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Irwin, Basic Engineering Circuit Analysis, 9/E 1

Chapter 11: Polyphase Circuits Problem 11.FE-1

SOLUTION:

The correct answer is d.

rmsAI 6

rmsVVR 85.84

rmsVVL 85.84

14.146

85.84

I

VR

R

14.146

85.84

I

VL

L

14.1414.14 jZload

loadZIS2

3 3

14.1414.1463 23 jS

kVAS 4516.23

Irwin, Basic Engineering Circuit Analysis, 9/E 1

Chapter 11: Polyphase Circuits Problem 11.FE-2

SOLUTION:

The correct answer is a.

1212 jZ

Finding the equivalent per-phase wye:

4566.544 jZY

rmsVVAB 230

rmsVVAN 79.1323

230

rmsAZ

VI

Y

AN

aA 5.2366.5

79.132

kWIVP ZaAAN 62.645cos)5.23)(79.132(3cos33

Irwin, Basic Engineering Circuit Analysis, 9/E 1

Chapter 11: Polyphase Circuits Problem 11.FE-3

SOLUTION:

The correct answer is b.

683

18241 j

jZY

462 jZY

rmsVVAB 208

rmsVVAN 1203

208

Aj

I aN

87.3612

68

01201

Aj

I aN

69.3364.16

46

01202

rmsAIII aNaNaA 02.3563.2821

Irwin, Basic Engineering Circuit Analysis, 9/E 1

Chapter 11: Polyphase Circuits Problem 11.FE-4

SOLUTION:

The correct answer is c.

VAjkVAS 1200061.2078430243

kWP 78.203

kWP 93.61

Irwin, Basic Engineering Circuit Analysis, 9/E 1

Chapter 11: Polyphase Circuits Problem 11.FE-5

SOLUTION:

The correct answer is d.

By use of the power triangle:

222 QPS 22 PSQ

22 )90()100( kkQ var59.43 kQ