Essay: Universal Monitoring & Protection System

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  • Universal Monitoring & Protection System
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Chapter :1 Introduction
1.1 Introduction:-
Three phase and Single phase equipment protection is a branch of electrical power engineering that deals with the protection of electrical power systems from faults through the isolation of faulted parts from the rest of the electrical network. The objective of a protection scheme is to keep the equipment stable by cleared the fault, whilst leaving as much of the network more and as possible still in operation. Thus, protection schemes must important in the operation electrical equipment.
1.2 What is System Protection?
System protection is the art and science of find problems with power system components and cleared the faulty part which connected to healthy part.
1.3 Purpose of System Protection:-
• Protect the public against the fault.
• Increase system stability
• Reduces damage to equipment
• Protect against overloads and over current.
1.4 In these system protection following parameter are monitored:-
• Over Voltage • Short Circuit
• Under Voltage • Over Frequency
• Over Current • Under Frequency
• Under Current • Over Temperature
Protection and Switchgear is designed as a textbook for undergraduate students of electrical and electronics engineering. The book aims at introducing students to the various abnormal operating conditions in power systems, and the apparatus, system protection schemes, and the phenomena of current interruption, to study various switchgears. The book describes in detail the protection principles of each element of the power system network. The details of relay design and relay settings have also been covered. Further, the book contains a wide coverage of digital/numerical relaying schemes. Besides the relays, the book covers detailed theories of the circuit breaking phenomenon, and the construction and working of switchgears. The book is pedagogically rich with detailed relay and circuit diagrams, numerous solved examples, review questions, multiple choice questions, and numerical exercises in each chapter. At the end of the book, an additional chapter on recent developments in protective relays covers the application of artificial intelligence techniques in protective relays and discusses the concept of synchronized phasor measurements and wide area protection, along with other important topics.”–Publisher\’s description.
Chapter :3 Block Diagram
3.1 Block diagram:-
Fig.1 Block Diagram
3.2 Why we required power supply circuit:-
Almost all basic household electronic component need an unregulated AC to be converted to constant DC, in order to operate the electronic equipment. All devices will have own a certain power supply limit and the electronic circuits inside these devices must be able to supply a constant DC voltage within this limit. That is, all the active and passive electronic equipment will have a certain DC operating point (Q-point or Quiescent point), and this point must be achieved by the DC source power. The DC power supply is practically changed to each and every stage in an electronic system.
All phase require dc power supply for that operation .some small power system can be operate with a battery. But, for long period of operating devices, battery is costly and complicated for long period of operation. The best method used is in the form of an unregulated power supply is a combination of a transformer, rectifier and filter.
Every electrical and electronic devices that we have to use in our daily life will require a power supply. We use an AC supply at 230V 50Hz. There are different types of power electronic converters such as step-down converter, step-up converter, voltage stabilizer, AC to DC converter, DC to DC converter, DC to AC converter, and so on.
3.3 Simulation circuit of power supply:-
This circuit is a small +5V power supply, which is useful when operation with digital are electronics, and easy to connect. Small inexpensive wall transformers with variable o/p voltage are available from any electronics shop and market. Those transformers easily available in market, but usually their voltage regulation and efficiency is very poor, which makes them it is not very useful for digital circuit experimenter unless a better regulation can be achieved in some way.
This circuit can give a +5 Volt output at about 150 milli Ampere current, but it can be increased to 1 Ampere when good cooling is provided to 7805 regulator chip. The circuit has an overload and terminal protection.
If you need the other voltages than +5V, you can change the circuit by replacing the 7805 chips with another regulator which are easily available in the market but efficiency and operation different with different output voltage from regulator 78xx chip family.
The last numbers in the the chip code tells the output voltage. Remember that the input voltage must be at least 3 Volt is greater than regulator output voltage to otherwise the regulator does not work proper.
Fig.2 simulation circuit of power supply
Fig.3: Hardware model of power supply
The step-down transformer are used for converting the high voltage into low voltage. These is also known as converter with output voltage less than the input voltage is called as a step-down converter, and the converter with output voltage higher than the input voltage is called as step-up converter.
There are two type of transformer step-up and step-down transformers which are used to step up the voltage or step down the voltage levels. For single phase 230V AC is converted into 12V AC using a step-down transformer.
12V output of step-down transformer is an RMS value and its peak value is given by the product of square root of two with RMS value, which is approximately 17V.
Construction of Step-down transformer, it consists of two windings, name as primary and secondary windings where primary can be designed using a less-gauge wire.
