An Online Education Right For every person in all over the world.

ONLINE EDUCATION - :

We live in the information age. We have grown so accustomed to information at the speed of light that the prospect of not having immediate access to countless numbers of facts and figures with the mere click of a few buttons for many of us is simply disconcerting. For this reason, it only makes sense that there are many people across the nation and around the world that are embracing the idea of online learning and educational opportunities with every ounce of enthusiasm they can muster.

At the same time there are equal numbers of people around the world who are trying desperately to hold on to traditional methods of dealing with certain things. In fact, some people actually still play solitaire with a deck of playing cards. For people who feel that the information age has left them behind to some degree the chances are quite good that online learning may not be the best available option for you.

Below you will find a few questions that can help you narrow down whether or not you would truly benefit by taking some of the many online courses that are being offered in today’s information age of learning.

1) Are you disciplined? This may seem like such an innocuous question because we would all like to think that we are disciplined to some degree. The problem is that when you are in the driver’s seat for your own education you need to have a little more than some small degree of discipline. You need to be able to meet deadlines, take the tests, and hold yourself responsible for actually learning the information that you need to learn in order to pass the course. There is no one to blame but yourself if you do not manage to do well in your online classes and some people simply do not like being in the drivers seat when it comes to motivating and pacing themselves and their learning practices.

2) How do you learn best? We all have different methods of learning for which we retain information better than others. Online courses are reading intensive. If you have difficulties retaining the information you read you may need to find an alternate learning method or seek solutions with the assistance of the course instructor before moving forward in an online learning environment.

3) Do you have a true desire to succeed? The answer to this question is quite important in determining whether or not online learning is in your best interest. There are many paths you can take in order to achieve the education and degree you desire. This is not the path of the masses, at least not yet. This type of learning, more than any other is easy to give up on through apathy. If you aren’t determined to do the assignments, to study the notes, and to really learn the material that is presented to you then you really do not need to waste your time or the instructor’s time by continually making up excuses. Online courses are largely self-paced but you do have a limited amount of time in which to learn the material before you need to move on. The teacher is responsible for providing you the information and material but you are responsible for everything that happens from that moment on. Are you ready for that responsibility?

Whether you are a first time college student or a professional that is returning to school after a long absence online learning can open new doors of opportunity for your learning pleasure. You must be willing to walk through those doors and take the information that is presented to you however in order to be successful. My sincere hope is that everyone reading this will carefully consider whether or not the lack of structure that many online courses provides is going to be conducive to your specific learning and educational needs before taking the plunge.

EQUIVALENT CIRCUIT REFERRED TO PRIMARY SIDE AND SECONDARY SIDE, VOLTAGE REGULATION OF A TRANSFORMER

 EQUIVALENT CIRCUIT REFERRED TO PRIMARY SIDE - :

When all parmeter are reffered to primary side, 

  Secondary emf referred to primary side, E'2=KE2

Secondary terminal voltage referred to primary, V'2 =KV2

Secondary current referred to primary, I'2=I2/K

Secondry resistance referred to primary! R'2=K™2X2

primary side       

  

Let R, Z and Z represents the equivalent resistance,equivalent reactance and equivalent impedance repectively of the whole transformer reffered to the primary. Then

 R=primary resistance +secondry resistance reffered to primary 

R=R1+R'2 =R1 +R2(N1/N2) ™2=R1 +K™2R2

X=X1+X'2=X1+X2 (N1/N2) ™2=X1+K™2X2

Z=Z1+Z'2=Z1+Z2(N1/N2)™2=Z1+K™2Z2

also,

Z=R+jX

EQUIVALENT CIRCUIT REFERRED TO SECONDARY SIDE-:

when all parameter are reffered to secondry side

    

Electrical and Electronics Measurment

 MEASURMENT- measurment is a process or the result between rhe quantities.

METHODE OF MEASURMENT - The methods of methode may be brodaly classified into two categories.

1.DIRECT METHODE- In these methods, the unknown quality is directly compared against a standered. The result is expressed as a numerical number and a unite.

Direct methods are quite common for the measurment like lenth, mass and time.

