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994 ⏐⏐⏐ POLYPHASE SYSTEMS<br />

c. The apparent power is<br />

Sf � VfIf � (100 V)(20 A) � 2000 VA<br />

ST � 3Sf � (3)(2000 VA) � 6000 VA<br />

or ST � �3�ELIL � (1.732)(173.2 V)(20 A) � 6000 VA<br />

d. The power factor is<br />

P T<br />

3600 W<br />

Fp �����0.6 lagging<br />

ST 6000 VA<br />

D-Connected Balanced Load<br />

Please refer to Fig. 22.24 for the following discussion.<br />

E L<br />

E L<br />

E L<br />

Average Power<br />

Reactive Power<br />

Apparent Power<br />

I L<br />

I L<br />

I L<br />

V ��<br />

+<br />

FIG. 22.24<br />

D-connected balanced load.<br />

Pf � VfIf cos v Vf<br />

If � I 2 fRf � � VR<br />

�<br />

Rf P T � 3P f<br />

Qf � VfIf sin v Vf<br />

If � I 2 fXf � � V X<br />

�<br />

Xf Q T � 3Q f<br />

S f � V fI f<br />

Z Z<br />

I ��<br />

–<br />

I ��<br />

Z<br />

+<br />

(W) (22.24)<br />

(W) (22.25)<br />

2<br />

I ��<br />

– V�� +<br />

2<br />

V ��<br />

–<br />

Z = R ± jX<br />

� �<br />

(VAR) (22.26)<br />

(VAR) (22.27)<br />

(VA) (22.28)

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