Electrical & Electronics Engineering Department … · Electrical & Electronics Engineering...

Electrical & Electronics Engineering Department BRCM COLLEGE OF ENGINEERING & TECHNOLOGY BAHAL – 127028 ( Distt. Bhiwani ) Haryana, India

Electrical Technology Lab

ELECTRICAL TECHNOLOGY LAB

Paper Code EE-103-F (Common for All Branches)

List of experiments :

.

1

S.no Name of Experiments Page no1. To study various types of measuring

instrument and basic electrical component

2-9

2. To verify the Kirchhoff’s voltage law (KVL).

10-11

3. To verify the Kirchhoff’s current law (KCL).

12-14

4. To verify the thevenin’s theorem 15-185. To verify the Norton’s theorem. 19-21

6. To verify the superposition theorem. 22-25

7. To verify the maximum power transfer theorem in A.C and D.C.

26-29

8. To measurement the power by three voltmeter

30-32

9. To perform O.C and S.C test of a transformer.

33-37

10. To measurement of power in three phase system by two wattmeter method.

38-39



EXPERIMENT NO:-1

Study of measuring instruments and electrical component.

AIM: - To study various types of measuring instrument and basic electrical

component.

APPARATUS REQUIRED:-Resistors, inductor, capacitor of different values and Ammeter, Voltmeter, Wattmeter, and Multimeter.

THEORY:-

Resistor (R) :

In an electrical circuit, the electrical resistance R of a wire in which current I is flowing is givenby Ohm’s Law:

where V is potential difference across wire.R is measured in ohms, V in volts, and I in amps.Doubling length of wire or increasing its diameter changes the resistance.Resistance is NOT a fundamental characteristic of the metal in the wire. Capacitance (C):

Capacitance is an electric component which store the charge.

2



Symbolic representation

INDUCTOR : The study of inductance presents a very challenging but rewarding segment ofelectricity. It is challenging in the sense that, at first, it will seem that new concepts are beingintroduced. You will realize as this paragraph progresses that these "new concepts" are merelyextensions and enlargements of fundamental principles that you learned previously in the studyof magnetism and electron physics. The study of inductance is rewarding in the sense that athorough understanding of it will enable you to acquire a working knowledge of electricalcircuits more rapidly.

3



Working Principle

AMMETER:-

An ammeter is a measuring instrument used to measure the electric current in a circuit. Electriccurrents are measured in amperes (A), hence the name. Smaller values of current can bemeasured using a millimeter or a micro ammeter. Early ammeters were laboratory instrumentsonly which relied on the Earth's magnetic field for operation. By the late 19th century, improvedinstruments were designed which could be mounted in any position and allowed accuratemeasurements in electric power systems.

Symbolic Representation

4



Oprating Principle

o Instrument used to measure current in the circuit.o Always connected in series with the circuit and carries the current to be measured.o This current flowing through the coil produces the desired deflecting torque.o It should have low resistance as it is to be connected in series

VOLTMETER:

5



A voltmeter is an instrument used for measuring the electrical potential differencebetween two points in an electric circuit. Analog voltmeters move a pointer across a scale inproportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage byuse of an analog to digital converter.

Voltmeters are made in a wide range of styles. Instruments permanently mounted in apanel are used to monitor generators or other fixed apparatus. Portable instruments, usuallyequipped to also measure current and resistance in the form of a multimeter, are standard testinstruments used in electrical and electronics work. Any measurement that can be converted to avoltage can be displayed on a meter that is suitably calibrated; for example, pressure,temperature, flow or level in a chemical process plant. General purpose analog voltmeters mayhave an accuracy of a few per cent of full scale, and are used with voltages from a fraction of avolt to several thousand volts. Digital meters can be made with high accuracy, typically betterthan 1%. Specially calibrated test instruments have higher accuracies, with laboratoryinstruments capable of measuring to accuracies of a few parts per million. Meters usingamplifiers can measure tiny voltages of microvolts or less. Part of the problem of making anaccurate voltmeter is that of calibration to check its accuracy. In laboratories, the Weston Cell isused as a standard voltage for precision work. Precision voltage references are available based onelectronic circuits.

