Transformer failure prevent

Substation
Monitoring
and
Control
System
With GSM
Modem
July 12
2013
VITTHAL ADAHV MANOJ VIKRANT PUNE

Substation Monitoring and Control System With GSM Modem
Chapter 01
Introduction
Distribution transformers have a long service life if they are operated under good
and rated conditions. However, their life is significantly reduced if they are overloaded,
resulting in unexpected failures and loss of supply to a large number of customers thus
effecting system reliability. Overloading and ineffective cooling of transformers are the
major causes of failure in distribution transformers.
The fault free operation of power transformers is a factor of major economic
importance and safety in power supply utilities and industrial consumers of electricity.
Distribution transformers have a long service life if they are operated under good and
rated conditions. However, their life is significantly reduced if they are overloaded,
resulting in unexpected failures and loss of supply to a large number of customers thus
effecting system reliability. Overloading and ineffective cooling of transformers are the
major causes of failure in distribution transformers.
Distribution transformers are currently monitored manually where a person
periodically visits a transformer site for maintenance and records parameter of
importance. This type of monitoring cannot provide information about occasional
overloads and overheating of transformer oil and windings. All these factors can
significantly reduce transformer life. Our system is designed based upon online
monitoring of key operational parameters of distribution transformers can provide
useful information about the health of transformers which will help the utilities to
optimally use their transformers and keep the asset in operation for a longer period. This
project will help us to identify problems before any catastrophic failure, thus resulting in
a long life service for transformers. It is also has the advantages of significant cost
savings and greater reliability.
Page 1

Chapter 02
Literature Survey
Electricity is an extremely handy and useful form of energy. It plays an ever
growing role in our modern industrialized society. A power system consists of
components such as generators, lines, transformers, loads, switches and compensators.
However, a widely dispersed power sources and loads are the general configuration of
modern power systems. Electric power systems can be divided into two sub-systems,
namely, transmission systems and distribution systems. The main process of a
transmission system is to transfer electric power from electric generators to customer
area, whereas a distribution system provides an ultimate link between high voltage
transmission systems and consumer services. In other words, the power is distributed to
different customers from the distribution system through feeders, distributors and
service mains. Supplying electricity to consumers necessitates power generation,
transmission, and distribution. Initially electric power is generated by using electric
generators such as: nuclear power generators, thermal power generators and hydraulic
power generators and then transmitted
Through transmission systems using high voltage, Power departs from the
generator and enters into a transmission substation, where huge transformers convert
the generator's voltage to extremely high voltages (155kV to 765 kV) for long-distance
(up to about 300 miles) transmission. Then, the voltage level is reduced using
transformers and power is transferred to customers through electric power distribution
systems. Power starts from the transmission grid at distribution substations where the
voltage is stepped-down (typically to less than 10kV) and carried by
Smaller distribution lines to supply commercial, residential, and industrial users.
Novel electric power systems encompassing of power transmission and distribution
grids consist of copious number of distributed, autonomously managed, capital-intensive
assets. Such assets comprise: 1.) power plants, 2.) transmission lines, 3.) transformers,
and 4.) protection equipment. Electric utility substations are used in both the
transmission and distribution system and operate independently to generate the
electricity. A typical substation facility consists of a small building with a fenced-in yard
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that contains transformers, switches, voltage regulators, and metering equipment that
are used to adjust voltages and monitor circuits.
A reliable and efficient process of these networks alone is not very significant
when these electricity systems are pressed to their parameters of its performance, but
also under regular operating conditions. Generators and loads are some components that
coerce the continuous dynamic behaviour
The distance between the Generators and loads may be in terms of hundreds of
miles. Hence, the amount of huge power exchanges over long distances has turned out as
a result of the lack of quality of the electric power. During the earlier development stages
the issues on quality of power were not frequently reported. Quality of supply is a
mixture of both voltage quality and the non-technical features of the interaction from the
power network to its customers. Demanding the quantity of power being delivered at the
user side has raised the alarm due to the increase in demand of electricity in the
customer’s side. The power generated at the main stations is transported hundreds of
miles using transmission lines before they reach the substations. A huge amount of
power is lost during the transportation of the generated power which leads to the
reduction in the quantity of power received at the substations. Also the electric lines
users have identified that the number of drawbacks caused by electrical power quality
variations are increasing rapidly. These variations have already existed on electrical
systems, but recently they are causing serious problems. Therefore, measurements must
be acquired either from one end or from both the ends of a faulted line.
Distribution transformers are currently monitored manually where a person
periodically visits a transformer site for maintenance and records parameter of
importance. This type of monitoring cannot provide information about occasional
overloads and overheating of transformer oil and windings. All these factors can
significantly reduce transformer life. A number of techniques are currently being used
for offline as well as online monitoring of power transformers. In other conventional
system, the protection relay equipment serves as a server, the PC in an office serves as a
client, and the PC and relay equipment communicate by 1 to 1. We can perform and
follows some personal computer in an office; download of the voltage and current data
stored in the relay equipment when relay equipment is activated by some power failure;
checking and changing the setting values of the protection relay; detecting an abnormal
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occurrence and the relay activation caused by power system faults. As an excellent
information terminal which can acquire the real time data from a power system.
It is important that the information in a relay can be easily accessed from an office
and of which mechanism for performing the function described above is simple. The PC
and protection relay equipment are connected with the relations of 1 to 1, and while
operating this system, it is necessary that the operator looks at the PC browser
continually all the time. Moreover, in order to acquire information from a numbers of
relay equipment, an operator must specify the address of each relay to access them in
turn, which is complicated and time consuming. Furthermore, in this system, even when
relays are connected within the same network, the relays cannot communicate and
cooperate with each other. That is to say, relay equipment works only as a server
providing data to PCs located in the remote office.
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Chapter 03
Problem statement and solution
The purpose of this project will be to develop a design and to propose a plan to
design hardware for protection purpose, increasing life and reliability of the
Transformer to measure the output parameter and controlling them using Control
System.
In our project we are going to
 Measure the temperature of transformer windings, output current and voltage
automatically. 

