bee final lab manual

DEPT OF EEE EE LAB MANUAL

LENDI INSTITUTE OF ENGINEERING & TECHNOLOGY 1

ELECTRICAL LABORATORYEQUIPMENTS

Different types of supply systems, instruments and other apparatus required in laboratory are asfollows:-Supply systems-

(a) A.C. Supply:(i) Single phase 230 volts 50Hz.(ii)Three phase 415 volts 50Hz.Three phase terminals and fourth neutral terminal.

(b) D.C. Supply:(i) 220 volts D.C. from generator or rectifier.(ii) 6 volts or 12 volts from battery or rectifier.

Ø A.C. as well as D.C. supply is available through switch and fuse unit.

Laboratory apparatus:

Rheostat:Rheostat is an adjustable resistor used in applications that require the adjustment of current

or the varying of resistance in an electric circuit. Therheostat can adjust generator characteristics, dim lights,and start or control the speed of motors. Its resistanceelement can be a metal wire or ribbon, carbon, or aconducting liquid, depending on the application. Usuallyrheostat has two fixed terminals and a third terminalconnected to a variable contact arm. It is available inSingle tube shape and Double tube shape.

Electric fuse:Electric fuse is a safety device used to protect an electric circuit againstan excessive current. A fuse consists essentially of a strip of low-melting alloy enclosed in a suitable housing. It is connected in serieswith the circuit it is to protect. Because of its electrical resistance , thealloy strip in the fuse is heated by an electric current. If the currentexceeds the safe value for which the fuse was designed, the strip melts,opening the circuit and stopping the current. The fuse housing isdesigned to resist the pressure generated if the over current vaporizesthe alloy strip, provided the voltage across the fuse does not exceed itsrating. Some fuses, called slow-blow fuses, are designed to carry asmall overload for a short time without opening the circuit, whileothers are designed to open very rapidly if the rated current isexceeded. The choice of one type or the other depends on theruggedness of the equipment to be protected and whether large pulses



of current often occur in the circuit; a slow-blow fuse is usually used to protect motors, anda fast-blow fuse to protect electronic equipment. The available fuse ratings in the laboratoryare 5A, 10A, and 15A.

Electrical Switches:Switches are devices used to allow electric current to flow when closed, and when opened,they prevent current flow. Common switch types include pushbutton, rocker, toggle, rotarycoded DIP, DIP, rotary, key lock, slide, snap action, and reed

Pole and throw configurations for switchescan be single pole single throw (SPST),single pole double throw (SPDT), doublepole single throw (DPST), double poledouble throw (DPDT),Triple pole singlethrow (TPST) or Triple pole double throw(TPDT).SPST is a switch that makes or breaks theconnection of a single conductor in a singlebranch circuit. This switch typically has twoterminals. It is commonly referred to as a"Single-Pole" Switch. SPDT is a switch thatmakes or breaks the connection of a single

conductor with either of two other single conductors. This switch typically has 3 terminals,and is commonly used in pairs and called a "Three-Way" switch. DPST is a switch that makes or breaks the connection of two circuit conductors in a singlebranch circuit. This switch typically has four terminals.DPDT is a switch that makes or breaks the connection of two conductors to two separatecircuits. This switch typically has six terminals

Variac (Auto transformer):

Autotransformer is a device used to obtain variable acvoltages. By using this device we can obtain voltages of valueshigher than its input voltage. This unit would normally bemounted behind an instrument or product panel, with only theknob and dial plate protruding.Device like this may be used for small motor speedadjustment, light control or other controller application.This is available in three phase and single phase.



Electric motors:An electric motor is a machine used to convert electrical

energy to mechanical energy. Electric motors are extremelyimportant to modern-day life, being used in many different places,e.g., vacuum cleaners, dishwashers, computer printers, faxmachines, video cassette recorders, machine tools, printingpresses, automobiles, subway systems, sewage treatment plantsand water pumping stations.

The major physical principles behind the operation of an electricmotor are known as Ampere’s law and Faraday's law. The first states that an electricalconductor sitting in a magnetic field will experience a force if any current flowing throughthe conductor has a component at right angles to that field. Reversal of either the current orthe magnetic field will produce a force acting in the opposite direction. The secondprinciple states that if a conductor is moved through a magnetic field, then any componentof motion perpendicular to that field will generate a potential difference between the endsof the conductor.

An electric motor consists of two essential elements. The first, a static component whichconsists of magnetic materials and electrical conductors to generate magnetic fields of adesired shape, is known as the stator. The second, which also is made from magnetic andelectrical conductors to generate shaped magnetic fields which interact with the fieldsgenerated by the stator, is known as the rotor. The rotor comprises the moving componentof the motor, having a rotating shaft to connect to the machine being driven and somemeans of maintaining an electrical contact between the rotor and the motor housing(typically, carbon brushes pushed against slip rings). In operation, the electrical currentsupplied to the motor is used to generate magnetic fields in both the rotor and the stator.These fields push against each other with the result that the rotor experiences a torque andconsequently rotates.Electrical motors fall into two broad categories, depending on the typeof electrical power applied-direct current (DC) and alternating current (AC) motors.

Measuring Instruments:

For measurement of current, voltage, power, speed and torquedifferent meters are used in laboratories which are:Ammeter:This is an Instrument that measures electric current (flow ofcharge per unit time), usually in Amperes, through a conductor. Itshould not be confused with a voltmeter, which measurespotential difference between two points in a circuit. The ammeteris placed in series with the component through which current isto be measured, and is constructed with a low internal resistancein order to prevent the reduction of that current as it flows



through the instrument itself.The common types are the Moving-Coil meter, which measures direct current(DC),Moving Iron meter, which can measure both A.C. as well as D.C.( Hot-wire, moving-iron, and dynamometer ammeters can be used for both DC and AC). The nature andmagnitude of current decides the rating and type of ammeter.

Voltmeter:

Voltmeter is an instrument that measures voltages of eitherdirect or alternating electric current on a scale usually graduatedin volts, mill volts (0.001 volt), or kilovolts (1,000 volts). Thetypical commercial or laboratory standard voltmeter in usetoday is likely to employ an electromechanical mechanism inwhich current flowing through turns of wire is translated into areading of voltage. The voltmeter should be connected acrossthe two points between which the potential difference is to bemeasured. They are also classified into many types. Thecommon types are Moving-Coil meter, which measures DCvoltage, Moving Iron meter, which can measure both A.C. aswell as D.C. voltage. Like ammeters the nature and magnitudedecides the type and range of the voltmeter.

Wattmeter:For measuring the power directly the instrument used is wattmeter. It has two coils namely

current coil and pressure coil. The current coil carriesthe current and is connected in sense like ammeter.The pressure coil has the circuit voltage across it andis connected in sense like voltmeter. In D.C. circuitsthe power measured is the product of voltage andcurrent i.e,

And in A.C. circuits power measured is the product ofvoltage, current and power factor i.e,

It is necessary that the two coils of wattmeter areconnected properly otherwise it gives the deflectionin opposite direction.



Tachometer:Tachometer is a measuring device that indicates rotational (angular)speed in revolutions per minute (rpm). The word tachometer is acombination of the Greek words tachos, meaning speed, and metria,meaning measure.Tachometer is to be inserted in tapered hole in the rotating shaft endof machine for measurement of speed. As it rotates and displays theresults on a gauge. There are many different types of tachometers,beyond the familiar dashboard gauge. These vary in appearance,operation, and application. Other type is digital tachometer.

Digital multi meters:Gradually in laboratory and also in field digital meters are replacinganalog meters for measurement of voltage, current, resistance etc.

Digital multi meters with great accuracy are generally used for measurement of differentquantities.

Obtaining variable voltage from the supply system:(a) D.C Circuits: From a D.C. Supply system of a given constant voltage, the variable

voltage can be obtained using potentiometer arrangement. In this arrangement theconstant D.C. input is applied between the two fixed terminals of the rheostat and theoutput is taken between the variable terminal and one of the two fixed terminals.Variable D.C. output voltage can be obtained by varying the variable arm of therheostat.

(b) Single phase and three phase A.C. circuits: In A.C. circuits’ variable voltage isgenerally obtained by using single phase or three phase auto transformer or variac.

Electrical loading arrangements:To load a generator or a supply system electrically, a rheostat is used.

Mechanical loading of the motors:Brake pulley:-The motor is coupled to a pulley. This pulley is braked by belt tensions atthe two ends of the belt. The belt tensions are adjustable by tightening and there are springbalances to know the tensions. Thus the net tension is the difference of the two. Thus if T1and T2 are the tension in Newton with T2>T1, and is the angular speed of the motor inradians/sec and R is the pulley radius in meters.The torque is then obtained by the product of the net tension and the pulley radius.

=(T T ) × R NmThe power output is obtained by the product of the torque and the pulley speed inradians/sec., the power output is

= × =(T T ) × R ×



General precautions while working in the electrical laboratories.It is desirable that student should go to the laboratory after understanding the circuitdiagram and the procedure of performing the experiment.General precautions:

• Understand the equipment to be tested and apparatus to be used, before working withthem.

• Make all the connections tight.• Do not leave loose wires.• Do not touch live terminals.• Use suitable wire types and sizes.

Connection of three phase circuits: The diagrams of the three phase systems are generallydrawn with color code i.e., red (for R-phase), yellow (for Y-phase) and blue (for B-phase).Itis highly desirable to use the connecting wires with their insulation as per the code. Thusthe red phase will be connected with red wires and the yellow and blue phase with theyellow and blue wires respectively. The neutral point can be connected with black or whiteor any other color.



VERIFICATION OFSUPERPOSITION AND

RECIPROCITY THEOREMS



Experiment no: 1

VERIFICATION OF SUPERPOSITION& RECIPROCITY THEOREMS

AIM : To verify Superposition & Reciprocity theorems for the given network.

