Circuit Switching Versus Packet Switching

Nurhazimah Binti Mohd Za’ba
Nursyafikah Binti Farakkasi 
Nursyahirah Binti Mohd Sanusi 
Nur Hidayu Binti Salleh
Nur Syafiqah Binti Zulkiflee
Nurul Ain Binti Mohd Nassir Adabi

The purpose of this study is to describe difference between packet switching and circuit switching. Circuit switching is dedicated communication between two stations that connected sequence of links between network nodes. It consist 3 phase communication which are establish, transfer and disconnect. Packet switching is data transmitted in small packets that each packet contains a portion of user data plus some control information. There are a few difference between packet switching and circuit switching include the bandwidth, dedicated path, call setup delay and so on.
In telecommunication networks they carried the information signals among an entity involved in the process of information transfer which may be in the form of a telephone conversation. In order to connect multiple devices, it must be point to point connection between pair of devices which we called as switches. Unfortunately, it will increase the number of connection. There are two types of switching techniques including circuit switching and packet switching. Switching is a collection of switching elements arranged and controlled to setup communication path between any distant points.

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Circuit switching is a network which allows the associated voice which it will followed between the two respective users refer in the Figure 1 is the circuit switching network.. The end to end communication was established during the duration of the call. It is a dedicated link or path which established between the sender and the receiver. It is maintained for the entire duration of the conversation.

Figure 1: Circuit SwitchingNetwork
Packet switching is a network which it does not requires establishing the connection in initially. Next, the connection or channel available usually used by many users. But, if the capacity of the users increases, it will lead to congestion in the network. This network mainly used for data and voice applications requiring non-real time scenarios. It also can handle in two ways which are datagram and virtual circuit refer Figure 2 is the Packet Switching network.

Figure 2: Packet Switching Network.
Data communications have been achieved by using a variety network such as PSTN, leased-lines and more recently ISDN and ATM/ Frame relay. These networks are partly or totally analogue or digital using technology such as circuit-switching, packet-switching etc. Main difference between Packet Switching and Circuit switching is that communication lines are not dedicated to passing massage from the sources to the destination. In Packet Switching, different message (and even different packet) can passed through the routes, and when there is a ‘dead time” in the communication between the source and the destination, the lines can be used by other sources. Oguntala George Adeyinka(2013) said that packet switching is an attempt to make a better utilization of the existing network by splitting the message to be sent to packets. Each packet contains information about the sender, the receiver, the position of the packet in the message as well as part of the actual massage. There are many protocols defining the ways packet can be sent from the sender to the receiver.
Then, Pablo Molinero-Fernandez & Nick McKeown (2004) said that Circuit Switching can be decomposed into a fast path without per-packet processing, and a slower path for establishing/releasing circuit, which is similar in complexity to forwarding a single packet in Packet Switching. However the slow path needs to be taken much less often (for example, the average TCP connection lasts more than 10 packets, which mean that connection are established at an average rate at least 1/10 that of packet processing in router ). For these, we argue that circuit switches can operate much faster than packet switches.
The concept of packet switching had two independent beginnings, with Paul Baran and Donald Davies [4]. Leonard Kleinrock [5] conducted early research and authored a book in 1961 in the related field of digital massage switching (without explicity using the concept of the packet), and also later a played a leading roles in building and management of the world’s first packet switched network, namely the ARPANET.
After that, K.Giridhar stated Packet switching is also called connectionless networking because no connections are established. The advantage of the connectionless packet model in that packets are forwarded independent of other packets. Packets are forwarded on the fly by routers based on the most current best path to a destination. If a link or routers fails, packets are quickly diverted along another path.
Dr.FaridFarahmand&DR.Qiong (Jo) Zhang stated the most common example of a circuit-switched network can be found in public telephone network (PTN) supporting services such as POTS (plain old telephone system) and long distances calls. Other examples of a circuit switched services are integrated service digital network (ISDN) and switched 56, 64, 384 (Kbps) services. The majority of wireless application protocols (WAP) enables phone also operate on top of circuit-switched networks. Furthermore, many public networks dedicated to data transport also use circuit-switching techniques; an example of a network in Europe is circuit-switched public data network (CSPDN), which transport data on circuit-switching networks using the X.21 protocol. Circuit-switching also has wide applications in optical networks including wavelength division multiplexed (WDM) systems and WDM SONET networks.
Topic for our assignment is packet switching. We make a research to get the information about this topic in library and also internet. There’s a lot information we get from internet that give information about definition, benefit and function. The definition of packet switching give us simple introduction to us to understand the concept of packet switching. After we understand the concept, we find out the article or journal from internet that can give us a more information about packet switching. The article must be from year 2012 to make sure that information are relevant with our topic and current study. This article can be found from OPAC system that can used in library website. Every article has their own writer and bibliographic databases that make us easier to find the reference if there’s a question refer to packet switching if we are not understand to topic. In internet, we find extra information by inserting the term of packet switching in key words in Google to get more explanation about function of packet switching. The bibliographies are used for us for further study and this way give us more information packet switching. The journal is created by other university and this journal help us to understand the topic. The history about packet switching also found in internet and the technology in packet switching also change and it make data can be transfer in good ways even though the data is large. Based from the information get from internet will make us more understand about the topic and help us to success give simple explanation about the topic of packet switching in report.
After make research in internet, we go to library to find information regarding our topic which is packet switching. There’s some book that have some explanation about the benefit of packet switching. We also know about the main concept of packet switching from the book in library. The main concepts give more information about how the packet switching work in real situation. After that, we know the weakness and benefit of packet switching in transfer data in computer or cellphone. Even this packet switching have a disadvantage when transferring the data and it still can function more efficient after they develop a new technology this make sure the data can send to location. We also can refer from our senior journal in library after they done their final year project which related with topic packet switching. This information can help us to know the function packet switching with a technology that still use the concept during transferring data in destination address in packet. We also make a small interview with a friend who already work in IT department but the information that we get from him are not related to our topic. So, we are not use that information to be write in this report.
Lastly, we combine all the information about packet switching that we found from internet, journal and book to be write in this report. Before we write this report, we already discuss and make some explanations in this report to make sure this report are occupy our objective to understand the topic of packet switching. We try to help each other understand the topic based from information we get from internet , journal , article and book. Everyone have knowledge and information after done this project that can be used in career life. We take about more than one month to finish this research and this report can be use as reference for our junior if they want to continue this research in their present time in future.
At the end of this article, we present the two switching techniques used in networks: circuit switching and packet switching; whereas datagram packet switching and virtual circuit packet switching. Then, we also are able to compare a difference between circuit switching and packet switching.

Circuit Switching

Datagram Packet Switching

Virtual Circuit Packet Switching

Fixed bandwidth

Dynamic bandwidth

Dynamic bandwidth

Overload can block packet delay

Overload increases packet delay

Both; can block and increases packet delay

A dedicated path

Not a dedicated path

Not a dedicated path

Path is established before data transmission begins

Route is established before any packets sent

Route is established before any packets sent

Call setup delay

Packet transmission delay

Both; call setup and packet transmission delay

No speed or node conversion

Speed and node conversion

Speed and node conversion

[1] Oguntala George Adeyinka, “Network Solution, Applications and challenges of Mobile Computing In Africa,” International Journal of Scientific & Engineering Research, volume 4, issues 10, pp. 884-889, October 2013.
[3] Pablo Molinero-Fernandez & Nick McKeown, The Performances of Circuit Switching in the Internet, Computer System Laboratory, Stanford University (2004).
[4] Roberts L.G (1978). The Evolution of Packet Switching, Proceedings of the IEEE, vol.66, no11, pp.1307-1313. 1978.
[5] Kleinrock L. (1961), Information Flow in Large Communication Nets, RLE Quarterly Progress Report, July 1961.
[6] K.Giridhar, “Packet Switched Data Network and Its Evolution”, Information Technology and Communications Resources for development, Telecommunications and Computer Networks (Tenet) Group, Department Of Electrical Engineering, Indian Institute Of Technology Madras, Chennai-600036, India (2007).
[7] Dr.Farid Farahmand & DR.Qiong (Jo) Zhang, Circuit Switching, Central Connecticut State University & Arizona State University at West Campus (2007).
[9] Telecommunication System Engineering, Technical University of Malaysia Malacca, chapter 5.

