Page 175 - Electrician - TT (Volume 1)
P. 175
ELECTRICIAN - CITS
Star connection
The three ends of the three windings are connected together to form a common or neutral point.
It is clear that current flowing through phase windings will be same as that flowing through the line.
Line current (I )=Phase Current (I )
L ph
But line voltage V is not same as phase voltage V . Because two phase winding is connected between two lines.
ph
L
Voltage generated in each phase is the phase voltage. They are represented by OE ,OE & OE Which are 120
C.
A
B
deg elect apart.The vector difference of OE and OE yields line voltage.
A
B
According to parallelogram law
In star connection,
Line voltage = √3phase voltage
Delta connection
Three coils of three phase winding can also be connected in delta as shown in figure. The three junctions thus
formed are taken as phase wires.
Only one phase winding is included between any two lines .
Line voltage (V ) = Phase voltage(V )
L
ph
But line current is not equal to phase current.
162
CITS : Power - Electrician & Wireman - Lesson 26-29