APPARATUS :

THEORY:-

I. Superposition Theorem Statement:

In a linear network with several independent sources which include equivalentsources due to initial conditions and linear dependent sources, the overall response in any partof the network is equal to the sum of the individual responses due to each independent source,considered separately, with all other independent sources reduced to zero.

Note: 1. The sources which are considered one at a time making all other sources zero,are the independent sources including sources due to initial conditions only. The dependentsources are retained as they are in the network. 2. When one independent source is considered & all other independent sources arereduced to zero means that all the other independent voltage source are replaced with shortcircuit and all the other independent current sources are replaced with open circuit. If the sourcescontain internal impedances, that sources are replaced by their internal impedances.

II. Reciprocity Theorem Statement:

The Reciprocity theorem states that the ratio of response to excitation is invariantto an interchange of the position of the excitation and response in a single source network.However if the excitation is a voltage source, the response should be a current and vice versa.

S. No Name of Apparatus Type Range Quantity

1 Voltmeter PMMC 0-300V 2

2 Ammeter PMMC 0-2.5A 1

3 RheostatWWWWWWWW

50 /5A110 /2A

300 /1.7A300 /2A

2112

4. Fuse TCC 5A 4



(0-300)V, MC

300 /1.7A

300 ,2A

300 ,2A

(0-300)V, MC



(0-300)V, MC

300 ,2A

300 ,2A



PROCEDURE:-

I. SUPERPOSITION THEOREM:

1. Connect the circuit as per the Circuit diagram.2. Close Switch S1 on to the Supply mains & remain Switches S2 & S3 open and Switch S4

closed.3. Note down the Voltmeter readings V1 ,V2 & Ammeter reading as I' in the S.No1 of Table14. Now close Switch S2 on to the Supply mains & remain Switches S1 & S4 open and Switch

S3 closed. Adjust the potential divider so that the voltmeter V2 reads 150V.5. Note down the Voltmeter readings V1 ,V2 & Ammeter reading as I" in the S.No2 of Table16. Now Close Switches S1 & S2 on to the Supply mains & remain Switches S3 & S4 open. 7. Note down the Voltmeter readings V1 ,V2 & Ammeter reading as I in the S.No3 of Table18. Finally disconnect the circuit from the Supply mains by open all the Switches.

II. RECIPROCITY THEOREM:

CASE : I

1. Connect the circuit as per the Circuit diagram.2. Close Switch S1 on to the Supply mains3. Note down the Voltmeter V1& Ammeter A1 readings in S. No. 1 of Table 24. Disconnect the circuit from the Supply mains by opening the Switch S1.

CASE : II

1. Connect the circuit as per the Circuit diagram.2. Close Switch S2 on to the Supply mains.3. Note down the Voltmeter V2 Ammeter A2 readings in S. No. 2 of Table 2.4. Disconnect the circuit from the Supply mains by opening the Switch S2.



OBSERVATION TABLE:-

TABLE 1 SUPERPOSITION THEOREM:

S.No. Switches Positions Voltmeter Reading Voltmeter Reading Ammeter Reading

1. S1 & S4 ON,S2 & S3 OFF V1 = V2 = I' =

2. S1 & S4 ON,S2 & S3 OFF V1 = V2 = I" =

3. S1 & S4 ON,S2 & S3 OFF V1 = V2 = I =

TABLE 2 RECIPROCITY THEOREM:

S.No. Voltmeter Reading Ammeter Reading1. V1 = I1 =2. V2 = I2 =

PRECAUTIONS:

1. Avoid Loose Connections.2. Readings must be taken without parallax error.3. Before switching on the supply for the circuit , ensure that all rheostats are at maximum position and during the experiment these should not be disturbed.

RESULTS:


1. I' = A

2. I" = A

3. I = A


1. V1/ I1 =

2. V2/ I2 =



CONCLUSIONS:

VIVA QUESTIONS:

1) What are the Statements of the above theorems?2) What is a linear network?3) Where the above theorems are used practically?4) What are the practical applications of the above theorems?5) What is a bilateral network? Give examples.6) What are the limitations of above theorems?



VERIFICATION OFMAXIMUM POWER

TRANSFER THEOREM



Experiment no: 2

VERIFICATION OF MAXIMUM POWERTRANSFER THEOREM

AIM : To verify Maximum Power transfer theorem for the given circuit.

APPARATUS:


1 Voltmeter MC

MC0-300V0-150V

11

2 Ammeter MC 0-2A 1

3 RheostatWWWWWW

100 /5A50 /5A200 /2A

211

4. Fuse TCC 5A 2

THEORY:

Statement: The Maximum Power transfer theorem states that A Resistance load RL, being connected to a DC network, receives maximum power when it is equal to the internal resistance of the source network as seen from the load terminals i.e. Rth”



CIRCUIT I

V

0-300V,MC

+ -220V

,D

CSu

pply

DPS

TFU

SE5A

V

0-2A

,MC

A10

0,5

A

50 ,5A

200 ,2A

0-150V,MC

FUSE

5A

+

+

+

-

-

-

100

,5A

Max

imum

Pow

erT

rans

fer

The

orem

MA

INC

IRC

UIT



CIRCUIT II



With reference to Fig(B)

Lth

thL RR

VI+

=

While the power delivered to the resistive load is

( )( ) L

Lth

thLLL R

RRVRIP ×+

== 2

22

PL can be maximized by varying R and hence, maximum power can be delivered when(dPL/dRL) = 0

( ) ( ) ( )

( )04

2222

=+

+−+⇒

Lth

LthL

LthLthL

Lth

RR

RRdR

dRVRVdR

dRR

( ) ( ) ( )( )

02

4

222

=+

+⋅⋅−+⇒

Lth

LthLththLth

RRRRRVVRR

( ) 02 =⋅−+⇒ LLth RRR

thL RR =⇒

Hence it has been proved that power transfer from a dc source network to a resistivenetwork is maximum when the load resistance of the network is equal to the internal resistanceof the dc source Again with RL=Rth, the system being perfectly matched for load and source, powertransfer becomes maximum and this amount of power (Pmax) can be obtained as

( ) th

th

thth

thth

RV

RRRVP

4

2

2

2

max =+

=

The total power supplied is thus

th

th

th

thin R

VR

VP24

222

=⋅=

During maximum power transfer the efficiency of the circuit becomes,.

%50100max =×=inP

Pη



PROCEDURE:-

I) TO FIND POWER VARIATIONS WITH RL

1. Connect the circuit as per the Circuit diagram 1.2. Apply 220 V DC Supply to the circuit by closing the DPST Switch.3. Note down the readings of Ammeter & Voltmeter in Table 1 which are connected across the load after keeping the load rheostat, RL at its minimum value.4. Increase the load resistance in steps and for each step, note down the corresponding Ammeter and Voltmeter readings in Table 1.5. Disconnect the circuit from the supply by opening the DPST Switch.

II) TO FIND Rth

1. Connect the circuit as per the Circuit diagram 2.2. Apply 220 V DC Supply to the circuit by closing the DPST Switch.3. Note down the readings of Ammeter & Voltmeter in Table 2 .4. Disconnect the circuit from the supply by opening the DPST Switch.

OBSERVATION TABLE:-

TABLE 1

S No VL (Volts) IL (Amps) RL = VL/ IL ( ) PL = IL2RL

(Watts)1.2.3....

10.

TABLE 2

S No VS (Volts) IS (Amps) Rth = VS/IS )

1.



MODEL GRAPH:-

PRECAUTIONS:-

1. Avoid loose connections.2. Avoid Parallax error.3. Take more number of readings for a better plot.

RESULTS:-

1. Pmax = ---------- Watts2. RL = ---------- Ohms3. Rth = ---------- Ohms4. = ---------- %

CONCLUSIONS:-

VIVA QUESTIONS:-

1) What is the Statement of Maximum Power Transfer theorem?2) What is a linear network?3) What is a bilateral network?4) What are the applications of the above theorem?5) What are the advantages & disadvantages of the above theorem?



VERIFICATION OF THEVENIN S &NORTON S THEOREMS



Experiment no: 3

VERIFICATION OF THEVENIN’S& NORTON’S THEOREMS

AIM : To verify Thevenin’s & Norton’s theorems for the given circuit.

APPARATUS:

S. No Name of Apparatus Range Type Quantity1 Voltmeters 0-300V MI 22 Ammeter 0-2A MI 2

3 Rheostats50 , 5A

110 , 2A200 , 2A

WWWWWW

211

4 1- Variac 230V / (0-270)V,15A ---- 1

5. SPST 5A ---- 26. Fuse 5A TCC 2

THEORY:-

I) Thevenin’s Theorem Statement:

Any combination of linear bilateral circuit elements and active sources, regardless ofthe connection or complexity, connected to a given load RL, may be replaced by a simple twoterminal network consisting of a single voltage source of Vth volts and single resistance Rth inseries with the voltage source, across the two terminals of the load RL . The Vth is the opencircuit voltage measured at the two terminals of interest, with load resistance RL removed. Thisvoltage is also called Thevenin s equivalent voltage. The Rth is the Thevenin s equivalentresistance of the given network as viewed through the open terminals with RL removed and allthe active sources are replaced by their internal resistances . If the internal resistances are notknown then independent voltage sources are to be replaced by the short circuit while theindependent current sources must be replaced by open circuit.