2. INDIRECT METHODS- in engineering applications, for measurment purposes indirect methods are required because the measurment by direct methode are not always possible, feasibal and praticable. These methode in most of the cases are inaccurate because they involve human factors. They are also less sensitive. Hence, direct methode are not preferred and are rarely used.

CLASSIFICATION OF INSTRUMENT-

1.ABSOLUTE INSTRUMENT- The instruments which gives the value of parameter in terms of physical constant of instrument.

These instruments based on their operations on the indirect methodology of measurment and are generally used as standred instrument in calibrating are tangent galvanometer and Rayleighc's current balance.

2. SECONDARY INSTRUMENTS- These instruments gives the value if measurment directly and their operations based on directly methodology of operations.

these instrument are used for day to day used in the industry.

in comparison to secondry instrument absolute instrument are higly accurate as they contain less number of moving parts resulting in lower opration consumption powe

3. ANALOG INSTRUMENT - The instruments whose output various continusly with respect to time, while maintainig constant relationship with the input.

4.DIGITAL INSTRUMENT - The instrument whose output various directly with respect to time while maintaining a constant relationships with the input.

Analog instruments can be further classified as deflecting and null deflectin instrument.

DEFLECTING INSTRUMENT - the instrument which give the value of parameters under measurment in term of deflection of a pointer away fram the zero position.

5.DEFLECTING INSTRUMENTS - The instruments which give the value of parameter under measurment in term of deflection of a pointer awaty from zero position.

6.NULL DEFLECTION INSTRUMENT - these instrument indicate the end of their measurment with zero deflection. bridge circuit

6.INDICATING INSTRUMENT - these instrument give the instantaneous value of measurment parameter eg. ammeter, voltmeter.

7.INTEGRATING INSTRUMENT - these instrument maintain a contain record of measurment over a specifiex period of time eg. Energy meter.

8.RECORDING INSTRUMENT - These instrument gives the total sum of electrical power consumption ovar a specified period of time eg. recording voltmeter.

ERRORS ANALYSIS-error is defined as the deviation of the true value from the desired value. it is expressed either as absolute value.

STATIC ERROR-it isdefinid as the difference between the true value of the variable and The measured value of the varible.

TYPES OF STATIC ERROR-They are sub divide as follows:

1. gross errors

2.systematic errors

3. random error

1.GROSS ERRORS-.These errors are due to human mistake ib reading instrument, recording and calculation measurment result.

gross errors may be of any amount and therefore their

mathematical analysis is immopable, however, they can be adapating two means they are-

1.More care should be taken in reading should be taken for quality.

2.SYSTEMATIC ERRORS-

Systematic error (also called systematic bias) is consistent, repeatable error associated with faulty equipment or a flawed experiment design. These errors are usually caused by measuring instruments that are incorrectly calibrated or are used incorrectly. However, they can creep into your experiment from many sources, including:

A worn out instrument. For example, a plastic tape measure becomes slightly stretched over the years, resulting in measurements that are slightly too high,

these errors arise due to following three main reason-

A person consistently takes an incorrect measurement. For example, they might think the 3/4″ mark on a ruler is the 2/3″ mark.

3. RANDOM ERRORS- Random errors in experimental measurements are caused by unknown and unpredictable changes in the experiment. These changes may occur in the measuring instruments or in the environmental conditions.

The probable reeors is determined from the formula -

probabal errors =0.6745.standred deviation

in pratice, the number of observations is finite.

The Gaussian normal distribution. m = mean of measurements. s = standard deviation of measurements. 68% of the measurements lie in the interval m - s < x < m + s; 95% lie within m - 2s < x < m + 2s; and 99.7% lie within m - 3s < x < m + 3s.

The precision of a measurement is how close a number of measurements of the same quantity agree with each other. The precision is limited by the random errors. It may usually be determined by repeating the measurements.

Measurement of Power and Energy

 

Measurement of power and energy

Measurement of power and energy-:

Measurment of power and energyinclude the current and voltage range to be tested, the frequency, applied voltage, the applied current and the power factor. Ammeter, voltmeter, wattmeter and galvanometer are used in these measurment. The relative expende uncertain for power or energy measurment is specialy tesred may be low.