Flip Flop Circuit Explanation and Study

A flip-flop is a term referring to an electronic circuit (a bistable multivibrator) that has two stable states and thereby is capable of serving as one bit of memory. Today, the term flip-flop has come to mostly denote non-transparent (clocked or edge-triggered) devices, while the simpler transparent ones are often referred to as latches; however, as this distinction is quite new, the two words are sometimes used interchangeably .
A flip-flop is usually controlled by one or two control signals and/or a gate or clock signal. The output often includes the complement as well as the normal output. As flip-flops are implemented electronically, they require power and ground connections.
Introduction – Basic Flip-Flop Circuit
A flip-flop circuit can be constructed from two NAND gates or two NOR gates. Each flip-flop has two outputs, Q and Q’, and two inputs, set and reset. This type of flip-flop is referred to as an SR flip-flop or SR latch. The flip-flop in figure has two useful states. When Q=1 and Q’=0, it is in the set state (or 1-state). When Q=0 and Q’=1, it is in the clear state (or 0-state). The outputs Q and Q’ are complements of each other and are referred to as the normal and complement outputs, respectively. The binary state of the flip-flop is taken to be the value of the normal output.
When a 1 is applied to both the set and reset inputs of the flip-flop in Figure 2, both Q and Q’ outputs go to 0. This condition violates the fact that both outputs are complements of each other. In normal operation this condition must be avoided by making sure that 1’s are not applied to both inputs simultaneously.
The NAND basic flip-flop circuit in figure operates with inputs normally at 1 unless the state of the flip-flop has to be changed. A 0 applied momentarily to the set input causes Q to go to 1 and Q’ to go to 0, putting the flip-flop in the set state. When both inputs go to 0, both outputs go to 1. This condition should be avoided in normal operation.

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Master-Slave Flip-Flop
A master-slave flip-flop is constructed from two seperate flip-flops. One circuit serves as a master and the other as a slave. The logic diagram of an SR flip-flop is shown in figure.The master flip-flop is enabled on the positive edge of the clock pulse CP and the slave flip-flop is disabled by the inverter. The information at the external R and S inputs is transmitted to the master flip-flop. When the pulse returns to 0, the master flip-flop is disabled and the slave flip-flop is enabled. The slave flip-flop then goes to the same state as the master flip-flop.
In addition to these two flip-flops, the circuit also includes an inverter. The inverter is connected to clock pulse in such a way that the inverted CP is given to the slave flip-flop. For example, if the CP=0 for a master flip-flop, then the output of the inverter is 1, and this value is assigned to the slave flip-flop. In other words if CP=0 for a master flip-flop, then CP=1 for a slave flip-flop.
A master-slave flip flop can be constructed using any type of flip-flop which forms a combination with a clocked RS flip-flop, and with an inverter as slave circuit.
An RS master-slave flip-flop consists of two RS flip-flops; one is the master flip-flop and the other a slave. The inverted CP is given to the slave flip-flop. Now when CP=0, the master flip-flop is disabled. So the external inputs R and S of the master flip-flop will not affect the circuit until CP goes to 1. The inverter output goes to 1 and it enables the slave flip-flop. The output Q=Y and Q’=Y’.
When CP=1, the master flip-flop is enabled and the slave flip-flop remains isolated from the circuit until CP goes back to 0. Now Y and Y’ depends on the external inputs R and S of the master flip-flop.
Assume that the flip-flop is in a clear state and no clock pulse is applied to the circuit. The external inputs given are S=1 and R=0. This input will not affect the state of the system until the CP=1. Now the next clock pulse applied should change the state to SET state (S=1, R=0). During the clock pulse transition from 0 to 1, the master flip-flop goes to set state and changes the output Y to 1. However this does not affect the output of the system since the slave flip-flop is isolated from the system (CP=0 for slave). So no change is observed at the output of the system.
When the CP returns to 0, the master flip-flop is disabled while the slave is enabled. So the information from the master is allowed to pass through to the slave. Since Y=1, this changes the output Q to 1.
In a master slave flip-flop it is possible to change the output of the flip-flop and the external input with same clock pulse. This is because the external input S can be changed at the same time while the pulse goes through its negative edge transition. When CP=0, change in external input S would not affect the state of the system. From this behavior of the master slave flip-flop it is quite clear that the state change in flip-flops coincide with the negative edge transition of the pulse.
Negative edge transition means an inverter is attached between the CP terminal and the input of the slave. In positive edge triggered master slave flip-flops an additional inverter is attached between the CP terminal and the input of the master. Such flip-flops are triggered with negative pulses. Negative edge of the pulse affects the master and positive edge affects the slave.
Timing Diagram
The timing relationship is shown in figure and is assumed that the flip-flop is in the clear state prior to the occurrence of the clock pulse. The output state of the master-slave flip-flop occurs on the negative transition of the clock pulse. Some master-slave flip-flops change output state on the positive transition of the clock pulse by having an additional inverter between the CP terminal and the input of the master.
Let us say that a clock of certain frequency is fed to the FF, and consider the case of JK being 11. The propagation delay of FF is very very less than the clock pulse time.The FF continues complementing the output an unpredictable number of times, thus leading to anomaly in the final output after the pulse time of the clock is completed.At the end the clock pulse, the value of O is uncertain.This continuous toggling of output when clock is HIGH is known asRace Around condition. This can be eliminated by

Clock time should be less than the propagation delay time of the latch.
By using Masterslave JK Flip flop.

Pulse-Triggered Master-Slave
These flip-flops are constructed from two separate flip-flops. The term pulse-triggered means that data are entered into the flip-flop on the leading edge of the clock pulse, but the output does not reflect the input state until the trailing edge of the clock pulse. This is due to the master flip-flop being rising edge triggered and the slave flip-flop being falling edge triggered as illustrated in the figure below.
Master-Slave J-K Flip-Flop
A master slave flip flop is a cascade of two S R flip flops with feedback from the outputs of the second to the inputs of the first. Positive clock pulses are applied to the first flip flop and clock pulses are inverted before these are applied to the second flip flop.
The logic symbol for the master-slave flip-flop only indicates the initial inputs to the master and the outputs from the slave as indicated by the J-K master-slave flip-flop shown in figure
Operation of master-slave J-k flip flop
Whe CK=1, the first flip flop is enabled and the outputs Q and Q(toggle) respond to the J & K according to its truth table.At this time the second flip flop is inhibited because its clock is LOW. When CK goes LOW, the first flip flop is inhibited and the second flip flop is enabled, because now its clock isHIGH.Since the second flip flop simply follows the first one it is referred to as slave and he first one as the master.
Master-slave D flip-flop
Consider the following terms:
RIPPLE THROUGH: An input changes level during the clock period, and the change appears at the output.
PROPAGATION DELAY: The time between applying a signal to an input, and the resulting change in the output.
These problems can be overcome by masterslave D Flip flop.
A master-slave D flip-flop is created by connecting two gated D latches in series, and inverting the enable input to one of them. It is called master-slave because the second latch in the series only changes in response to a change in the first (master) latch.
The term pulse-triggered means that data is entered on the rising edge of the clock pulse, but the output does not reflect the change until the falling edge of the clock pulse.
It responds on the negative edge of the enable input usually a clock.
For a positive-edge triggered master-slave D flip-flop, when the clock signal is low (logical 0) the “enable” seen by the first or “master” D latch (the inverted clock signal) is high (logical 1). This allows the “master” latch to store the input value when the clock signal transitions from low to high. As the clock signal goes high (0 to 1) the inverted “enable” of the first latch goes low (1 to 0) and the value seen at the input to the master latch is “locked”. Nearly simultaneously, the twice inverted “enable” of the second or “slave” D latch transitions from low to high (0 to 1) with the clock signal. This allows the signal captured at the rising edge of the clock by the now “locked” master latch to pass through the “slave” latch. When the clock signal returns to low (1 to 0), the output of the “slave” latch is “locked”, and the value seen at the last rising edge of the clock is held while the “master” latch begins to accept new values in preparation for the next rising clock edge.
By removing the leftmost inverter in the above circuit, a D-type flip flop that strobes on the falling edge of a clock signal can be obtained. The truth table obtained is as follows:

The circuit is set means output = 1
The circuit is reset means output = 0
Flip-flops have two output Q and Q’ or (Q and Q)
Due to time related characteristic of the flip-flop, Q and Q’ (or Q) are usually represented as followed:
Qt or Q: present state
Qt+1 or Q+: next state


When using a real flip-flop, the following information is needed to be considered:
propagation delay (tpLH, tpHL) – time needed for an input signal to produce an output signal
minimum pulse width (tw(min)) – minimum amount of time a signal must be applied
setup and hold time (tsu, th) – minimum time the input signal must be held fixed before and after the latching action.


A flip-flop is used to store one bit, or binary digit, of data.
Any one of the flip-flop types can be used to build any of the others.
Many logic synthesis tools will not use any other type than D flip-flop and D latch.
Level sensitive latches cause problems with Static Timing Analysis (STA) tools and Design For Test (DFT).
Many FPGA devices contain only edge-triggered D flip-flops
The data contained in several flip-flops may represent the state of a sequencer, the value of a counter, an ASCII character in a computer’s memory or any other piece of information.
One use is to build finite state machines from electronic logic. The flip-flops remember the machine’s previous state, and digital logic uses that state to calculate the next state.
Frequency division: a chain of T flip-flops as described above will also function to divide an input in frequency by 2n, where n is the number of flip-flops used between the input and the output.
Master Slave Flip Flop is useful in eliminating race around condition.
They are used in both asynchronous and clocked sequential systems.