II) Norton’s Theorem Statement :

Any combination of linear bilateral circuit elements and active sources, regardless ofthe connection or complexity, connected to a given load RL, can be replaced by a simple twoterminal network, consisting of a single current source of IN amperes and a single resistanceRN in parallel with it, across the two terminals of the RL. The IN is the short circuit currentflowing through the short circuited path, replaced instead of RL. It is also called Norton scurrent. The RN is the equivalent resistance of the given network as viewed through the loadterminals, with RL removed and all the active sources are replaced by their internalresistances. If the internal resistances are unknown then the independent voltage sources mustbe replaced by short circuit while the independent current sources must be replaced by opencircuit.



CIRCUIT I:



CIRCUIT II:

0-300V, MI

200 , 2A



CIRCUIT III:

0-300V, MI

SPST

110 , 2A



CIRCUIT IV:

0-300V, MI

200 , 2A

110 , 2A



PROCEDURE:-

I) FOR CIRCUIT 1:

1. Connect the circuit as per the circuit diagram.2. Apply 230 V AC Supply to the Variac (with its variable position at C ) by closing the DPST Switch.3. Gradually vary the variable position of the Variac until the Voltmeter1 reads 200 V.4. Note down the corresponding readings of Ammeter & Voltmeter2 in Table 1 with the Conditions i) SPST 1 Closed & SPST 2 Open ii) SPST 1 Open & SPST 2 Open iii) SPST 1 Closed & SPST 2 Closed5. Gradually vary the variable position of the Variac until the Voltmeter1 reads 0 volts6. Disconnect the Variac from the supply by opening the DPST Switch.

II) FOR CIRCUIT 2:

1. Connect the circuit as per the circuit diagram.2. Apply 230 V AC Supply to the Variac (with its variable position at C ) by closing the DPST Switch.3. Gradually vary the variable position of the Variac until the Voltmeter reads 150 V & note down the corresponding reading of Ammeter in Table 2.4. Gradually vary the variable position of the Variac until the Voltmeter reads 0 volts5. Disconnect the Variac from the supply by opening the DPST Switch.III) FOR CIRCUIT 3:

1. Connect the circuit as per the circuit diagram.2. Apply 230 V AC Supply to the Variac (with its variable position at C ) by closing the DPST Switch.3. Gradually vary the variable position of the Variac until the Voltmeter reads Vth , as obtained in Table 14. Close the SPST Switch & vary the rheostat until the Ammeter reads current I for which Vth / I gives Rth , the value as obtained in Table 2 .5. Once the Rheostat set to Rth , open the SPST Switch & note down the reading of the Ammeter in Table 36. Gradually vary the variable position of the Variac until the Voltmeter reads 0 volts7. Disconnect the Variac from the supply by opening the DPST Switch

IV) FOR CIRCUIT 4:

1. Connect the circuit as per the circuit diagram.2. Use the same Rheostat which set to Rth as in the Circuit 33. Apply 230 V AC Supply to the Variac (with its variable position at C ) by closing the



DPST Switch.4. Gradually vary the variable position of the Variac until the Ammeter1 reads current IN as obtained in Table 1 & note down the corresponding reading of the Ammeter2 in Table 4.5. Gradually vary the variable position of the Variac until the Voltmeter reads 0 volts6. Disconnect the Variac from the supply by opening the DPST Switch

OBSERVATION TABLE:-

TABLE 1 (For Circuit 1)

S.No Switch conditions Voltmeter V1 Voltmeter V2 Ammeter1. SPST 1 Closed

SPST 2 OpenVS = VL = IL =

2. SPST 1 Open SPST 2 Open

VS = Vth = IL = 0

3. SPST 1 ClosedSPST 2 Closed

VS = VL = 0 IN =


S.No Voltmeter Ammeter Rth = VS / IS

1. VS = IS = Rth =


S.No Voltmeter Ammeter

1. Vth = IL =


S.No Ammeter I1 Ammeter I2

1. IN = IL =



PRECAUTIONS:-

1. Avoid loose connections.2. Avoid Parallax error.3. Before switching on the supply for each circuit ensure that all rheostats are at maximum position and during the experiment these should not be disturbed.4. Variable position of the Variac(auto transformer) should be at minimum position before switching on the power supply.

RESULTS:-

1. IL from the Main circuit =

2. IL from the Thevenin’s Equivalent Circuit =

3. IL from the Norton’s Equivalent circuit =

CONCLUSIONS:-

VIVA QUESTIONS:-

1) What is the Statement of Thevenin’s theorem?2) What is a linear network?3) What is a bilateral network?4) What are Active & Passive elements?5) What are the applications of the above theorem?6) What are the limitations of application of this theorem ?



DETERMINATION OF TWO PORTNETWORK PARAMETERS



Experiment no: 4

DETERMINATION OF TWO PORT NETWORK PARAMETERS

AIM : To determine Z & Y parameters of a given two port Network.

APPARATUS:

S.No Specification Range Type Quantity1 Voltmeter (0-300)V PMMC 22 Ammeter (0-5)A PMMC 23 Rheostat (50 , 5A) Wire Wound 3

4 Switches ------ DPDT 2

5 Fuses 5A Tin CoatedCopper 2

6 Connecting Wires 1 Square mm Insulated copper As perRequirement

THEORY:

A network containing two pairs of terminals is called as two port network. Normallyone pair of terminals coming together to supply power or to withdraw power or to measure theparameters, are called as port. To achieve simplicity, the whole network is shown with a singleblock.

A typical two port network is as shown below in fig (a)



OPEN CIRCUIT IMPEDANCE PARAMETERS (Z-parameters):

Z-parameters can be defined by the following equations

V1 = Z11I1 + Z12I2 …………………… (1)

V2 = Z21I1 + Z22I2 …………………… (2)

Matrix form :

If port 2-21 is open circuited, i.e. I2 = 0 then

Z11 = V1/I1 & Z21 = V2/I1

If port 1-11 is open circuited, i.e. I1 = 0, then

Z12 = V1/I2 & Z22 = V2/I2.

Here,

Z11 is the driving point impedance at port 1-11 with 2-21 open circuited. It can also be called asopen circuit input impedance.

Z21 is the transfer impedance at port 1-11 with 2-21 open circuited. It can also be calledas open circuit forward transfer impedance.

Z12 is the transfer impedance at port 2-21 with 1-11 open circuited. It can also be called asopen circuit reverse transfer impedance and

Z22 is the driving point impedance at port 2-21 with 1-11 open circuited. It can also becalled as open circuit output impedance.

Z-parameter representation for a two port network, shown above, will be as shown belowin fig (b)

I1

I2

Z11V1

V2= Z21 Z22

Z12



If the network is

a) Reciprocal then V1/I2 (where I1 = 0) = V2/I1 (where I2 = 0) i.e. Z12 = Z21

b) Symmetrical then V1/I1 (where I2 = 0) = V2/I2 (where I1 = 0) i.e. Z11 = Z22

SHORT CIRCUIT ADMITTANCE PARAMETERS (Y-parameters):

Y-parameters can be defined by the following equations

I1 = Y11V1 + Y12V2 ________________ (1)

I2 = Y21V1 + Y22V2 ________________ (2)In matrix form

Y11

= Y21 Y22

Y12 V1

V2

I1

I2

1

21

I2I1

Z11

+_

+_

Z22

Z12I2 Z21I1

2

11

V2V1

Fig (b) Open circuit impedance parametric representation of a two port net work.



If port 2-21 is short circuited, i.e V2 = 0 then

Y11 = I1/V1 & Y21 = I2/V1


Y12 = I1/V2 & Y22 = I2/V2

Here, Y11 is the short circuit driving point admittance at port 1-11 with 2-21 shortcircuited. It will also be called as short circuit input admittance.

Y21 is the Transfer admittance at port 1-11 with 2-21 short circuited. It will also becalled as short circuit forward transfer admittance.

Y12 is the Transfer admittance at port 2-21 with 1-11 short circuited. It will also becalled as short circuit reverse transfer admittance and

Y22 is the driving point admittance at port 2-21 with 1-11 short circuited. It can alsobe called as short circuit output admittance.

Y-parameter representation for a two port network, shown above, will be as shown below

If the network is

a) Reciprocal then I2/V1 (where V2 = 0) = I1/V2 (where V1 = 0) i.e. Y21 = Y12

b) Symmetrical then I1/ V1 (where V2 = 0) = I2/ V2 (where V1 = 0) i.e. Y11 = Y22

1

21

I2I1

Y11 Y22Y12V2 Y21V1

2

11

V2V1

Fig(c) Short circuit admittance parameter representation of a two port net work.



PROCEDURE:-

1. Connect the circuit as per circuit diagram.2. With the Switches S2 open , S3 close to 11' and S4 open , note down the corresponding

readings of voltmeter and ammeter in S.No 1 in Tabular form after closing the Switch S1to supply mains

3. With the Switches S1 open ,S4 close to 33' and S3 open , note down thecorresponding readings of voltmeter and ammeter in S.No 2 in Tabular after closing theSwitch S2 to supply mains

4. With the Switches S2 open ,S3 close to 11' and S4 close to 44' , note down thecorresponding readings of voltmeter and ammeter in S.No 3 in Tabular after closing theSwitch S1 to supply mains

5. With the Switches S1 open ,S3 close to 22' and S4 close to 33 ' , note down thecorresponding readings of voltmeter and ammeter in S.No 4 in Tabular after closing theSwitch S2 to supply mains

OBSERVATION TABLE:-

S.NO Test Condition V1 (V) I1 (A) V2 (V) I2 (A) Parmeters

1Port 2 Open(I2 = 0) and

Port-1 Active

Z11 = V1/I1=

Z21 = V2/I1=

2Port 1 Open(I1=0) and

Port-2 Active

Z12 = V1/I2=

Z22 = V2/I2 =

3Port 2 Short (4 - 4’)

(V2=0) andport-1 active

Y11 = I1/V1=

Y21 = I2/V1=


(V1=0) andPort-2 active

Y22 = I2/V2=

Y12 = I1/V2 =



PRECAUTIONS:

1. Note down the readings of voltmeter and ammeter without parallax error.2. The current through a particular element should be maintained below its current rating.3. The conditions of switches should be thoroughly checked before making the circuit live

RESULTS:

The values of Z parameters are

Z11 = ________; Z12 = ________; Z21 = ________ ; Z22 = ________

The values of Y parameters are

Y11 = ________; Y12 = ________; Y21 = ________; Y22 = ________

CONCLUSIONS :

VIVA QUESTIONS:

1) What is the significance of the two port parameters?2) How you know the admittance parameters from impedance parameters?3) What are the application of Z& Y parameters?4) What is the condition for reciprocal network?5) What is the condition for symmetrical network?6) What is a Lattice network?7) What is a Ladder network?

