**EI 1254 ELECTRICAL & ELECTRONIC MEASUREMENTS LAB 0 0 3 100**

**AIM**

The aim of this lab is to impart the students an adequate knowledge and work experience of the different types of AC and DC bridges, electronic measurement methods for different electronic instruments.

**OBJECTIVE**

The objective this is, the student acquires sufficient knowledge experience and enhance his capability for handling the equipment and ease of measurement.

1. Measurement of medium resistance using Wheatstone ‘s bridge.

2. Kelvin’s Double Bridge.

3. Calibration of single-phase energy meter.

4. Calibration of wattmeter.

5. Schering and Anderson Bridges.

6. Calibration of ammeter, voltmeter.

7. Statistical analysis of random errors.

8. V / I, I / V converters.

9. CRO Measurements.

10. Study of transients.

**P = 45 Total = 45**

**Detailed Syllabus**

**1. Measurement Of Medium Resistance Using Wheatstone’s Bridge**

**Aim**

To measure the value of unknown resistance using Wheatstone’s Bridge.

Exercise

Find the value of unknown resistance.

**Procedure**

1. Connections are given as per the circuit diagram.

2. Supply is switched on.

3. When the unknown resistance s connected, the bridge becomes unbalanced.

4. The bridge is balanced by varying standard resistance.

5. The value of unknown resistance is calculated by the given formula.

6. The above steps are repeated for different value of unknown resistances.

**Equipment**

1. Resistors – 1 No

2. Galvanometer – 1 No

3. Regulated Power supply – 1 No

4. Bread board – 1 No

5. Decade resistance box – 1 No

6. Multimeter – 1 No

**2. Kelvin’s Double Bridge**

**Aim**

To find the unknown value of low resistance using Kelvin’s Double Bridge.

**Exercise**

Find the unknown value of low resistance.

**Procedure**

1. Connections are given as per the circuit diagram.

2. Supply is switched on.

3. The bridge becomes unbalanced when unknown resistance R is connected.

4. The bridge is balanced by varying standard resistance.

5. Unknown resistance is calculated using balance equation.

6. The above steps are repeated for various values of unknown resistance.

**Equipment**

1. Power supply – 1 No

2. Fixed resistance – 1 No

3. Unknown resistors – 1 No

4. Decade resistance box – 1 No

5. Multimeter – 1 No

6. Galvanometer – 1 No

7. Bred board - 1 No

**3. Calibration Of Single Phase Energy Meter**

**Aim**

To calibrate the given energy meter using two substandard wattmeters and to obtain percentage error.

**Exercise**

Calibrate the given energy meter and draw % error Vs load graph.

**Procedure**

1. Connections are given as per the circuit diagram.

2. The value of load current is adjusted to desire value.

3. When the red mark on the disk of the energy meter passes the observation point, the stopwatch is started and the number of revolution made by the disc is noted.

4. The load current is maintained by adjusting the load.

5. When the disc of the energy meter completes desired number of revolutions the stopwatch is stopped and the time taken is noted.

6. The procedure is repeated for different values of wattmeter reading and time taken, number of revolutions of the disc is noted down.

7. The graph is plotted between percentage error and load.

**Equipment**

1. Wattmeter – 2 No

2. Voltmeter – 1 No

3. Ammeter – 1 No

4. Resistive load – 1 No

**4. Calibration Of Wattmeter**

**Aim**

To calibrate the given wattmeter using direct loading.

**Exercise**

Calibrate the given wattmeter and draw the graph between % error and load

current.

**Procedure**

1. Connections are given as per the circuit diagram.

2. Supply is given at no load condition.

3. Resistive load is applied in steps and the readings are tabulated.

4. Graph is drawn between % error and load current.

**Equipment**

1. Ammeter – 1 No

2. Voltmeter – 1 No

3. Wattmeter – 1 No

4. Load – 1 No

**5(a) Schering’s Bridge**

**Aim**

To measure the unknown value of capacitance using Schering’s bridge

**Exercise**

Measure the unknown value of capacitance.

**Procedure**

1. Connections are given as per the circuit.

2. Supply is witched on.

3. When unknown value of capacitance is connected, bridge becomes unbalanced.

4. The bridge is balanced by varying the standard.

5. The unknown value of capacitance is calculated using the balance equation.

6. The above steps are repeated for different values of unknown capacitances.

**Euipment**

1. Resistors - Some set.

2. Capacitors – Some set.

3. Decade Resistance box – 1 No.

4. Decade Capacitance box – 1 No.

4. CRO – 1 No.

6. Function Generator – 1 No.

**5(b) Anderson’s Bridge**

**Aim**

To measure the unknown value of inductance using Anderson’s Bridge

**Exercise**

Measure the unknown value of inductance.