 Send all the data through GSM system. 
This system will help us to understand and develop a prototype type model which
will be used as a system used by people to fulfill their requirements for prevention of
damage.
Page 5

Chapter 04
System specification
In our project to achieve specified solution we required following system
specifications
 Input:230V,50Hz AC Supply 

 Output Voltage:230V +/-10% 

 Output Current:0 to 1A 

 Winding Temperature:55°C 

 Micro-controller LPC2148 3.3volt supply 

 GSM Bandwidth:850MHz-1900MHz 

 Display Module: -3 to -25,+3 to +25 

 Current sensor WCS2720 operating voltage:- 3 - 12volts 

 Temperature sensor LM35 operating voltage:- 4 to 30 V 
Page 6

Chapter 05
System Implementation
We are going to design a system based on microcontroller LPC2148 that monitors
and controls the voltage, current and temperature of a distribution transformer present
in a substation. The monitored output will be displayed on a PC at the main station that is
at a remote place, through the GSM Modem.
5.1 Block Diagram and Description
Following fig. shows the block diagram representation of the system.
Fig5.1:Block Diagram
Transformer which is a device that transfers electrical energy from one circuit to
another through inductively coupled conductors the transformer's coils. A varying
current in the first or primary winding creates a varying magnetic flux in the
transformer's core, and thus a varying magnetic field through the secondary winding.
This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in
the secondary winding.
Page 7

For monitoring the power transformer we used various sensors such as Voltage
transformer for measuring output voltage of power transformer, Current sensor for
measuring load current, Temperature sensor for measuring temperature of transformer
winding.
The LPC2148 microcontroller monitors and controls the voltage, current and
temperature of a distribution transformer present in a substation. The monitored output
will be displayed on a PC at the main station that is at a remote place, through GSM
Communication. The parameters monitored at the distribution transformer are
compared with the rated values of the transformer. Additionally the breakdowns caused
due to the overload and high voltage are sensed and the signals are transmitted to the
main station using GSM communication.
The LCD Display is used to display the output of various sensors through the
microcontroller.
5.2 Circuit Diagram & Description.
Fig5.2:Circuit Diagram
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From Fig5.2 It consist of power transformer, current sensor, voltage transformer,
temperature sensor, micro-controller (LPC2148), LCD display, GSM modem.
5.2.1 Power Supply
Regulated power supply consists of transformer, rectifier, filter and voltage
regulator (IC7805) as shown in circuit diagram. Transformer, rectifier and filter referred
as unregulated power supply, its output is connected to input of voltage regulator
IC7805.The voltage regulator is specially design circuit to keep output voltage constant.
The regulated output voltage is used to power microcontroller unit, it acts as a load on
voltage regulator.
Features of IC 7805
 Output current in excess of 1A. 