.



OC & SC TESTS ON A TRANSFORMER



Experiment no: 5

OPEN CIRCUIT & SHORT CIRCUIT TESTSON A SINGLE PHASE TRANSFORMER

AIM : To predetermine the efficiency, percentage regulation and equivalent circuit parameters of a given single phase transformer by conducting Open circuit and Short circuit tests on it.

NAME PLATE DETAILS:

S.No Type Transformer01 Rating 2 KVA, 102 L V winding 230 V03 H V winding 440 V

APPARATUS:

S.No Apparatus Required Rating Type Qty.

01 Voltmeter (0-230) V M.I 1


03 Ammeter (0-1) A M.I. 1

04 Ammeter (0-5) A M.I. 1

05 Wattmeter 300 V ,10A LPF 1

06 Wattmeter 150 V ,10A UPF 1

07 Variac 230V / 0-270V15A Contact 1

08 Fuse 10A T.C.C. 2



THEORY:

The performance of a transformer can be calculated on the basis of the equivalent circuitwhich contains four main parameters, the equivalent resistance R01 as referred to primary(or secondary R02), the equivalent leakage reactance X01 referred to primary (or secondaryX02), the core loss conductance G0 or resistance R0 and magnetizing reactance X0. Theseparameters can be easily determined by performing Open circuit test & Short circuit tests.The losses obtained are used in calculating the efficiency & regulation of the transformer.These tests are very economical and convenient because they furnish the requiredinformation with out actually loading the transformer.

OPEN CIRCUIT TEST:

Ø The purpose of this test is to determine no load loss or core loss and no load current ‘I0’which is helpful in finding R0 and X0.

Ø In this test , the transformer secondary winding (usually HV side) is left open and theprimary winding (LV side) is connected to supply of normal voltage and frequency.

Ø With normal voltage applied to the primary a small current ‘I0’ flows in the primarywhich produces magnetic flux in the core. The transformer draws reactive power from thesupply to establish the magnetic flux, active power is also absorbed by the transformer toovercome the core loss due to hysteresis and eddy current.

Ø The reactive power at no load is much higher than the active power so the power factor issmall. The primary no load current I0 is small (usually 2 to 10% of the rated loadcurrent),therefore copper loss is negligibly small in primary and nil in secondary (it beingopen).

Ø These core loss under no load condition is same for all loads as the net flux passingthrough the core is approximately the same as at no load.

SHORT CIRCUIT TEST:

Ø This is an economical method to determine equivalent impedance (Z01 or Z02), leakagereactance(X01 or X02), total resistance (R01 or R02) of the transformer and copper loss atfull load (or at any desired load).

Ø In this test the secondary side (usually low voltage winding) is solidly short-circuited.Now the primary is connected to a power source of reduced potential (usually 5 to10%of normal voltage) that is enough to cause the rated current to flow in both primary andsecondary windings.



Ø Since in this test the applied voltage is a small percentage of normal voltage, the mutualflux Ø produced is so small percentage of normal value. Hence the core losses are verysmall and the losses now taking place will be full load copper loss.

PROCEDURE:

OC TEST:

1. Connect the circuit as per the circuit diagram.2. The HV side of the transformer is kept open & the normal voltage of 230V is applied to LV

side by adjusting the autotransformer ( variac)3. Note down the readings of ammeter, voltmeter and wattmeter on LV side.

SC TEST:

1. Connect the circuit as per the circuit diagram.2. The LV side of the transformer is short circuited & using the autotransformer adjust the HV

side voltage such that the ammeter reads the full load current of HV winding3. Note down the readings of ammeter, voltmeter and wattmeter on HV side.

OBSERVATION TABLE:

OC TEST:

S. No. V0(volts) I0 (amps) W0(watts)

1.

SC TEST:

S. No. Vsc(volts) Isc(Amps) Wsc(watts)

1.



CALCULATION TABLE:

Efficiency characteristics:

S.No

Load current

Corelosses(W)

Copperlosses(W)

Totallosses(W)

Input

(W)

Output

(W)

Efficiency

1

2

.

.

10

Voltage Regulation characteristics:

S.No Cos Φ SinΦLagging p.f Leading p.f

full load half load full load half load



MODEL CALCULATIONS :

O.C. TEST:

WO = VO IO Cos 0; Cos 0 = ( WO ) / ( VO IO ) =

I = IO Sin 0 ; I = IO Cos 0

RO = VO / I ; XO = VO / I

S.C TEST :

WSC = ISC2 Re2 ; Re2 = WSC / ISC

2

Ze2 = Vsc / Isc ; Xe2 = ( Ze22 - Re2

2 )

% Efficiency ( ) = [ ( x KVA Cos ) / ( x KVA Cos + Wi + x2 W cu )] x 100

%Voltage Regulation = x 100

PRECAUTIONS:

1. Avoid loose connections2. Initially position of the variable on Variac must be in minimum position.3. Note down the readings from the meters without any parallax error4. Apply the reduced voltage (only 5 to 10% of rated voltage) slowly to HV side during SC

test

MODEL GRAPHS:

RESULTS:

2 2 2 2

2

I Re Cos I Xe SinV

φ φ±



The parameters of transformer are:

R0 = ____ Ω ; X0 = ____ Ω ; Re2 = ____ Ω ; Xe2 =____ Ω

From the graphs plotted, it has been determined that

(i) Maximum efficiency of ____ % occurs at a load current of ____A

(ii) Maximum regulation occurs at ____ Pf.

(iii) Zero regulation occurs at _____ pf.

CONCLUSIONS:

VIVA VOCE QUESTIONS:

1. What is the principle of operation of transformer?2. What are the different types of 1 transformers available?3. Why Copper losses in Open circuit test & Core losses in Short circuit4. are considered negligible?5. What is the advantage of deriving the Equivalent circuit?6. What is the condition for maximum efficiency?7. What are the conditions of power factors for maximum & minimum regulation?



BRAKE TEST ON AD.C. SHUNT MOTOR



Experiment no: 6

BRAKE TEST ON A D.C. SHUNT MOTOR

AIM : To obtain the Performance characteristics curves of a D.C. shunt motor byconducting brake test on it.

NAME PLATE DETAILS:

S.No Type DC Shunt Motor01 Rating 3.0 HP02 Volts. 220 V DC03 Current 12 A04 Exc. Volts. 220 V DC05 Exc. Current 0.6A06 Duty S107 Ins. Class B08 Speed 1500 rpm

APPARATUS:


01 Voltmeter (0-300) V M.C 1

02 Ammeter (0-1) A M.C. 1

03 Ammeter (0-20) A M.C. 1

04 Rheostat 300 , 2 A Wire Wound 1

05 Tachometer 0-10,000 RPM Analog 1




THEORY:

Ø It is a simple method of testing low rating DC machines and consists of applying a braketo a water-cooled drum mounted on the motor shaft.

Ø The four important characteristics curves of a D.C. Shunt Motor, namely, Torque, Speed,Armature Current & efficiency, each plotted against the useful Power, as shown in themodel graph are known as Performance characteristics

Ø A belt is wound round the brake drum and its two ends are attached to two springbalances S1 & S2. The tension of the belt can be adjusted with the help of swivels.

Ø The force acting tangentially on the drum is equal to the difference between the readingsof the two spring balances.

Ø The net force, F applied on the brake drum is 9.81(S1 – S2) Newtons where , S1 & S2 are the readings of Spring balances 1& 2 in Kg.f.

Ø Shaft torque, T developed by the motor is 9.81 (S1 – S2) R Nm where, R is the radius of the pulley in meters & N is the speed in rpm

Ø Useful Output Power = (2 N T) / 60 Watts

Ø Input Power = V IL Watts, where IL = (Ia + Ish)

Ø % Efficiency , = (Output power / Input power) x 100.

Ø Speed Regulation = [ (No Load speed ) – ( Full load speed )] / Full Load.

Ø The size of the motor that can be tested by this method is limited from the considerationof the heat that can be dissipated at the brake drum

Ø Where the output power exceeds about 2 H.P., or where the test is of long duration, it’snecessary to use a water – cooled brake drum.

PROCEDURE:

1. Connect the circuit as per the Circuit diagram.2. Initially the starter must be in off position.3. Switch on the D.C. Motor to 220V D.C. Supply by closing the DPST Switch.4. Start the D.C. motor using the three point starter and thereby adjust the speed to its

rated speed using field rheostat.5. Note down the readings of Voltmeter & Ammeters in Table under No Load condition.6. Apply the Load on the drum gradually in steps by tightening the belt around it.



At each step, note down the readings of the Ammeters, Voltmeter, two Springbalances and the Tachometer.

7. Pour water in the pulley and cool it often when the motor is loaded. 8. When the full load is reached, slowly reduce the load and switch off the

Motor from 220V D.C. Supply by opening the DPST Switch

OBSERVATION TABLE:

S.No. InputVoltage

(V)

ArmatureCurrent

(Ia)

Fieldcurrent

(Ish)

Spring BalancesSpeed (N)

S1 S2

123....

