{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

# Grad Practice Test 1 - EE 5343 Test 1 Spring 2002...

This preview shows pages 1–2. Sign up to view the full content.

R base_p 23.04 = R base_s 208 volt 3 I rat_s := R base_s 4.326 = R wp 0.01 R base_p := R wp 0.23 = R ws 0.01 R base_s := R ws 0.043 = Problem 3: A three-phase load is drawing 250 kW real power at a power factor of 0.75 lagging. a) Find the apparent power S drawn by the load in kVA 333.3 . b) Find the reactive power Q drawn by the load in kVAR 220.5 . c) Find the capacitor bank rating in kVAR to increase the combined power factor to 0.95 lagging. S V I = P V I pf = Q V I sin acos pf ( ) ( ) = S P 2 Q 2 + = acos 0.75 ( ) 41.41 deg = S P pf = S 250 kW 0.75 := S 333.3 kVA = Q 075 S sin acos 0.75 ( ) ( ) := Q 075 220.5 kVAR = EE 5343, Test 1, Spring 2002: Dr. M. Giesselmann, February 14, 2002 Definitions: freq 60 Hz := ω 2 π freq := MW 1000 kW kVA kW kVAR kW m 1000 MVA 1000 kW MVAR 1000 kW Problem 1: a) What is the principal advantage of AC power systems compared to DC power systems? The ability to step voltages up and down for long distance transmission. b) Give two solutions to eliminate oscillations of the instantaneous power in AC power systems. Use a balanced two-phase system with voltages 90 deg apart, or a balanced three-phase system with voltages 120 deg apart. c) Which of the solutions listed in (b) is better for long distance power distribution and why? Three-phase systems transmit more power per line since the currents add up to zero.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 5

Grad Practice Test 1 - EE 5343 Test 1 Spring 2002...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online