POWER IN DC CIRCUIT-:

power consumed by load in DC circuit can be calculated as the power of current drawn and the voltage drop across the load.

Hence the most simple and effective methode for a measurment of power in DC circuit is by the voltmeter ammeter methode.

These two figure show the two possible connection for a measurment of power in DC circuit.

the resistance of voltmeter circuit.

as the power loss in voltmeter circuit is a small and constant magnitude would be a sutible connection for measurment power of high valur load.

the power loss in ammeter circuit being depends on the current drawn by the load, this connection would be suitable for low voltage.

power indicated by instrument =power consumed in load+power loss in ammeter

hence power indicated by instrument =power consumed in load +power load in voltmeter.

thus, in both the cases, the power indicated by the instrument is equal to the power consumed by the load plus the power consumed by the instrument nearer to the load ternimal. In order to obtain the true power? correction must be applued for power loss in measurment.

B-MEASURMENT OF POWER IN AC CIRCUIT-:

Power in ac circuit is the porduct of I, the current being drawn by the load. V be the supply voltage and be the power factor, where is the phase angle between V and I.

from the above is the statement, it becoms clear that a simple for the measurment of power in Ac circuit.

A basic electrodynamometer type instrument could be modify into a wattmeter in order to measure power in a ACcurrent as follow.

the fix coil of the electrodynamometer instrument would with a thick standred wire is connected along the load.

Now, know as the current of electrodynamometer instrument would with a thick syandred wire is connected along the load.

now know as the current coilv(CC), it carries a current equal to the current drawn by the load.

The moving coil is wound with a thin wire in order to keep the torque to weight ratio high. Now, known as the pressure coil, it carries acurrent proportional to supply voltage

A high resistance is connected in series with pressure coil in order to limit the current through it to small value.

there are two types of wattmeter

1. induction type wattmeter

2. Electrodynamometer type wattmeter

1 INDUCTION TYPE WATTMETER-:

The induction type wattmeter is used to measure AC power only.

PRINCIPLE-: - The principle of opration of an induction wattmeter is the same as that of induction ammeters and voltmeter. Induction principal. however, it differs from induction ammeters or voltmeter in so far that separate two colis, are used to produced the rotating fluxbin place of one coil with spilt arrangment.

WORKING OF INDUCTION TYPE WATTMETER - :At the point when the wattmeter is associated in the circuit to gauge a.c power, the shunt magnet conveys current relative to the gracefully voltage and the arrangement magnet conveys the heap current. The two transitions delivered by the magnets incite vortex flows in the aluminum plate. The communication between the transitions and swirl flows produce the avoiding force on the circle, causing the pointer associated with the moving framework to move over the scale.

2 ELECTRODYNAMOMETER TYPE WATTMETER - :

Presently let us take a gander at constructional subtleties of electrodynamometer. It comprises of following parts.

There are two sorts of curls present in the electrodynamometer. They are :

Moving Coil

Moving loop moves the pointer with the assistance of spring control instrument. Restricted of current moves through the moving loop to abstain from warming. So as to restrict the current we have associated the high worth resistor in arrangement with the moving curl. The moving is air cored and is mounted on a rotated axle and can move uninhibitedly. In electrodynamometer type wattmeter, moving curl functions as weight loop. Consequently moving loop is associated over the voltage and hence the current coursing through this curl is consistently relative to the voltage.

Electrical Machine, Types of transformer, Phase diagram of transformer and equivalent circuit of transformer

 TYPES OF TRANSFORMER - :

There are many types of transformer -

Measurement 

1.CORE TYPE  TRANSFORMER - : In core type transformer, two winding are arranged as concentric coils, therefore these are called concentric winding or cylindrical winding. The low voltage winding is placed next to the  core and the high voltage winding is placed around the low voltage winding to reduce the insulation material requirement. 

SHELL TYPE TRANSFORMER - : In the shell type of transformer bith primary and secondry winding are wound on tje central limb and the two outer limbs complete the low reluctance flux paths. 

                                            Each winding is subdivided into sections. Low volrage and High voltage subsections are alternatly lut in the form of a sandwich. Therefore, such a winding is placed called sanfwich or disc winding. 

