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Ahmed Nagy Hassan

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  • Cairo-Egypt
  • Electrical Engineer
  • faculity of Engineering-Cairo University
  • Reading-Writing of Technological Articles-Translation-Writing in Electrical Engineering Area.
  • Cairo-Egypt
  • Electrical Engineer
  • faculity of Engineering-Cairo University
  • Reading-Writing of Technological Articles-Translation-Writing in Electrical Engineering Area.

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  • Importance of "Electronics" in Our Lives

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    There is no doubt that electronics is a vast sea of sail modern science, it's a very Important s...

    Category: Engineering

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  • Importance of "Electronics" in Our Lives

    There is no doubt that electronics is a vast sea of sail modern science, it's a very Important science .. cares always everything that is new, also it's responsible for the progress and the Renaissance, and it's the First Science in the Manufacturing of Airplanes,computers and other such modern Industries Which recently appeared in our Life, Unless The Existence of This Science ... Man didn't Reach to all this prosperity and all this remarkable progress in our world now, Man has been able to Make robots, which can Do millions of jobs without exaggeration, which is based mainly in industry aware of the programming language, whether C Language or JavaScript, or other languages ​​that almost electronic Materials Are Based On It . Hence the protection devices of the utmost importance, such as relay, Contactors and other machines, control and protection that can not be dispensed with in any plant produce electricity, or control firm . Hence, we can realize how importance of this great science in our lives.

  • Importance of "Electronics" in Our Lives

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    Created by Ahmed Nagy Hassan

    There is no doubt that electronics is a vast sea of sail modern science, it's a very Important s...

    Category: Engineering

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  • Breakthrough progress in the world

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    There is little question that the planet has evolved and up to date progress considerably and attrac...

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  • Breakthrough progress in the world

    There is little question that the planet has evolved and up to date progress considerably and attractive marvel, they gave the man's ability to fly when it's been blocked into constant contact planar, and was able to conquer area, riding cars and talking together with his friend on the phone to finish a task pressing action as quickly as attainable, and may not be impatient, and therefore the man became able to perform several of the tasks that appeared not possible from the purpose of read before, however with the progress of your time and therefore the development of science within the concrete and really strange, then had to the rights to develop an equivalent in accordance with this development that occurred all told around him, in line with this boom scientific strange, and so unreal the fashionable machines, that enabled the human rights abandon labor and gave him the chance to try and do sometime is nearly not possible, and unreal a machine of metal, and was able to management it volitionally utilized in most areas of his life, and so, will never lose sight of the mechanism automotive, those exotic machine that emerged within the era, and specifically within the seventies, and this man was ready through this device that controls several of the industries that trust entirely on the numerous factories, particularly in Japan, which has, to form a replacement breakthrough within the world of robots. Where will mortal man that he makes this strange god-like man somewhat, to be used in several industrial fields, area unit for mechanical style controlled by alittle device, typically referred to as "microcontrollers" . The Mechanism will arm the one that conveys some risky industrial materials from one place to a different, it's conjointly capable of movement and transition, together with pilotless craft, and craft self-control victimisation artificial neural networks. In order to create the mechanism avoid some obstacles that may not be offset by, It should be an explicit system that enables him to skip these obstacles simply and handily, programmed so as to be able to cope with the mechanism is programmed merely and on this basis, should the existence of questionable "sensors" .... Sensors referred to as Sensors accustomed facilitate the mechanism to external influences Sense Some area unit capable of sensing high temperatures, like a candle burning simply two meters. Handler referred to as Microcontrollers It is the mechanism's mind and his ability to try and do several of the roles Ktmiaz patterns of Foreign Affairs {and the|and therefore the|and conjointly the} wizard also directed the robot. It conjointly identifies shapes. In short, is accountable of the applying of various algorithms that area unit required in an automatic Allansan perform its mission. And a mechanism that may every with its own processor, or that each one of them participate within the C.P.U. is moving several of the mechanism. 

  • Breakthrough progress in the world

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    There is little question that the planet has evolved and up to date progress considerably and attrac...

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  • Alternative Sources Of Energy

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    The World Is Full Of Natural ingredient That Can Help People To Live In a Progres and Welfare, But T...