10

CALCULATION TABLE:

Radius of the Brake Drum, R = ______ mts.

S.No.Input

Voltage(V)

InputCurrent

(IL)Torque,Nm

(T)OutputPower

InputPower %

123....

10



PRECAUTIONS:

1. The field rheostat of the motor must be kept in minimum before switching ON the motor.2. Ensure that the starter arm is at extreme left position.3. Avoid loose connections4. Note down the readings from the meters without any parallax error5. Tachometer should be kept horizontal to the shaft while measuring the speed.6. Before switch OFF the motor make sure that there is nos load connected to motor.

MODEL GRAPHS:

RESULTS:

At full load:

i) Torque = __________ Nm.ii) Speed = __________ rpmiii) Armature Current = __________ Aiv) Efficiency = __________ %.

v) Speed Regulation = __________%

CONCLUSIONS:


1) What is Speed regulation?2) What are the different types of motor?3) What are the characteristics of D.C shunt motor?4) What is the condition for maximum efficiency?5) What are the different methods to reduce the iron losses?6) What are the application of D.C Shunt Motor?



SWINBURNE’S TEST ON D.C.SHUNT MACHINE



Experiment no: 7

SWINBURNE’S TEST ON A DC SHUNT MACHINE

AIM : To Pre-determine the efficiency and performance characteristics of aDC Shunt machine. (both as a generator & motor)

NAME PLATE DETAILS:

S.No Type DC Shunt Motor01 Ratings 3.0 HP02 Volts. 220 V DC03 Current 12 A04 Exc. Volts. 220 V DC05 Exc. Current 0.6A06 Duty S107 Ins. Class B08 Speed 1500 rpm

APPARATUS:





04 Rheostat 300 , 2 A WIREWOUND 1

05 Tachometer 0-10,000 RPM ANALOG 1

06 Fuse 6A T.C.C. 2



THEORY:

SWINBURNE’S TEST:-

Ø It is a simple method in which losses are measured separately and from their knowledge,efficiency at any load can be pre-determined in advance. The only running test needed isa no load test.

Ø Swinburne’s test is applicable to those machines in which flux is practically constant i.e.Shunt wound and Compound wound machines.

Ø The machine is running as a motor on no-load at its rated voltage and its speed beadjusted to its rated value using Shunt regulator.

Ø The no-load armature current Iao is measured using an ammeter, where as shunt fieldcurrent Ish is given by another ammeter. The no-load input current is given by Io = Iao +Ish

Ø Let the supply voltage be V volts

No-load input = V Io watts

Power input to armature = V Iao watts

Power input to shunt = V Ish watts

No-load input supplies Copper losses (Armature & Field), Iron losses (Hysteresis & Eddy current) & Mechanical losses ( Friction losses & Windage).

Constant losses = No load input power – Armature copper losses Wc = V Io – Iao² Ra watts .

Ø Predetermination of efficiency of a motor at any load

Input = V I watts.

Armature Cu losses = (I - Ish)² Ra

Constant losses = Wc

Total losses = Wc + ( I - Ish)² Ra



= (Input – Total losses) / (Input)

Ø Predetermination of efficiency of a generator at any load

Output = V I watts.

Armature Cu losses = (I + Ish)² Ra

Constant losses = Wc

Total losses = Wc + ( I + Ish)² Ra

= (Output) / (Output + Total losses)

Ø Maximum Efficiency : Variable losses (Ia² Ra) = Constant losses ( Wc)

PROCEDURE:

1. Connect the circuit as per the Circuit diagram.2. Initially the starter must be in off position.3. Switch on the D.C. Motor to 220V D.C. Supply by closing the DPST Switch.4. Start the D.C. motor using the three point starter and thereby adjust the speed to its rated

speed using field rheostat.5. Note down the readings of Voltmeter & Ammeters in Table6. Switch off the D.C. Motor to 220V D.C. Supply by opening the DPST Switch.

OBSERVATION TABLE:

At Constant speed of 1500r.p.m.

S.No. Input Voltage V Armature Current Field current

1

Wc = V Io – Iao² Ra Watts = ________ Watts



CALCULATION TABLE:

I) For Motor

S.No.

InputVoltage

(V)

InputCurrent(I)

Fieldcurrent(Ish)

ArmatureCopperLosses

TotalLosses

InputPower

12...

10

II) For Generator

S.No.

OutputVoltage

(V)

OutputCurrent

(I)

Fieldcurrent

(Ish)

ArmatureCopperLosses

TotalLosses

OutputPower

12...

10

MODEL GRAPHS:



PRECAUTIONS:-

1. The field rheostat of the motor must be kept in minimum before switching on the 220VD.C. supply.

2. Ensure that the starter arm is at extreme left position.3. Avoid loose connections4. Note down the readings from the meters without any parallax error

RESULTS:

Ø Constant losses = _________ Watts

Ø Current at which Max. occurs for motor = _________ %

Ø Current at which Max. occurs for generator = _________ %

Ø Maximum Efficiency for motor = __________ %.

Ø Maximum Efficiency for generator = __________ %.

CONCLUSIONS:


1) What is the significance of Swinburne’s test?2) What are the advantages & disadvantages of this test?3) Why this test is not suitable for D.C series motor?4) What is the purpose of 3 point starter?5) What happens if field is open in D.C motor?6) Why we have to keep the field rheostat in minimum position?



MAGNETIZATIONCHARACTERISTICS OF AD.C. SHUNT GENERATOR



Experiment no: 8

MAGNETIZATION CHARACTERISTICS OF A D.C. SHUNTGENERATOR

AIM : To obtain the Magnetization Characteristics of a D.C. ShuntGenerator and to determine its Critical field resistance

& Critical speed.

NAME PLATE DETAILS:

Type DC Shunt Motor DC Shunt Generator

Ratings 3.0 HP 2 KW

Volts. 220 V DC 220 V DC

Current 12 A 12A

Exc. Volts. 220 V DC 220 V DC

Exc. Current 0.6A 0.7A

Duty S1 S1

Ins. Class B B

Speed 1500 rpm 1500 rpm

APPARATUS:






05 Tachometer 0-10,000 RPM ANALOG 1



THEORY:

I) Magnetization Characteristics

Ø The magnetization characteristics shows the relation between the no load generated emfin armature, E0 and the field (or) exciting current, If at a given fixed speed as shown inmodel graph.

Ø These characteristics are also known as the No load saturation characteristics or Opencircuit characteristics. The shape of these characteristics is practically same for allgenerators whether separately excited or self excited

Ø Due to the residual magnetism in the poles, some emf is generated even when If = 0represented by OD**. Hence, the curve starts a little way up.

Ø The slight curvature, DE** at the lower end is due to magnetic inertia. It is seen that thefirst part of the curve, EC** is practically straight. This is due to the fact that at low fluxdensities, reluctance of iron path being negligible (due to high permeability), totalreluctance is given by the air gap reluctance, which is constant. Hence, the flux andconsequentially the generated emf are directly proportional to the exciting current.

Ø How ever at high flux densities, where µ is small, iron path reluctance becomesappreciable and straight relation, CF** between Eo and If no longer holds good, i.e.,saturation of poles start.

(** refers to the model graph)

II) Critical resistance

Ø It is that maximum value of the field resistance, above which the machine fails to excitei.e. there will be no “build up” of the voltage.

Ø This resistance corresponds to the straight-line position of the magnetizationcharacteristic because the magnetic circuit does not offer any appreciable reluctance tothe magnetic flux.

III) Critical speed

Ø It is that speed for which the given shunt field resistance will represent critical fieldresistance

(OR)

It is that minimum value of the speed of the machine below which the machine fails to excite .



PROCEDURE:

7. Connect the circuit as per the circuit diagram.8. Initially the starter must be in OFF & SPST Switch in open positions.9. Switch on the D.C. Motor to 220V D.C. Supply by closing the DPST Switch.10. Start the D.C. motor using the three point starter and thereby adjust the speed of it to the

rated speed of the D.C.generator using field method of speed control.11. Note down the voltage of the voltmeter which represents the residual voltage of the

generator when SPST switch is in open condition.12. Close the SPST switch and Excite the field winding D.C.generator in steps by decreasing

its external resistance gradually and note down various corresponding readings ofammeter and voltmeter till 1.1 to 1.25 times the rated voltage of the generator is reached,maintaining constant speed .

13. Gradually reduce the field current of generator and make it to zero finally by openingSPST switch. and disconnect the D.C. Motor from the 220V D.C. Supply

.OBSERVATION TABLE:

At constant speed of 1500r.p.m.

S.No. Field current( If ) A Armature Voltage ( Eo ) V

12...

10

MODEL GRAPHS:



CALCULATIONS:

TO FIND CRITICAL FIELD RESISTANCE:

1. Plot the magnetization curve.2. Draw the tangent such that it touches most of the linear part of the curve. This line is the Critical field resistance line.3. The slope of the above line gives the Critical field resistance.

TO FIND CRITICAL SPEED:

1. Draw the constant field resistance line Rf .2. From point ‘A’ draw a line on to the Critical field resistance line. Now the Critical speed, Nc = (AB /AC) ×N, where N is the rated speed of D.C. generator i.e., 1500 r.p.m.

PRECAUTIONS:-

5. The field rheostat of the motor must be kept in minimum & for the generator inmaximum positions before switching on the D.C. supply.

6. Ensure that the starter arm is at extreme left position.7. Avoid loose connections8. Note down the readings form the meters without any parallax error

RESULT:

Ø Critical field resistance = ________ ohms.

Ø Critical speed = ________ r.p.m.

