FR. CONCEICAO RODRIGUES COLLEGE OF ENGINEERING
Department of Electronics Engineering
5. PHASE LINE RELATIONSHIP.
1.
Course, Subject LC
& Experiment
Details
RESONANCE
Academic Year
2014 – 2015
Estimated Time
Course & Semester
Chapter No.
Experiment Type
F.E. (ALL) – Sem. I
3
Hardware Performance
Subject Name
Chapter Title
Subject Code
2.
Experiment No.5 – 02 Hours
Basic Electrical and Electronics
Engineering Laboratory
Three phase circuits
FE 105
Aim & Objective of Experiment
To verify the phase line relationship in star and delta connected 3 phase system.
3.
Expected Outcome of Experiment
This experiment helps students in understanding the basics of 3-phase star and delta connected
system and their phase line relationship.
4.Brief Theoretical Description
a)Three phase STAR connection
Figure below shows a three phase ,star connected system. As load is balanced ,all
phase voltages VRN, VYN and VBN are equal in magnitude and 120 0 apart. The magnitude
of each phase voltage is denoted by VPH. Thus
For a balanced system, VRN = VYN = VBN = VPH
Three phase Star connection
Basic Electrical and Electronics Laboratory- Experiment 5
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FR. CONCEICAO RODRIGUES COLLEGE OF ENGINEERING
Department of Electronics Engineering
The line voltage between the lines R & Y is
VRY = VR – VY
Similarly
and
VYB = VY – VB
VBR = VB – VR
Thus for a balanced system magnitudes of VRY = VYB = VBR = VL
b)Three phase Delta connection:-
In balanced delta connectin
VL=Vph
IL=√3 Iph


Line current lags behind the respective phase phase current by 30 degree.
Basic Electrical and Electronics Laboratory- Experiment 5
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FR. CONCEICAO RODRIGUES COLLEGE OF ENGINEERING
Department of Electronics Engineering
5.r
Circuit Diagram & Experimental Setup
6.
Apparatus Required
1.
2.
3.
4.
5.
Star and delta connected 3 phase circuit boards
Ammeter
0-2.5 A,M/I
3 Nos
Voltmeter
0-500V,M/I
1 No.
Voltmeter
0-300V,M/I
1 No
Connecting wires
Basic Electrical and Electronics Laboratory- Experiment 5
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FR. CONCEICAO RODRIGUES COLLEGE OF ENGINEERING
Department of Electronics Engineering
7.
Experimental Procedure
1.
2.
3.
4.
5.
6.
8
Connect the circuit as shown in fig.1( for Delta connected load)
Switch on the supply and note the readings.IL,IPH,VL & VPH
Verify the relationships IL = √3 IPH, VL = VPH
Connect the circuit as shown in fig.2 ( for Star connected load)
Switch on the supply and note the readings.IL,IPH, VL & VPH
Verify the relationships IL= IPH and VL = √3 VPH.
Observation Table
VL
VPH
IL
IPH
Connect (V)
ion
(V)
(A)
(A)
VL/VPH
IL/IPH
Practical Theoretical Practical Theoretical
Star
Delta
9
Conclusions & Inferences
100
Post Lab Questions
1)State the advantages of the poly phase circuit.
2)Prove that for the same 3phase balanced load power drawn in a delta
system is 3 times the power drawn in a star connected system.
3)Compare 3 phase delta and star connection.
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Basic Electrical and Electronics Laboratory- Experiment 5
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