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  • Alternative Sources Of Energy

    The World Is Full Of Natural ingredient That Can Help People To Live In a Progres and Welfare, But The Main Idea That People Use This Ingredients in a Right Manner to be able to reach The Honor . and As We All See : The World Suffers From The Lake Of Energy Sources , Those Sources That are Very Important For a Comfortable lives . From Here , It's Necessary For Us To Begin To Search about a Renewable Sources Of Energy . In This Field , We Can Say That We Can Use Alternative Sources Of Energy Instead Of Gasoline and Gases . We Have The Sun Which Provides Us With The Heat and Light , We Can Exploit It To Can Overcome The Problems Of Energy . The Solar Energy Is a Very Important and Strong Competitor Against Gases and Gasoline . We Can Store The Light and Energy Of The Sun Into Batteries and Use It To Lighten Houses , Industries , Companies , Stadiums ..... , Etc . 

    We Can Use The Solar Energy in This Fields By Using Solar Panels Which Became Available Today in The Engineering Market . and Store The Heat and Light into Batteries During The Day To Use Them During The Evening. Then , Why Don't We Think Of That Great Alternative Sources , Which Can Be Converted into Electricity Easily By Using Some Complex and Simple Components? Another Alternative Source Of Energy Can Be Used in Generation Of Electricity , It's a Great Source Which Can Serve The Humanity If We Tried To Think For a Little Time : It's "The Wind Energy" , That Source Which Used as a Main Source Of Energy in Lots Of Countries . We Can Generate The Wind Energy By Using Wind Turbines With Very Big Radius Turbines, By Positioning Them In The Huge Areas Of The Desert . All Of That Is a Small Part Of The Natural Ingredient That God Gave To Us.

  • Alternative Sources Of Energy

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    The World Is Full Of Natural ingredient That Can Help People To Live In a Progres and Welfare, But T...

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  • Factors affecting on Transmission Line Design.

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    There are lots of Factors that can affect on the design of a T.L. These factors are considered as t...

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  • Factors affecting on Transmission Line Design.

    There are lots of Factors that can affect on the design of a T.L.

    These factors are considered as the Responsible for Success and Failure of the Transmission Line Performance.

    1. Selection of the Line Voltage That will be applied on the T.L.
    2. Selection of Conductor Material.
    3. Get The Line Current That will be carried by The T.L.
    4. Get The Initial Estimate for The Minimum Number of Circuits.
    5. Add one more Circuit for Reliability.
    6. Select an initial Number of Sub-conductors per Phase.
    7. Get Sub-conductor Current.
    8. Select The Best Size from Tables to satisfy The Thermal Limit.
    9. Get The Constants (A,B,C,&D).
    10. Get Line Voltage (Vs) & (Is).
    11. Get Efficiency, Regulation, and Power Losses.

    Then, there will be Constraints that should be taken in Consideration, such that:

    1. Electric Constraints:

    Stability, Reliability, Thermal Capacity, Voltage Profile, Corona, Over Voltage, and Different Imposed Regulations.

    1. Mechanical Constraints:

    Different Forces Existing on Conductors, The Suspension String and The Towers, Specially in Short Circuit Conditions.

    1. Environmental Constraints:

    Guarantee The Protection of The Health of People Surrounding The T.L.

    1. Economical Constraints:

    All That Requirements must be satisfied using The Minimum Cost.

    While Designing a T.L, We should avoid many Phenomena that may damage The T.L.

    1. Corona:

    Corona is a Discharge that forms when the voltage of Conductor passes the Disruptive Critical Voltage and disappears when the Voltage descends through the same value , this occurs on each Conductor every half Cycle since the Effective Capacitance of the Conductor increases.

    Methods to avoid Corona Discharge:

    (i) The Critical Voltage can be raised either by Increasing The Spacing between Conductors, or The The Diameter of Conductor.

    (ii) Steel-Cored AL Conductors have a Large Diameter for a given Conductivity and Weight, and Thus are Good from the Point of View of Corona.

    (iii) For very High Voltage, 275 kv, it has been found that it’s Economical to use The Hollow Conductors.

    (iv)  A Line is usually designed to work at a Voltage just below the Disruptive Critical Voltage for Fair Weather.

    *Corona Disadvantages:

    (1) Losses.                                   (2) Noise.

    (3) Radio Interference.                (4) Mechanical Vibration.

                              (5) Chemical Effect.

     

    *Corona Advantages:

    (1) Van-De graf Generator.

