Circuit Thoery Lab Manual

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    EE2155 Electrical Circuits Lab Manual

    DepartmentofElectrical&ElectronicsEngineeringSUDH RS N ENGINEERING COLLEGE

    pudukkottai

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    OHMS LAW

    CIRCUIT DIAGRAM

    TABULATION

    S.No

    Resistance(R)

    ()

    Current in Amperes

    (I)

    Voltage across RL(V)

    The Exp The Exp

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    Ex.No:1

    VVEERRIIFFIICCAATTIIOONNOOFFOOHHMMSSLLAAWWAANNDDKKIIRRCCHHOOFFFFSSLLAAWW

    AIMTo study and verify the Ohms law and kirchoffs laws by conducting suitable

    experiment on the given Electric circuit.

    APPARATUS REQUIRED

    S.No Apparatus Name Range Type Quantity

    1

    23

    4

    Ammeter

    Trainer kitMultimeter

    Patch Chords

    0-100mA

    ------

    ---

    MC

    ----Digital

    ----

    3

    11

    As required

    THEORY

    Ohms law

    At constant temperature, the potential difference (E) across the ends of a conductor is

    proportional to the current (I) flowing through it.

    i.e. E=IR

    Where R is the resistance of the conductor in ohm.

    PROCEDURE

    1. The resistor values in the circuit are designed for 100 mA, 12V.2. Connections are made as per the circuit diagram.3. Switch on the trainer kit.4. The corresponding voltages & currents are tabulated for variable load resistance (RL)

    values.

    5. By comparing theoretical and experimental values, the ohms law is verified.

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    KIRCHOFFS VOLTAGE LAW

    CIRCUIT DIAGRAM

    TABULATION

    S.No VS (V)V1(V) V2 (V) V3 (V) V= V1+ V2+ V3

    The Exp The Exp The Exp The Exp

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    KIRCHOFFS VOLTAGE LAW

    Kirchoffs voltage law states that In a closed loop Electric circuit the sum of potential

    drop is equal to the sum of potential rise.

    Along the current direction the polarity of voltage from ve to +ve is considered as

    potential rise and +ve to ve is known as potential drop. In the resistor the current entering

    terminal is marked as positive and current leaving terminal is marked as negative.

    V = V1+ V2 + V3

    = IR1+ IR2 + IR3

    PROCEDURE

    1. Connections are made as per the circuit diagram.2. R1, R2and R3are selected such that the total current in the circuit is within 100mA.3. The voltage across the resistor V1, V2and V3are measured by a Digital

    voltmeter/Multimeter for 8V as input voltage and tabulated.

    4. Repeat the above procedure for input voltages 10V & 12V.5. By comparing theoretical and experimental values the Kirchoffs voltage law is verified.

    KIRCHOFFS CURRENT LAW

    Kirchoffs current law states that the sum of current entering into a junction is equal to

    the sum of current leaving away from it.

    The junction may be interconnection of two or more branches. In the given circuit, the

    current entering the node a are I1 and I2and current leaving the node is I3.

    PROCEDURE

    1. The resistor values in the circuit are designed for 100mA and 12V.2. Connections are made as per the circuit diagram.3. 8V, 10V and 12 V supply is given to the circuit.4. The values of currents are measured by Analog Ammeter and tabulated.5. By comparing theoretical and experimental values Kirchoffs current law is verified.

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    RESULT

    Thus ohms law and kirchoffs laws were verified with the given resistive circuit.

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    THEVENINS THEOREM

    CIRCUIT DIAGRAM

    TO FIND Rth

    TO FIND Vth

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    Ex.No:2

    VVEERRIIFFIICCAATTIIOONNOOFFTTHHEEVVEENNIINNSSAANNDDNNOORRTTOONNSSTTHHEEOORREEMM

    AIM

    To verify Thevenins theorem and Nortons theorem by conducting suitable

    experiment on the given Electrical circuit.