 No external components required. 

 Internal thermal overload protection. 

 Internal short circuit current limiting. 

 Package in plastic case. S 

5.2.2 Transformer
A transformer is a device that transfers electrical energy from one circuit to
another through inductively coupled conductors—the transformer's coils. A varying
current in the first or primary winding creates a varying magnetic flux in the
transformer's core, and thus a varying magnetic field through the secondary winding.
This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in
the secondary winding. This effect is called mutual induction. If a load is connected to the
secondary, an electric current will flow in the secondary winding and electrical energy
will be transferred from the primary circuit through the transformer to the load. In an
ideal transformer, the induced voltage in the secondary winding (VS) is in proportion to
the primary voltage (VP), and is given by the ratio of the number of turns in the
secondary (NS) to the number of turns in the primary (NP) as follows:
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By appropriat1e selection of the ratio of turns, a transformer thus allows an alternating
current (AC) voltage to be "stepped up" by making NS greater than NP, or "stepped down"
by making NS less than NP.
Fig5.3:Distribution Transformer
5.2.3 Voltage Transformer
For measuring the output voltage of power transformer we use the voltage
transformer. It is basically the step down transformer which has turn’s ratio less than
power transformer. Using the following relationship of Voltage and turn’s ratio of
transformer we can calculate output voltage of power transformer.
Where VP=Input voltage from power transformer to voltage
transformer. Vs=Output voltage of voltage transformer.
Np=Number of turns of primary windings of voltage transformer.
Ns=Number of turns of secondary windings of voltage transformer.
Page 10

5.2.4 Thermal Sensors LM35-
+Vss GND
Fig 5.4: LM35 Sensor
The LM35 series are precision integrated-circuit temperature sensors, with an
output voltage linearly proportional to the Centigrade temperature. Thus the LM35 has
an advantage over linear temperature sensors calibrated in ° Kelvin, as the user is not
required to subtract a large constant voltage from the output to obtain convenient
Centigrade scaling. The LM35 does not require any external calibration or trimming to
provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full −55°C to
+150°C temperature range.The low output impedance, linear output, and precise
inherent calibration of the LM35 make interfacing to readout or control circuitry
especially easy. The device is used with single power supplies, or with plus and minus
supplies. As the LM35 draws only 60 μA from the supply, it has very low self-heating of
less than 0.1°C in still air. The LM35 is rated to operate over a −55°C to +150°C
temperature range, while the LM35C is rated for a −40°C to +110°C range (−10° with
improved accuracy).
Features:
• Calibrated Directly in ° Celsius (Centigrade)
• Linear + 10 mV/°C Scale Factor
• 0.5°C Ensured Accuracy (at +25°C)
• Rated for Full −55°C to +150°C Range
• Suitable for Remote Applications
• Low Cost Due to Wafer-Level Trimming
• Operates from 4 to 30 V
• Less than 60-μA Current Drain
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• Low Self-Heating, 0.08°C in Still Air
• Nonlinearity Only ±¼°C Typical
• Low Impedance Output, 0.1 Ω for 1 mA Load
5.3 Current Sensor WCS2720
The Winson WCS2720 provides economical and precise solution for both
DC and AC current sensing in industrial, commercial and communications
systems. The unique package allows for easy implementation by the customer.
Typical applications include motor control, load detection and management, over-
current fault detection and any intelligent power management system etc. The WCS2720
consists of a precise, low-temperature drift linear hall sensor IC with temperature
compensation circuit and a current path with 0.4 mΩ typical internal conductor
resistance. This extremely low resistance can effectively reduce power loss, operating
temperature and increase the reliability greatly. Applied current flowing through this
conduction path generates a magnetic field which is sensed by the integrated Hall IC and
converted into a proportional voltage. The terminals of the conductive path are
electrically isolated from the sensor leads. These allow the WCS2720 current sensor to
be used in applications requiring electrical isolation without the use of opto-isolators or
other costly isolation techniques and make system more competitive in cost.
Fig 5.5:WCS2720 Sensor
Features:
 Low noise analog signal path 

 0.4 mΩ internal conductor resistance 
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 Output voltage proportional to AC and DC current z Min. sensing current 0~20A
at 5V voltage supply High Sensitivity 64 mV/A
 Wide operating voltage range 3.0~12 V. z Low operating current 3mA 

 Nearly zero magnetic hysteresis. 