Experiment on Pencil Resister Effect on Circuit Output

Contents (Jump to)
Research Background
Figure 1: Metallic Bonding
Figure 2: Molecular structure of diamond and graphite
Figure 3: Graphite grading scale
Figure 4: Resistance proportional to length
Figure 5: Resistance proportional to cross sectional area
Experiment 1
Experiment 2
Experiment 3
Experiment 1
Experiment 2
Experiment 3
Justification of hypothesis
Experiment 1
Experiment 2
Experiment 3
Experiment 1 (length)
Experiment 2 (cross sectional area)
Experiment 3 (type of pencil)
Diagram of the experiment
Ohm’s Law
Independent Variables
Dependent Variables
Controlled Variables
Table 1: Experiment 1 (length)
Table 2: Experiment 2 (cross sectional area)
Table 2: Experiment 3 (pencil type)
Experiment 1
Experiment 2
Experiment 3
Research Background
The electrical conductivity of a substance is a measure of the ease with which the valence electrons move throughout its structure, and thus is dictated by its bonding. Metallic bonding produces the greatest conductivity, as it involves a lattice of positively charged nuclei, with electrons free to move throughout the lattice (Science Daily, 2010).

Figure 1: Metallic Bonding
Hence, when an electrical charge is applied to the metal, the electrons are able to easily move through it and therefore it can be said to be a good conductor. Substances bound by covalent bonding, on the other hand, are usually poor conductors (called insulators) as the electrons are tightly held within the covalent bonds. They are materials that do not permit the free flow of electrons.

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While a conductor lets the flow electrons pass through and an insulator impede the flow of electrons. A resistor’s resistance limits the flow of electrons throughout the circuit. The resistor’s ability to reduce the current is called resistance and is measured in units of ohms (symbol: Ω). Resistance is caused by the collisions of the electrons with positive ions in the lattice.
Ohm’s Law

The resistor’s current(I)in amps (A) is equal to the resistor’s voltageVin volts (V) divided by the resistanceRin ohms (Ω)
Electrical current (Amps) is the rate at which charged particles move from one part of the conductor to another current has the symbol I. Voltage is a measure of the difference inelectrical energybetween two parts of a circuit. The bigger the difference in energy, the bigger the voltage.
An ohmic resistor obeys the ohm’s law. Ohm’s law states that the proportional energy drop across a resistor is proportional to its resistance and the current the flows through is. This can be represented in the form of a formula:
So, if a current of 1 A is passing through a conductor of resistance of 1Ω the potential difference between the ends of the conductor will be 1V. Additionally, resistance is equal to voltage divided by current, and voltage is equal to current multiply by resistance. Therefore, in a circuit, if a resistor’s resistance is equal to voltage divided by current, the resistor is ohmic.
Resistivity is the measure of resistance inherent to a particular material.

Provided that the dimensions (length and cross sectional area) of any conductor do not change, its resistance will remain the same. If two conductors of exactly the same dimensions have a different resistance, they must be made of different materials. Resistivity is given the symbol (ρ) called rho. The resistivity of a material is defined as the resistance of a piece of material having a length of one metre and a cross sectional area of one square metre.
Graphite is a pure carbon substance, where three of its valence electrons are covalently bonded to three other carbon atoms, forming a layered structure. However, the fourth valence electron is left unbonded, and thus is able to move freely. These valence electrons allow the flow of electricity through the substance in certain directions when an electrical current is applied to graphite.

Figure 2: Molecular structure of diamond and graphite
Each carbon atom in graphite is covalently bonded to three neighboring carbon atoms and these form layers of hexagonal network which are separated by a large distance. Although the fourth valence electrons are remained free which enables the electrons to flow through graphite this makes graphite a good conductor of electricity. Although this does not happen in diamond, each of the carbon atoms in diamond makes bonds with four other carbon atoms. So there is no free electron with carbon atoms to conduct electricity blocking the flow of electrons.

Figure 3: Graphite grading scale
The “lead” in pencil is made up of a combination of graphite and clay, with wax and other additives in small quantities. Clay, unlike graphite, is an insulator as it does not conduct electricity well, due to the covalent bonds holding valence electrons tightly in place. This is because clay is mainly made out of silicate minerals; these minerals have very low conductivity which makes them good insulator. The shade of pencil is dependent on percentage of each component. Pencils range from 9H, with 41% graphite and 53% clay, to 9B, with 93% graphite and 2% clay.
Given that graphite is more conductive than clay, as the concentration of graphite increases, the conductivity should increase. The resistance of an object, a measure of the conductivity of a circuit component, this can be calculated using Ohm’s law explained before above, which considers electrical resistance as the ratio of the voltage applied to the current which flows through it, or the degree to which the voltage is resisted.
Factors that would be affect the resistance of the graphite are length, cross sectional area and temperature. As the length of the conductor is shorter it would allow more electrons to pass through at a higher rate rather than a longer one. While as the radius of the cross sectional area of a conductor (or thickness) is wider the more electrons can pass through compared to a narrower conductor restricting high rate of flow of electrons. Finally, although temperature would not be tested as it would have less effect on the resistance of the conductor. As the temperature of the conductor increase stronger the resistance as the protons inside the conductor would be vibrating slowing the flow of electrons.
Resistance isproportional to length. If the pencil’s resistor has a different length and give each a particular potential difference across its ends, the longer the pencil’s resistor the less volts each centimetre of it will get. A smaller potential gradient in the graph would have fewer volts per metre means current decreases with increased length and resistance increases.

Figure 4: Resistance proportional to length

Figure 5: Resistance proportional to cross sectional area
Resistance isinversely proportional to cross sectional area. The bigger the cross sectional area of the pencil’s resistor the greater the number of flow of electrons can pass through the conductor. If the length of the pencil’s resistor does not change the conductor still gets the same number of volts across the potential gradient does not change and so the average drift velocity of individual electrons does not change.
Experiment 1
The aim of this experiment is to test if the length of a pencil resistor affects the output of the circuit.
Experiment 2
The aim of this experiment is to test if the cross sectional area of a pencil resistor affects the output of the circuit.
Experiment 3
The aim of this experiment is to test if the type of a pencil resistor (HB, 2H, 2B and 6B) affects the output of the circuit.
Experiment 1
It is predicted that the longer the length of a pencil’s resistor the lower the current as the electrons would have to travel further which gives a higher resistance.
Experiment 2
It is predicted that the thicker the cross sectional area of the pencil’s resistor the more electrons would flow through which gives a low resistance.
Experiment 3
It is predicted that as the concentration of clay in the pencil’s resistor increases, the resistance increases.
Justification of hypothesis
Experiment 1
As the length of a conductor increases, the resistance increases. Increasing the length of the graphite in the pencil will increase the resistance of the whole circuit. As the resistance through the pencil increases, more voltage is used there and the potential energy across the circuit decreases.
Experiment 2
As the cross sectional area of the conductor increases, the resistance decreases. As the radius of the cross sectional area of a conductor (or thickness) is wider, the more electrons can pass through compared to a narrower conductor restricting high rate of flow of electrons.
Experiment 3
Graphite is more conductive than clay, as the concentration of clay in the pencil’s resistor increases, the resistance increases. Clay compared to graphite is an insulator and does not conduct with electricity well blocking the flow of electrons. This shows that a 2B would be more conductive than a HB as it contains more graphite than clay.



