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### Sdes bee lab manual

1. 1. SDESCIRCUIT DIAGRAM:E&E LAB Page 1
2. 2. SDES THEVININ’S THEOREMAIM: Verification of Thevinin’s Theorem.APPARATUS:S. no Apparatus Type Range Quantity1 Thevinin’s Theorem 1 Trainer it2 Regulated power supply (0-40)V 13 Ammeter Digital (0-100)mA 14 Voltmeter Digital (0-15)V 15 Digital Multi meter 16 Different load resisters 75Ω,100 Ω,150 Ω7 Connecting wiresSTATEMENT: Thevenins theorem states that any circuit having no, of sources, resistances and AB openO/P terminals can be replaced by a simple equivalent circuit consisting of single voltage sourcein series with a resistance where the values of voltage source is equal to the open circuit voltageacross the output terminals and series resistance is equal to the resistance seen in to the networkfrom output terminals with all sources are replaced by their internal resistance.PROCEDURE:1 . Connect the circuit as shown in the circuit diagram.2. Measure the current through the load resistance and note down IL .3. Remove the load resistance and measure the voltage across A,B which givn the Thevivinsvoltage(VTH)4. Measure the resistance between AB by short circuiting the voltage source which givesThevenins resistance (RTH).5. Connect the circuit as shown in Fig.2 with VTH, RTH and the load resistance.6. Measure the load current and compare with the current flowing through the R L in originalcircuit.7. Thus Thevinin,s theorem is verified.E&E LAB Page 2
3. 3. SDESTABULAR COLUMN:S.no. Vs(V) IL (mA) ILl (mA) Rth(Ω) Vth(V)CALCULATIONS:E&E LAB Page 3
4. 4. SDESRESULT:E&E LAB Page 4
5. 5. SDESCIRCUIT DIAGRAM:E&E LAB Page 5
6. 6. SDES MAXIMUM POWER TRANSFER THEOREMAIM: Verification of Maximum Power Transfer Theorem and find out the value of loadresistance when max power transferred to it.APPARATUS:S. no Apparatus Type Range Quantity1 Max. Power Transfer 1 Theorem Trainer it2 Regulated power supply (0-40)V 13 Ammeter Digital (0-200)mA 14 Voltmeter Digital (0-15)V 15 Digital Multi meter 16 Connecting wiresSTATEMENT: Max. Power Transfer theorem states that in a DC Network Max. PowerTransferred from the source to the load when load resistance is equal to the load resistance.PROCEDURE:1. Connect the circuit as shown in figure.2. Measure the current passing through the load resistance RL and voltage across it for a supplyvoltage of V Volts3. Now vary the load resistance RL and measure the value of IL and VL_4. Tabulate all the values and find the power absorbed by the load. Resistance in each case.5. Observe the load resistance for which Max. Power is transferred and compare with the sourceresistance.6. Hence Max. Power Transfer Theorem is verified. .E&E LAB Page 6
7. 7. SDESTABULAR COLUMN:S.NO. Load Current Load Voltage Power (PL) Resistance(RL) (mA) (mA) (mW) (mΩ) 1 2. 3. 4. 5. 6. 7. 8. 9. 10. 11.EXPECTED GRAPH:E&E LAB Page 7
8. 8. SDESGRAPH: A Graph is drawn by taking different values of load resistance on X-axis and therespective powers on Y-axisCALCULATIONS:RESULT:E&E LAB Page 8
9. 9. SDESCIRCUIT DIAGRAM: mE&E LAB Page 9
10. 10. SDES SUPER POSITION THEOREMAIM: Verification of Super position Theorem.APPARATUS:S.no Apparatus Type Range Quantity1 Superposition 1 Theorem Trainer kit2 Regulated power supply (0-40V) 13 Ammeter Digital (0-200) mA 14 Voltmeter Digital (0-15)V 15 Digital Multi meter 16 Connecting wiresSTATEMENT: Super position theorem states that in any linear bilateral network consisting of two ormore sources, the response in any element is equal to the algebraic sum of the responses causedby individual source acting alone, while the other sources are non operative that is voltage sourceare replaced by a short circuit and current sources replaced by a open circuitPROCEDURE:1. Connect the circuit as per the circuit diagram2. Set V1=15V and V2=0Volts.3. Measure the current flowing through the ammeter I1,I2,I3.4. Now short circuit the voltage source V2 and Measure the current flowing through theresistance I1.5. Short circuit the voltage source V1, reconnect the voltage source V2, Measure the current I1’’ .6. It is found that I1= I1’+ I1’’7. Hence super position theorem is verified.E&E LAB Page 10
11. 11. SDESTABULAR COLUMN: I1 (ma)V (VOLTS) THERITICAL PRACTICALV1=V2=V1=V2=V1=V2=CALCULATIONS:E&E LAB Page 11
12. 12. SDESRESULT:E&E LAB Page 12