 Ratiometric output from supply voltage 


5.4 Microcontroller LPC2148
The LPC2148 microcontrollers are based on a 32/16 bit ARM7TDMI-S CPU with
real-time emulation and embedded gateways and protocol converters, soft modems,
voice recognition and low end imaging, providing both large buffer size and high
processing power. Various 32-bit timers, single or dual 10-bit ADC(s), 10-bit DAC, PWM
channels and 45 fast GPIO lines with up to nine edge or level sensitive external interrupt
pins make these microcontrollers particularly 1suitable for industrial control and
medical systems. Trace support that combines the microcontroller with embedded high
speed flash memory ranging from 32 KB to 512 KB. A 128-bit wide memory interface
and unique accelerator architecture enable 32-bit code execution at the maximum clock
rate. For critical code size applications, the alternative 16-bit Thumb mode reduces code
by more than 30 % with minimal performance penalty. Due to their tiny size and low
power consumption, LPC21418are ideal for applications where miniaturization is a key
requirement, such as access control and point-of-sale. A blend of serial communications
interfaces ranging from a USB 2.0 Full Speed device, multiple UARTS, SPI, SSP to I2Cs and
on-chip SRAM of 8 KB up to 40 KB, make these devices very well suited for
communication
The controller consists of a sensing unit which collects the essential parameters
such as current, voltage and the winding temperature within the distribution
transformer. The digital display connected to the processing unit displays corresponding
parameter values at the substation for any technical operations. The controller also
senses the overload and high current flow conditions in the internal windings that may
lead to breakdown of the corresponding unit. The microcontroller is programmed in
such a manner so as to continuously scan the transformer and update the parameters at
a particular time interval. The parameter values sensed by the microcontroller are
transmitted through the GSM transmitter connected to the microcontroller unit.
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Fig 5.6: Pin configuration of LPC2148
Features
• 16/32-bit ARM7TDMI-S microcontroller in a tiny LQFP64 package.
• 8 to 40 kB of on-chip static RAM and 32 to 512 kB of on-chip flash program
memory
• In-System/In-Application Programming (ISP/IAP) via on-chip boot-loader
software.
Single flash sector or full chip erase in 400 ms and programming of 256 bytes in 1
ms.
• Single 10-bit D/A converter provides variable analog output.
• Two 32-bit timers/external event counters.
• Low power real-time clock with independent power and dedicated 32 kHz clock
input.
• Multiple serial interfaces including two UARTs.
• Vectored interrupt controller with configurable priorities and vector addresses.
Page 14

5.5 GSM
GSM stands for Global System for Mobile Communications and is the most
popular standard for mobile phones in the world. GSM phones are used by over a billion
people across more than 200 countries. The ubiquity of the GSM standard makes
international roaming very common with "roaming agreements" between operators.
GSM differs from its predecessors most significantly in that both signalling and speech
channels are digital, which means that it is seen as a second generation (2G) mobile
phone system. This fact has also meant that data communication was built into the
system very early. GSM is an open standard which is developed by the 3GPP. The key
advantage of GSM systems from the point of view of the consumer has been early
delivery of new services at low costs, for example text messaging was developed first for
GSM, whilst the advantage for network operators has been the low infrastructure cost
which is caused by open competition. Disadvantage is that GSM's radio network is based
on TDMA technology, which is considered less than CDMA based systems. The GSM
standard continues to develop and packet data capabilities were added in the Release '97
version of the standard with GPRS. Higher speed data transmission has been introduced
by providing a new modulation scheme with EDGE.
.
Fig 5.7: GSM Module
Page 15