Pencils (HB,2H,2B,6B)


Insulated alligator clip set


Power supply


Multimeter (Amp meter and Volt meter)


Ruler (30cm)


Experiment 1 (length)
The circuit was setup using two alligator clips, in a power battery. Then one wire was attached to one end of the terminal of the battery and the other end of the wire was attached on to one end of the pencil’s graphite. Next, the seconds wire was attached to the other end of the terminal of the battery and the other end of the wire was attached into one end of the pencil’s graphite. Finally, the two multimeter was placed next to the pencil and the two wires from the multimeters were attached on to the ends of the pencil. The circuit was tested with different lengths of pencils. Then the experiment was recorded in a table and graph.
Experiment 2 (cross sectional area)
The circuit was setup using two alligator clips, in a power battery. Then one wire was attached to one end of the terminal of the battery and the other end of the wire was attached on to one end of the pencil’s graphite. Next, the seconds wire was attached to the other end of the terminal of the battery and the other end of the wire was attached into one end of the pencil’s graphite. Finally, the two multimeter was placed next to the pencil and the two wires from the multimeters were attached on to the ends of the pencil. The circuit was tested with different cross sectional area of pencils. Then the experiment was recorded in a table and graph.
Experiment 3 (type of pencil)
The circuit was setup using two alligator clips, in a power battery. Then one wire was attached to one end of the terminal of the battery and the other end of the wire was attached on to one end of the pencil’s graphite. Next, the seconds wire was attached to the other end of the terminal of the battery and the other end of the wire was attached into one end of the pencil’s graphite. Finally, the two multimeter was placed next to the pencil and the two wires from the multimeters were attached on to the ends of the pencil. The circuit was tested comparing HB, 2H, 2B and 6B. Then the experiment was recorded in a table and graph.
Diagram of the experiment

Ohm’s Law

The resistance was then measured by dividing the total voltage (V) and the current (I).
Pencil 1 (HB 8.5 cm)

Independent Variables
The resistor (pencil)
Dependent Variables
The volt and the amp meter
Controlled Variables
The voltage
Table 1: Experiment 1 (length)



Voltage of battery

total voltage (V)

Current (A)

Resistance (Ω)

Pencil 1 (HB 8.5cm)

2 V

1.5 V

0.21 A

7.14 Ω


4 V

2.9 V

0.41 A

7.07 Ω


6 V

4.4 V

0.66 A

6.67 Ω


8 V

6 V

0.77 A

7.79 Ω

Pencil 2 (HB 17.5cm)

2 V

1.6 V

0.1 A

16 Ω


4 V

3.2 V

0.2 A

16 Ω


6 V

4.9 V

0.28 A

17.5 Ω


8 V

6.8 V

0.4 A

17 Ω

Pencil 3 (HB 11.5cm)

2 V

2 V

0.18 A

11.11 Ω


4 V

4 V

0.32 A

12.5 Ω


6 V

6 V

0.5 A

12 Ω


8 V

8 V

0.73 A

10.96 Ω

Pencil 4 (HB 7cm)

2 V

1.9 V

0.27 A

7.03 Ω


4 V

3.9 V

0.56 A

6.96 Ω


6 V

5 V

0.79 A

6.33 Ω


8 V

6.7 V

1.2 A

5.58 Ω


Total Resistance
Pencil 1
7.14 Ω + 7.07 Ω + 6.67 Ω+ 7.79 Ω/ 4= 7.1675 Ω
Pencil 2
16 Ω+ 16 Ω+ 17.5 Ω+ 17 Ω/4= 16.625 Ω
Pencil 3
11.11 Ω+ 12.5 Ω+ 12 Ω+ 10.96 Ω/ 4= 11.6425 Ω
Pencil 4
7.03 Ω+ 6.96 Ω+ 6.33 Ω+ 5.58 Ω/4= 6.475 Ω

Pencil 1

Pencil 2

Pencil 3

Pencil 4

Table 2: Experiment 2 (cross sectional area)

Cross sectional area


Voltage of battery

total voltage (V)

Current (A)

Resistance (Ω)

Pencil 1 (HB 17.5cm)

4 V

1.07 V

0.15 A

16.40 Ω


6 V

1.53 V

0.21 A

16.90 Ω


8 V

1.99 V

0.27 A

17.19 Ω

Pencil 2 (HB 17.5cm)

4 V

1.55 V

0.19 A

8.16 Ω


6 V

2.17 V

0.26 A

8.35 Ω


8 V

2.78 V

0.33 A

8.42 Ω

Pencil 3 (HB 17.5cm)

4 V

2.46 V

0.18 A

5.94 Ω


6 V

3.55 V

0.27 A

5.67 Ω


8 V

4.64 V

0.36 A

5.53 Ω


Cross Sectional Area
Pencil 1
3.14 x 1 =3.14
Pencil 2
3.14 x 2= 6.28
Pencil 3
3.14 x 3= 9.42
Total resistance
Pencil 1
16.40 Ω+ 16.90 Ω+ 17.19 Ω/ 3= 16.83 Ω
Pencil 2
8.16 Ω+ 8.35 Ω+ 8.42 Ω/ 3= 8.31 Ω
Pencil 3
5.94 Ω+ 5.67 Ω+ 5.53 Ω/3= 5.71 Ω

Pencil 1

Pencil 2

Pencil 3

Table 2: Experiment 3 (pencil type)

Pencil types


Voltage of battery

total voltage (V)

Current (A)

Resistance (Ω)

Pencil 1 (2H 10.5cm)


7.35 V

0.16 A

45.94 Ω



9.70 V

0.20 A

48.50 Ω

Pencil 2 (2B 10.5cm)


2.63 V

0.35 A

7.51 Ω



3.18 V

0.42 A

7.57 Ω

Pencil 3 (HB 10.5cm)

6 V

3.18 V

0.34 A

9.35 Ω



3.88 V

0.40 A

9.7 Ω

Pencil 4 (6B 10.5cm)


0.59 V

0.41 A

1.44 Ω



0.71 V

0.48 A

1.48 Ω


Total Resistance
Pencil 1
48.50 Ω+ 45.94 Ω/ 2= 47.22 Ω
Pencil 2
7.57 Ω+ 7.51 Ω/ 2= 7.54 Ω
Pencil 3
9.35 Ω+ 9.7 Ω/ 2= 9.525 Ω
Pencil 4
1.44 Ω+ 1.48 Ω/ 2= 1.46 Ω

Pencil 1 (2H)

Pencil 2 (2B)

Pencil 3 (HB)

Pencil 4 (6B)

Experiment 1 According to the data and the graph shown previously it supports the hypothesis for all the experiments. For experiment 1, it supports the hypothesis that as the length increase the resistance increase. Using the ohm’s law formula:

For Pencil 2 (HB 17.5cm) with an applied volts of 2V, it shows that the total voltage was decrease to 1.6V with a current of 0.1 A and resistance of 16Ω. Compared to Pencil 4 (HB 7cm) with an applied volt of 2V, it shows that the total voltage was decreasing to 1.9V a 0.1 difference in voltage. With a current of 0.27A and a resistance of 7.03Ω it shows that as the length of the pencil resistor increases the resistance increase. Increasing the length of the graphite in the pencil will increase the resistance of the whole circuit as the flow of electrons would have to travel longer than a short pencil resistor.
Experiment 2
For experiment 2, referring to the graphs and tables it supports the hypothesis that as the cross section area of the conductor increases, the resistance decrease. For Pencil 1 with an applied of 4V, it shows that the total voltage was decrease to 2.46V with a current of 0.15A and resistance of 16.40 Ω. Compared to Pencil 3 with an applied volt of 4V, it shows that the total voltage was decreasing to 1.55V a 2.58 difference in voltage. With a current of 0.19A and a resistance of 7.03 Ω it shows that as the cross section area of the pencil resistor increases, the resistance decreases. As the radius of the cross sectional area of a conductor (or thickness) is wider, the more electrons can pass through compared to a narrower conductor restricting high rate of flow of electrons.
Experiment 3
For the experiment 3, it supports the hypothesis that as the concentration of clay in the pencil’s resistor increases, the resistance increases. For Pencil 1 (2H 10.5cm) with an applied volt of 6V, it shows that the total voltage was decrease to
Graphite is more conductive than clay, as the concentration of clay in the pencil’s resistor increases, the resistance increases. Clay compared to graphite is an insulator and does not conduct with electricity well blocking the flow of electrons. This shows that a 2B would be more conductive than a HB as it contains more graphite than clay.

Efficiency of High Voltage Circuit Breaker


 A circuit breaker is essential in any electrical protection system. By measuring an imbalance in a circuits current, it will trip open in order to protect the wires and equipment from overheating. Circuit breakers, like most electrical equipment, have become increasingly efficient with implementations of new materials. Since an electrical arc can reach temperatures over
, there is a need for an insulating material inside the bushing to help rapidly extinguish the arc and keep temperatures in an ideal range. The four main insulating materials for high voltage breakers are: air blast, oil, vacuum, and
. Of those, the most commonly used in modern installations is
. With the addition of an insulating material, the temperatures within the circuit breaker falls into a tolerable range when an arc is caused by the opening of the breaker. However, over the lifespan of a piece of electrical equipment that is exposed to high voltage arcing, the contact points either need to be able to withstand such conditions, or will need to be replaced over time.

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 A circuit breaker is a very valuable component in any electrical system acting as a protection device. Circuit breakers can be found in every home and are used to protect expensive appliances and everyday electronics. A circuit breaker detects a current on the line that is either too low or high, and opens the circuit. A circuit breaker can be reset to close the circuit again, where a fuse protection simply burns up from a high current in order to open the circuit which would need a replacement to reclose. On the high voltage side of things, circuit breakers are used in substations to protect much more expensive equipment and ensure that a safe level of power is delivered to various populated areas. There are 4 main types of insulation used in the high voltage circuit breakers ranging in efficiencies and specific uses.