CONCLUSIONS:


1. What are Magnetization Characteristics?2. What do you mean by Critical field resistance?3. What do you mean by Critical speed?4. How do you obtain the O.C.C at any other speed other than rated speed?5. What are the different types of Generators?6. What are the applications of D.C Shunt Generators?



BRAKE TEST ON A SQUIRREL CAGE

INDUCTION MOTOR



Experiment no: 9

BRAKE TEST ON A THREE PHASE SQUIRREL CAGE INDUCTION MOTOR

AIM : To obtain the Performance characteristics curves of a 3 Squirrel cageInduction motor by conducting brake test on it.

NAME PLATE DETAILS:

S.No Type Squirrel cage Induction Motor

01 Rating 3.0 HP / 2.2KW02 Volts. ,415 A.C.03 Current 4.7 A04 Connection Delta07 Ins. Class B08 Speed 1400 rpm

APPARATUS:



02 Ammeter (0-10) A M.C. 1

03 Wattmeter 600 V ,10A UPF 2





THEORY:

Ø It is a simple method of testing 3 Squirrel Cage Induction motor and consists ofapplying a brake to a water-cooled drum mounted on the motor shaft.

Ø The five important characteristics curves of a 3 Squirrel cage Induction motor Motor,namely, Speed, Slip, Armature Current, Efficiency & Power factor, each plotted againstthe useful Power, as shown in the model graph are known as Performance characteristics.

Ø Squirrel cage Induction Motor of low rating can be started by Direct-on-line Startingmethod or Auto Transformer Method of Starting

Ø A belt is wound round the brake drum and its two ends are attached to two springbalances S1 & S2. The tension of the belt can be adjusted with the help of swivels.

Ø Shaft torque, T developed by the motor is 9.81 (S1 – S2) R Nm where, R is the radius of the pulley in meters & N is the speed in rpm

Ø Useful Output Power = (2 N T) / 60 Watts

Ø Input Power = W1 +W2 Watts

Ø % Efficiency , = (Output power / Input power) x 100.

Ø % Slip = [Ns-N/Ns] ×100 ,where, Synchronous Speed of Rotating flux is Ns=120 f / P & N is Rotor Speed

Ø Power Factor, Cos = W1+W2 3VIØ The size of the motor that can be tested by this method is limited from the consideration

of the heat that can be dissipated at the brake drum

PROCEDURE:

1. Connect the circuit as per the Circuit diagram.2. Close the TPST switch to 3 AC Supply and apply the voltage gradually to the Stator of the

Induction Motor by means of the Variac.3. At no load, note down the readings of all Meters( Ammeter, Voltmeter, Wattmeters &

Tachometer) & Spring balances.4. Gradually apply the load & for various values of current up to rated current, note down all

Meter readings & Spring balance readings.5. Now release the load gradually and reduce the applied Voltage to zero using Variac.6. Disconnect the Variac by opening the TPST Switch



OBSERVATION TABLE:

S.No. InputVoltage

(V)

ArmatureCurrent

(A)

Wattmeters Spring BalancesSpeed (N)

(RPM)W1 W2 S1 S2

123....

10

CALCULATION TABLE:

Radius of the Brake Drum, R = ______ mts.

S.No.

ArmatureCurrent

(IL)Torque

(T)OutputPower

InputPower % % Slip Cos

123....

10

PRECAUTIONS:

1. Avoid loose connections2. Initially position of the variable on Variac must be in minimum position.3. Note down the readings from the meters without any parallax error4. Tachometer should be kept horizontal to the shaft while measuring the speed.5. Before switch OFF the motor make sure that there is no load connected to motor.



MODEL GRAPHS:

RESULTS:

At full load:i) Speed = __________ rpmii) Slip = __________ %.iii) Armature Current = __________ Aiv) Efficiency = __________ %.

v) Power factor = __________

CONCLUSIONS:


1. What are the different types of 3 I.M?2. Explain the Performance Characteristics of 3 I.M.3. Explain the Slip-Torque Characteristics of 3 I.M4. Explain different methods of starting 3 Squirrel cage I.M?



REGULATION OF 3 ALTERNATOR



Experiment no: 10

REGULATION OF 3 ALTERNATOR

AIM : To predict the regulation of 3 alternator usingSynchronous impedance method

NAME PLATE DETAILS:

Type DC Shunt Motor Alternator

Ratings 3.0 HP 3 KVA

Volts. 220 V DC ,415V AC

Current 12 A 4.2 A

Exc. Volts. 220 V DC 220 V DC

Exc. Current 0.6A 1.4A

Duty S1 S1

Ins. Class B B

Speed 1500 rpm 1500 rpm

APPARATUS:



02 Ammeter (0-10) A M.I. 1

03 Rheostat 300 , 2 A Wire Wound 1


05 Switch -- Triple pole 1



THEORY:

Voltage regulation is defined as the rise in terminal voltage, when the full load at aparticular power factor is removed keeping the field excitation and speed constant divided by therated terminal voltage.

% regulation = (EO-V) / V X100

For small rating machines regulation can be found by direct load where as in the case oflarge machines the cost of finding regulation by direct loading becomes expensive. Hence anindirect method is used for obtaining the regulation of an alternator is Synchronous impedance orEMF method In order to calculate the regulation by this method, it requires

a) Armature or stator resistance Ra.b) Open circuit or No-load characteristics.c) Short circuit characteristics.

OD = Eo

Eo = (OB2 + BD2)1/2

OB = OA + AB = V Cos + IRa

BD = BC + CD = V Sin + IXs



For lag pf, Eo = [ (V Cos + IRa)2 + (V Sin + IXs)2 ]1/2

For lead pf, Eo = [ (V Cos + IRa)2 + (V Sin – IaXs)2 ]1/2

For UPF, Eo = [ (V + IaRa)2 + (IaXs)2 ]1/2

where V= Rated voltage, Cos - power factor

% Regulation = (Eo- V) / V X 100

PROCEDURE:OC test:

1) Connect the circuit as per the circuit diagram.2) Initially the starter must be in OFF & SPST Switch in open positions.3) Switch on the D.C. Motor to 220V D.C. Supply by closing the DPST Switch.4) Start the D.C. motor using the three point starter and thereby adjust the speed of it to

the rated speed of the Alternator using field method of speed control.5) With the TPST Switch open , Switch ON the Excitation unit of Alternator & by varying

the field current tabulate the corresponding open circuit voltage readings.

SC test:

6) Conduct the Short circuit test by closing the TPST switch and adjust the alternatorfield current for which the armature current corresponds to its rated value & tabulate it.

7) Gradually reduce the field current of alternator and disconnect the D.C. Motor from the220V D.C. Supply.

OBSERVATION TABLE:-

OPEN CIRCUIT TEST SHORT CIRCUIT TEST

Armature resistance per phase Ra =___

S. No. VOC (volts) If (Amps) S.No Isc (amps) If (amps)



MODEL GRAPHS:

1. O.C.C. And S.C.C.:

2. Power factor Vs Regulation



CALCULATIONS:

Z = [Open cicuit Voltage per Phase] / [Short circuit current], at constant field current

where Short circuit current can be taken as rated armature current, Ia

Z = Eo per phase / Ia , at constant If

Xs = (Z2 – Ra2 )

CALCULATION TABLE:

Voltage Regulation characteristics

S.No Cos Φ SinΦLagging p.f Leading p.f

full load half load full load half load

PRECAUTIONS:-

1. The field rheostat of the motor must be kept in minimum position before switching onthe D.C. supply.

2. Ensure that the starter arm is at extreme left position.3. Avoid loose connections4. Note down the readings form the meters without any parallax error5. Speed must be maintained constant through out the experiment.6. Make ensure that the terminal voltage is reduced to zero before doing short circuit

test .



RESULTS:

Ø Voltage regulation at full load 0.8 pf. lag is _____& 0.8 pf. lead is ______

Ø Maximum positive voltage regulation occurs at pf of _______

Ø Zero voltage regulation occurs at pf of _______

CONCLUSIONS:


1. What is the principle of operation of an alternator?2. What are the different types of alternators available?3. What are the different factors affecting the Voltage regulation?4. Explain the variations of terminal voltage under different power5. factor conditions.6. Why the synchronous impedance method is termed as “Pessimistic method”



APPENDIX



VERIFICATION OFSUPERPOSITION AND

RECIPROCITY THEOREMSIN AC SYSTEM



Experiment no: 1VERIFICATION OF SUPERPOSITION

& RECIPROCITY THEOREMS

AIM : To verify Superposition & Reciprocity theorems for the given network.

APPARATUS :

THEORY:-I. Superposition Theorem Statement:

In a linear network with several independent sources which include equivalentsources due to initial conditions and linear dependent sources, the overall response in any partof the network is equal to the sum of the individual responses due to each independent source,considered separately, with all other independent sources reduced to zero.Note: 1. The sources which are considered one at a time making all other sources zero,are the independent sources including sources due to initial conditions only. The dependentsources are retained as they are in the network. 2. When one independent source is considered & all other independent sources arereduced to zero means that all the other independent voltage source are replaced with shortcircuit and all the other independent current sources are replaced with open circuit. If the sourcescontain internal impedances, that sources are replaced by their internal impedances.

II. Reciprocity Theorem Statement:

The Reciprocity theorem states that the ratio of response to excitation is invariantto an interchange of the position of the excitation and response in a single source network.However if the excitation is a voltage source, the response should be a current and vice versa.


