.2 THE CELLULAR NETWORK

GSM REFERENCE MODEL

MS The MS consist of physical equipment used by the subscriber to access a PLMN for offered telecommunication services. The MS includes a Mobile Terminal and depending on the services it can support various Terminal Equipment(TE).Various type of MS, such as vehicle mounted station, portable station, or handheld station, are used. The MSs come in five power classes which which define the maximum RF power power level that the unit first part contains the hardware can transmit. Basically Basically,, an MS can be divided into two parts. The first and software to support radio and human interface functions. The second part contains terminal/user- specific data in the form of a smart card, which can effectively be considered a sort of logical terminal. The SIM card plugs in to the first part of the MS and remains in for the duration of use. Without the SIM card, the MS is not associated with any user and cannot make or receive calls (except possibly an emergency cal l if the network allows). The SIM card is issued by the mobile m obile service provider after subscription, while the first part of the MS would be


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available at retail shops to buy orrent. This type of SIM card mobility is analogous to terminal mobility, but provides a personal-mobility-like service within the GSM mobile network.

IMSI The IMSI is assigned to an MS at subscription time. It uniquely identifies a given MS. The IMSI will be transmitted over the radio interface only if necessary. The IMSI contains 15 digits and includes 

Mobile Country Code (MCC) — (MCC) — 3 digits (home country)



Mobile Network Code (MNC) — 2 digits (home GSM PLMN)



Mobile Subscriber Identification (MSIN)



National Mobile Subscriber Identity (NMSI)

TEMPORARY MOBILE SUBSCRIBER IDENTITY (TMSI ) The

TMSI

is assigned to an MS by the VLR. The MSI uniquely identifies an MS within the

area controlled by a given VLR. The maximum number of bits that can be used for the TMSI is 32

. IMEI The IMEI uniquely identifies the MS equipment. It is assigned by the equipment manufacturer. The IMEI contains 15 digits and carries 

The Type Approval Code (TAC) — (TAC) — 6 digits



The Final Assembly Code (FAC) — (FAC) — 2 digits



The serial number (SN) — (SN) — 6 6 digits



A Spare (SP) — 1 digit


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SIM The SIM carries the following information 

IMSI



Authentication Key (Ki)



Subscriber information



Access control class



Cipher Key (Kc)



TMSI



Additional GSM services



Location Area Identity (LAI)



Forbidden PLMN

BSS The BSS is the physical equipment that provides radio coverage to prescribed geographical areas, known as the cells. It contains equipment required to communicate with the MS. Functionally, a BSS consists of a control function carried out by the BSC and a transmitting function performed by the BTS. The BTS is the radio transmission equipment and covers each cell. A BSS can serve several cells because it can have multiple BTSs.The BTS contains the Transcoder Rate Adapter Unit (TRAU). In TRAU, the GSM- specific speech encoding and decoding is carried out, as well as the rate adaptation function for data. In certain situations the TRAU is located at the MSC to gain an advantage of more compressed transmission between the BTS and the MSC

NSS Department of ECE,DSCE

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The NSS includes the main switching functions of GSM, databases required for the subscribers, and mobility management. Its Its main role is to manage the communi cat ions between GSM and other

network users.Within the NSS, the switching functions are performed by the MSC.

Subscriber information relevant to provisioning of services is kept in the HLR. The other database in the NSS is the VLR. The MSC performs the necessary switching functions required for the MSs located in an associated geographical area, called an MSC area. The MSC monitors the mobility of its subscribers and manages necessary resources required to handle and update the location registration procedures and to carry out the handover functions. The MSC is involved in the interworking functions to communicate with other networks such as PSTN and ISDN. The interworking functions of the MSC depend upon the type of the network to which it is connected and the type of service to be performed. The call routing and control and echo control functions are also performed by the MSC. The HLR is the functional unit used for management of mobile subscribers. The number of HLRs in a PLMN varies with the characteristics of the PLMN. Two types of information are stored in the HLR: subscriber information and part of the mobile information to allow incoming calls to be routed to the MSC for the particular MS. Any administrative action by the service provider on subscriber data is performed in the HLR. The HLR stores IMSI, MS ISDN number, VLR address, and subscriber data (e.g., supplementary services). The VLR is linked to one or more MSCs. The VLR is the functional unit that dynamically stores subscriber information when the subscriber is located in the area covered by the VLR. When a roaming MS enters an MSC area, the MSC informs the associated VLR about the MS the MS goes through a registration procedure. The registration procedure for the MSincludes these activities: 

The VLR recognizes that the MS is from another PLMN.



If roaming is allowed, the VLR finds the MS’s HLR in its home PLMN.