5.5.1 GSM security
GSM was also been designed for a moderate level of security. The system is
designed to authenticate the subscriber using shared secret cryptography.
Communications between the subscriber and the base station can be encrypted. GSM's
original encryption algorithm has been broken, but, in principle at least, the system
supports multiple algorithms so operators may replace that cipher with a stronger one.
5.5.2 Radio interface
GSM employs TDMA between stations on a frequency duplex pair of radio
channels, with slow frequency hopping between channels. GSM uses also SDMA and
FDMA. It uses a modified Gaussian shift-key modulation. This modulation scheme
inherently gives mobile units better battery life because it encodes the data by varying
the frequency of the signal, not the amplitude. This allows amplifiers to be run at high
power levels without distorting the transmitted data(good power efficiency). However,
the tradeoff is that each user consumes more bandwidth, which means that more
spectrum is necessary to serve the same number of users than with other modulation
schemes (poor spectral efficiency).
5.5.3 GSM frequency ranges
GSM exists in four main versions, based on the band used: GSM-900, GSM-1800,
GSM-850 and GSM-1900. GSM-900 (900 MHz) and GSM-1800 (1.8 GHz) are used in most
of the world, excluding the United States and Canada. The United States and Canada use
GSM-850 and GSM-1900(1.9 GHz) instead, since in the U.S. the 900 and 1800 bands were
already allocated. GSM-850 is also sometimes called GSM-800.
Another less common GSM version is GSM-450 (450 MHz), sometimes also called
GSM-400. It uses the same frequency as and can co-exist with old analog NMT systems.
NMT is a first generation (1G) mobile phone system which was in some widespread
usage in Europe and other areas. Widespread is of course a relative term since the boom
of mobile phones started later with GSM. GSM-900 uses 890 - 915 MHz to send
information from the Mobile Station to the Base Transciever Station (uplink) and 935 -
960 MHz for the other direction (downlink), providing 124 RF channels spaced at 200
kHz. Duplex spacing of 45 MHz is used.
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GSM-1800 uses 1710 - 1785 MHz to send information from the Mobile Station to
the Base Transciever Station (uplink) and 1805 - 1880 MHz for the other direction
(downlink), providing 299 channels. Duplex spacing is 95 MHz.
5.6 Crystal Oscillator
Crystal Oscillator forms the heart of the microcontroller. Crystal oscillators are
oscillators where the primary frequency determining element is a quartz crystal.
Because of the inherent characteristics of the quartz crystal the crystal oscillator may be
held to extreme accuracy of frequency stability. Temperature compensation may be
applied to crystal oscillators to improve thermal stability of the crystal oscillator. Crystal
oscillators are usually, fixed frequency oscillators where stability and accuracy are the
primary considerations.
5.7 LCD Display-
LCD displays are set up as 16 to 20 characters by 1 to 4 lines and noted as 16*2,
20*2, 16*4, 20*4 etc. Following figure lcd1.0 shows the basic pin diagram of 16*2 LCD
display.
Fig 5.8: LCD Display
The LCD panel's Enable and Register Select is connected to the Control Port. The
Control Port is an open collector / open drain output. While most Parallel Ports have
internal pull-up resistors, there is a few which don't. Therefore by incorporating the two
10K external pull up resistors, the circuit is more portable for a wider range of
computers, some of which may have no internal pull up resistors.
We make no effort to place the Data bus into reverse direction. Therefore we hard
wire the R/W line of the LCD panel, into write mode. This will cause no bus conflicts on
the data lines. As a result we cannot read back the LCD's internal Busy Flag which tells us
Page 17

if the LCD has accepted and finished processing the last instruction. This problem is
overcome by inserting known delays into our program. The 10k Potentiometer controls
the contrast of the LCD panel. Nothing fancy here. As with all the examples, I've left the
power supply out. We can use a bench power supply set to 5v or use an onboard +5
regulator. Remember a few de-coupling capacitors, especially if we have trouble with the
circuit working properly.
General specifications are as follows
 Drive method: 1/16 duty cycle 

 Display size: 16 character * 2 lines 

 Character structure: 5*8 dots. 