Oil filled circuit breakers are one of the oldest types. In these circuit breakers, mineral oil is typically used since it has a high dielectric strength. When the circuit breaker detects a fault, the contacts inside the circuit breaker separate that creates an arc between the two contacts. The oil, typically mineral oil, in contact with the arc begins to vaporize, producing hydrogen gas which cools and ionizes the arc. In the early 1940’s the oil filled circuit breakers had a maximum interrupting capacity of 3.5 GVA with an interrupting time rating of five to eight cycles [1]. With an increasing load, there is a need for an increase in power and protection. By the early 1950’s the maximum interrupting capacity increased to 10 GVA with an interrupting time rating of 20 cycles [1]. These circuit breakers were mostly found at high generation substations, but the two substations that contained these 10 GVA circuit breakers were at the Grand Coulee Dam in Washington and the Hoover Dam in Nevada. The rest of the large generation substations contained 5 GVA maximum circuit breakers with a maximum reclosing rate of three-cycles. At this time, the efficiency of the 10 GVA circuit breaker was far behind the 5 GVA circuit breaker, but the power out of that generation plant was necessary. Within 5-7 years the interruption rate of the 10 GVA circuit breaker had the ability to match the 5 GVA breakers at a maximum reclosing rate of three-cycles. These, however, were the maximum available at the time and therefore very expensive. Most generation plants could afford to have reclosing times around 25 cycles. These circuit breakers are rated to withstand up to 40 kA of current. It was found that silver-tungsten contacts had the ability to handle such a large current without welding or cause excessive pitting of the contacts [1]. One of the advantages to using a circuit breaker instead a fuse-type protection, is that circuit breakers can simply reclose the circuit either manually or automatically. For the high voltage oil circuit breakers in the 1950’s, it was common for circuit breakers across the board to have a common reclose time of 20-cycles. There is a short delay between when the circuit breaker interrupts the circuit and when it recloses the circuit. Various tests are performed to ensure the circuit breaker is operating correctly. To verify its current rating, 25kA is passed over four second intervals and is then checked for deterioration. To test its heat retention, a continuous load of 1.2kA is passed while monitoring the temperature to ensure it stays within desired limits [1]. Even though all of these tests seem promising, there is a reason there was a shift from oil circuit breakers in the mid to late 1960’s. The reaction producing hydrogen gas is effective, but over time that reaction causes impurities in the oil, decreasing its dielectric strength, making it less efficient over time. Also, in the engineering world, there is always a push for smaller size and higher efficiency. Typical high voltage oil circuit breakers were very large and the oil posed an environmental threat if the tank were to leak. The interrupter assemblies inside the 230kV, 10 GVA circuit breakers could be as large as 40 inches tall [1]. The oil tank has to consist of enough oil to insulate the interrupter from the steel exterior. The mineral oil was commonly used because of its high dielectric strength; however, it is also very flammable so there is always a chance of combustion. In order to improve on the current design of the circuit breaker, a new insulating medium had to be implemented.

There was a European push to find a new insulating medium in the late 1930’s after suffering multiple explosions from high voltage oil circuit breakers. However, it wasn’t until post World War II when they could implement any sort of design [8]. The air blast circuit breaker uses a current transformer to monitor the current in the circuit to ensure it is operating in a correct range. One main advantage of the air blast circuit breaker is that it is oil-less so there is no danger of combustion. The speed of arc-interruption and automatic reclosing is much faster than the oil circuit breaker. Even in the mid to late 1940’s, researchers were able to limit the duration of the arc to 0.007 seconds and obtain a full close-open-close cycle of approximately 0.05 seconds on a 142kV, 640 MVA rated circuit breaker. Because the duration of the arc was so small, it resulted in a much shorter arc length than when compared to the oil circuit breaker. This, in turn, allowed for a much smaller piece of equipment that took up less real estate in the substation.  The 150KV, 1.8 GVA air blast circuit breaker automatically reclosed with a delay of under 0.2 seconds. This shows that at the same voltage but nearly a three times higher power rating, or a higher current carrying capacity, the delay for reclose is still relatively short being between 10-12 cycles. For the same style breaker rated at 230kV and 2.5 GVA, it was able to reclose with a delay of 16 cycles. This delay is shorter than what is needed for the oil circuit breaker is 20 cycles at the same rating [6,13]. If the fault happens to remain present when the circuit recloses, the circuit breaker will reopen and stay open. The blast of air used is a short pulse with high velocity ensuring the first arc is extinguished. However, if the contacts are still within clearance, the arc has the ability to restrike multiple times until it loses its energy. This can cause a loss in efficiency of the breaker at higher current applications.

Once the high voltage air blast circuit breaker began to be phased out of common installation, the vacuum style circuit breaker became more popular. Unlike the high voltage oil circuit breaker and the air blast circuit breaker, the vacuum circuit breaker had little to no threat of combustion or explosion, making it a safer medium of insulation. Also, the high voltage vacuum circuit breakers have a substantially longer operating life and nearly zero environmental impact making them more appealing to new installations [4]. However, unlike the previous mentioned circuit breakers, the vacuum circuit breaker relies more on the shape and material of the contacts to extinguish the arc instead of the actual medium that insulates the circuit breaker. Since there is essentially no medium that interacts with the arc, other means of adaption have to be taken into consideration. By increasing the radius of the contacts 1.3 times, the maximum dielectric strength was increased 10% [4]. By adding a ring to the back of the electrode the maximum dielectric strength was increased by 30% [4]. Since the contact gap is relatively short, typically between 30mm and 80mm for high voltage, there is a lot of heat present at the surface of the contacts. When comparing materials,
was able to maintain its physical properties after multiple arcs, where
showed signs of strain and deformation via microscopic holes [9]. 

The high voltage
circuit breakers are currently the most popular to be installed in new and existing substations. Since the introduction of the oil circuit breaker, the interruption capability and efficiency has continually increased, and the
circuit breakers have been found to be the most effective at interrupting up to 20 GVA. It has been found that
is 100 times more effective at extinguishing an arc than the air blast circuit breaker at voltages ranging from 33kV up to 800kV. This is important because as we move into the future, the Earth’s population increases, which ultimately results in an increase in power demand and power transmission safety. To protect the main contacts, there are rounded arcing contacts in place to take the arc once the main contacts slide behind a certain point [2]. This not only protects the main contacts, but the entire circuit breaker as well. If the charge remained on the main contacts cannot be extinguished and would ultimately lead to breaker failure [2]. When the arcing contacts take control of the arc, the
gas rapidly absorbs all of the free electrons present in the arc to extinguish it at a fast rate. When reacting with the free electrons, the
molecule can either take on the electron and become negatively charged,
, or a fluorine can break its bond with sulfur and bond with a free electron creating
and F [10]. Along with a short arc time, the
gas also has the ability to dissipate heat most effectively and since there is no loss of pressure during the extinguishing process, unlike the air blast circuit breaker, the pressure inside the
tank is easily monitored and maintained. These breakers can operate reliably with internal temperatures ranging anywhere from
300°K to 3000°K
at around 30 psi. When the temperature is at or below
is the dominant molecule at 99.97%. However, as the temperature of the gas increases there is a breakdown into multiple different combinations of
. Once the temperature reaches over
, neutral fluorine, a
is bonded with an
, is the dominant molecule at 64%, followed by
SF4, SF5, and SF6 
as the next most abundant molecules with
being only 3% prevalent [10]. This results in a lower dielectric strength and a less effective arc interrupter because the subset molecules of
are much weaker in those areas. Therefore, at internal temperatures above
there is a decrease in efficiency of the
circuit breaker. However,
has very good cooling properties, so this phenomenon only happens for a short period after it extinguishes an arc. When the pressure is dropped to around 3 psi, the
could reliably operate up to
[10]. This follows Paschen’s Law stating that the breakdown voltage of an arc is correlated with the pressure of the insulating gas multiplied by the contact gap distance. Because of this law, when the breaker is in it closed position, the contacts are surrounded by
at roughly 40 psi, once the contacts separate and open the valve to the stored
the pressure increases to nearly 200 psi. This ensures that the circuit breaker can safely operate at and above 20 GVA. The
high voltage circuit breakers are the most commonly installed breakers today in new and existing substations because of their efficiency, size, and power handling capability. However, even though the gas is not harmful to animals or humans, it is considered a potent greenhouse gas because of its long lifetime and strong infrared absorption [6]. With global warming becoming a continuously growing issue, there is a clear motive to move past using such harmful greenhouse gases.