It consist of more number of turns as it is used for carrying low-current high-voltage power, and the secondary winding using a high-gauge wire and it consist of less number of turns as it is used for carrying high-current low-voltage power. Principle of Transformer work on the Faraday’s laws of electromagnetic induction.
3.5 Bridge rectifier:-
230V AC power is converted into 12V AC by the use of transformer but the power required is 5V DC; for this reason , 17V AC power must be first converted into DC power and then it can be stepped down to the 5V DC. But first and foremost, we must know about how to convert AC to DC? AC power can be change into DC using one of the power electronic device called as Rectifier.
There are so many types of rectifiers, such as half-wave rectifier, full-wave rectifier and bridge rectifier. Due to the advantages or dis-advantages of the bridge rectifier over the half and full wave rectifier, the bridge rectifier is frequently used for converting AC to DC.
Bridge rectifier use four diodes which are connected in the form a bridge. We know about the diode is an uncontrolled rectifier which will operates only forward bias and will not operates during the reverse bias. If the diode anode voltage is higher than the cathode voltage then the diode is said to be in forward bias.
During positive half cycle, only two diodes D2 and D4 will conduct and during negative half cycle only two diodes D1 and D3 will conduct. Thus, AC is converted into DC; but this is not pure DC as it consists of pulses. Hence, it is called as pulsating DC power. But voltage drop across the diodes is 0.7; therefore, the peak voltage at the output of this rectifier circuit is 15V approx.
15V DC can be converted into 5V DC using a step-down converter, but before this, but it is not pure so it required to obtain pure DC power. The output of the diode bridge is a DC consisting of ripples also called as pulsating DC.
This pulsating DC can be filtered using an inductor filter or a capacitor filter or a resistor-capacitor-coupled filter for removing the ripples. Consider a capacitor filter which is used in most cases for smoothing.
We know that a capacitor is an energy storing device. In the circuit, capacitor stores energy while it is in operation the input increases from zero to a peak value and, while the supply voltage decreases from peak value to zero, capacitor starts discharging. This charging and discharging of the capacitor it will be make the pulsating DC into pure DC.
3.7 Voltage Regulator:-
15V DC voltage can be stepped down to 5V DC voltage using a DC step-down device called as voltage regulator IC7805. The first two digits ‘78’ of IC7805 voltage regulator indicates the positive series. Voltage regulators and the last two digits ‘05’ indicates the output voltage of the voltage regulator. Transistor as a series pass element used for discharging extra energy as heat ; SOA protection (Safe Operating Area) and heat sink are used for heat protection in case of excessive supply voltages.
In general, an IC7805 regulator can withstand voltage ranging from 7.2V to 35V and gives maximum efficiency of 7.2V voltage and if the voltage exceeds 7.2V, then there is power loss of energy in the form of heat. To protect the regulator from over heat, thermal protection is required so heat sink will be used for protection. Thus, a 5V DC is obtained from 230V AC power.
3.8 Light Emitting Diode:-
Light emitting diode which indicates the circuit will work proper and glow. Some connection or component is not correct LED is not glow, so it indicates the circuit is improper.
Chapter :4 Transistor Switch Driving a Relay
A relay is most important part of electrical line, it is electro-magnetic switch which is useful if you want to use a low voltage circuit, this is useful for switch on and off a light bulb (or anything else) connected to the 220v mains supply line. Relays are electrical devices that use a different principle to operate a pair of movable contacts from an open position to a closed position.
The advantage of relays is that it takes a small amount of power to operate the relay coil, but the relay is only device to control motors, heaters, lamps or AC circuits which themselves can draw a lot more electrical power. A transistor switch is used for allow to pass a 12 volt relay to be operated (turned on and off) by a small input voltage.
The voltage level of the input can be changed by changing the black arrow goes head up and down on this vertical scale. Changing the input voltage affect the changes in the base current, collector current, and in the collector voltage. When the current in the relay coil (i.e. the collector current) reaches a certain value, the relay switches turn on. The diode reduces the large transient voltages that are produced when the current passes through an inductor (the relay coil) is changed quickly by switching (called “inductive kick”).
A typical relay switch circuit has the coil driven by a NPN transistor switch, TR1 as shown depending on the input voltage level. When the Base voltage of the transistor is zero (or negative), the transistor is cut-off and acts as an open switch. If a large enough positive current is now driven into the Base to saturate NPN transistor, the current flowing from Base to Emitter (B to E) controls the larger relay coil current flowing through the transistor from the Collector to Emitter.