Symbol of Voltmeter:-

6



• Instrument used to measure voltage between two points in a circuit.• Always connected in parallel.• Current flowing through the operating coil of the meter produces deflecting torque.• It should have high resistance. Thus a high resistance of order of kilo ohms is connected

in series with the coil of the instrument

WATTMETER:-

The wattmeter is an instrument for measuring the electric power (or the supply rate of electricalenergy) in watts of any given circuit.An instrument which measures electrical energy in watt hours (electricity meter or energyanalyser) is essentially a wattmeter which accumulates or averages readings; many suchinstruments measure and can display many parameters and can be used where a wattmeter isneeded: volts, current, in amperes, apparent instantaneous power, actual power, power factor,energy in [k]Wh over a period of time, and cost of electricity consumed.

Symbolic Represerntation

7

http://en.wikipedia.org/wiki/Electric_power

http://en.wikipedia.org/wiki/Energy_analyser

http://en.wikipedia.org/wiki/Energy_analyser

http://en.wikipedia.org/wiki/Electricity_meter

http://en.wikipedia.org/wiki/Watt_hour

http://en.wikipedia.org/wiki/Energy

http://en.wikipedia.org/wiki/Electrical_network

http://en.wikipedia.org/wiki/Watt

http://en.wikipedia.org/wiki/Electrical_energy

http://en.wikipedia.org/wiki/Electrical_energy



MULTIMETER:-A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter may include features such as the ability to measure voltage, current and resistance.

8

http://en.wikipedia.org/wiki/Electrical_resistance

http://en.wikipedia.org/wiki/Electric_current

http://en.wikipedia.org/wiki/Voltage

http://en.wikipedia.org/wiki/Measuring_instrument

http://en.wikipedia.org/wiki/Electronics



Multimeters may use analog or digital circuits—analog multimeters (AMM) and digital multimeters (often abbreviated DMM or DVOM.) Analog instruments are usually based on a microammeter whose pointer moves over a scale calibrated for all the different measurements that can be made; digital instruments usually display digits, but may display a bar of a length proportional to the quantity being measured.A multimeter can be a hand-held device useful for basic fault finding and field service work or a bench instrument which can measure to a very high degree of accuracy. They can be used to troubleshoot electrical problems in a wide array of industrial and household devices such as electronic equipment, motor controls, domestic appliances, power supplies, and wiring systems.

MULTIMETER

EXPERIMENT NO: 2

AIM:- To verify the Kirchhoff’s voltage law(KVL).

9

http://en.wikipedia.org/wiki/Power_supply

http://en.wikipedia.org/wiki/Domestic_appliance

http://en.wikipedia.org/wiki/Electronic_equipment

http://en.wikipedia.org/w/index.php?title=Bench_instrument&action=edit&redlink=1

http://en.wikipedia.org/wiki/Fault_(electric)

http://en.wikipedia.org/wiki/Microammeter

http://en.wikipedia.org/wiki/Digital_circuit

http://en.wikipedia.org/wiki/Analog_circuit



APPARATUS REQUIRED:-S.No. Apparatus Name Quantity1. Voltmeter(0-30)volt 32. Power Supply(0-30)volt 13. Resistance 34. Connecting wires 105. Ammeter 1

THEORY:- Kirchhof's Voltage Law (KVL) states that in a loop, the sum of the voltageDrops across all the resistors is equal to the voltage supplied by the source.Now, consider the circuit below:

CIRCUIT DIAGRAM:-

Applying KVL, we can write:

V = V 1 + V 2 + V 3V = i(R1 + R2 + R3)

PROCEDURE:-1. Make the connection according to the ckt diagram2. Set the three rheostats to their max value.

10



3. Switch on the power supply4. Change the setting of the rheostats to get different readings in all the three ammeters.5. Measure the current in the three ammeters6. Check that at every time current in the main branch is equal to the sum of currents in the twobranches. repeat the setting of the rheostat7. Switch off the power supply.

OBSERVATION TABLE:-S.NO. VOLTAGE(Vin) V1(iR1) V2(iR2) V3(iR3) V=V1+V2+V3 Remark

1.

2.

Results Calculations I:Verification of KVL:Source voltage, V Total voltage drops = V1 + V2 + V3

Source voltage= Total voltage drops

PRECAUTION:-1. Switch off the supply before starting the connection.