The move away from
is not necessarily an easy step due to its high dielectric strength and its interruption capability. However, it being a greenhouse gas makes the transition seem logical for the environments sustainability. Since
has such superior properties as an insulation medium, naturally found gases cannot simply be substituted for the greenhouse gas since their dielectric strength and current interrupting properties are far inferior. This led to the idea of mixing
with an environmentally-friendly gas. Since
has already been manufactured in lower voltage circuit breakers, it is the most viable candidate. This raises the dielectric strength and current interrupting capability of
when mixed with
. Since
has a lower temperature molecular breakdown than
, at around
a 75%-
to 25%-
mixture breaks down into
SF6, CF4, and SO2F2
with both
SF6  and CF4
being potent greenhouse gases [6]. This indicates that the mixture would not be able to return back to the initial gaseous mixture at a convenient rate during the cooling process. Another option is to completely remove
as a gas used inside the circuit breaker. Mixtures containing
CO2, N2, and CF3I 
have been considered [5]. However, the dielectric strength and current interrupting capability of this gaseous mixture is much lower than pure
. Another main issue is the voltage breakdown of the compound is also lower. On top of that, when the molecule
breaks down, it prefers to lose either a fluorine ion or an iodine ion to water in the air. This results in either the production of HF or HI which are very corrosive acids and dangerous to humans and animals.

When circuit breakers were first introduced in the early 1900’s, the power handling capability far exceeded the power supplied. However, they were and still are a vital piece to all of our energy systems. Like most things, circuit breakers have evolved and adapted along with the growing demand for electrical power. The high voltage oil circuit breakers rated at 230kV and 10 GVA that monitored the power produced by the Hoover Dam, have been continuously improved with new insulating mediums and technology. Today we have high voltage circuit breakers with near immediate interrupting times and automatic reclosing rated over 35 GVA. Along with improvements to efficiency and power increase, engineers have been able to decrease the size of the circuit breaker unit. This in turn has decreased the size of space needed in a substation. For future applications, a push from using harmful greenhouse gases seems apparent in case there is a leak or another type of disaster that could lead to harming the planet. There are other means available, it is just a matter of being able to match the superior properties of
gas. I would like to see an improvement in vacuum circuit breakers in the high voltage realm since they can be much more compact and are currently very efficient at lower voltages. It seems that this is a material property issue since the high temperatures in a compact area destroy the contacts at the high currents needed in high voltage transmission.


[1] W. M. Leeds and R. E. Friedrich, “High-voltage oil circuit breakers,” in Electrical Engineering, vol. 69, no. 7, pp. 629-634, July 1950.

[2] P. Simka, U. Straumann and C. M. Franck, “SF6 high voltage circuit breaker contact systems under lightning impulse and very fast transient voltage stress,” in IEEE Transactions on Dielectrics and Electrical Insulation, vol. 19, no. 3, pp. 855-864, June 2012.

[3] A. K. Leuthold, “Design and operation of high-voltage axial air-blast circuit breakers,” in Electrical Engineering, vol. 61, no. 12, pp. 869-874, Dec. 1942.

[4] Z. Liu et al., “Development of High-Voltage Vacuum Circuit Breakers in China,” in IEEE Transactions on Plasma Science, vol. 35, no. 4, pp. 856-865, Aug. 2007.

[5] Y. Cressault, V. Connord, H. Hingana, P. Teulet and A. Gleizes, “Transport properties of CF3I thermal plasmas mixed with CO2, air or N2as an alternative to SF6plasmas in high-voltage circuit breakers”, Journal of Physics D: Applied Physics, vol. 44, no. 49, p. 495202, 2011.

[6] W. Wang, M. Rong, Y. Wu and J. Yan, “Fundamental properties of high-temperature SF6 mixed with CO2 as a replacement for SF6 in high-voltage circuit breakers”, Journal of Physics D: Applied Physics, vol. 47, no. 25, p. 255201, 2014.

[7] L. Zhong, Y. Cressault and P. Teulet, “Thermophysical and radiation properties of high-temperature C4F8-CO2 mixtures to replace SF6 in high-voltage circuit breakers”, Physics of Plasmas, vol. 25, no. 3, p. 033502, 2018.

[8] D. Johnston and D. Kingsbury, “An introduction to high-voltage air-blast circuit-breakers,” Journal of the Institution of Electrical Engineers, vol. 1952, no. 10, pp. 247–248, 1952.

[9] H. Wang, Y. Geng, Z. Liu, J. Lin, X. Li and Y. Li, “Prestrike characteristics of arc-melted CuCr40 and infiltration CuCr50 contact materials in 40.5 kV vacuum interrupters under capacitive making operations,” in IEEE Transactions on Dielectrics and Electrical Insulation, vol. 24, no. 6, pp. 3357-3366, Dec. 2017.

[10] M. Yousfi, P. Robin-Jouan, and Z. Kanzari, “Breakdown electric field calculations of hot SF/sub 6/ for high voltage circuit breaker applications,” IEEE Transactions on Dielectrics and Electrical Insulation, pp. 1192–1200, 2005.

Maximum Power Point Tracking Circuit Driven by an Arduino

Progress Report


MPPT circuit driven by an Arduino














MPPT (Maximum Power Point Tracking) are electronic devices that  Engineers are designing, making and improving to get the maximum power out of solar panels at various  condition.


As we all know, most of the energy currently consumed comes from the use of fossil fuels like oil, coal, natural gas or even nuclear energy. Recent studies and forecasts inform us that

the massive use of these resources will certainly lead to the total depletion of these

reserves. In addition, everyone is globally convinced by the danger of this process

on the environment.

From this observation, it was necessary to look for other energy resources. renewable (Green) energies such as photovoltaic and wind are alternatives, they are becoming more and more used in our days. This type of energy is not only free and inexhaustible, but also very clean for the environment. Moreover, we often talk about “Green”, an energy

witch completely avoids polluting the Earth compared with traditional sources [1]

Power grid distribution networks cannot be enough to provide electricity to the entire world population whether they are in the mountains or on an island, in the less inhabited or in the middle of the desert, sites that are difficult to access or very isolated cannot always be connected to the grid for lack of technical solutions or economic viability. Whereas (PV) panel can be implemented in any remote areas.

Solar Energy is one of the greener renewable form of power widely used today. However, harvesting this source to the maximum can be very challenging as there are many factors to consider.

MPPT (Maximum Power Point Tracking) are electronic devices that  Engineers are designing, making and improving to get the maximum power out of solar panels at various conditions. The objective of this work was to design and build an MPP Tracking circuit for a photovoltaic panel system that uses (DC/DC) Buck converter based on an Arduino Uno Board. The Algorithm Perturb and Observe( P&O) was implemented to compute and track the maximum power of the Solar panel at any given voltage inputs ranging from 23V to 70V DC. The circuit  was simulated on MATLAB . for analysis and built and  tested on a PV simulator in the Lab.

3.Aims and Objectives:

The aim is to illustrate the importance Of an MPPT device in increasing the Power

efficiency of PV panels by

Identifying different components of the MPPT

List the various Algorithm used to track the maximum power

Implement two MPPT algorithms, compare and analyse the efficiency

4.Approach & methodology:

 To illustrate the importance of MPPT devices and for designing ,making an MPPT circuit for solar panel,this project is divided into different activities each activity is given a specific time frame and task.

 the following activities adopted are:

Activity 1:

literature review of photovoltaic system is important to understanding the concept and the working condition of solar cells

importance of MPPT devices

highlight the different MPPT algorithms used and their advantages and disadvantages

different MPPT circuit used and the proposed Buck converted circuit will be investigated and the components choice justified.

Activity 2:

Identify the different components of an MPPT:

Build a Buck converter Circuit and test its functionality

Voltage sensor used

Current sensor type

Microcontroller (Arduino Board)

Activity 3:

   Build and test the MPPT circuit

Checking the performance of the built MPPT circuit under a different irradiance condition

Compare the Perturb and Observe (P&O) algorithm with a fixed set algorithm

MATLAB simulation of the built circuit

Activity 4:

Highlight any issues and any improvement to the circuit 

Draw a conclusion

 5.Literature Survey/Theory:

Photovoltaic cell

  A photovoltaic cell is an opto-electrical component that transforms solar light into electricity, discovered by E. Becquerel in 1839.Photovoltaic cell consists of a P-N type semiconductor material.  linked together to form a p-n junction .this will form an electric field in the region of the junction as electrons jump to the positive p-side and holes shift to the negative n-side[5] 

  photons in the sun light, cause the electrons in the PV Cell  to jump to a higher energy state known as the conduction band. In their new state, these electrons are free to move through the material, this motion of the former generates an electric current in the Photovoltaic cell.

 Since that time work have been made to improve efficiency and make affordable solar cells. Figure (1.1) represents a sample configuration of the photovoltaic cell.

