Obtain the threephase average and reactive powers if W1 read

Obtain the three-phase average and reactive powers if W_1 reads 4.5 kW and W_2 reads-2 kW. What is the value of Z_Y if Vab is 200V?

Solution

Abb1) pt= average active power

= w1+w2=4.5-2=2.5 kW

Pr= reactive power= w1-w2=6.5 kw

(2) tan(theta)=3(w1-w2)/(w1+w2)

tan(theta)=4.5

theta= 77.5 degree

cos(theta)=power factor= 0.216 lagging

iL= line current=(w1+w2) /[3*Vab*cos(theta)]

iL=2.5/(3*200*0.216)=33.4

Zy= (Vab/iL)<77.5

=5.98<77.5

=5.98(cos77.5+j*sin77.5)