13. 13. SDESCIRCUIT DIAGRAM:E&E LAB Page 13
14. 14. SDES RECIPROCITY THEOREMAIM: Verification of Reciprocity Theorem.APPARATUS:S no Apparatus Type Range Quantity1 Reciprocity Theorem 1 Trainer it2 Regulated power supply (0-40)V 13 Ammeter Digital (0-200)ma 14 Voltmeter Digital (0-15)V 15 Digital Multi meter 16 Connecting wiresSTATEMENT: Reciprocity Theorem States that in any linear Bilateral network if a single voltage sourceVa in Branch a produce a current Ib in Branch b, then the removal of voltage source frombranch a and its insertion in branch b will produce a current Ib in Branch a.PROCEDURE:1. Connect the circuit as per the diagram.2. Set the voltage of power supply of 10V.and connect across the terminals A&B3. A milli Ammeter connected to a terminal A&B and note down the current I.4. Now interchange the position of ammeter and voltage source and note down the current valuelet it be I’.5. it is found that both the currents are equal that is I=I’.6. Calculate the ratio of Voltage to current in both the cases.7. It is found that both are Equal.8. Hence Reciprocity theorem is verified.E&E LAB Page 14
15. 15. SDESTABULAR COLUMN:Voltage Current (mA) Voltage/CurrentV1=V2=V1=V2=CALCULATIONS:RESULT:E&E LAB Page 15
16. 16. SDES CYCLE-IIE&E LAB Page 16
17. 17. SDESCIRCUIT DIAGRAM:E&E LAB Page 17
18. 18. SDES Magnetization Characteristics of a D.C. Shunt GeneratorAim: To draw the magnetization characteristics of a DC shunt generator to determine thecritical resistance (Rc) and critical speed (Nc).Name Plate Details:Motor GeneratorPower = KW Power = KWArmature voltage = volts Speed = rpmField voltage = volts Armature voltage = voltsField current = amps Armature current = ampsSpeed = rpm Field voltage = voltsArmature current = amps Field current = ampsWound = Shunt Wound = ShuntApparatus Required:S no Apparatus Type Range Quantity1 Rheostat Wire wound 2A/200Ω 22 Ammeter Moving coil 0-2A 13 Volt meter Moving coil 0-300V 24 Tachometer Digital 0-10000 rpm 1Theory:Magnetization Curve: The graph between the field current and corresponding flux per pole iscalled the magnetization characteristic of the machine. This is same as B-H curve of the materialused for the pole construction. In a d.c. generator, for any given speed, the induced e.m.f in the armature is directlyproportional to the flux per pole. ZN P Eg = X 60 A Where, Φ is the flux per pole in Weber’s, Z is the no. of conductors in the armature, N isthe speed of the shaft in rpm, P is the no. of poles and A is the no .of parallel paths. A = 2 (wave) A = P (lap)E&E LAB Page 18
19. 19. SDESObservation Table:Vs=220VS.No. If (Field) Eg Eg Eg amps (increasing) (decreasing) (Average) volts volts volts12345678Critical Resistance Calculations Critical speed calculations Sl.No. Speed (rpm) Induced emf(volts) 1 2 3 4E&E LAB Page 19
20. 20. SDESOpen – Circuit Characteristics: The armature is driven at a constant speed and the field current is increased graduallyfrom zero to its rated value. The terminal voltage (VL) at no-load condition is measured atdifferent If values. The graph, VL vs. If is called open-circuit characteristic. VL differs from Egdue to (a) Armature reaction (b) voltage drop in the armature circuit. Ia is very small at no-loadcondition, these effects are negligible. Hence, VL = Eg at no-load condition. Thus, the opencircuit characteristic is same as magnetization curve.As shown in the figureCritical Field Resistance (RC): Critical Field Resistance is defined as the maximum field circuit resistance at whichthe shunt generator would just excite at any given speed. At this value the generator will justexcites. If the field circuit resistance is increased beyond this value, the generator will fail toexcite. Rc is given by initial slope value of the O.C.C. curve in the linear region (AB) passingthrough the origin for the speed at which data is obtained. If the field circuit resistance (Rf) is increased to RC, the machine fail to excite and noe.m.f. is induced in the generator. For exiting the generator, Rf < RC.Critical Speed: For any given field circuit resistance, the speed above which the generator builds upan appreciable voltage is called critical speed. As E α N, the value of critical speed, Nc can be given as Nc = (B/A)*NE&E LAB Page 20
21. 21. SDESEXPECTED GRAPH: Rsh critical field resistance X C Eg volts Y B A Z O If ampsE&E LAB Page 21
