
Transformer 147
V
ωt
No load (open
terminals)
(a) Transformer with line breaker open and no load
Supply
Lines
V
max
v∙dt
ωt
(b) Breaker closed at V
max
instant
0
V
180°
90°
180°
v∙dt
0
(c) Breaker closed at V = 0 instant
0
ωt
Inrush current
(d) Inrush current on connecting primary coil (three cycles)
FIGURE 6.5 Magnetizing inrush current on connecting transformer to supply lines with no
load on the secondary side.