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882 ⏐⏐⏐ POWER (ac)<br />

+<br />

E = 30 V ∠0°<br />

–<br />

+<br />

E = 100 V ∠0°<br />

–<br />

I s<br />

I s<br />

Load 1<br />

FIG. 19.49<br />

Problem 12.<br />

500 VAR (C)<br />

0 W<br />

P q<br />

s<br />

10. An electrical system is rated 10 kVA, 200 V at a 0.5 leading<br />

power factor.<br />

a. Determine the impedance of the system in rectangular<br />

coordinates.<br />

b. Find the average power delivered to the system.<br />

11. An electrical system is rated 5 kVA, 120 V, at a 0.8 lagging<br />

power factor.<br />

a. Determine the impedance of the system in rectangular<br />

coordinates.<br />

b. Find the average power delivered to the system.<br />

*12. For the system of Fig. 19.49:<br />

a. Find the total number of watts, volt-amperes reactive,<br />

and volt-amperes, and Fp. b. Find the current Is. c. Draw the power triangle.<br />

d. Find the type of elements and their impedance in<br />

ohms within each electrical box. (Assume that all elements<br />

of a load are in series.)<br />

e. Verify that the result of part (b) is correct by finding<br />

the current Is using only the input voltage E and the<br />

results of part (d). Compare the value of Is with that<br />

obtained for part (b).<br />

Load 1<br />

600 VAR (C)<br />

0 W<br />

FIG. 19.50<br />

Problem 13.<br />

Load 2<br />

200 VAR (L)<br />

300 W<br />

*13. Repeat Problem 12 for the system of Fig. 19.50.<br />

Load 2<br />

0 VAR<br />

300 W<br />

Load 3<br />

500 VAR (L)<br />

600 W

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