1 Voltmeter MI 0-300V 2

2 Ammeter MI 0-2.5A 1

3 RheostatWWWWWW

50 /5A110 /2A300 /2A

212

4 1- Variac 230V / (0-270)V,15A ---- 1

5. Fuse TCC 5A 4



300 ,2A

300 ,2A

(0-300)V, MI

(0-300)V, MI



300 ,2A

300 ,2A

(0-300)V, MI



PROCEDURE:-


1. Connect the circuit as per the Circuit diagram.2. Close Switch S1 on to the Supply mains & remain Switches S2 & S3 open and Switch S4

closed.3. Note down the Voltmeter readings V1 ,V2 & Ammeter reading as I' in the S.No1 of Table14. Now close Switch S2 on to the Supply mains & remain Switches S1 & S4 open and Switch

S3 closed. And increase the variac position so that the voltmeter V2 shows 150V.5. Note down the Voltmeter readings V1 ,V2 & Ammeter reading as I" in the S.No2 of Table1 and decrease the variac position to initial condition.6. Now Close Switches S1 & S2 on to the Supply mains & remain Switches S3 & S4 open. And again increase the variac position so that the voltmeter V2 shows 150V. 7. Note down the Voltmeter readings V1 ,V2 & Ammeter reading as I in the S.No3 of Table1.8. Finally disconnect the circuit from the Supply mains by open all the Switches.


CASE : I

5. Connect the circuit as per the Circuit diagram.6. Close Switch S1 on to the Supply mains7. Note down the Voltmeter V1& Ammeter A1 readings in S. No. 1 of Table 28. Disconnect the circuit from the Supply mains by opening the Switch S1.

CASE : II

5. Connect the circuit as per the Circuit diagram.6. Close Switch S2 on to the Supply mains7. Note down the Voltmeter V2 Ammeter A2 readings in S. No. 2 of Table 28. Disconnect the circuit from the Supply mains by opening the Switch S2.



OBSERVATION TABLE:-

TABLE 1 SUPERPOSITION THEOREM:

S.No. Switches Positions Voltmeter Reading Voltmeter Reading Ammeter Reading

1. S1 & S4 ON,S2 & S3 OFF V1 = V2 = I' =

2. S1 & S4 ON,S2 & S3 OFF V1 = V2 = I" =

3. S1 & S4 ON,S2 & S3 OFF V1 = V2 = I =

TABLE 2 II. RECIPROCITY THEOREM:

S.No. Voltmeter Reading Ammeter Reading1. V1 = I1 =2. V2 = I2 =

PRECAUTIONS:

1. Avoid Loose Connections .2. Readings must be taken without parallax error.3. Before switching on the supply for the circuit , ensure that all rheostats are at maximum position and during the experiment these should not be disturbed.

RESULTS:


1. I' = A

2. I" = A

3. I = A




1. V1/ I1 =

2. V2/ I2 =

CONCLUSIONS:

VIVA QUESTIONS:

7) What are the Statements of the above theorems?8) What is a linear network?9) Where the above theorems are used practically?10) What are the practical applications of the above theorems?11) What is a bilateral network? Give examples.12) What are the limitations of above theorems?



VERIFICATION OFMAXIMUM POWER

TRANSFER THEOREMIN AC SYSTEM



Experiment no: 2

VERIFICATION OF MAXIMUM POWERTRANSFER THEOREM

AIM : To verify Maximum Power transfer theorem for the given circuit.

APPARATUS :


1 Voltmeter MI

MI0-300V0-150V

11

2 Ammeter MI 0-2A 1

3 RheostatWWWWWW

100 /5A50 /5A200 /2A

211

4. Fuse TCC 5A 2

THEORY:

Statement: The Maximum Power transfer theorem states that An Impedance load ZL, being connected to an AC network, receives maximum power when it is equal to the internal impedance of the source network as seen from the load terminals i.e. Zth”



With reference to Fig(B)

Lth

thL RR

VI+

=

While the power delivered to the resistive load is

( )( ) L

Lth

thLLL R

RRVRIP ×+

== 2

22

PL can be maximized by varying R and hence, maximum power can be delivered when (dPL/dRL)= 0

( ) ( ) ( )

( )04

2222

=+

+−+⇒

Lth

LthL

LthLthL

Lth

RR

RRdR

dRVRVdR

dRR

( ) ( ) ( )( )

02

4

222

=+

+⋅⋅−+⇒

Lth

LthLththLth

RRRRRVVRR

( ) 02 =⋅−+⇒ LLth RRR

thL RR =⇒

Hence it has been proved that power transfer from a dc source network to a resistive network ismaximum when the load resistance of the network is equal to the internal resistance of the dcsource. Again with RL=Rth, the system being perfectly matched for load and source, powertransfer becomes maximum and this amount of power (Pmax) can be obtained as

( ) th

th

thth

thth

RV

RRRVP

4

2

2

2

max =+

=

The total power supplied is thus

th

th

th

thin R

VR

VP24

222

=⋅=

During maximum power transfer the efficiency of the circuit becomes,.

%50100max =×=inP

Pη



CIRCUIT I

V

0-300V,MI

+ -

230V

,50H

zSi

ngle

phas

eA

CSu

pply

DPS

TFU

SE5A

V

0-2A

,MI

A10

0,5

A

50 ,5A

200 ,2A

0-150V,MI

FUSE

5A

+

+

+

-

-

-

100

,5A

Max

imum

Pow

erT

rans

fer

The

orem

MA

INC

IRC

UIT



CIRCUIT II

0-300V,MI

50 ,5A



PROCEDURE:-

I) TO FIND POWER VARIATIONS WITH RL

1. Connect the circuit as per the Circuit diagram 1.2. Apply 230 V AC Supply to the circuit by closing the DPST Switch.3. Note down the readings of Ammeter & Voltmeter in Table 1 which are connected across the load after keeping the load rheostat, RL at its minimum value.4. Increase the load resistance in steps and for each step, note down the corresponding Ammeter and Voltmeter readings in Table 1.5. Disconnect the circuit from the supply by opening the DPST Switch.

II) TO FIND Rth

1. Connect the circuit as per the Circuit diagram 2.2. Apply 230 V AC Supply to the circuit by closing the DPST Switch.3. Note down the readings of Ammeter & Voltmeter in Table 2 .4. Disconnect the circuit from the supply by opening the DPST Switch.

OBSERVATION TABLE:-

TABLE 1

S No VL (volts) IL (amps) RL = VL/ IL ( ) PL = IL2RL

1.2.3....

10.

TABLE 2

S No VS (volts) IS (amps) Rth = VS/IS

1.



MODEL GRAPH:-

PRECAUTIONS:-

1. Avoid loose connections.2. Avoid Parallax error.3. Take more number of readings for a better plot

RESULTS:-

1. Pmax = ----------2. RL = ---------3. Rth = ---------4. = ---------

CONCLUSIONS:-

VIVA QUESTIONS:-

1) What is the Statement of Maximum Power Transfer theorem?2) What is a linear network?3) What is a bilateral network?4) What are the applications of the above theorem?5) What are the advantages & disadvantages of the above theorem?



VERIFICATION OF THEVENIN SNORTON S &MAXIMUM POWER

TRANSFER THEOREMSIN DC SYSTEM



Experiment no:3

VERIFICATION OF THEVENIN’S& NORTON’S THEOREMS

AIM : To verify Thevenin’s & Norton’s theorems for the given circuit.

APPARATUS:

S. No Name of Apparatus Range Type Quantity1 Voltmeters 0-300V PMMC 22 Ammeter 0-2A PMMC 2

3 Rheostats50 , 5A

110 , 2A200 , 2A

WWWWWW

212

5. SPST 5A ---- 26. Fuse 5A TCC 2

THEORY:-

I) Thevenin’s Theorem Statement:

Any combination of linear bilateral circuit elements and active sources, regardless ofthe connection or complexity, connected to a given load RL, may be replaced by a simple twoterminal network consisting of a single voltage source of Vth volts and single resistance Rth inseries with the voltage source, across the two terminals of the load RL . The Vth is the opencircuit voltage measured at the two terminals of interest, with load resistance RL removed. Thisvoltage is also called Thevenin s equivalent voltage. The Rth is the Thevenin s equivalentresistance of the given network as viewed through the open terminals with RL removed and allthe active sources are replaced by their internal resistances. If the internal resistances are notknown then independent voltage sources are to be replaced by the short circuit while theindependent current sources must be replaced by open circuit.



II) Norton’s Theorem Statement :

Any combination of linear bilateral circuit elements and active sources, regardless ofthe connection or complexity, connected to a given load RL, can be replaced by a simple twoterminal network, consisting of a single current source of IN amperes and a single resistanceRN in parallel with it, across the two terminals of the RL. The IN is the short circuit currentflowing through the short circuited path, replaced instead of RL. It is also called Norton scurrent. The RN is the equivalent resistance of the given network as viewed through the loadterminals, with RL removed and all the active sources are replaced by their internalresistances. If the internal resistances are unknown then the independent voltage sources mustbe replaced by short circuit while the independent current sources must be replaced by opencircuit.



CIRCUIT 1:

0-300V, MC

200 , 2A

110 , 2A

SPST2



CIRCUIT II:



CIRCUIT III:



CIRCUIT IV:



PROCEDURE:-

I) FOR CIRCUIT 1:

1. Connect the circuit as per the circuit diagram.2. Apply 220 V DC Supply to the ciruit by closing the DPST Switch.3. Note down the corresponding readings of Ammeter & Voltmeter2 in Table 1 with the conditions i) SPST 1 Closed & SPST 2 Open ii) SPST 1 Open & SPST 2 Open iii) SPST 1 Closed & SPST 2 Closed5 Disconnect the supply by opening the DPST Switch.

II) FOR CIRCUIT 2:

1. Connect the circuit as per the circuit diagram.2. Apply 220 V DC Supply to the circuit by closing the DPST Switch.3. Note down the readings of ammeter and voltmeter.4. Disconnect the supply by opening the DPST Switch.