    APPARATUS REQUIRED

    S.No Apparatus Name Range Type Quantity

    1

    2

    3

    4

    Ammeter

    Trainer kit

    Multimeter

    Patch Chords

    0-100mA

    ---

    ---

    ---

    MC

    ----

    Digital

    ----

    1

    1

    1

    As required

    THEVENINS THEOREM

    A linear, bilateral, lumped network with open output terminals can be reduce to asimple circuit consisting of a single voltage source in series with a resistance .The value

    of the voltage source is equal to the open circuit voltage across the open terminals and the

    value of resistance is equal to the resistance seen in to the network across the open

    terminals.

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    TABULATION

    S.No RL() IL(A)

    The Exe

    TO FIND Rth&Vth

    S.NoVth(V) Rth()

    The Exe The Exe

    THEVENINS EQUIVALENT CIRCUIT

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    Let us find the value of the current I using Thevenins theorem. First we disconnect RL

    and make its terminal open.

    The voltage across the open circuit terminals is called as Thevenins voltage Vth.

    The value of Rthis found after replacing the voltage source V by short circuit.

    Thevenins Equivalent circuit is drawn with Vthand Rth.The disconnected

    element is placed at the open circuit terminals of the Thevenins equivalent circuit.

    PROCEDURE

    1. Connections are given as per the circuit diagram.2. For various values of RL,measure ILvalues.3. To find open circuit voltage Vth, remove RLand measure open circuit voltage

    across output terminals.

    4. To find Rth,a. Replace the supply sources by their internal resistances.b. Remove load resistor RL.c. Using Multimeter the equivalent resistance across the load terminal was

    found.

    5. Using the formula IL = Vth/ (Rth+ RL), current value is calculated.

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    NORTONS THEOREM

    CIRCUIT DIAGRAM

    TO FIND RN

    TO FIND IN

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    NORTONS THEOREM

    A linear, bilateral, lumped network with open output terminals can be reduced to

    a simple circuit consisting of single current source in parallel with a resistance.

    The value of current source is equal to the current passing through the short-circuited

    output terminals. The value of the resistance is equal to the resistance seen into the

    network across the output terminal.

    Let us find the value of current I using Nortons theorem. First we disconnect RLand

    short-circuit its terminals.

    The current through the short-circuited output terminals is called Nortons current IN. The

    RNvalue is found across the open circuit terminals as found in Thevenins theorem, after

    short circuiting the voltage source E.

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    TABULATION

    S.No RL() IL(A)

    The Exe

    TO FIND RN&IN

    S.NoIN(mA) RN()

    The Exe The Exe

    NORTONS EQUIVALENT CIRCUIT

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    Nortons equivalent circuit is drawn with IN and RN.

    The disconnected element RLis placed across the open output terminal. Now Nortons

    equivalent circuit is,

    PROCEDURE

    1. Connections are given as per circuit diagram2. For various values of RLmeasure ILvalues.3. To find Nortons short circuit current IN, remove the load resistor RLand connect

    ammeter between the terminals, the current through short circuit terminal was

    found.

    4. To find RN,a. Replace the supply sources by their internal resistances.

    b. Remove load resistor RL.

    c. Using multimeter the equivalent resistance across the load terminal was found.

    5. Using the formula IL = (RN* IN)/ (RN+ RL), current value is calculated.

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    RESULT

    Thus Thevenins theorem and Nortons theorem were verified both theoretically

    and experimentally.

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    SUPERPOSITION THEOREM

    CIRCUIT DIAGRAM

    TO FIND IL

    TO FIND IL

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    Ex.No:3

    VVEERRIIFFIICCAATTIIOONNOOFFSSUUPPEERRPPOOSSIITTIIOONNTTHHEEOORREEMM

    AIM

    To verify the superposition theorem experimentally.