    (2) Ozone Production.

    (3) Electrostatic Precepetators.

    (2) Ferrantie Effect:

    It’s known as The Phenomena in which the Receiving Voltage is Greater than The Sending Voltage, because of the Stray Capacitance of the T.L, and that may damage the Distribution Transformers and cause Unbalance for the System.

  • Factors affecting on Transmission Line Design.

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    Created by Ahmed Nagy Hassan

    There are lots of Factors that can affect on the design of a T.L. These factors are considered as t...

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  • Protection System & Elements

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    Switch Gear : is a General Term Covering a Wide Range of Equipment connected with Switching and Inte...

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  • Protection System & Elements

    Switch Gear : is a General Term Covering a Wide Range of Equipment connected with Switching and Interrupting the Currents, During Normal and Apnormal  Conditions .

    In Addition, The Equipment associated with Controlling Protecting and Measuring is also covered by Switch Gear.

    Switch Gear includes Switches, Fuses, Circuit Breakers, Insulators, Relays, Control Panels, Lightening Arrestors, Current Transformers, Potential Transformers, and Other associated Items.

     *Circuit Breakers :

     During the Normal Operating Condition, The C.B can be Opened or closed Manually by the Station Operator for the Purpose of Maintenance.

    During Apnormal or Faulty Conditions, The Relay senses the Fault and close The Trip Circuit of the C.B.

    Therefore, The C.B opens.

    The C.B has Two Working Positions, Namely Open and Closed.

    The Apnormal Conditions of the C.B Operation are The Following:

    1. Faults : The Faults in an Electric Circuit may be Defined as Partial or Total Failure of the Insulation.

    For The Purpose of Analysis, Fault can be Classified as :

    1. Single Line to Ground Fault.
    2. Double Line to Ground Fault.
    3. Line to Line Fault.
    4. Three Phase Fault.
    5. Winding Faults (Generators, Transformers, and Motors).
    6. Open Circuits (Arc due to Ionization of Air).

    Beside Faults, There are Other Apnormal Conditions in Power Systems, This includes:

    1. Instability of the System.
    2. Over Voltage and Over Current.
    3. Under Voltage and Under Current.
    4. Over Frequency and Under Frequency.
    5. Power Reverse.
    6. Temperature Rise.
    7. Unbalanced Conditions.

    The Standards defined The Circuit Breakers as a Device Capable of Making and Breaking of an Electric Circuit Under Normal Conditions and Upnormal Condituins such as, Short Circuits.

    *The Process of Fault Clearing :

    (1) As the Fault occurs, The Current increases and the Relay gets actuated or energized.

    The Moving Part of the Relay moves because of the increasing in the Current.

    The Relay tales some Time to close its Contacts.

    1. Relay Contacts close the Trip Circuit of the Circuit Breakers, and Trip is energized.
    2. The Operating Mechanism starts for the Opening of the Circuit Breaker, and The C.B Contacts separate.
    3. Arc is Drown between the Breaker Contacts, and That Arc is interrupted in the C.B BY Suitable Techniques. The Current reaches Final Zero as The Arc is interrupted and doesn’t restrike again.

    *Maintenance of the Arc Extinction :

    The Electrons so librated from the Cathode of The C.B make many Collisions with The Atoms of Gases, and produce more Electrons .

    To interrupt The Arc, The Following Methods can be used:

    1. Lengthening of the Arc.
    2. Cooling the Arc.
    3. Splitting the Arc.
    4. Constraining the Arc.  

  • Protection System & Elements

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    Created by Ahmed Nagy Hassan

    Switch Gear : is a General Term Covering a Wide Range of Equipment connected with Switching and Inte...

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  • Protection of Generators.

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    Generator Apnormal Conditions : Faults in the Winding . Loss of Excitation. Motoring of Generat...

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  • Protection of Generators.

    Generator Apnormal Conditions :

    1. Faults in the Winding .
    2. Loss of Excitation.
    3. Motoring of Generator.
    4. Overload.
    5. Overheating.
    6. Over speed.
    7. Unbalanced Operation.
    8. Out of Synchronization.
    9. External Faults.
    1. Faults in the Winding :

    *Stator Faults:

    (i) Inter phase Fault.

    (ii) Inter turn Fault in Stator.

    (iii) Stator Earth Fault.