 Display data RAM: 80 characters (80*8 bits) 

 Character generate ROM: 192 characters 

 Character generate RAM: 8 characters (64*8 bits) 

 Both display data and character generator RAMs can be read from MPU. 
5.7.1 Display Data RAM (DDRAM)
Display data RAM (DDRAM) is where you send the characters (ASCII code) you want to
see on the LCD screen. It stores display data represented in 8-bit character codes. Its
capacity is 80 characters (bytes). Below you see DD RAM address layout of a 2*16 LCD.
In the
above memory map, the area shaded in black is the visible display (For 16x2 display).
For first line addresses for first 15 characters is from 00h to 0Fh. But for second line
address of first character is 40h and so on up to 4Fh for the 16th character. So if you
want to display the text at specific positions of LCD, we require to manipulate address
and then to set cursor position accordingly.
5.7.2 RAM (CGRAM)- Character Generator User defined character RAM
In the character generator RAM, we can define our own character patterns
by program. CG RAM is 64 bytes, allowing for eight 5*8 pixel, character patterns to be
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defined. However how to define this and use it is out of scope of this tutorial. So I will not
talk any more about CGRAM.
5.7.3 Registers
The HD44780 has two 8-bit registers, an instruction register (IR) and a data
register (DR). The IR stores instruction codes. The DR temporarily stores data to be
written into DDRAM or CGRAM and temporarily stores data to be read from DDRAM or
CGRAM. Data written into the DR is automatically written into DDRAM or CGRAM by an
internal operation. These two registers can be selected by the register selector (RS)
signal. See the table below
RS R/W Operation
IR write as an internal operation (display clear, etc.)
0 0
Read busy flag (DB7) and address counter (DB0 to DB6)
0 1
DR write as an internal operation (DR to DDRAM or CGRAM)
1 0
DR read as an internal operation (DDRAM or CGRAM to DR)
1 1
Table no.1:Register Selection
Page 19

Chapter 06
Hardware Implementation
Hardware implementation of our system includes design of power supply, interfacing
of GSM, Interfacing of LM35, interfacing of WCS2720 and interfacing of voltage
transformer with LPC2148.
6.1 Power Supply
The circuit diagram of power supply which gives output of 5V, as only that much is
required for microcontroller. Its circuit diagram and designing calculation are given
below.
Figure: 6.1: +5 V DC Regulated Power Supply
The +5 volt power supply is based on the commercial 7805 voltage regulator IC. This IC
contains all the circuitry needed to accept any input voltage from 8 to 18 volts and
produce a steady +5 volt output, accurate to within 5% (0.25 volt). It also contains
current-limiting circuitry and thermal overload protection, so that the IC won't be
damaged in case of excessive load current. The advantage of a bridge rectifier is you
don’t need a centre tap on the secondary of the transformer. A further but significant
advantage is that the ripple frequency at the output is twice the line frequency (i.e. 50Hz)
and makes filtering somewhat easier. The use of capacitor c1 and c2 is to make signal
ripple free. The capacitor used before the regulator is to make ac signal ripple free and
then later which we are using is for safety, if incase there is a ripple left after regulating,
then c2 will remove it.
Page 20

6.1.1 Design Of Step Down Transformer
The following information must be available to the designer before he commences
for the design of transformer.
1) Power Output.
2) Operating Voltage.
3) Frequency Range.
4) Efficiency and Regulation.
6.1.2 Size Of Core
Size of core is one of the first considerations in regard of weight and volume of
transformer. This depends on type of core and winding configuration used. Generally
following formula is used to find area or size of core.
Ai = Area of cross - section in Sq. cm. and
P1 = Primary voltage.
In transformer P1 = P2
For our project we required +5V regulated output. So transformer
secondary rating is 9V, 500mA.
So secondary power wattage is,
P2 = 9 x 500 x 10
-3 w.
= 4.5w.
So
Generally 10% of area should be added to core to accommodate all turns for low
Iron losses and compact size.
So Ai = 2.88.

6.1.3 Turns Per Volt
Turns per volt of transformer are given by relation
Here,
f is the frequency in Hz
Bm is flux density in Wb/m2
Ai is net area of cross section.
Generally lower the flux density better be quality of transformer.
For project for 50 Hz the turns per Volt for 0.91 Wb/m
2 from above table.
Turns per Volt =
=
 17
Thus for Primary winding = 220 × 17 = 3800.
6.1.4 Rectifier Design
Fig 6.2: Rectifier Output