    APPARATUS REQUIRED

    S.No

    APPARATUS

    NAMERange Type Quantity

    1

    2

    3

    4

    Ammeter

    Trainer kit

    Multimeter

    Patch Chords

    0-100mA

    ---

    ---

    ---

    MC

    ----

    Digital

    ----

    1

    1

    1

    As required

    THEORY

    The superposition theorem states that In a linear, lumped element, bilateral

    electric circuit that is energized by two or more sources the current in any resistor is equal

    to the algebraic sum of the separate current in the resistor when each source acts

    separately. While one source is applied, the other sources are replaced by their respective

    internal resistance. To replace the other sources by their respective internal resistance,

    the voltage sources are short-circuited and the current sources open circuited.

    Consider the given electric circuit,

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    Tabulation

    S.No RRLL() V1 (V)IL(mA)

    V2 (V)IL(mA) IL = IL+ IL

    The Exe The Exe The Exe

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    To find the current through RL, first short circuit the voltage source V2by the internal

    resistance.

    Let IILL= current through the load while source V1acting alone.

    And find current through RL

    IILL =

    Now short circuit the voltage source V1by the internal resistance and energize the

    voltage source V2

    Let IILL = current through the load while source V2acting alone.

    And find IILL =

    IL= IILL+ IILL

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    PROCEDURE

    1. Connections are made as per the circuit diagram.2. By adjusting the pot, set the load resistor (RL) value.3. Now set the voltage level of V1 & V2 for a constant voltage and measure the

    branch current IL.

    4. Now short circuit the voltage source V2, and keep the voltage source V1remainsconstant value and measure IL (the current through RL)

    5. Now short circuit the voltage source V1, and keep the voltage source V2remainsconstant value and measure IL(the current through RL).

    6. Repeat the above procedure for different values of load resistor RLand tabulate it.7. Now the total current through RLis IL= IILL +IILL.8. By comparing the theoretical and experimental values, the super position theorem

    is verified.

    RESULT

    Thus the superposition theorem was verified practically and theoretically.

    Then current through RL is IL= IILL+ IILL.

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    MAXIMUM POWER TRANSFER THEOREM

    CIRCUIT DIAGRAM

    TABULATION

    Vs= V, Rs=

    S.No RL()

    IL

    (A) Pout

    (W)

    Actual Calculated Actual Calculated

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    Ex.No:4

    VVEERRIIFFIICCAATTIIOONNOOFFMMAAXXIIMMUUMMPPOOWWEERRTTRRAANNSSFFEERRTTHHEEOORREEMM

    AIM

    To verify Maximum power transfer theorem experimentally.

    APPARATUS REQUIRED

    S.No Apparatus Name Range Type Quantity

    1

    2

    3

    4

    Ammeter

    Trainer kit

    Multimeter

    Patch Chords

    0-100mA

    ---

    ---

    ---

    MC

    ---

    Digital

    ----

    1

    1

    1

    As required

    THEORY

    Many circuits basically consist of sources, supplying voltage, current or power to

    the load. Sometimes it is necessary to transfer maximum voltage, current or power from

    the source to the load.

    More voltage is delivered to the load when the load resistance is high as

    compared to the resistance of the source. Maximum current is transferred to the load

    when the load resistance is small compared to the source resistance.

    Thus, Maximum power transfer theorem states that, Maximum power is

    delivered from a source to a load when the load resistance is equal to the source

    resistance.

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    Current in the circuit is I = VS / ( RS+RL ).

    Power delivered to the load RLis P = I

    2

    RL ( )2

    2

    LS

    LS

    RR

    RV

    +

    =

    To determine the value of RLfor maximum power to be transferred to the load, we

    have to set the first derivative of the above equation with respect to RL, i.e., whenL

    dR

    dP

    equals zero.

    ( )

    +=

    2

    2

    LS

    LS

    LL RR

    RV

    dR

    d

    dR

    dP

    ( ) ( ){ }( )

    +

    ++=

    4

    222

    2

    LS

    LSLLSS

    RR

    RRRRRV

    ( ) ( )LSLLS

    RRRRR ++22

    2 = 0

    0222 222

    =++LSLLSLS

    RRRRRRR

    RS= RL

    So, maximum power will be transferred to the load when load resistance is equal to

    the source resistance.