22. 22. SDESProcedure:  Note down the ratings of the d.c .shunt motor and the d.c .shunt generator.  Connect the circuit as shown in the diagram.  Keep the generator field rheostat at maximum resistance position and motor field rheostat in minimum resistance position.  Now start the motor using a 3-point starter  Adjust the motor field rheostat to bring the motor speed to rated value.  Now decrease the field rheostat of generator and note down If and Eg up to the rated- voltage of the generator.  The experiment is repeated for decreasing order of If  Maintain the speed of the motor (Prime Mover) at a constant value during the experiment.  Plot the magnetization curveGraphs:Draw the graph for (1) Eg Vs If & (2) Eg Vs NPRECAUTION:  The motor initially should be started without any load.  The rotor resistance starter should be in the maximum resistance position while starting.Result:E&E LAB Page 22
23. 23. SDESCIRCUIT DIAGRAM:,E&E LAB Page 23
24. 24. SDES Swinburne’s TestAim: To pre-determine the efficiency of a D.C. shunt machine considering it as a generatoror as a motor by performing Swinburne’s test on it.Name plate details: MotorPower = hp Speed = rpmArmature voltage = volts Field voltage = voltsArmature current = amps Field current = ampsApparatus Required:SL NO Apparatus Type Range Quantity1 Voltmeter Moving coil 0-300V 12 Ammeter Moving coil 0-2A 13 Ammeter Moving coil 0-20A 14 Rheostat Wire wound 1.5/ 300 Ω 15 Tachometer Digital (0-10000 )rpm 1Theory: Testing of D.C .machines can be divided into three methods: (i) direct, (ii) Regenerativeand (iii) indirect. Swinburne’s Test is an indirect method of testing a dc machine. In this method, theconstant losses of the D.C. machine are calculated at no-load. Hence, its efficiency either asmotor or as a generator can be pre-determined. In this method, the power requirement is verysmall. Hence, this method can be used to pre-determine the efficiency of higher capacity dcmachines as a motor and as a generator.Disadvantages: (i) Efficiency at actual load is not accurately known (ii) Temperature rise on load is not known and (iii) Sparking at commutator on load is not known.Power input at No-load = Constant losses + Armature copper losses (which is negligible)Power input at No-load = Constant lossesPower input = Va Ia + Vf IfE&E LAB Page 24
25. 25. SDESObservation table:S.No VL(V) IL(A) If(A) Stray losses Fixed lossesAs a motor: Sl. IL Power Copper Total Power Efficiency No. Input Loss Loss Output 1. 2. 3. 4. 5.As a Generator: Sl IL Power Copper Total Power Efficiency No. Input Loss Loss Output 1. 2. 3. 4. 5.E&E LAB Page 25
26. 26. SDESLosses in a DC machine: The losses in a D.C. machine can be divided as 1) Constant losses 2) Variable losses,which changes with the load.Constant losses:Mechanical Losses: Friction and Wind age losses are called mechanical losses. They depend upon the speed.A dc shunt machine is basically a constant speed machine both as a generator and as a motor.Thus, the mechanical losses are constant.Iron Losses: For a dc shunt machine, the field current hence the flux per pole is constant (Neglectingthe armature reaction which reduces the net flux in the air gap). Hence, hysteresis and eddycurrent losses (which are also called as iron losses) remains constant.Field Copper Losses: Under normal operating conditions of a D.C. shunt machine, the field current remainsconstant. Thus, power received by the field circuit (which is consumed as field copper losses) isconstant.Constant losses in a dc shunt machine=Mechanical + losses Iron losses+ Field cu. Losses.Variable Losses: The power lost in the armature circuit of a dc machine increases with the increase in load.Thus, the armature copper loss is called as variable losses.Procedure:  Note down the ratings of the dc shunt motor  Connect the circuit as shown in the diagram.  Keep motor field rheostat in minimum resistance position.  Now start the motor using a 3-point starter  Adjust the motor field rheostat to bring the motor speed to rated value.  Run the machine as a motor at no-load.  Note down the voltage and current readings of the motor and generator at no-load.  Calculate the efficiency of the machine working as motor and generator after taking the values of field and armature circuit resistances.E&E LAB Page 26