When the transistor switches “OFF”, the current flowing through the relay coil decreases and the magnetic field collapses. However the stored energy within the magnetic field has to go somewhere and a reverse voltage is developed across the coil as it tries to maintain the current in the relay coil. This action produces a high voltage spike across the relays coil that can damage the switching NPN transistor if allowed to build up.
So in order to prevent damage to the semiconductor transistor, a “flywheel diode”, also known as a freewheeling diode, is connected across the relay coil. This flywheel diode clamps the reverse voltage across the coil to about 0.7V dissipating the stored energy and protecting the switching transistor. Flywheel diodes are only applicable when the supply is a polarized DC voltage. An AC coil requires a different protection method, and for this an RC snubber circuit is used.
Fig.3 Simulation Circuit of Transistor Relay Driver
Chapter :5 Relay as an Electrical Switch
In electrical engineering, a switch is an electrical component that can break and close an electrical circuit. Interrupting the current or change it from one conductor to another.
The part of a switch may be operated directly by a human operator and also automatically to control a circuit. (for example, a light switch or a keyboard button), may be operated by a moving object such as a car -operated switch, or may be operated by some detecting element for pressure, temperature or flow.
Chapter :6 Sensing Devices
6.1 Current Transformer:-
A current sensor is an electrical equipment that detects electric current (AC or DC) in a cable, and generates a signal proportional to passes through in it. The generated signal could be analog voltage or current or may be digital output. It can be shown in to display and then utilized to display the measured current in an ammeter or can be stored for further analysis in a data acquisition system or can be utilized for control purpose.
A current transformer (CT) is in a series connected measurement equipment designed to provide a current in its secondary coil proportional to the current flowing in its primary. Current transformers are commonly used for measuring and protective electrical component and also monitoring and protective relays in the electrical power industry.
Fig : 4 – Circuit diagram of current transformer
Fig : 5 – Hardware model of current transformer
6.2 Potential transformer:-
Voltage transformers (VT) (also called potential transformers (PT)) are a parallel connected with the electrical line type of instrument transformer, used for monitoring and protection in high-voltage circuits or phasor phase shift isolation. They are designed to present express load to the supply being measured and to have an accurate voltage ratio to enable accurate monitoring. The primary may be connected phase to ground or phase to phase. The secondary is always grounded on one terminal.
Fig : 6 – Ciruit diagram of potential transformer
Fig : 7 – Hardware model of potential transformer
6.3 Zero crossing detector:-
A zero-crossing is a point where the sign of a mathematical function changes (e.g. from positive to negative), expressed by a crossing of the axis (zero value) in the graphical (graph) of the function. It is a commonly used term in electronics, mathematics, sound, and image processing.
In alternating current (AC), the zero-crossing is the point at which there is no voltage present. In a sine wave or other simple waveforms this normally occurs twice during each cycle.
The zero-crossing is important for electrical line and most important in AC because of AC have a frequency systems which send digital data over AC circuits, such as modems, X10 home automation control systems, and Digital Command Control type systems for Lionel and other AC model trains.
Counting of zero-crossings is also a method used in speech processing to estimate the fundamental frequency of speech.
6.4 LM35:-
The LM35 is a sensor for detecting temperature and connect with series are precision integrated-circuit temperature devices with an output voltage linearly proportional to the Centigrade temperature. The LM35 equipment 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.
Chapter : 7 Microcontroller ATmega 16
7.1 Introduction of MICROCONTROLLER:-
A microcontroller often is the “brain” of a mechatronic system. Like a mini, self-contained computer, it can be programmed as requirement to interact with both the hardware of the system and the user. Most of the basic microcontroller can perform simple math operations, control the digital outputs, and the monitor digital inputs. Present day, the computer industry has evolved, so the many technology involved and associated with microcontrollers.
Newer microcontrollers are much faster than older, and have more memory, and have a host addition feature of input and output and that dwarf the ability of earlier models. Most modern controllers have analog-to-digital converters (ADC), and have high-speed timers and counters, interrupt capabilities, outputs that can be pulse-width modulated, serial communication ports, flash memory etc. The microcontroller and the development board used in every electronic circuit and this lab were donated by Atmel for your use.
In industry, price of microcontroller you can expect to pay anywhere from $50 to $400 for just a development board and up to $1000 for a professional compiler and programming interface! SO BE CAREFUL AND RESPECTFUL and give the blessing to provide of the microcontrollers and development boards! Like any electronic device, they are costly, delicate and may be easily damaged! BE ESPECIALLY CAREFUL of static charges!
7.2 The ATmega16 Microcontroller:-
ATmega16 microcontroller is an 8-bit high performance microcontroller of Atmel’s Mega AVR family with high speed and low power consumption.