    PROCEDURE

    1. The resistor value in the circuit is designed such that RS= RL.2. Connections are made as per the circuit diagram.3. 12 V supply is given to the circuit.4. The current IL is measured for various values of RLby using ammeter.5. By using I = VS/ R, current value is calculated and the output can be calculated as

    POUT = I2RL.

    6. By comparing the both powers, we can conclude that maximum power will betransferred at RS= RL.

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    RESULT

    Thus the maximum power transfer theorem was verified.

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    RECIPROCITY THEOREM

    CIRCUIT DIAGRAM

    Circuit 1

    Circuit 2

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    Ex.No:5

    VVEERRIIFFIICCAATTIIOONNOOFFRREECCIIPPRROOCCIITTYYTTHHEEOORREEMM

    AIM

    To verify Reciprocity theorem experimentally.

    APPARATUS REQUIRED

    S.NoAPPARATUS

    NAMERange Type Quantity

    1

    2

    3

    4

    Ammeter

    Trainer kit

    Multimeter

    Patch Chords

    0-100mA

    ---

    ---

    ---

    MC

    ----

    Digital

    ----

    1

    1

    1

    As required

    THEORY

    The Reciprocity theorem states that In a linear, bilateral network a voltage

    source V volts in a branch gives rise to a current I in another branch, the ratio V/ I is

    constant when the position of V and I are interchanged.

    According to this theorem if a source voltage and ammeter are interchanged, the

    magnitude of the current through the ammeter will be same. Consider the given network

    fig 1 with two loops 1 and 2 if an ideal voltage source V in loop 1 produces a current I

    in loop 2, then interchanging positions as shown in fig - 2, The same ideal source V in

    loop 2 produces the same current I in loop 1. The network is said to be reciprocal.

    Fig 1 Fig - 2

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    TABULATION

    Table 1 (For Circuit 1)

    S.No Voltage (Vs)Current I1(A)

    The Exe

    Table 2 (For Circuit 2)

    S.No Voltage (Vs)

    Current I2(A)

    The Exe

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    PROCEDURE

    1. Connections are made as shown in circuit diagram (1).2. Measure the value of current I1 for various voltage levels and record them in

    table1.

    3. Change the voltage source position as shown in circuit diagram (2).4. Measure the value of current I2for various voltage levels as in step 1 and record

    them in table2.

    5. By comparing theoretical and experimental values, the reciprocity theorem isverified.

    RESULT

    Thus the Reciprocity theorem was verified both theoretically and experimentally.

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    Ex.No:6

    FREQUENCY RESPONSE OF SERIES AND PARALLEL RESONANCE

    AIMTo analyze the characteristics of RLC series and parallel resonance circuits

    experimentally.

    APPARATUS REQUIRED

    S.No Apparatus Name Range Type Quantity

    1

    2

    3

    4

    5

    6

    Resistor

    Capacitor

    Inductor

    Functional Generator

    Multimeter

    Connecting Probes

    500

    0.1F

    70 mH

    --------

    --------

    --------

    ------

    disc

    Decade box

    -------

    Digital

    -------

    1

    1

    1

    1

    1

    As required

    THEORY

    SERIES RESONANCE

    Consider a circuit consisting or resistor R, inductor L and capacitor C all

    connected in series. A fixed voltage, variable frequency sinusoidal voltage is applied

    across this series combination. The following observations are based on experimental

    study of the behavior of the above circuit:

    1. As the supply frequency is varied, the current drawn by the circuit phase varieswith applied frequency. Also, the phase difference between the applied voltage

    and the current drawn varies with frequency. The phase difference is a function of

    the frequency.2. The current is maximum at a particular frequency, called resonant frequency fr,

    and hence the impedance offered by the circuit is minimum at minimum fr. The

    voltage applied and the current drawn, are in phase with each other at fr. The load

    appears purely resistive at resonant frequency.

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    3.( )LC

    fr2

    1=

    i. for f < fr - I leads V,ii. for f > fr - I lags V

    4. At f= fr, VR=VS.By measuring the voltage drop across R (VR), for each applied frequency, the

    corresponding value of IScan be calculated, by using IS =V/R.