27. 27. SDESE&E LAB Page 27
28. 28. SDESConclusion:  The power required to conduct the test is very less as compared to the direct loading test.  Constant losses are calculated from this method are used to compute the efficiency of a dc machine as a generator and as a motor without actually loading it. Hence, this is an economic methodRESULT:E&E LAB Page 28
29. 29. SDESCIRCUIT DIAGRAM:E&E LAB Page 29
30. 30. SDES Brake test on a DC Shunt MotorAim: To obtain the performance characteristics of a DC Shunt motor by a load test. 1) Armature current Vs Speed 2) Armature current Vs Torque 3) Armature current Vs Induced emf 4) Armature current Vs Flux per pole 5) Torque Vs Speed 6) Output Vs EfficiencyName plate details: MotorPower = hp Speed = rpmArmature voltage = volts Field voltage = voltsArmature current = amps Field current = ampsApparatus require:Si no Equipment Range Type Quantity1 Volt meter 0-300V Moving coil 12 Ammeter 0-2A Moving coil 13 Ammeter 0-20A Moving coil 14 Rheostat Wire wound 1.5/300Ω 15 Tachometer Digital 10000 rpm 1Theory: This is a direct method of testing a dc machine. It is a simple method of measuring motoroutput, speed and efficiency etc., at different load conditions A rope is would round the pulleyand its two ends are attached to two spring balances S1 andS2. The tensions provided by thespring balances S1 and S2 are T1 and T2 the tensions of the rope can be adjusted with the help ofswivels. The force acting tangentially on the pulley is equal to the difference between the readingsof the two spring balances in kg- force. The induced voltage Eb =V-Ia Ra and Eb= KΦN, Thus, KΦ=Eb /NV= applied voltage, Ia =armature current, Ra =Armature resistance. Total power input to the motor Pin =Field circuit power + Armature powerE&E LAB Page 30
31. 31. SDESObservation table:Armature voltage =Field voltage =Field current =No load speed =Sl. Ia N T1 T2 Input Shaft ω Shaft % E KNo. amps rpm kg kg (Pin) Torque (rad/sec) Output η (volts) Vs/r watts (j/rad) (watts)1.2.3.4.5.6.E&E LAB Page 31
32. 32. SDES= VfIf + Va Ia If ‘r’ is the radius of the pulley , then torque at the pulley is given byTshaft = 9.81 (T1~T2 )r = 1.5 (T1~T2) N-m 2 N  = is the angular velocity of the pulley, in rad/sec. 60 2 N Motor output power Pout =Tshaft *  =1.5 (T1~T2) 60 Pout % Efficiency = X 100 Pin A dc shunt motors rotates due to the torque developed in the armature when the armature andfield terminals are connected to the dc supply. The direction of rotation can be explained with thehelp of Fleming’s left hand principle. A counter emf or back emf (Eb) is induced in the armature conductors while the armature(rotor) rotating in the magnetic field. The direction of the induced emf can be explained with thehelp of Fleming’s right hand principle and Lenz’s law. The is induced emf is also called as backemf Eb. ZN P The equation of the motor is V= Eb + Ia Ra Where Eb = X 60 A V  Eb Ia = Ra The value of Eb is zero while starting the motor. Hence the voltage across the armature has tobe increase gradually. 2 N The power developed in the rotor (armature) = EbIa = T ω Where ω = 60 In a dc motor T α Φ Ia where Φ= Flux produced by the shunt field per pole Ia = Armature current The torque developed in the motor is opposed by the torques due to (a) Friction and windage(b) eddy currents and hysterisis and (c) mechanical load connected at the shaft. The motor runs ata stable speed when the developed torque and resisting torques balance each other. Let a small load be increased, then the resisting torque increases and motor speed falls. The V  Ebback emf reduces due to the fall in the speed. Hence, the armature current increases (Ia = ) RaE&E LAB Page 32