                                        Figure (1.1): Diagram of a photovoltaic cell


Photovoltaic effect

      solar energy comes from the direct transformation of part of the solar radiation into electrical energy. This energy conversion is done through a cell called photovoltaic based on a physical phenomenon named photovoltaic effect system which consists in producing an electromotive force when the surface of this cell is exposed to light [1] [2].

   The elementary photovoltaic cell creates a very low power generator. A cell only ten centimeters square delivers at most, a few watts at a voltage less than one volt [ 3].

   To produce more power, several cells must be assembled in order to create a module or a photovoltaic field. The serial connection of the cells allows to easily increase the voltage of the set, while parallel connection increases the current Serial / parallel wiring is therefore used to obtain an overall PV generator with the desired characteristics.

Photovoltaic module

     The most crucial component of any PV installation is the photovoltaic module, which consists of interconnected solar cells. These modules are connected to each other to form power (station fields) so that they can satisfy different levels of energy needs. Figure (1.2) shows a photovoltaic module.

   More and more powerful modules are available on the market, especially for the

network connection, but there is still a limit related to weight and manipulation.

                                            Figure (1.2): Photovoltaic Module

Photovoltaic power station

   The photovoltaic power station consists of photovoltaic modules interconnected in

series and in parallel in order to produce the required power. These modules are mounted on a metal frame with an angle of inclination for a better power outcome

Figure (1.3) shows a photovoltaic power station.

                                            Figure (1.3) Photovoltaic Power Station

1.3 Photovoltaic Modeling

1.3.1 Ideal photovoltaic model

 The photovoltaic module can be represented by its equivalent electrical circuit

given by figure (1.4)

                                      Figure (1.4): Ideal circuit of the PV cell

 This circuit is composed of a current generator source which produces a current proportional to the incident sun light power, a parallel diode which corresponds to the transition area P-N junction of the PV module [4].

The current generated by the module is mathematically written to describes the Current and voltage (I-V) characteristic.


symbols are defined as follows



Ipv      Output current of the cells (directly proportional to the Sun irradiation).

Id         diode equation.

q          the electron charge (1.60217646 × 10−19 C).

k           Boltzmann constant (1.3806503 × 10−23 J/K).

I0         cell is the reverse saturation or leakage current of the diode.

Iph       function of irradiation level and junction temperature (5 A).

T          the temperature of the p–n junction (in Kelvin).

A          diode ideality constant. e: electron charge (1.602 × 10-19 C).

Ic          cell output current  (A).

I0          reverse saturation current of diode (0.0002 A).

Tc        reference cell operating temperature (20 °C).

Vc:        cell output voltage ( V).

Rs         series resistance of cell (0.001 Ω).


1.3.2 Real photovoltaic model

 In the real case, there is a loss of voltage at the output as well as currents leakage

thus, the previous photovoltaic model did not account for all the phenomena

present during the conversion of sun light energy. We model this voltage loss

by series resistance and leakage currents by parallel resistance [4]. The

figure (1.5) represents equivalent electrical diagram of a real photovoltaic module.

                                      Figure (1.5): real circuit of the PV cell

The current generated by the PV module is given by Kirchhoff’s law

is the current supplied by the PV module.
is the photo- current depending on the illumination (G)

 K is the Boltzmann constant (1.381 joule / Kelvin)

q is the electron charge = 1.602*

 T is the temperature of the PV module in kelvin.

 A is the ideality factor of the junction (1
1.4 Electrical parameters of the photovoltaic module

 The different parameters characterising a photovoltaic module are the open voltage circuit. Short circuit current, maximum power, Fill Factor and efficiency.

They are extracted from current/voltage characteristics, they are used to compare different Pv modules when illuminated under identical conditions.

1.4.1 Open circuit voltage

 when a PV module is  placed under a constant light source without any current flow, no load connected we obtain at its terminals a maximum continuous voltage, called open circuit voltage
where 0.6 V is the voltage for an elementary PV cell and N is the number of cells. We measure
by directly connecting a voltmeter to the terminals of the PV module [5].

1.4.2 Short circuit current

  When the PV module is short-circuited, it delivers its maximum voltage current.

It is said short circuit current Icc. Its value is obtained by connecting an ammeter

at the terminals of the module. In silicon PV modules, the current is of the order of

12mA / cm² [5].

1.4.3 Maximum Power

The power supplied to the external circuit by a photovoltaic module depends on the load resistance (external resistance placed across the module).

This power is maximum (noted Pmax) for an operating point Pmax of the current-voltage (I/V) curve.

1.4.2 Fill Factor

The form factor is the ratio of the maximum power provided by the

PV module, and the product of the ICC short-circuit current by the voltage of

open essentially a measure of quality of the solar cell.

1.4.3 Solar panel efficiency


It quantifies a solar panel (module) ability to convert sunlight into electricity

It’s given to be:

2.3.4. Disturbance method and observation

The P & O control principle is to cause a low disturbance

value on the voltage, which generates a variation of the power. Figure (2.8) shows

that if an increase in voltage causes an increase in power, the point of

operation is to the left of the PPM, if on the contrary the power decreases, it is

right. In the same way, we can make a reasoning for a reduction of the tension.

In summary, for a voltage disturbance, if the power increases, the direction of the

disturbance is maintained. If not, it is reversed so that the operating point

converges towards the PPM [10].

Figure (2.8): Power-Voltage Characteristic of a Photovoltaic Module

                    Figure (2.8): Power-Voltage Characteristic of a Photovoltaic Module


6.Progress Made:

 (up to 5 pages)

Discuss the progress made during the first semester and include preliminary observations/results.



Work plan for the second semester (1 page)

 Detail how the remainder of the project is to be carried out. Include a work plan.




Use the recommended format (either Harvard-SHU or APA 6) for more info see






























Fitness Levels In Circuit Training

The chosen activity for this assignment is circuit training.Circuit training improves general fitness which is health-related and specific fitness,for a specific activity; here circuit training.In pursuing such activity I may improve both my strength and cardiovascular fitness. Circuit training is essentially structured exercise.Aerobic fitness,strength and flexibility are all improved pursuing circuit training.Incorporated into such an exercise structure are fixed weights/machine ‘stations’ which isolate specific muscle groups.A complete exercise set is achieved within a given period of time,usually 20 minutes.An uninterrupted flow of activity from machine to machine may enable proper gain of aerobic benefit.The heart is pumping at a steady high level.