III) FOR CIRCUIT 3:

1. Connect the circuit as per the circuit diagram.2. Apply 220 V C Supply to the circuit by closing the DPST Switch.3. Close the SPST Switch & vary both the rheostats until the ratio of Ammeter reading I to the Voltmeter reading gives Rth , the value as obtained in Table 24. Once the Rheostat set to Rth , open the SPST Switch .5. Gradually vary the variable position of the potential divider 300/2A until the Voltmeter reads Vth, as obtained in Table 1.Note down the reading of the Ammeter in Table 36. Gradually vary the variable position of the potential divider until the Voltmeter reads 0 volts.7. Disconnect the supply by opening the DPST Switch.

IV) FOR CIRCUIT 4:

1. Connect the circuit as per the circuit diagram.2. Use the same Rheostat which set to Rth as in the Circuit 33. Apply 220 V DC Supply to the circuit by closing the DPST Switch.4. After closing the SPST switch gradually vary the variable position of the potential divider

until the Ammeter1 reads current IN as obtained in Table 1 & note down the correspondingreading of the Ammeter2 in Table 4.

5. Disconnect the supply by opening the DPST Switch.



OBSERVATION TABLE:-


S.No Switch conditions Voltmeter V1 Voltmeter V2 Ammeter1. SPST 1 Closed

SPST 2 OpenVS = VL = IL =

2. SPST 1 Open SPST 2 Open

VS = Vth = IL = 0

3. SPST 1 ClosedSPST 2 Closed

VS = VL = 0 IN =


S.No Voltmeter Ammeter Rth = VS / IS

1. VS = IS = Rth =


S.No Voltmeter Ammeter1. Vth = IL =


S.No Ammeter I1 Ammeter I2

1. IN = IL =



PRECAUTIONS:-

1. Avoid loose connections.2. Avoid Parallax error.3. Before switching on the supply for each circuit ensure that all rheostats are at maximumposition and during the experiment these should not be disturbed.4. Variable position of the Variac (auto transformer) should be at minimum position before switching on the power supply.

RESULTS:-

1. IL from the Main circuit =

2. IL from the Thevenin’s Equivalent Circuit =

3. IL from the Norton’s Equivalent circuit =

CONCLUSIONS:-

VIVA QUESTIONS:-

1) What is the Statement of Thevenin’s theorem?2) What is a linear network?3) What is a bilateral network?4) What are Active & Passive elements?5) What are the applications of the above theorem?6) What are the limitations of application of this theorem ?



DETERMINATION OF TWO PORTNETWORK PARAMETERS

IN AC SYSTEM



Experiment no: 4

DETERMINATION OF TWO PORT NETWORK PARAMETERS

AIM: To determine Z, Y, ABCD and H parameters of a given two port Network.

APPARATUS:

S.No Specification Range Type Quantity1 Voltmeter (0-300)V MI 22 Ammeter (0-5)A MI 23 Rheostat (50 , 5A) Wire Wound 3

4 Variac 230/(0-270)V15A ------- 1

5 Switches ------ DPDT 2

6 Fuses 5A Tin CoatedCopper 2

7 Connecting Wires 1 Square mm Insulated copper As perRequirement

THEORY:

A network containing two pairs of terminals is called as two port network. Normallyone pair of terminals coming together to supply power or to withdraw power or to measure theparameters, are called as port. To achieve simplicity, the whole network is shown with a singleblock.

A typical two port network is as shown below in fig (a)



OPEN CIRCUIT IMPEDANCE PARAMETERS (Z-parameters):

Z-parameters can be defined by the following equations

V1 = Z11I1 + Z12I2 …………………… (1)

V2 = Z21I1 + Z22I2 …………………… (2)

Matrix form :

( )3...............................2

1

2221

1211

2

1

∗

=

II

ZZZZ

VV

If port 2-21 is open circuited, i.e. I2 = 0 then

Z11 = V1/I1 & Z21 = V2/I1

If port 1-11 is open circuited, i.e. I1 = 0, then

Z12 = V1/I2 & Z22 = V2/I2.

Here,

Z11 is the driving point impedance at port 1-11 with 2-21 open circuited. It can also be called asopen circuit input impedance.

Z21 is the transfer impedance at port 1-11 with 2-21 open circuited. It can also be calledas open circuit forward transfer impedance.

Z12 is the transfer impedance at port 2-21 with 1-11 open circuited. It can also be called asopen circuit reverse transfer impedance and

Z22 is the driving point impedance at port 2-21 with 1-11 open circuited. It can also becalled as open circuit output impedance.

Z-parameter representation for a two port network, shown above, will be as shown belowin fig (b)



If the network is

a) Reciprocal then V1/I2 (where I1 = 0) = V2/I1 (where I2 = 0) i.e. Z12 = Z21

b) Symmetrical then V1/I1 (where I2 = 0) = V2/I2 (where I1 = 0) i.e. Z11 = Z22

SHORT CIRCUIT ADMITTANCE PARAMETERS (Y-parameters):

Y-parameters can be defined by the following equations

I1 = Y11V1 + Y12V2 ………………. (1)

I2 = Y21V1 + Y22V2 ………………. (2)

In matrix form

1

21

I2I1

Z11

+_

Z22

Z12I2 Z21I1

2

11

V2V1

Fig (b) Open circuit impedance parametric representation of a two port net work.

+_



( )3...............................2

1

2221

1211

2

1

∗

=

VV

YYYY

II


Y11 = I1/V1 & Y21 = I2/V1


Y12 = I1/V2 & Y22 = I2/V2

Here, Y11 is the short circuit driving point admittance at port 1-11 with 2-21 shortcircuited. It will also be called as short circuit input admittance.

Y21 is the Transfer admittance at port 1-11 with 2-21 short circuited. It will also becalled as short circuit forward transfer admittance.

Y12 is the Transfer admittance at port 2-21 with 1-11 short circuited. It will also becalled as short circuit reverse transfer admittance and

Y22 is the driving point admittance at port 2-21 with 1-11 short circuited. It can alsobe called as short circuit output admittance.

Y-parameter representation for a two port network, shown above, will be as shown belowIf the network is

1

21

I2I1

Y11 Y22Y12V2 Y21V1

2

11

V2V1

Fig(c) Short circuit admittance parameter representation of a two port net work.



a) Reciprocal then I2/V1 (where V2 = 0) = I1/V2 (where V1 = 0) i.e. Y21 = Y12

b) Symmetrical then I1/ V1 (where V2 = 0) = I2/ V2 (where V1 = 0) i.e. Y11 = Y22

Hybrid Parameters (h-Parameters):

h-parameters can be defined by the following equations

)2.....(..............................)1......(..............................

2221212

2121111

VhIhIVhIhV

+=+=

In matrix form

)3(..............................2

1

2221

1211

2

1

⋅

=

VI

hhhh

IV


h11 = V1/I1 & h21 = I2/I1

h11 is called input impedence and h21 is called forward current gain.

If port 1-11 is open circuited, i.e., I1=0 then

2

222

2

112 &

vIh

vvh ==

h22 is called output admittance and h12 is called reverse voltage gain.



ABCD Parameters:

ABCD parameters can be defined by the following equations

)2..(....................).........()1.(....................).........(

221

221

IDCVIIBAVV

−+=−+=

In matrix form

)3.........(....................2

2

1

1

−

=

I

VDCBA

IV

If port 2-21 is open circuited i.e., I2=0 then

2

1

2

1 &VIC

VVA ==

A is called reverse voltage ratio and C is known as transfer admittance.

If port 2-21 is short circuited i.e., V2=0 then

2

1

2

1 &I

IDI

VB−

=−

=

B is called transfer impedence and D is called reverse current ratio.

h22

1

I1

h11

+-h12V2

11

V1

Fig (d) Hybrid parametric representation of a two port net work.

21

I2

h21I1

2

V2



PROCEDURE:-

1. Connect the circuit as per circuit diagram.2. With the Switches S2 open , S3 close to 11' and S4 open , note down the corresponding

readings of voltmeter and ammeter in S.No 1 in Tabular form after closing the Switch S1to supply mains

3. With the Switches S1 open ,S4 close to 33' and S3 open , note down thecorresponding readings of voltmeter and ammeter in S.No 2 in Tabular after closing theSwitch S2 to supply mains

4. With the Switches S2 open ,S3 close to 11' and S4 close to 44' , note down thecorresponding readings of voltmeter and ammeter in S.No 3 in Tabular after closing theSwitch S1 to supply mains

5. With the Switches S1 open ,S3 close to 22' and S4 close to 33 ' , note down thecorresponding readings of voltmeter and ammeter in S.No 4 in Tabular after closing theSwitch S2 to supply mains

OBSERVATION TABLE:-

S.NO Test Condition V1 (V) I1 (A) V2 (V) I2 (A)

1Port 2 Open(I2 = 0) and

Port-1 Active

2Port 1 Open(I1=0) and

Port-2 Active


(V2=0) andport-1 active


(V1=0) andPort-2 active

PRECAUTIONS:

1. Note down the readings of voltmeter and ammeter without parallax error.2. The current through a particular element should be maintained below its current rating.3. The conditions of switches should be thoroughly checked before making the circuit live



RESULTS:

The values of Z parameters are

Z11 = ________; Z12 = ________; Z21 = ________ ; Z22 = ________

The values of Y parameters are

Y11 = ________; Y12 = ________; Y21 = ________; Y22 = ________

CONCLUSIONS :

VIVA QUESTIONS:

1) What is the significance of the two port parameters?2) How you know the admittance parameters from impedance parameters?3) What are the application of Z& Y parameters?4) What is the condition for reciprocal network?5) What is the condition for symmetrical network?6) What is a Lattice network?7) What is a Ladder network?

bee final lab manual

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