    A Graph is drawn between ISand f on semi log graph sheet. The variation in

    the phase difference between the applied voltage and current drawn by the circuit is a

    function of frequency.

    PARALLELRESONANCE

    In parallel resonant circuit, an inductor and a capacitor are connected in

    parallel to each other, with respect to the supply source. The current through the

    inductance has the value VS / XLand lags VSby 900. Thus, two currents are out of phase

    with each other.

    If XC < XL, then IC > IL and the circuit acts capacitive, if XC > XLthen the

    circuit in inductive. When XC = XLthe inductive and capacitive currents are equal and the

    circuit is said to be in resonant condition.

    At resonance, the resonant frequency for the parallel resonant circuit is thesame as that for the series resonant circuit. The frequency at which resonant occurs in a

    parallel LC circuit is sometimes called as the anti resonant frequency to distinguish it

    from the resonant frequency of the series LC circuit.

    For a parallel resonant circuit, at resonance condition,

    i. XL = XC and IL = IC.ii.

    ( )LCfr

    2

    1=

    iii.P

    S

    Z

    VI = (minimum and in phase with applied voltage)

    iv. ZPis maximum and resistive.

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    TABULATION

    PARALLEL RESONANCE

    S.No Frequency F (Hz) Current I (A)

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    PROCEDURE

    SERIESRESONANCE

    1. Connect the RLC components as shown in diagram.2.

    Connect the sine signal from a functional generator to the sockets marked as Input

    3. Select digital multi meter with AC milli ampere range and connect it across thesocket marked as output.

    4. Set the input amplitude to a pre-defined level say RMS volt in DMM 2V (P-P)and this amplitude is said to be maintained constant throughout the experiment.

    5. Repeat the same procedure for different frequency settings and the correspondingreadings are noted down in the tabular column.

    6. Use the readings to draw the resonance curve.

    PARALLELRESONANCE

    1. Connect the RLC components as shown in circuit diagram.2. Repeat the above procedure from steps 2 to 6.

    RESULT

    1. Thus the Resonance curves for RLC series and parallel resonance circuits aredrawn.

    2. Resonant frequencya) For series fr= ------------ Hzb) For parallel fr= ------------ Hz

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    MESH CURRENT ANALYSIS

    CIRCUIT DIAGRAM

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    Ex.No:7

    VVEERRIIFFIICCAATTIIOONNOOFFMESH AND NODAL ANALYSIS

    AIM

    To verify Mesh and Nodal analysis by conducting suitable experiment on the

    given Electrical circuit.

    APPARATUS REQUIRED

    S.No Apparatus Name Range Type Quantity

    1

    2

    3

    4

    Ammeter

    Trainer kit

    Multimeter

    Patch Chords

    0-100mA

    ---

    ---

    ---

    MC

    ----

    Digital

    ----

    3

    1

    1

    As required

    MESH CURRENT ANALYSIS

    In the loop current method, we need to write and solve equations for as many

    currents as the number of independent loops. The number of independent loops is equal

    to (b-n+1). This is based on kirchoffs voltage law applicable to only planar networks.

    Here KCL is applied automatically. In this method the loop current is an independent

    variable. The number of loop current equations is equal to number of independent loops.

    Consider the networks shown below. For convenience numerical values are not

    given.

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    TABULATION

    V1= V,V2 = V

    S.NO RL()I1(A) I2(A)

    I3=I1I2

    (A)

    Exe The Exe The Exe The

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    NODAL VOLTAGE ANALYSIS

    CIRCUIT DIAGRAM

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    In general the above matrix form is expressed as below:

    R11 R12 I1 V1

    R21 R22 I2 = V2

    Here , V1= the algebraic sum of the emf in the loop 1.

    V2= the algebraic sum of the emf in the loop 2

    An emf is assigned positive if the loop current leaves at positive terminal of the

    source.