R.M.S. Secondary voltage at secondary of transformer is 9V.
So maximum voltage Vm across Secondary is
= Rms. Voltage ×
= 9 × 2
= 12.72
D.C. O/p Voltage at rectifier O/p is
=
= 8.10 V
PIV rating of each diode is
PIV = 2 Vm.
= 2 × 12.72
= 25.44 V
& maximum forward current which flow from each diode is 500mA.
So from above parameter we select diode IN 4007 from diode selection manual.
& for Secondary winding = 9 × 17 = 153.
6.2 Interfacing LM35 with LPC2148
Read the temperature in LPC2148 Tyro Board from temperature sensor LM35.
The ARM7 LPC2148 Tyro board uses the ADC pin for reading temperature from
temperature sensor LM35. The reading output is displayed into PC through UART1.The
10 bit ADC used for reading the temperature from LM35. Basic clocking for the A/D
Page 23

converters is provided by the VPB clock. A programmable divider is included in each
converter, to scale this clock to the 4.5 MHz (max) clock needed by the successive
approximation process. A fully accurate conversion requires 11 of these clocks.
The LM35 does not require any external calibration or trimming to provide typical
accuracies of ± 1⁄4˚C at room temperature and ± 3⁄4˚C over a full −55 to +150˚C
temperature range. Low cost is assured by trimming and calibration at the wafer level.
The LM35’s low output impedance, linear output, and precise inherent calibration make
interfacing to readout or control circuitry especially easy. The LM35 is rated to operate
over a −55˚ to +150˚C temperature range. The LPC2148 contains two analog to digital
converters. These converters are single 10-bit successive approximation analog to digital
converters. While ADC0 has six channels, ADC1 has eight channels. Measurement range
of 0V to VREF (2.0 V VREF VDDA).
In our project we designed the interfacing circuit with ADC0 of LPC2148 As
shown in fig 6.2 the LM35’s pin no.1 (VDD) is connected to +5V power supply, pin no.2
(DO) is connected to pin 28 of port 0 of microcontroller LPC2148 i.e. AD0.1 - ADC 0, input
1. And pin no.3 (GND) is connected to ground. Since the ADC0 has 10 bit resolution with
maximum 1024(2^10) steps and the LM35 produces 10mV for every degree to produce
a Vout of 10240mV (10.24V) for full scale Vout of 10.24V for ADC0, we need to set
Vref=10.24V. But according to measurement range of ADC it is not possible and we are
Page 24

going to measure maximum temperature up to 34˚C so we don’t have any issue with
corresponding condition. Here we set Vref =3.3V.
6.3 Interfacing WCS2720 & Voltage transformer with LPC2148
Read the current in LPC2148 Tyro Board from current sensor WCS2720
connected to port0 i.e. P0.30 and The voltage transformer through pot connected to the
P0.29 of the LPC2148.
6.4 Interfacing Of LCD with LPC2148
The LCD used for communication purpose is connected to port 1(P1.16 – P1.22)
Of the LPC2148.

Chapter 07
Software Implementation
Software implementation of our system includes algorithm and flowchart of the system.
7.1 Algorithm:
Algorithm for the different parts of system is given below
7.1.1 For displaying the parameter:
1. Start.
2. Initialize the system.
3. Sensor continuously sends data to ADC.
4. Wait for conversion time.
5. Digital data is given to processor.
6. Processor manipulates the data.
7. Readings are shown in LCD
7.1.2 For sending message:
1. Start.
2. Initialize GSM module.
3. Monitoring the current status of parameters.
4. IF parameters are greater than threshold values o
YES, then processor sends commands to GSM. o
No, Repeat step 3
5. Message will go to the authorized phone number given in MSEB centre.

7.2 Flowchart:
START
Fig 7.1 Flowchart for the system

Chapter 08
Result Analysis
To test the effectiveness of the developed system, an experiment is designed for
small distribution transformer. For testing purpose we connect the some load to the
output of transformer. Firstly we set the threshold values for load current, line voltage
and winding temperature. If these values exceed the threshold then we observe the
following results as per our system design.
Sr.
Threshol Action Taken
Sensor d
No
If the values If the values
Level <=Threshold >Threshold
1
Current sensor
800mA Message does not send Message send
WCS2720
2
Temperature sensor
50°C Message does not send Message send
LM35
3 Voltage Transformer 240V Message does not send Message send