The VLR constructs a Global Title (GT) from the IMSI to allow signaling from the VLR to the MS’s HLR via the PSTN/ISDN networks.



The VLR generates a Mobile Subscriber Roaming Number (MSRN) thatis used to route incoming calls to the MS.


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The MSRN is sent to the MS’s HLR.


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ZIGBEE ZigBee is a low-cost, low-power, wireless mesh network standard. The low cost allows the technology to be widely deployed in wireless control and monitoring applications. Low powerusage allows longer life with smaller batteries. Mesh networking provides high reliability and more extensive range. ZigBee chip vendors typically sell integrated radios and microcontrollers with between 60 KB and 256 KB flash memory. ZigBee operates in the industrial, scientific and medical (ISM) radio bands; 868 MHz in Europe, 915 MHz in the USA and Australia, and 2.4 GHz in most jurisdictions worldwide. Data transmission rates vary from 20 to 900 kilobits/second. The ZigBee network layer natively supports both star and tree typical networks, and generic mesh networks. Every network must have one coordinator device, tasked with its creation, the control of its parameters and basic maintenance.

TYPES OF ZIGBEE DEVICE Zigbee devices are of three types: 

ZigBee coordinator (ZC): The most capable device, the coordinator forms the root of the

network tree and might bridge to other networks. There is exactly one ZigBee coordinator in each network since it is the device that started the network originally. It stores information about the network, including acting as the Trust Center & repository for security keys. 

ZigBee Router (ZR): As well as running an application function, a router can act as an

intermediate router, passing on data from other devices. 

ZigBee End Device (ZED): Contains just enough functionality to talk to the parent node

(either the coordinator or a router); it cannot relay data from other devices. This relationship allows the node to be asleep a significant amount of the time thereby giving long battery life. A ZED requires the least amount of memory, and therefore can be less expensive to manufacture than a ZR or ZC.

USES OF ZIGBEE Department of ECE,DSCE

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ZigBee protocols are intended for embedded applications requiring low data rates and low power — individual devices consumption. The resulting network will use very small amounts of power — individual must have a battery life of at least two years to pass ZigBee certification. Typical application areas include: 

Home

Entertainment

and

Control — Home — Home

automation,

smart

lighting,

advanced

temperature control, safety and security, movies and music 

Wireless Sensor Networks — Networks — Starting with individual sensors like Telosb/Tmote and Iris from Memsic



Industrial control



Embedded sensing



Medical data collection



Smoke and intruder warning



Building automation

8.2 PIEZO BUZZER A buzzer or beeper is an audio signaling device, which may be mechanical, electromechanical, or piezoelectric. Typical uses of buzzers and beepers include alarm devices, timers and confirmation of user input such as a mouse click or keystroke. The piezo buzzer produces sound based on reverse of the piezoelectric effect. The generation of pressure variation or strain by the application of electric potential across a piezoelectric material is the underlying principle. These buzzers can be used alert a user of an event corresponding to a switching action, counter signal or sensor input. They are also used in alarm circuits.

The buzzer produces a same noisy sound irrespective of the voltage variation applied to it. It consists of piezo crystals between two conductors. When a potential is applied across these crystals, they push on one conductor and pull on the other. This, push and pull action, results in a sound wave. Most buzzers produce sound in the range of 2 to 4 kHz. The Red lead is connected to the Input and the Black lead is connected to Ground. Department of ECE,DSCE

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CIRCUIT DIAGRAM OF BUZZER

This buzzer is an piezo type audio signaling device, which has a piezo element and a oscillating circuit inside which oscillates the piezo brass base plate, which when given voltage difference produces sound of a predefined frequency. You must be aware of such sounds of buzzer like BEEP sound in many appliances.


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INTERFACING INTERFACING 16x2 LCD WITH MICROCONTROLLER A 16x2 LCD means it can display 16 characters per line and there are 2 such lines. In this LCD each

character

is

displayed

in

5x7

pixel

matrix.

This

LCD

has

two

registers.

1. Command/Instruction Register- stores the command instructions given to the LCD. A command is an instruction given to LCD to do a predefined task like initializing, clearing the screen, setting the cursor position, controlling display etc. 2. Data Register- stores the data to be displayed on the LCD. The data is the ASCII value of the character to be displayed on the LCD.

