# Study Star and Delta Conn

Aim:- To study Star and Delta Connection in 3-Phase AC Circuit.

Apparatus Required:-

S.No:

# Quantity

1.

Voltmeter

0-600V

MI

1

2.

Voltmeter

0-300V

MI

1

3.

Ammeter

0-2A

MI

2

4.

Rheostat

100 ohm,5A

Double Tube

3

Theory:-

STAR CONNECTION

Line Voltage = Voltage between any two line terminals,

VL =VRY = VRB =VBY

Phase Voltage = Voltage between any one line & neutral,

VPH =VRN = VBN = VYN

Line & phase current is equal in case of star connection,

VRY=VRN +(-VYN)

V 2RY =[V­RN +(-VYN)] 2

=V2RN  + V2YN + 2VRN VYN Cos60

VL = VRY = √3 VPH

Circuit Diagram:-

DELTA CONNECTION

Line Current - Current coming from the line terminal

IL = IR = IB = IY

Phase current - It is the current flowing through the load connected between two terminals

IPH = IRY = IYB = IBR

IR = IRY - IBR

I2R­ = [IRY + (-IBR) ]2

= I2RY + I2BR + 2 IRY IBR Cos60

IR = IL = √3 IPH

Circuit Diagram:-

Observation Table:-

# Connection

IL(A)

IPH(A)

VL(V)

VPH(V)

Star

1.6

1.6

300

173.2

Delta

3.2

1.84

200

200

Result:-

1.     Ratio Of VL/VPH = 1.732 for Star Connection

2.     Ratio Of IL / IPH  = 1.732 for Delta Connection