Question

Meter readings for a three-phase wye-connected alternator supplying power to a motor indicate that the line voltages are 330 V, the line currents are 8.4 A, and the total line power is 4.5 kW. Find: (a) the load in VA (b) the load pf (c) the phase current (d) the phase voltage

S
3ϕ
​

S
3ϕ
​

S
3ϕ
​

​

=
3
​
(I
L
​
)(V
L
​
)
=
3
​
(8.4)(330v)
=4801.24 V
A
​

​

Given: P
L
​

Pf
P
f
​
=0.93
​

=45 kW
S
P
​
=
4.8kVA
45 kW
​
+5
​

V
LL
​

+4
3
​

V
LL
​

​

Vϕ
​

=
3
​
⋅V
ϕ
​

=
3
​

330
​
=V
ϕ
​

=190.53 V
​

Answer 1

Step-by-step explanation:

(a) Load in VA:

The apparent power (load) can be calculated by multiplying the line voltage by the line current:

Load (VA) = Line voltage (V) * Line current (A)

Load (VA) = 330 V * 8.4 A

(b) Load power factor (pf):

The power factor (pf) can be calculated by dividing the total line power by the apparent power:

pf = Total line power (W) / Load (VA)

pf = 4.5 kW / (330 V * 8.4 A)

(c) Phase current:

The phase current (I) can be calculated by dividing the line current by the square root of 3:

Phase current (A) = Line current (A) / √3

Phase current (A) = 8.4 A / √3

(d) Phase voltage:

The phase voltage (V) is equal to the line voltage:

Phase voltage (V) = Line voltage (V)