**Procedure**

1. Connections are given as per the circuit diagram.

2. Supply is switched on.

3. When unknown value of inductance is connected the bridge becomes unbalanced.

4. The unknown value of inductance is calculated by using the balance equation.

5. The above step are repeated for different values of unknown inductance.

**Equipment**

1. Resistors – Some set

2. Decade Inductance box – 1 No.

3. Decade Condenser box – 1 No.

4. Regulated power supply – 1 No.

5. CRO – 1 No.

6. Bread board - 1 No.

**6(a) Calibration of Ammeter**

**Aim**

To calibrate the given ammeter using standard ammeter

**Exercise**

Calibrate the given ammeter and draw the graph between % error and As.

**Procedure**

1. Connections are given as per the circuit diagram.

2. The standard ammeter should be selected properly.

3. Supply is switched on.

4. At no load condition the readings of all the meters are noted.

5. By gradually increasing the load, the respective readings are taken from the meters.

6. The readings are tabulated and % error is calculated from the formula.

7. Graph is drawn between As and % error.

8. The procedure is repeated for both ac and dc supply.

**Equipment**

1. Standard ammeter – 1 No.

2. Ammeter – 1 No.

3. Variable resistive load – 1 No.

4. RPS – 1 No.

**6(b) Calibration of Voltmeter**

**Aim**

To calibrate the given voltmeter using standard voltmeter.

**Exercise**

Calibrate the given voltmeter and draw the graph between % error and VS.

**Procedure**

1. Connections are given as per the circuit diagram.

2. The standard voltmeter should be selected properly.

3. Supply is switched on.

4. At no load condition the readings of all the meters are noted.

5. By gradually increasing the voltage, the respective readings are taken from the meters.

6. The readings are tabulated and % error is calculated from the formula.

7. Graph is drawn between Vs and % error.

8. The procedure is repeated for both ac and dc supply.

**Equipment**

1. Standard voltmeter – 1 No.

2. Voltmeter – 1 No.

3. Auto transformer – 1 No.

4. RPS – 1 No.

**7. Statistical Analysis Of Random Errors**

**Aim**

To analyze the measured data statistically.

**Exercise**

Take a set of data and calculate the arithmetic mean, deviation from the mean, average deviation, standard deviation and variance.

**Procedure**

1. Connect the voltage source to the load.

2. Measure the load current or load voltage using the digital meter.

3. After taking the reading switch off the supply.

4. Switch on the supply and repeat the experiment.

5. Take 4 readings for same supply voltage or same load current.

6. Using the data calculate the Arithmetic mean, Deviation from the mean, Average deviation, Standard deviation, Variance.

**Equipment**

1. Digital voltmeter or ammeter of suitable range – 1 No

2. Resistor to act as load – 1 No

3. Voltage source – 1 No

**8. Voltage To Current, Current To Voltage Converter**

**Aim**

To construct a current to voltage & Voltage to current converter circuit.

**Exercise**

Voltage To Current Converter

Observe the changes in o/p current for changes in i/p voltage.

1. Connect the circuit

2. Vary the R.P.S

3. Observe the O/P current

Current To Voltage Converter

Observe the changes in o/p voltage for changes in i/p current.

1. Connect the circuit

2. Vary the i/p current by varying the R.P.S

3. Tabulate the changes in o/p voltage

**Equipment**

1. IC 741 Trainer kit – 1 No

2. Resistors – A set

3. RPS – 1 No

4. Multimeter – 1 No

5. Ammeter – 1 No

6. Voltmeter – 1 No

**9. CRO Measurements**

**Aim**

To determine the unknown frequency & phase angle using CRO BY Lissajous

pattern.

**Exercise**

1. Measure the frequency of a signal.

2. Measure the Phase angle between any two signals.

**Procedure**

1. The function generators are connected in the channels of CRO.

2. The unknown frequency is applied to Y-plate and known frequency to X-plate.

3. The known frequency is set to a constant value and unknown frequency is adjusted in multiples or sub multiples of known frequency to get Lissajous pattern.

4. When the pattern becomes stable, these are graphed, tabulated and analysed.

**Equipment**

1. CRO with probes – 1 No.

2. Function generator – 2 Nos.

3. Connecting wires

**10. Study Of Transients**

**Aim**

Trace the transient waveform and peek time, settling time.

**Exercise**

Wire up a RLC circuit and obtain its waveform on CRO. Find out peak time,

settling time etc., form the waveform.

**Procedure**

1. Wire ups as PLC circuit.

2. Give a suitable (Sine wave input).

3. Observe the output waveform storage oscilloscope.

4. Find out peak line setting time etc, from the waveform.

**Equipment**

1. Breadboard – 1 No.

2. Storage C.R.O. – 1 No.

3. Resisters – A set.

4. Capacitors – A set.

5. Inductors – A set.