ATmega16 is based on enhanced RISC (Reduced Instruction Set Computing, Know more about RISC and CISC Architecture) build up architecture with 131 powerful instructions. Moreover of the instructions execute in one machine cycle. Atmega16 microcontroller can work on a maximum frequency of 16MHz.
ATmega16 microcontroller has 16 KB programmable flash memory, static RAM of the 1 KB and EEPROM of 512 Bytes. The endurance cycle of the flash memory and EEPROM is 10,000 and 100,000, respectively.
ATmega16 have a 40 pin microcontroller. There are 32 input/output lines which are divided into four category 8-bit ports designated as PORTA, PORTB, PORTC and PORTD.
7.3 ATmega 16 is better than 8051:-
ATmega16 and 8051 both are microcontroller and both are fundamentally same. But what makes them differ from each other and for what you want to use them. 8051, is a very good micro-controller to learn about embedded systems and it use; It is powerful enough to run most of your projects and application. There are now a day use of these microcontroller is goes down.
But comparing 8051 with ATmega16, Atmega16 have additional feature and is all about high speed prototyping and getting your project running is most smoothly, simplest and fastest way with least possible part count.
ATmega16 has the better reduced instruction set (RISC) for the operation, most of them being single cycle execution thus faster code execution, while 8051 still supports slower Complex instruction set computing(CISC) for the operation which require multiple machine cycles for execution.
7.4 Comparison between atmega16 and atmega32:-
• Both microcontroller same internal architecture but some feature different.
• Atmega16 microcontroller have 16kb flash memory and atmega32 microcontroller have 32kb.
• Atmega16 microcontroller have 1kb SRAM and ATmega32 microcontroller have 2kb.
• Atmega16 microcontroller have 512byte EEPROM and atmega32 microcontroller have 1kb.
• Both have inbuilt analog to digital converter (ADC).
Fig.8 Pin Diagram
The above diagram shows about 40 pin DIP package ATmega16 microcontroller. The AVR has 4 ports of the 8 bits and 8 other pins: PINS 1 to 8 (PORT B) PIN5 to PIN8: input/output.
7.6 Pin Descriptions of atmega16:-
VCC Digital supply voltage
GND Ground
Port A (PA7…PA0)
Port A convert the analog inputs to the A/D Converter. Port A also serves as an 8-bit bi-directional input/output port, if the analog to digital Converter is not used. Port pins can be provide the internal pull-up resistors (selected for each bit). The Port an output buffers have a symmetrical drive characteristics with both the high sink and source capability of the controller. When pins PA0 to PA7 are used as the inputs and are externally pulled low, they will be a source current if the internal pull-up resistors are activated and operated. The Port a pins are tri-stated when a reset condition is active with help of the reset pin, even if the clock is not running at a time.
Port B (PB7.PB0)
Port B is an 8-bit bi-directional Input/output port with internal pull-up resistors (selected for each bit). The Port B has output buffers have symmetrical drive for the characteristics with both high sink and source capability. As the inputs, Port B pins are activated externally pulled low will source current if the pull-up resistors are activated. The Port B pins are tri-stated when a reset condition becomes active with the help of the reset pin, even if the clock is not running.
Port C (PC7.PC0)
Port C is an 8-bit bi-directional Input/output port with internal pull-up resistors (selected for each bit). The Port C has output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up resistors are activated. The Port C pins are tri-stated when a reset condition becomes active with the help of the reset pin, even if the clock is not running or not active. If the JTAG interface is enabled or operate, the pull-up resistors on pins PC5 (TDI), PC3 (TMS) and PC2 (TCK) will be turn on even if a reset occurs.
Port D (PD7.PD0)
Port D is an 8-bit bi-directional Input/output port with internal pull-up resistors (selected for each bit). The Port D has output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs, Port D pins that are externally pulled low will source current if the pull-up resistors are activated or turn on. The Port D pins are tri-stated when a reset condition becomes active with the help of the reset pin, even if the clock is not running.
Reset Input. A low level on this pin for longer period than the minimum pulse length will generate and pin will be active and a reset, even if the clock is not running or not active.
Input to the inverting Oscillator amplifier and the input to the internal clock operating circuit given by this pin.
Output from the inverting Oscillator amplifier.
AVCC is the supply voltage pin for Port A and the Analog/Digital Converter. It should be connected with VCC but externally, even if the analog to converter is not used. If the analog to digital is used, it should be connected to VCC through a low-pass filter.
AREF is the analog reference pin for the analog to digital Converter.