Chapter09
Conclusion
Due to increased load of power system it is necessary to maintain communication
between transformer health and operator so that any kind of abnormality doesn’t cause
large harm to the system. All data transfer must be important to keep transformer
healthy and power system reliability too. Use of Automation system makes such things
possible very easily. Also automation system has less manual operation more accurate.
Use of GSM technique provides speed of communication with distance independentancy
also it enables bidirectional communication as a message.
age 30

Chapter10
Future Enhancements
In future we can use this project in several applications by adding additional
components to this project. This project can be extended by using GPRS technology, which
helps in sending the monitored and controlled data to any place in the world. The
temperature controlling systems like coolant can also use in places where temperature
level should be maintained.
By connecting wireless camera in industries, factories etc we can see the entire
equipments from our personal computer only by using GPRS and GPS technology. The
monitoring and controlling of the devices can be done from the personal computer and we
can use to handle so many situations.
1

Publications
[1] “Transformer Health Condition Monitoring Through GSM Technology” in
Marathwada Mitra Mandal College Of Engineering,Pune on the date 18th Feb 2014
[2] “ Transformer Health Condition Monitoring Through GSM Technology” in College
Of Engineering on the date 27,28,29th Sep 2013
Page 32

References
[1] Jyotishman Pathak, Yuan Li, Vasant Honavar and James D. McCalley, "A Service-
Oriented Architecture for Electric Power Transmission System Asset
Management", In ICSOC Workshops, pp: 26-37, 2006.
[2] B. A. Carreras, V. E. Lynch, D. E. Newman and I. Dobson, "Blackout Mitigation
Assessment in Power Transmission Systems", Hawaii International Conference on
System Science, January 2003.
[3] Xiaomeng Li and Ganesh K. Venayagamoorthy, "A Neural Network Based Wide
Area Monitor for a Power System", IEEE Power Engineering Society General
Meeting, Vol. 2, pp: 1455-1460, 2005.
[4] Argonne National Laboratory, "Assessment of the Potential Costs and Energy
Impacts of Spill Prevention, Control, and Countermeasure equirements for
Electric Utility Substations", Draft Energy Impact Issue Paper, 2006.
[5] R.R. Negenborn, A.G. Beccuti, T. Demiray, S. Leirens, G. Damm, B. De Schutter and
M. Morari, "Supervisory hybrid model predictive control for voltage stability of
power networks", Proceedings of the 2007 American Control Conference, New
York, New York, pp: 5444-5449, July 2007.
[6] Daponte, M. Di Penta and G.Mercurio, "TRANSIENTMETER: A Distributed
Measurement System for Power Quality Monitoring", IEEE Transactions on Power
Delivery, Vol. 19, Issue. 2, pp: 456-463, 2004.
[7] G. Pudlo, S. Tenbohlen, M. Linders and G. Krost, "Integration of Power
Transformer Monitoring and Overload Calculation into the Power System Control
Surface", IEEE/PES Transmission and Distribution Conference and Exhibition, Vol.
1, pp: 470-474 Asia Pacific, 2002.
[8] Zhi-Hua Zhou, Yuan Jiang, Xu-Ri Yin, and Shi-Fu Chen, "The Application of
Visualization and Neural Network Techniques in a Power Transformer Condition
Monitoring System", In: T. Hendtlass and M. Ali eds. Lecture Notes in Artificial
Intelligence 2358, Berlin: Springer- Verlag, pp: 325-334, 2002. Microcontroller
Based Substation Monitoring and Control System with Gsm Modem
www.iosrjournals.org

[9] Overbye and Weber, "Visualization of power system data", in proceedings of 33rd
Annual Hawaii International Conference on System Sciences, January 2000.
[10] Johan Driesen , Geert Deconinck, Jeroen Van Den Keybus, Bruno Bolsens, Karel De
Brabandere, Koen Vanthournout, Ronnie Belmans, "Development of a
Measurement System for Power Quantities in Electrical Energy Distribution
Systems", in proceedings of IEEE Instrumentation and Measurement Technology
Conference, Anchorage, AK, USA, May 2002.
Books
[1] “Power Transformers (Principles and Applications)”
John J. Winders.
[2] “Microcontrollers Architecture, Programming, Interfacing and System Design”
Raj kamal
[3] “Embedded Systems” – Mazidi and Mazidi.
Thesis
[1] Amit sachan “Microcontroller based substation monitoring & Control system with
GSM modem”

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