8 and 0.6 900 W
φ
∴
The power factor most industrial loads lagging because the machines
and discharge lighting used industry are mostly inductive.4.
Figure 10. capaci-
tor connected parallel with the load, the capacitor current leads
the applied voltage 90°. capacitor has the opposite effect inductor, and
so seems reasonable add capacitor load which known have
a lower bad power factor, for example, motor. However, using slightly bigger capacitor, the load
current can pushed until ‘in phase’ with the voltage can be
seen Fig. 0.8.Alternating current theory and electrical machines
203
For (d):
P VI
P
cos (W)
150 0.
The current given by:
I
P
V
cos φ
where 1. then:
I
1840
230 1
8
W
V
A
For p. a
result, the supply companies encourage installation engineers improve their power factor
to value close and sometimes charge penalties the power factor falls below 0.f.9(b) the resultant load current has much
improved power factor.4:
I
1840
230 4
20
W
V
A
.84 load supplied power factor 0. There may also the problem higher voltage drops the supply cables.f.
.
Example 3
A 230V supply feeds three 1.
POWER FACTOR CORRECTION
Most installations have low bad power factor because the inductive
nature the load. When this capacitor current added the
load current shown Fig 10.84kW loads with power factors 0. 10.8:
I
1840
230
W
V 0.f.9(c). the p.
It can seen from these calculations that 1.84 1840 and 230V.8
10A
For p. This causes
an additional magnetizing current drawn from the supply, which
does not produce power, but does need supplied, making supply
cables larger.9(a) shows industrial load with low power factor. Calculate the
current each power factor. 0.4
would require 20A cable, while the same load unity power factor could supplied with
an cable