    PROCEDURE

    1. Connections are made as per the circuit diagram.2. Set the load resistor value RLto constant value.3. Note down the branch current I1, I2& I3values by using ammeter.4. Repeat the above procedure for different values of load resistor RL.5. On comparing the theoretical and experimental values Mesh current analysis was

    verified.

    NODAL VOLTAGE ANALYSIS

    Consider the network shown below. The voltages V1and V2can be calculated by

    using Nodal Voltage analysis.

    In the above circuit three nodes are there. Consider the third node (node 3) as the

    reference node. To calculate the node voltages the matrix form can be written as follows.

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    TABULATION

    VA = V,VB = V

    S.NO RL()V1(V) V2(V)

    Exe The Exe The

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    RA-1

    + RB-1

    + RC-1

    -RC-1

    V1 = Va/RA

    -RC-1

    RC-1

    + RD-1

    + RE-1

    V2 Vb/RE

    GA+ GB + GC

    -GC

    V1 = I1

    -GC GC+ GD+ GE V2 I2

    Here, Conductance G = R-1

    By solving the above matrix, V1, V2 can be found.

    PROCEDURE

    1. Connections are made as per the circuit diagram.2. Set the load resistor value RLto constant value.3. Note down the node voltage V1 & V2values by using voltmeter.4. Repeat the above procedure for different values of load resistor RL.5. On comparing the theoretical and experimental values Nodal voltage analysis was

    verified.

    RESULT

    Thus Mesh and Nodal analysis were verified by theoretically and experimentally.

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    Ex.No 8

    TTRRAANNSSIIEENNTTAANNAALLYYSSIISSOOFFRRLLAANNDDRRCCCCIIRRCCUUIITTSSAIM

    To study the transient response of RL and RC circuit using series D.C and A.C

    circuit trainer.

    APPARATUS REQUIRED

    S.No Apparatus Name Range Type Quantity

    1.

    2.

    3.

    4.

    Series A.C and D.C circuit

    trainer kit

    D.C ammeter

    A.C Ammeter

    Patch chords (or) wires

    -

    (0-200) mA

    (0-200 )mA

    -

    -

    -

    -

    -

    1

    1

    1

    As required

    THEORY

    RESPONSE OF AN R-LCIRCUIT

    Consider the RL circuit shown in fig.1 with switch S and applied DC voltage

    V. When the switch S closed, we can determine the complete solution to apply the

    kirchoffs voltage law to the circuit.

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    dt

    diLRiV += -------------------------- (!)

    Divide equation 1 by L

    L

    Vi

    L

    R

    dt

    di+= -------------------------- (2)

    The above equation is linear differential equation; it should refer like this,

    kPxdt

    dx=+

    Whose solution is

    ptptptcedtkeex

    += ---------------------- (3)

    Where c is arbitrary constant. In a similar way to write the current equation,

    ( ) ( ) ( )dte

    L

    Vecei

    t

    LRt

    LRt

    LR

    +=

    ( )

    R

    Vcei

    tL

    R

    +=

    ---------------------------- (4)

    To determine the constant c to apply the initial condition at t=0 (i.e.) just before closing

    the switch and the current in the inductor is zero, so at t=0, I=0 to substitute in equation 4,

    we get,

    R

    VC = ------------------------- (5)

    Substitute equation 5 in 4,

    += t

    LR

    RV

    RVi exp

    = tL

    R

    R

    Vi exp1 ------------------------- (6)

    In the above equation, steady state part V/R and the transient part (V/R) e-(R/L) t

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    Error!

    In Fig. 2 when switch S is closed, the response reaches the steady state

    value after some time interval. Thus the transient period is defined as the time taken for

    the current to reach the final value.

    DC RESPONSE OF AN R-CCIRCUIT

    Consider the RC circuit shown in fig. 3. with switch S and applied DC voltage

    V. When switch S closed, we can determine the complete solution to apply Kirchoffs

    voltage law to the circuit.