2. Make all connection tight properly.

3. Reading should be taken carefully.

EXPERIMENT NO:-3

11



AIM:- To verify the Kirchhoff’s current law(KCL).

APPARATUS REQUIRED:- S.No. Apparatus Name Quantity Range

1. Voltmeter 1 (0-30)volt

2. DC Power Supply 1 (0-30)volt

3. Resistance 3 (10-20)kΩ

4. Connecting wires 10 --------

5. Ammeter 3 (0-10)mA

THEORY:- Kirchoff’s Current Law or KCL, states that the "total current or charge entering a junction or node is exactly equal to the charge leaving the node as it has no other place to go except to leave,as no charge is lost within the node". In other words the algebraic sum of ALL the currents entering and leaving a node must be equal to zero, I(exiting) + I(entering) = 0. This idea by Kirchhoff is commonly known as the Conservation of Charge.

Kirchhoff’s Current Law

CIRCUIT DIAGRAM:-

12



Applying KCL, we can write:I = i1 + i2 + i3

PROCEDURE:-1. First of all check the wires by multimeter.2. Connect the wires according to the circuit as shown in the circuit diagram.3. Switch on the supply.4. Note down reading of all voltmeters.5. Note down the reading and repeat this process again and again for at least two or three

times.

OBSERVATION TABLE:-S.NO. VOLTAGE(Vin) I1(mA) I2(mA) I3(mA) I=I1+I2+I3 Remark

1.

2.

13



Results Calculations:

Verification of KCL:Incoming current, I = Total outgoing current = i1 + i2 + i3

Incoming current =Total outgoing current

PRECAUTION:-

1. Switch off the supply before starting the connection.

2. Make all connection tight properly.

3. Reading should be taken carefully.

EXPERIMENT NO:-4

Aim:- To verify Thevenin’s theorem.

Apparatus:-

S.No. Apparatus Name Quantity Range






6. Thevenin network kit 1 -------------

Theory: - “Any linear two terminal network can be replaced by an equivalent network consisting of a voltage source (VTh) in series with a resistance (RTh) .Where, VTh = Open circuit voltage at load terminals. RTh = Equivalent resistance at load terminal when sources are made inoperative.

14



Circuit:-

To find Vth:

To find Rth

15



So Rth can be calculated as:

Rth=V/In

To find IL:

16



Current through load

IRL = V th /(R L +Rth )

PROCEDURE:-

1. To find the current flowing through the load resistance RL as shown in fig. Remove RL from the ckt temporarily and leave the terminals A and B open circuited.

2. Calculate the open ckt voltage Vth which appears across terminal A and B.Vth=I.Rth

This is called thevenin’s voltage. 3. Now calculate Rth=R1 R2 /R1+R2. This is called thevenin’s resistance. 4. Calculate IL= Vth/(RL+Rth).

OBERVATION TABLE:

S.NO. APPLIED VOLTAGE(V)

VOLTAGE(V th)

Rth+RL

(Ω)IL(mA)

ILth(mA).

Remark

1.

2.

17



RESULT .

Current through load resistance IL =

Current through load resistance using Thevenins theorem IRth =

Current through load resistance= thevenins current

PRECAUTION:-

1. The safety material should be weared.2. Connection should be verified correctly3. Maintain some distance from equipments and stand4 Keep the power supply “OFF” when making connection

EXPERIMENT NO:-5

AIM:- To verify the Norton’s theorem.

APPARATUS REQUIRED:-



18







6. Norton’s network kit 1 -------------

THEORY: NORTON’S THEOREM replaces the electrical network by an equivalent constant currentsource and a parallel resistance.Norton’s equivalent resistance RN=R1*R2/R1+R2Actual load current in the circuit IL1 Theoretical load current IL2=ISC*RN/(RN+RL), ISC is the short circuit current.

CIRCUIT DIAGRAM:

To find In/Isc:

19



To find Rn:

Rn=V/In

PROCEDURE :1. Connect the ckt as per the ckt diagram

20



2. Remove the load resistance3. Find the Norton’s resistance Rn4. Measure the Norton’s current In5. Now measure the current in the load resistance directly6. Find out the current in the load7. Using formula find out the current in the load resistance8. Verify that these two are equal.

