Laboratory No 3 Electrical System EC-101

SRI LANKA INSTITUTE OF INFORMATION TECHNOLOGY

ELECTRICAL SYSTEMS EC101

STUDENT NUMBER:EN 14522116

NAME:Mohamed Althaf

GROUP: 04

LABORATORY: AC NETWORKS

LABORATORY SUPERVISOR:

LABORATORY PARTNERS:

DATE PERFORMED:9th of April

DATE DUE:2nd of May

DATE SUBMITTED:2nd of May 2014

I hereby declare that the calculation, results, discussion and conclusions submitted in this report is entirely my own work and have not copied from any other student or past student.

Student Signature:________________________________________

AC Laboratory Equipment & Circuits

Introduction

This experiment concentrates on AC network analysis and comparisons between theoretical and practical results. Mostly, the theorems used in DC analysis, like Mesh analysis, noodle Analysis, super position are applicable here.

The phasor diagrams for the practical values & theoretical values are attached with this report for comparison reasons.

The aim of this lab is to understand the AC circuit analysis & handling the measuring devices in practical way.

Methodology

Oscilloscope was switched ON, probes were connected & Default Setup key in the front panel was pressed.

Required frequency was selected by the keys in Function Generator & Oscilloscopes Channel 1 is connected with function generators terminals.

A fine form of wave is gained by adjusting Press to zoom (time/division) knob & Push for fine (volt/division) nob and then required peak to peak voltage is tuned by adjusting Amplitude knob in Function generator.

Measure function was used to set the peak to peak voltage.

The given circuit were designed using breadboard.

Oscilloscopes Channel 1, Channel 2 were connected and, the volt/division of Channel-2 was selected equivalent to Cannel-1s using Push for fine knob.

The measurements were taken using Measure & Cursor functions.

Laboratory Tabulated Results

Circuit 4.1

QuantitiesChannel 2

Vpp4.3V

Vrms1.52V

Period500

24

Phase Angle14

VC2 = VR2 = 1.52 v

iC2 = = = 0.897 mA

iR2 = = = 1.85 mA

Circuit 4.2 QuantitiesChannel 2

Vpp4.38V

Vrms1.55V

Period500

74

Phase Angle51

VR1 = 1.55 v

iR1 = = = 1.55 mA

Circuit 4.3

QuantitiesChannel 2

Vpp7.73V

Vrms2.73V

Period500

52

Phase Angle-37

VC1 = 2.73 v

iC1 = = = 1.92 mA

Calculations

ZR1 = 820ZR2 = 1000ZC1 = 1421.03ZC2 = 1693.13

ZR2//ZC2 = i2i1

= = 860.97

ZT = 820 j1421.02 + 741.61 j438.09 =1561.30 j1858.91 = 2427.59

By Kirchhoffs voltage law

Loop 1Loop 2

4.750- (820 j1421.02)i1 1000(i1 i2) = 0-(-j1693.14)i2 + 1000(i2 i1) = 0(1820 j1421.03)i1 1000i2 = 4.750-1000i1 + (1000 + j1693.14)i2 = 02309.05-37.98i1 - 10000i2 = 4.750-10000i1 + 1966.3659.43i2 = 0

In Matrix

=

By Crammers rule

i1 = i1 =

= 2.6337.98mA = 1.34 59.43mA VR1 = i1 R1VR2 = (i1 i2) R2= 2.6337.98 10-3 820 =(2.6337.981.34 59.43 10-3 1000 = 2.16V = (1.39 + j0.45) V = 1.4617.94 V

VC1 = i1 Zc1VC2 = i2 Zc2 = 2.6337.98 10-3 1421.03 = 1.34 59.43 10-3 1693.13 = 3.7452.02 V = 2.27 30.57 V

Discussion

In this practical, Channel 1 is used to indicate the (Input) reference wave and channel 2 is to measure the voltage drop across the elements parallel to Channel 2 probe.

Calculated and the measured values are compared & it has some variations between them in magnitude and the phase angle. Tolerance of the testing equipment, surrounding disturbance, improper connection and visual errors are some practical issues which may cause these variations between theoretical & practical results.

The total impedance of the circuit can be determined by simplyZT = = = 2473.96 .But theoretically calculated value is 2427.59 .

In circuit 4.1, the components have to be rearranged each time before measuring voltage of it. So the connection errors in this practical could be high.

Voltage has to be measured with reference to the ground. As the component is not before the ground but next to the other component, its not possible to measure the voltage drop across it directly. The output wave indicates only the voltage difference. So, to measure the voltage of the component, it should be shifted to the ground.

To measure the component voltage without shifting to ground. Two channels of the oscilloscope have to place across that component to measure those point voltages. After that have to subtract channel 2 voltage from channel 1 voltage to determine that component voltage. By this the component voltage magnitude and the phase angle can be measured without shifting it to the ground.

Conclusion

Most of the theorems applying in DC analysis are applicable in AC analysis too.

To measure the voltage across the components in circuit 4.1, the components have to be rearranged each time like in circuit 4.2 and circuit 4.3.

AC calculations are in complex form as it has a magnitude and a phase angle.

Components have to be shifted to ground to get the voltage of it directly through the measurement, but phase angle can be measured without shifting the components to the ground.

Practical results and the theoretically calculated one are not equal because of practical issues like tolerance of the testing equipment, surrounding disturbance, improper connection and visual errors.

Phasor diagram can be used to show that the sum of the voltage drop across the components is equal to the input voltage.

Reference

User Manuel of DSO 1052B User Manual of TENMA 72-1016 User Manual of SFG-2110 Digital Function Generator Boylestad Introductory Circuit Analysis 11th EditionEN 14522116 M.F.M. ALTHAF8