7.7 Simulation circuit of ATmega16:-
Fig :9 Simulation Circuit of ATmega 16
Chapter :8 LCD 16*2
8.1 Introduction of LCD16*2:-
LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications for various purpose. A 16×2 LCD display is very basic module and is very commonly used in various devices and circuits for various operation. These modules are mostly preferred over seven segments and other multi segment LEDs. The reasons is are as: LCDs are economical; easily programmable; have no limitation of displaying special & even custom character (unlike in seven segments), animations and so on.
A 16×2 LCD means it can be display 16 characters per line and there are 2 such lines. In this display each character is displayed in 5×7 pixel matrix. This LCD has a two registers, namely, Command and Data.
The command register stores the command and instructions given to the LCD. A command is an instruction given to LCD to do a specific task like initializing it, clearing its screen, setting the cursor position, controlling display etc. for the requirement. The data register stores the data on the LCD display. The data is the ASCII value of the character to be displayed on the LCD.
8.2 Pin diagram of LCD16*2:-
Fig : 10- Pin Diagram of LCD 16*2
8.3 Pin Description of LCD16*2:-
8.4 LCD Simulation circuit:-
Fig : – 11 LCD Simulation Circuit
Fig : 12 – Hardware model of microcontroller interfacing with LCD
Chapter : 9 Cooling Devices
Cooling methods can be classified according to the mechanism or medium used to transfer for the one medium to another the heat during the cooling process. A commonly used method of cooling is for the power semiconductors is air cooling, which includes the natural air cooling and forced air cooling.
Another type of cooling is the liquid cooling. In liquid cooling is often accomplished by use of the water or a water/glycol mixture to perform thermo syphon cooling or forced cooling.
Other medium can also be used for liquid cooling such as oil and several other inert fluids. Cooling can also be achieved by use of the different medium advantage of the heat transfer that occurs when materials experience phase transitions.
Air blowers/fans are used in the forced air cooling in order to increase the air velocity for cooling. This increased velocity aims to produce turbulent air flow rather than a laminar flow, effectively reduce the heat dissipation and increase in the surrounding atmosphere.
The advantage of using forced air is that it has a far better cooling effect than natural air cooling for the operation. Disadvantages include the incredibly high amount of noise produced during operation application as well as resulting wear and tear.
The project is to introduce automatic cooling unit instead of manual cooling because of the more disadvantages in the manual cooling. Automatic cooling unit is the system typically delivers a controlled amount of coolant to specific locations on a machine. While the machine is operating and heating of the machine is higher than the certain limit, at specific times from a central location.
When the temperature at the work piece is increased above the reference temperature, the automatic coolant unit will be turn on and automatically pumps coolant activated and will reduce the temperature.
The temperature sensor or LM35 is placed near to the tool or work piece, as a result the LM35 senses the temperature from the tool -work piece interface and sends an electrical signal to the amplifier.
Some change occurs in the temperature, electrical signal is amplified by using amplifier, then this signal is send to the comparator then the comparator compares both input and reference signal.
If the input signal is higher than the reference signal then the relay gets turn on automatically to control the temperature to a certain level. So the coolant is providing cooling from the reservoir to the tool- work piece interface.
Similarly when the temperature decreases below the reference value the control unit deactivates the pump by using the relay and system will operate normally. The process will continue according to the temperature goes up and down.
Chapter : 10 Final Simulation Circuit And Hardware Circuit of power supply
Fig :13- Final Simulation Circuit
Chapter : 11 Merits, demerits, Application & conclusion
11.1 Merits:-
• We connect the all equipment’s. (e.g., generator, motor, transformer, etc.)
• System will be more reliable.
• Current, Frequency, voltage and temperature parameters fault are covered.
11.2 Demerits:-
• For high rating equipment is used cost will be increased.
• Circuit will be complex.
11.3 Applications:-
• For transformer protection.
• For motor protection.
• Line monitoring protection.
Chapter :13 Conclusion
From this project, we learn about the Proteus and Bascom which use in this project for simulation of circuit and programming of circuit. These system protect against the over voltage, under voltage, over current, under current, short circuit current, over frequency, under frequency, and over temperature. This system cover the three phase and single phase equipment.
• National Electric Code 2005 Edition. Quincy, MA: NFPA, 2005. Print
• EES003 NSW DPI Technical Reference – Practices for the Life-Cycles of Management of Explosion Protected Equipment.
• EES004 NSW DPI Technical Reference – Practices For Portable Electrical Apparatus.
• EES006 NSW DPI Technical Reference – Removal and Restoration of Power.

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