OBSERVATION TABLE:S.NO. APPLIED

VOLTAGE(V)CurrentIn(mA)

Rn(Ω) IL(mA)

ILn(mA).

Remark

1.

2.

Current through load

ILN= [ I n /(R L +Rn )]x Rn

RESULTCurrent through load resistance IL =

Current through load resistance using Norton’s theorem ILn=

Comment

If, Current through load resistance= Norton’s current

So Norton’s Theorem verified

.PRECAUTIONS:1. All connections should be tight and correct.2. SWITCH OFF the supply when not in use.3. Reading should be taken carefully.

EXPERIMENT NO:-6

AIM:-To verify superposition theorem.21










6. DC network kit 1 -------------

THEORY:-

If a number of voltage sources and current sources are acting simultaneously in a linear network, the resultant current in any branch is equal to the algebraic sum of the currents produced in it, when individual sources are acting alone by replacing all other sources.

CIRCUIT DIAGRAM:- I11

22



To consider source A

To Consider source B

23



PROCEDURE:-

1. Connect the circuit as shown in figure.2. Taking both the voltage sources connected, measure the current in branch using milli

ammeter.3. Short circuit the 5-V battery and measure current.4. 4. Short circuit battery and measure current.

OBSERVATION TABLE:-

S.NO. Ii Iii Iiii I’i I’ii I’iii I1= Ii+ I’i I2= Iii+ I’ii

1.

2.

3.

RESULT:

Current through resistance R1=I1

Using Superposition Current through resistance R1= Ii+ I’i

24



Comment:

If ,Current through load resistance= Superposition’s currents

Superposition theorem verified.

PRECAUTION:-

1. Directions of current should be correctly identified.2. Check zero setting of instruments before connection, rheostat terminals, connection should

be tight.3. Ratings of current to be kept in mind.

EXPERIMENT NO:-7

AIM:-To verify the maximum power transfer theorem.

APPARATUS REQUIRED:-25









6. DC network kit 1 -------------

THEORY:- The maximum power transfer theorem states that a load resistance will abstract maximum power from the network when the load resistance is equal to the internal resistance. For maximum power transfer Load resistance RL=RI Where RI equivalent resistance of the remaining circuitMaximum power= Pmax =V2/4RLWhere V is the dc supply voltage.

CIRCUIT DIAGRAM:-

To find RI

26



RI=V/In

To find RL :

RL=V1/Ii

PROCEDURE:-

1. Connect the circuit diagram as shown in fig.2. Take the readings of voltmeter and ammeter for different values of RL

27



3. Verify that power is maximum when RL =RI

OBSERVATION TABLE:-

RESULT:-

Source Resistance Ri =

Load Resistance RL=

Comment:

If , Source Resistance Ri = Load Resistance RL

So Maximum Power Theorem Verified

PRECAUTION:-

1.Value of resistance should be chosen that rheostat current rating should not be exceed.

2. For certain set of reading R1 should be fixed.

28

SNO. RI RL VL (in Volts) IL (in amps) P=V/4*RI(watt)

1.

2.

3.

4.

5.



EXPERIMENT NO:-8

AIM:- To measurement the single phase power and power factor by three voltmeter method.





3. Auto-transformer 1 (0-250)volt

4. Connecting wires 20 ---------

29



5. Rheostat 1 (0-100)ohm, 10A

6. Inductive load 1 230volt,10 A

7. Ammeter 1 (0-10)A

PROCEDURE:-

1. Connect the ckt as shown in fig2. Ensure that the output voltage is not zero3. Switch on the ac power supply4. Apply a certain voltage to the transformer through the auto transformer.5. Record the various voltage V1,V2 and V3and the currents6. Repeat the whole experiment for the different values of the voltage7. Find the value of V/I in all the cases8. Switch off the power supply after use.

CIRCUIT DIAGRAM OF AMMETER:-

CIRCUIT DIAGRAM OF VOLTMETER:-

30



OBERVATION TABLE:

Result:

Power P=( V 2s-V2 L-V2 R )/2R=…………..watt31

S.No Vs(volt) VL VR R(Ω) I(Amp) P=( V 2s-V2 L-V2 R )/2R

CosΦ=( V s-V L-VR)/2VLRL



Power Factor CosΦ=( V s-V L-VR)/2VLRL……………..