    *Rotor Faults :

    (i) Rotor Eatth Fault.

    (ii) Inter turn Fault in Rotor.

    1. Inter phase Short Circuit :

    It’s a Short Circuit between Parts of Different Phases of the Winding.

    It can be Protected Using Differential Protection, Which has High Speed of Operation.

    1. Inter turn Faults:

    It’s a Short Circuit between Turns of The Same Phase, it can be Protected Using Residual Voltage Method.

    A Voltage Transformer is connected between each phase Terminal and The Neutral, The Secondary Terminals are connected in Open Delta to a Voltage Relay.

    During The Normal Conditions :

    Vres = V12 + V23 + V31 .= Zero.

    At Short Circuit between Turns, Vres  doesn’t equal Zero, then Relay operates.

    The Relay shouldn’t operate for Earth Fault, The Earth Fault causes Voltages of Third Harmonics so, a Low Pass Filter LPF is used to prevent The 3rd Harmonic Current.

    1. Stator Earth Fault :

    The Protection against Earth Fault is affected by The Grounding Method of the Generator, so a Separate Additional Earth Fault Protection is Necessary in Addition to The Differential Protection, Because, The Differential Protection provides Earth Fault Protection to about 85% of the Generator Winding.

    Where: The % of Winding Unprotected = (Io*Rg / Vph).

    Io = The Relay Operating Current in The Primary Side of the Current Transformer.

    Rg = The Grounding Resistance.

    Vph = The Line to Neutral Voltage.

       (vi)   Rotor Earth Fault :

    The Field System isn’t connected to Earth, So That a Single Earth Fault doesn’t give Rise to any Fault Current, But a Second Earth Fault will cause short Circuit current and produce Force on the Rotor, Bearing, and Shaft, It can be protected by The Following Method:

    A High Resistance is Connected across the Rotor Circuit, The Center Point of This Resistance is connected to Earth Through a Sensitive Relay, Which detects The Earth Fault for most of the Rotor Circuit except the Center Point of The Rotor.

    AC Voltage Source is connected between the Field Circuit and Earth Through an Over Voltage Relay, a Single Earth Fault in The Rotor Circuit completes The Circuit and Then The Fault is sensed by The Voltage Relay.

    1. Loss of Excitation :

    When a Synchronous Generator loses its Excitation (Field), and If it’s connected in Parallel with Other Units, it can draw The Magnetization Curve from The Bus Bars and operate as an Induction Generator.

    It can be protected Using:

    *Under Current Relay connected in Field Circuit.

    *Distance Relay connected to A.C Voltage & Currents of the Generator Terminals.

      (3) Motoring of The Generator:

    When the Input to The Turbine is stopped, The Generator will operate as a Synchronous Motor, it can be protected by Using Power Reverse Protection.

       (4) Over Load Protection:

    Over Load Protection is Used to Back up Protection for Bus Bar or Feeder Faults than to protect the Machine Directly.

    It can be protected Using Thermal Relay which is used to monitor the Stator Winding Temperature and Signal an Alarm If a Certain Limit is exceeded.

      (5) Over Heating Protection:

    Over Heating may be due to Loss of Cooling System or Lubricating Oil, it may Damage The Mechanical System and Bearings.

    It can be protected Using Thermocouple System to monitor The Temperature an signal an Alarm if it’s Necessary.   

  • Protection of Generators.

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    Created by Ahmed Nagy Hassan

    Generator Apnormal Conditions : Faults in the Winding . Loss of Excitation. Motoring of Generat...

    Category: Engineering

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  • The Synchronous Machine

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    Hi Everybody, then, we will talk now about a very important Component in the Area of The Electric Po...

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  •   The Synchronous Machine

    Hi Everybody, then, we will talk now about a very important Component in the Area of The Electric Power and Machine, that component that is Irreplaceable, it's " The Synchronous Machine".

     

    The Synchronous Machine is one of the most important machines in the electric power Generation, where it's used as a main source for power Generation in all Power Stations around the world.

     

    this machine can be used as a Generator or a Motor but it's extensively used as a Generator, and it Operates with very High Efficiency Wheather it' mode of Operation.

     

    Why it is called "Synchronous"?

    To follow more, See the attached file ...... 

  • The Synchronous Machine

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    Hi Everybody, then, we will talk now about a very important Component in the Area of The Electric Po...

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