cos
p.6 750 W
φ
∴
Example 2
A capacitor reactance 12Ω connected series with resistor across 150V supply.
For (a):
Z X
Z
2
2 2
( )
(9 (12 15
Ω
∴ Ω
For (b):
I
V
Z
I
(A)
150 V
15
10A
∴
Ω
For (c):
p.f. cos
p.f., and (d) the power.f.Baisc Electrical Installation Work
202
In a.f.
For (a):
Z X
Z
2
2 2
( )
(30 (40 50
Ω
∴ Ω
For (b):
I
V
Z
I
(A)
250 V
50
5 A
∴
Ω
For (c):
p., and (d) the power.f. circuit the power consumed given the product the cur-
rent and that part the voltage which phase with the current.
Calculate (a) the impedance, (b) the current, (c) the p. The
in-phase component the voltage given cosφ, and power can
also given the equation:
P VI
cos (W)
φ
Example 1
A coil has resistance 30Ω and reactance 40Ω when connected 250V supply.6 leading
φ
R
Z
∴
Ω
Ω
.f.
Calculate (a) the impedance the circuit, (b) the current, (c) the p.
30
50
0.
9
15
0.c.6 lagging
φ
R
Z
∴
Ω
Ω
For (d):
P VI
P
cos (W)
250 0