33. 33. SDES If Φ is assumed constant, (i.e. neglecting the armature reaction) the torque developed by themot or increases and a new stable speed is reached at which the developed torque equals theresisting torque. Armature Current ~ Speed characteristics: The armature current Ia increases with increase in the load at the shaft. Hence Ia Ra dropincreases and counter emf (Eb) decreases. Eb = V-IaRa where Ra is armature resistance and Eb α ΦN, if Φ is constant in the shunt motorby neglecting the armature reaction; the speed falls as Eb falls. In a dc motor Ra is very small, hence Ia Ra is a small value and fall in Eb with increase in loadis small. Thus, the speed falls slightly as Ia increases.Armature current ~ Torque characteristics: If Φ is constant, developed torque increases with increase in Ia T= KΦ Ia In actual condition, Φ slightly falls withy increase in Ia due to the effect of armature reaction.Armature current ~ induced emf (back emf): Induced emf (back emf Eb ) falls slightly with increase in Ia as per the equation Eb =V-Ia RaArmature current ~ Flux per pole: The resultant Flux per pole decreases with the increase in Ia due to the effect of armaturereact ion and amp-turns of the file d is constant at any load.Torque ~ Speed: With increase in load, Ia and Ta increases since the shunt field Φ is constant. The fall in speed Ebis very small as the Ia Ra drop is very small compared to V. In a dc shunt motor N α Output ~ Efficiency The graph between Output ~ Efficiency indicates that max torque occurs when armaturecopper losses is equal to the constant losses. (Sum of field copper losses, mechanical losses andIron losses)E&E LAB Page 33
34. 34. SDES Procedure: 1. Note down the name plate details. 2. Connect the circuit as shown in the diagram. 3. Keep the motor field rheostat in minimum resistance position. 4. Loosen the rope on the brake drum and put some water inside the rim of the brake drum 5. Now start the motor using a 3-point starter 6. Adjust the motor field rheostat to bring the motor speed to rated value. 7. Record the readings of the meters at no-load condition. 8. Gradually, increase the load on the brake drum and record the readings as per the given table. 9. Do not exceed the armature current more than its rated value. 10. Gradually, reduce the load and switch off the supply.PRECAUTION:  The motor initially should be started without any load.  The rotor resistance starter should be in the maximum resistance position while starting.RESULT:E&E LAB Page 34
35. 35. SDESOPEN CIRCUIT TEST:SHORT CIRCUIT TEST:E&E LAB Page 35
36. 36. SDES O.C. TEST AND S.C. TEST ON A SINGLE PHASE TRANSFORMERAIM: 1. To obtain the equivalent circuit of the transformer (ref LV & HV side). 2. To predetermine the efficiency and voltage regulation at various assumed 3. To verify the predetermined results by a direct load test.NAME PLATE DETAILS: Rating: ____________KVA Primary Voltage: ____________ Volts Secondary Voltage _____________VoltsAPPARATUS: S.N. Components Type Specifications Quantity 1 Ammeter MI 0 – 20 A& 2A 1+1 No 2 Voltmeter MI 0 – 300 V&75V 1+1NO 3 Wattmeter LPF (Dynamo Type) 3KW, 0 – 300V,2 A 1 No. 4 Wattmeter UPF(Dynamo Type) 3KW, 0 – 300 V, 10A 1 No.THEORY: A Transformer is a static device which transfers the electrical energy from one circuitto a nother circuit with changes in voltages and current but without any change in thefrequency. The transformer works on the principle of electromagnetic induction between twowindings placed on a common magnetic circuit. The two windings are electrically insulatedfrom each other and also from the core. The approximate equivalent circuit of the transformer isshown in figure –2 The losses in transformer are (i) magnetic losses and ohmic losses or copper losses. Thesecan be determined by performing (a) open circuit test and given transformer can bepredetermined at any given load (b) short circuit test. From the above tests, the efficiency andvoltage regulation of a given transformer can be predetermined at any given load. The powerconsumed during these tests is very small compared to that in a load test. Another parting whatfollows, LV side parameters are denoted by suffix 1 and HV side parameters by suffix 2OPEN CIRCUIT TEST;In the open circuit test, HV side is usually kept open and supply given to the LV side, asShown in the figure; when rated voltage is applied to the LV side, the ammeter reads the no-loadcurrent I0 is 2 to 5% of full load current. Hence the copper losses at no-load are negligible. W0represents the iron or core losses. Iron losses are the sum of hysteresis and eddy current losses. W0 = VLV I0 Cos 0 Cos0 = W0 / VLV I0, I = I0 Sin 0 , Iw = I0 Cos0 R01 and X01 is ref LV. R0= VLV / Iw, X0 = VLV / IE&E LAB Page 36
37. 37. SDESOBSERVATIONS:1. O.C Test: O.C. Voltage (V) O.C Current (A) No-Load Power (w)2. S.C Test: S.C. Voltage (V) S.C Current (A) Power (w) EQUIVALENT CIRCUIT FOR 1Ø TRNSFORMER:E&E LAB Page 37