    += idtcRiV

    1 ---------------------- (7)

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    Differentiate the above equation,

    c

    i

    dt

    diRO += ----------------------- (8)

    Divide the equation 8 by R

    01

    =+ iRdt

    di ----------------------- (9)

    The above equation is a linear differential function with only complementary

    solution. The solution for this equation is

    RctCei /

    = ---------------------- (10)

    When switch S is closed at t=0, the capacitor never allow sudden changes in

    voltage, it will act as a short circuit. At t=0,i=V/R. substitute this current to equation 4.

    C=V/R

    The current equation becomes,

    RCte

    R

    Vi /

    = ------------------------- (11)

    InFig. 4 After 4TC the curve reaches the 99 percent of it final value. In that

    solution equation 5, the quantity 1/RC is time constant and is denoted by

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    PROCEDURE

    D.CSERIES R-L

    1. Switch ON the CRO.2. Connect 230v supply to the trainer.3. See the waveform in the CRO, it should be exponential manner.

    D.CSERIES R-C

    1. Switch ON the CRO.2. Connect 230v supply to the trainer.3. See the waveform in the CRO, it should be inverse exponential manner.

    RESULT

    Thus the Transient response of RL and RC circuits are studied and the output

    waveforms are seen using CRO.

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    Circuit Diagram:

    CONNECTION DIAGRAM:

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    Ex.No. 9

    MEASUREMENT OF SELF INDUCTANCE OF A COIL

    AIM:

    To study the measurements of self inductance of coil using Hays bridge method.

    Theory:-

    The hays bridge is the modification of the Maxwell Bridge. This bridge uses a resistance

    in series with the standard capacitor. The bridge has four resistive arms in which the arms one is

    consists of the resistor R1, L1.The arm 2 is consists of the variable resistance R3.The low value

    of the resistance is obtain by the low resistive arms of the bridge. The value of R4and C4is the

    standard value of the capacitor and resistance. By using the known non-inductive resistance R1,R2, R3& R4and standard capacitor C4value, the unknown value of inductor is calculated. The

    unknown value of inductance and Quality factor of the coil is obtained by formula.

    L1= (R2R3C4) / (1 + 2R4

    2C4

    2)

    Quality factor (Q) = (1 / 2R4

    2C4

    2)

    Basic AC bridges consist of four arms, source excitation and a balanced detector(G).

    Commonly used detectors for AC bridges are:

    (1) Head phones

    (2) Vibration galvanometers

    (3) Tunable amplifier detectors

    Vibration galvanometer is extremely useful at power and low audio frequency ranges. Vibration

    galvanometers are manufactured to work at various frequencies ranging from 5 KHZ to 1 KHZ.

    But one most commonly used between 200HZ.

    Advantage-1) This Bridge gives very simple expression for unknown for High Q coil.2) This bridge also gives a simple expression for Q factor.

    Disadvantage-1) The hays bridge is suited for the measurement of the High Q inductor.

    2) It is used to find the inductor having the Q value of the smaller then 10.

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    Model Calculation:

    By considering the Hay Bridge is in balanced condition,

    R1 = 6.25

    R2 = 10

    R3 = 5

    R4 = 8

    f = 50 HZ

    C4= 156 F

    = 2f = 314 rad/sec

    The unknown self inductance value of coil is calculated by using formulaL1 = (R2R3C4) / (1 +

    2R4

    2C4

    2)

    = (10515610^-6

    ) / (1 + (314)2(8)2(15610^-6

    )2)

    L1 = 6.8 mH

    The Quality factor of the coil is calculated by using formula

    Quality factor (Q) = (1 / 2R4

    2C4

    2)

    = (1 / ((314)2(8)

    2(15610^

    -6)

    2))

    Q = 6.5

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    Procedure:

    1) Study the given circuit.

    2) Make all connections to complete the bridge.

    3) Set the bridge is in balanced condition by adjusting R3.

    4) Note value of R1, R2, R3, and R4 from the circuit diagram.

    5) Measure value of L & Q by calculating using given formula.

    Result:-

    The measurements of self inductance of coil using Hays bridge were studied.