PRECAUTION:-

1. All connection should be tight.2. All meters should be of proper range.3. After taking the reading of all meter and remove all the connection properly.

RESULT:-We find out the value of all meters and measure the power.

EXPERIMENT NO:-9

AIM:-To predetermine the efficiency and regulation of a transformer by conducting open

circuit test and short circuit test and to draw equivalent circuit.

APPARATUS REQUIRED:

S.No. Apparatus Range Type Quantity

1 Ammeter(0-2)A

(0-5) A

MI

MI

1

12 Voltmeter (0-150)V MI 2

3 Wattmeter(150V, 5A)

(150V, 5A)

LPF

UPF

1

14 Connecting Wires 2.5sq.mm Copper Few

32



PROCEDURE:

OPEN CIRCUIT TEST:

1. Connections are made as per the circuit diagram.

2. After checking the minimum position of Autotransformer, DPST switch is closed.

3. Auto transformer variac is adjusted get the rated primary voltage.

4. Voltmeter, Ammeter and Wattmeter readings on primary side are noted.

5. Auto transformer is again brought to minimum position and DPST switch is opened.

SHORT CIRCUIT TEST:

1. Connections are made as per the circuit diagram.

2. After checking the minimum position of Autotransformer, DPST switch is closed.

3. Auto transformer variac is adjusted get the rated primary current.

4. Voltmeter, Ammeter and Wattmeter readings on primary side are noted.

5. Auto transformer is again brought to minimum position and DPST switch is opened.

33



34



Observation table:

OPEN CIRCUIT TEST:

Vo

(Volts)

Io

(Amps)

Wo

(Watts)

35



SHORT CIRCUIT TEST:

Vsc

(Volts)

Isc

(Amps)

Wsc

(Watts)

FORMULAE:

Core loss: Wo = VoIo cos φo

Wo Wo

cos φo = ------- φo = cos-1 ------- Vo Io Vo Io

Iω = Io cos φo (Amps) Iµ = Io sin φo (Amps)

Percentage Efficiency: for all loads and p.f.

Output Power (X) x KVA rating x 1000 x cos φ

Efficiency η% = -------------------- = ------------------------------------------------

Input Power Output power + losses

(X) x KVA rating x 1000 x cos φ

= -------------------------------------------------------------

(X) x KVA rating x 1000 x cos φ + Wo + X2Wsc

36



Where X is the load and it is 1 for full load, ½ for half load, ¾ load, ¼ load etc.. and the powerfactor is, upf, o.8 p.f lag and 0.8 p.f lead

EQUIVALENT CIRCUIT:

Precaution

1. Auto Transformer should be in minimum voltage position at the time of closing &

opening DPST Switch.

EXPERIMENT NO: 10

AIM:- Measurement of Power & Power factor in 3-φ load by 2- wattmeter method..

37






2. 3- Φ Power Supply 1 440volt

3. Auto-transformer(3Φ) 1 (0-250)volt

4. Connecting wires 20 ---------

5. wattmeter 2 (cc-10A, pc- 500V),

6. 3- Φ Load 1 230volt,10 A

7. Ammeter 1 (0-10)A

THEORY:- Power in 3- φ Load

P = √ 3 VL IL Cos φ

= 3 VP Ip Cos φ

Let W1 = Reading of wattmeter1 W2 = Reading of wattmeter2 The total p So, P= W1+ W2

Power factor ower is given as the sum of two wattmeter reading W1 & W2.

Cos Φ =cos tan−1√ 3(w1−w 2)

w1+w 2

CIRCUIT DIAGRAM:-

38



PROCEDURE:-

1.Connect the circuit as per circuit diagram.

2. The output voltage of 3-phase variac is at zero or low.

3. Switch on the 3- phase supply.

4. Apply a certain voltage to the circuit and note down the readings of all the meters connected in the circuit.

5. Reduce the voltage applied to 3-phase load and then switch off the supply.

OBSERVATION TABLE:-

S.NO. V I W1 W2 W1+W2 W1-W2 COS∅

1.2.3.4.5.PRECAUTION:-

1. All connection should be tight and clean.2. The reading in ammeters should not exceed the current value of wattmeter

RESULT:- Power and power factor of resistive load had been calculated at different load

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