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Every gym session will consist of a warm-up with mobility exercises;ending with the cool-down.Each exercise ‘station’ exercises a different muscle group from the last.The whole session should last one hour.(Pollock et al.,1998) Circuit training should not occur on consecutive days,two or three visits to the gym per week being sufficient.Selection of correct weights,repetitions and positions is necessary to minimise occurrence of injury and to achieve desired fitness objectives.
Aerobic endurance is exercised by completing a circuit as quickly as possible.Significant gains may occur for strength,muscular endurance and flexibility.Physical fitness consists of ‘components’.These are aerobic endurance,strength,speed,flexibility,muscular endurance,power and agility.Training programmes may be customized to improve on a selection of these.The most important aspects applicable to circuit training are aerobic endurance;muscular endurance,and flexibility.
When the body performs for a prolonged period of time with a low work rate aerobic endurance comes to the fore;such a training will condition the heart and lungs to function more efficiently.Choosing a work-out on the rowing machine for some 20 minutes as an example;this cardiovascular ergometer is very effective in establishing a proper base of muscular endurance that initiates improvement in other components of fitness.
Muscular endurance is a function of aerobic endurance without whose supply of oxygen it could not rapidly perform.It is defined as a single muscle or group performing recurrently against variable resistance.For example dumbbell(DB) lunges or shoulder press with a barbell(BB).Body resistance circuit training that includes both free and fixed weights is well suited to improve muscular endurance.
Usually overlooked is flexibility,the range of motion(ROM) at a joint or series of joints.This component however is vital in the prevention of inadvertent injury.It is sufficient to perform the warm up including mobility exercises(developing a full range of movement[ROM]) and cool down stretches;all being required for a main session of gym activity.
My gym circuit therefore is comprised of a warm-up lasting 5 minutes on a suitable cardiovascular machine eg the treadmill, that simulates a walking gait exercise aerobically.This is followed by the set of mobility exercises(not stretches) to loosen my joints and produce more synovial fluid;gently and rhythmically exercising.This is still aerobic.There follows a set of stretches to prepare the main muscle groups of the body for an imminent main activity session.These too are aerobic;not as intense yet steady,controlled,positioned for some ten seconds.
The main cardiovascular machine chosen for a full work-out of at least twenty minutes is the rowing machine,which exercises all main muscle groups with the heart as target muscle. A customized programme working the rower will produce an aerobic curve with a rising and falling RPE[rate of perceived exertion 0-10 on the Borg Scale](Gunnar Borg(1973) validated by(Kang et al.2003)also (Steed,Gaesser,and Weltman 1994) Aerobic contribution is present in the Cool down using a different cardiovascular machine followed by stretches including some that are developmental;included to improve flexibility in the bigger muscles eg the hamstrings(ACSM,2006)
As I want to improve my strength and endurance it is important that I obtain profile data from the apparatus and exercises outlined above so that I can clearly see whether I am making any improvements from when I began.
The Principles of Training should be applicable to every exercise and sporting category.Individuals and teams then have specific objectives and goals to aim for in their training schedules.Else, all would be blindfolded resulting in overtraining,burn out and poor performance results.
Demands on the body higher than the norm comprise what is known as Overload that in turn has related factors of intensity(how hard);duration(how long);type(sport/activity);frequency(how often).
Frequency is self-explanatory,often resulting in a higher level of performance. As workload steps up so does intensity.Heavier weights,longer stretches.Such results take time.Overload may be achieved with a higher number of repetitions or performing the same with reduced time-spans.
The body is a natural adapter to overloading,so training should be progressive to prompt a response.When this occurs improvement is tangible especially at the beginning.As sets increase muscle strength and endurance increase. It is important not to be too slow in progression. Biceps curls for example.If working with 10 lb weights taking it to 3-4 sets at 15 reps before muscle fatigue is experienced then it is better to do 2 sets of 15 lb weights.
Specificity of a chosen,pursued activity needs to be understood.What am I training for? This is very important and relevant for strength training.Exercise has to be specific for each muscle group and strength type required.Balance has also to be included and therefore other exercises of a general nature such as the squat provide an excellent base for development of specific exercise.
A training programme must cater/customize to the special, specific requirements of the participant.(Sharkey and Greatzer 1993).Working with dumbbells and the barbell,that is the free weights will improve muscular strength but will not significantly effect transport of oxygen to the muscles.Many sports have similar components of fitness and therefore it is quite feasible for transference of specifics from one to another.
The opposite of Progression is Reversibility.Training and performance when falling off will signal to the body for an appropriate response.Aerobic capacity diminishes rapidly with no exercise(Coyle,Hemmert,and Coggan 1986) also (Saltin et al.,1968) Muscular endurance with muscles no longer used falls away three times more rapidly than when gained.Performance of skills may be affected through physical deterioration(Greenleaf et al.1976)
A number of training methods exist designed for the different fitness components.Circuit training may be viewed as interval training containing high-intensity anaerobic periods with weights and low-intensity aerobic periods of recovery.This training method is able to improve specific areas of the body for muscular endurance.A circuit improves both aerobic fitness and strength thereby providing for much needed conditioning.Aerobic training also involves continuous/steady state training(McArdle et al.,2006)Other methods consist of interval(McArdie et al.,2006) and fartlek training.Flexibility training incorporates both passive and active,static stretching;dynamic and proprioceptive neuromuscular facilitation(PNF) stretching.
Suitable to my requirements is a muscular endurance circuit.This will enable me to withstand fatigue,hold to a given position,and to perform repeated muscular contractions for a given period of time.Selection of appropriate exercises needs a central focus of balanced muscle groups.Improvement of cardiovascular exercise and muscular endurance exercise may be achieved by alternating them within a circuit programme.The back squat for instance utilises many muscle groups,that work simultaneously.A main cardiovascular work-out,for example, requires at least 20 minutes on the rower, being correctly positioned within the circuit.The remaining floor-based stretches are performed at the end of the gym session.This saves the heart rate from decreasing too much.
Progression and overload are important to consider when a circuit training programme is being planned. The principle of overload indicates “your body systems must be stressed beyond their normal levels of activity if they are to improve.”(Williams 1993:18).Progression can be maintained simply by increasing the number of repetitions per exercise; reducing the recovery period(secs) between each set of exercises;increasing the resistance of the exercises by weight .
Stimulation is applied using the principles of overload and progression during circuit training so that adaptation may occur. Overload is delivered by adjusting one or more of the FITT principles.Frequency(how often);Intensity(how hard);Time(how long);Type(suiting sport/activity).
Principles are usually installed in most matters and physical activity is no exception. The principles of training are the rules to follow when using physical activity programmes.Sound and useful training takes into consideration all of the principles and their effects on the body;being essential to the planning of the training programme so that the participant is able to improve their fitness level. Fitness levels vary from person to person so the training needs be systematic taking into account individual needs ; variables of difficulty or intensity are set at the personal level.
An example from the free weights exercises for progression/adaptation is the Biceps Curl with barbell(BB).Apart from applying a progressively greater weight performance may be effected through different ranges of motion i.e. halfway up and down.All the way up and halfway down;up again and all the way down;all the way up and down.An example of an adaptation for a fixed weight machine is substituting the seated row for the lateral pull down.Again the seated cable row may be substituted by the single arm row with a dumbbell(DB).Or the Triceps pull down (cable) by selection of a Triceps extension with butterfly grip(DB).
It may be necessary to increase aerobic fitness and if so, use of one of the cardio-vascular machines is ideal. A most satisfactory work-out can be experienced with the rowing machine that works all major muscle groups with the heart as the target muscle,enabling safe non-impact exercise safe-guarding joint integrity,and if worked with the correct technique even for those with problems in the lower back can still be safe.
If aerobic fitness needs to be increased interval training is very effective when inserted into circuit training.Intervals of very rapid rowing(RPE 8) are followed by recovery periods(RPE 5) [ see Appendix] The term can refer to any cardiovascular workout;for example,rowing,involving very short stints of nearly optimum effort and periods of much lower intensity.The aerobic capacity of the participant improves and enables an extended period of delivery at variable intensity.Fat loss is more efficiently dealt with.
With no correction or improvement reversibility occurs.Having ceased training the body loses its conditioning and strength and also endurance.This is relevant to myself as I am pursuing a cardiovascular, strength and endurance programme.A study has been made of cessation of physical activity;in this case an Olympic rower.It was 20 weeks before he was able to resume his activity following an eight week convalescence. ‘The detraining and retraining of an elite rower:a case study’.J Sci Med Sport 2005;8;3:314-320. It is recommended there should be no more than three weeks interval since last specific activity.
A state of complete fitness involvesthemental,emotional,nutritional,social and medical,not only the physical. How we enjoy life;attention towards any diet at all;how we deal with stress;our emotional world;communicative ability;requirements for relaxation and also of course physical fitness.Circuit training is one of a number of ways to improve components towards a state of complete fitness.
Pollock,M.L.,Gaesser,G.A.,Butcher,J.D.,Despres,J.P.,Dishman,R.K.,Franklin,B.A.and Ewing Garber,C.(1998) ‘ACSM position stand:The recommended quantity and quality of exercise for developing and maintaining cardiorespiratory and muscular fitness,and flexibility in healthy adults’,Medicine & Science in Sport & Exercise,vol.30,pp.975-91
Borg,G. 1973.Perceived exertion:A note on history and methods.Medicine and Science in Sports and Exercise 5:90-93
Kang,J.,J.Hoffman,H.Walker,E.Chaloupka,and A.Utter.2003.Regulating intensity using perceived exertion during extended exercise periods.European Journal of Applied Physiology 89:475-482
Steed,J.,G.Gaesser,and A.Weltman.1994.Rating of perceived exertion and blood lactate concentration during submaximal running.Medicine and Science in Sports and Exercise 26:797-803
American College of Sports Medicine(2006) ACSM’s Guidelines for Exercise Testing and Prescription(7th edn0,London,Lippincott,Williams & Wilkins
Sharkey,B.J.,and D.Greatzer.1993.Specificity of exercise,training and testing.In ACSM’s resource manual for guidelines for exercise testing and prescription,ed.L.Durstine,A.King,P.Painter,and J.Roitman,82-92.Philadelphia:Lea & Febiger
Coyle,E.,M.Hemmert,and A.Coggan.1986.Effects of detraining on cardiovascular responses to exercise:Role of blood volume.Journal of Applied Physiology 60:95-99
Saltin,B.,G.Blomqvist,J.H.Mitchell,R.L.Johnson Jr.,K.Wildenthal,and C.B.Chapman.1968.Response to exercise after bed rest and after training.Circulation 38(Suppl.7):1-78
Greenleaf,J.E.,C.J.Greenleaf,D.VanDerveer,and K.J.Dorchak.1976.Adaptation to prolonged bedrest in man:A compendium of research.Washington,DC:National Aeronautics and Space Administration
McArdle,W.D.,Katch,F.I. and Katch,V.L.(2006) Essentials of Exercise Physiology (3rd edn),London,McGraw-Hill
Williams Melvin H.(1993) Lifetime Fitness & Wellness(3rd edn) Brown & Benchmartin: Iona
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