IDEAL TRANSFORMER - :An ideal transformer is one which has following assumptions:

1. Its winding haveno Ohmic resistance, therefore it jas no I2R loss (copper loss). 

2.    There is no magnetic leakage, hence which has no core losses(hystresis as well as eddy current loss). 

3.     The core has infinite permebilitycso that zero magnetizing current is needed to establish the requisite amount of flux in the core. 

MMF BALANCE IN IDEAL TRANSFORMER - 

       N1I1-N2I2=0

         N1/N2=I2/I1

        E1/E2=   N1/N2=I1/I2=K=V1/V2   

        E1I1=E2I2=S2=S1 

or, 

      It showes that the voltampere drawm from the primary supply is equal to the voltampere transfrlerred to the secondary supply without any loss in an ideal transformer. 

V1I1/1000=V2.I2/1000

(KVA)1= (KVA) 2

  INPUT KVA=OUTPUT KVA

Thus the kva input of an ideal transformer is equal the kva output  kva is the same an both sides of transformer. 

PHASE DIAGRAM OF TRANSFORMER - :

1.WHEN TRANSFORMER AT NO LOAD-:

               A transformer is said to be at no load when the second winding is open circuited. Thus, secondary current will be zero. When  an alternative  voltage is applied to the primary, a small current will be zero. When a alternative voltage is applied to the primary, a small current I0 flows in the primary winding. The current I0 is called the no load current or exiting current of the transformer. The no load curren I0 us small og the order of 3%to 5% of the rated current of primary wimding. It can be resolved into two components. 

(a)  The components is called the magnetizing current. it magnetizing the core. it sets up a flux in the core, therefore Im is in phase with. Itcis also called reactive or wattless component of no load current. 

(b). The component is called core current. It is also called active components of mo load active current. it is in phase with the primary induced voltage. the  componant supplies the hysteresis and eddy current loss in the core and the neglible loss in the primary winding. 

 

Electrical Machine, Transformer, Construction of transformer and it's working principle.

 TRANSFORMER - :   A transformer is a static device which transfers electrical energy from one circuit to another circuit without a change of frequency. Transformer worke on electromagnetic induction principle. 

The transformer which dilivers energy at a higher voltage level then it source voltage level then it is called step - up transformer. When the voltage of delivered energy of a transformer is less than its primary voltage than, it is called step- down transformer.

A transformer has no moving parts parts, si it is called static device, therefore it requires minimum repair and maintenance cost. its efficiency is much higher when compared to other apparatus.

CONSTRUCTION - :   A single phase transformer consists of primary and secondary windings put on a magnetic core. Boyh windings are magnetically connected but not electrically. Magnetic core is ised to confinr flux to certain path. A winding and winding connected on load side is called secondary winding.

Transformer cores are made from thin laminated sheets of high grade silicon steel. Since, the laminated reduce eddy current loss and silicon steel reduces hysterisis loss. There are basically two type of transformer cknstruction, the core type and shell type.

WORKING PRINCIPLE OF TRANSFORMER - :  

   Transformer consists of two inductive and colis which are electrically separated but magnetically linked through  a path of low resistance. If one coil is connected to a source of ternative voltage, an alternative flux is setup in the laminated core, most of which is linked with other coli in which is produce mutually - induced emf (according to Faraday's law of electromagnetic induction E=M. dI/dt) 

If the second coil circuit  is closed, a current flows i  it and so, energy is transferred (entirely magnetically) from the first coil to second coil.

   EMF EQUATION OF TRANSFORMER - :      

The primary wi di g draws a small amount of alternative current of instantaneous value  called the exiting current,from the voltage source with posutive direction as indicated on the diagram. The exiting current establishes flux in the core. all of which is assumed confined to the core there is no leakage of flux Consequently, the primary winding has flus linkage.

As per Lenz 's law the positive of this emf oppose the positive current direction and is shown by (+ve) and (-ve) polarity marks on the diagram. According to kirchoff law. 

V==E(winding has zero resistance) 

E1/E2=N1/N2 

E1/N1=E2/N2=K

EMF PER TURN IN PRIMARY=EMF PER TURN IN SECONDARY

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