Commonly used LCD Command codes:

Hex Code 1 2 4 6 E

Command to LCD Instruction Register Clear screen display Return home Decrement cursor Increment cursor Display

80 C0 38

Force the cursor to the beginning of the 1 line nd Force cursor to the beginning of the 2 line Use 2 lines and 5x7 matrix

ON,

Cursor

ON

st

The pin description of this module is given below: Department of ECE,DSCE

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Pin configuration:

Pin

Symbol

Description

1

VSS

Ground

0V

2

VCC

Main power supply

+5 V

3

VEE

Power supply to control contrast

Contrast adjustment by providing a variable resistor through V CC

4

RS

Register Select

RS=0 to select Command Register RS=1 to select Data Register

5

R/W

Read/write

R/W=0 to write to the register R/W=1 to read from the register

6

EN

Enable

A high to low pulse (minimum 450ns wide) is given when data is sent to data pins

7

DB0

8

DB1

9

DB2

10

DB3

11

DB4

12

DB5

13

DB6

14

DB7

15

Led+

Backlight VCC

+5 V

16

Led-

Backlight Ground

0V

To display letters or numbers, their ASCII codes are sent to data pins (with

RS=1).

8-bit data pins

Also instruction

command codes are sent to these pins.


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INTERFACING GSM MODULE WITH MICROCONTROLLER

GSM is widely used mobile communication architecture used in most of the countries. This project demonstrates the interfacing of microcontrollerAT89S52 with HyperTerminal and GSM module. module . It aims to familiarize with the syntax of AT Commands and their Information Response and Result Codes. The ASCII values of characters in the Information Response, Result Codes and their syntax can be monitored by an LED array. For the basic concepts, working and operation of AT commands and GSM module refer GSM/GPRS Module. A GSM module has an RS232 interface for serial communication with an external peripheral. In this case, the transmit pin (Tx) of the computer’s Serial port is connected with the receive pin (Rx) of the GSM module’s RS-232 interface. The transmit pin (Tx) of the RS-232 of GSM module is connected to receive pin (Rx) of microcontroller’s serial transmission pin. And the serial transmit pin of the microcontroller is connected to the receive pin of the computer’s Serial port.


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SOFTWARE USED

INTRODUCTION TO EMBEDDED ‘C’: Embedded is the extension of c language. Embedded C is a compiler which constitutes more build in function. By using c language it is easy to connect the comport easily. The embedded c compiler has the bias function to connect the comport. The command from fussing kit sends from the c program according to user wish.

HI-TEC ‘C’ HI-TEC HI-TEC ‘C’ is a set of software that translates the program written in the C language in to executable machine code versions are available which compile the program for the operation under the host operating system. Some of the Hi-Tec features are 



A simple batch file will compile, assemble and link entire program The compiler perform strong type checking and issues warning about various constructs which may represent programming errors



The generated code is extremely small and fast in execution



A full run time library is provided implementing all standard c input/ output and other function



The source code for all run time routine is provided



A power full general purpose macro-assembler is provided



Programs may be generated to execute under the host operating system or customized for installation in ROM.


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PROBLEMS RESOLVED BY THE SYSTEM: Early detection of failures in electric power transformers can be succeeded with neural modeling and the Local Statistical Approach to Fault Diagnosis • Neuro-fuzzy Neuro-fuzzy networks are proposed for modeling the dynamics of a critical parameter of the power transformer known as Hot Spot Temperature. • The output of the neural-fuzzy neural-fuzzy network is compared to the output of the exact model (Representing the fault-free condition of the transformer) and residuals are generated • The residuals undergo statistical signal processing according to a fault detection and isolation algorithm (Local Statistical Approach to FDI) • The Local Statistical Approach consists of the global test for fault detection and of the sensitivity and min-max tests for fault isolation • If a fault threshold defined by the FDI FD I algorithm is exceeded then deviation from normal operation can be detected at its early stages and an alarm can be launched • The proposed FDI approach can be applied to other components of the power grid, e.g power generators, etc.

ADVANTAGES: 

Detecting signs of failure conditions



Reducing probability of catastrophic failure



Reducing unscheduled outages



Addressing specific unit or population issues



Loading T&D equipment for maximum efficiency



Deferring upgrade capital costs



Managing & extending the life of equipment



Reducing Observation & Measurement costs.


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CONCLUSION Transformers are static devices, totally enclosed and generally oil immersed. Therefore chances of faults occurring on them are very rare. However the consequences of even a rare fault may be very serious unless the transformer is quickly disconnected from the system. This necessitates to provide adequate automatic protection for transformers against possible faults. The major faults on transformers occur due to short circuits in the transformers or in their connections. The basic system used for protection against these faults is the differential relay Protection of power transformer is a big challenge nowadays. By the help of microcontroller-based relay, protection of transformer is performed very quickly and accurately. This system provides a better and safer protection than the other methods which are currently in use. The advantages of this system over the current methods in use are fast response, better isolation and accurate detection of the fault. This system overcomes the other drawbacks in the existing systems such as maintenance and response time.


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Transformer Fault Detection Using Zigbee and GSM

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