ERRATA for Electrical and Computer Engineering Sample Questions and Solutions ISBN 1-932613-11-0 Morning Solutions p. 151, Solution 134: In line 3, P = 21.2. Errata for previous editions of this book are posted below. ERRATA for Electrical and Computer Engineering Sample Questions and Solutions REV 0: lower right corner of first page (errata posted July 7, 2003) Morning Solutions p. 146, Solution 111: In the second line of the solution, add the subscript number 1 to the first variable I. V ( s ) = I 1 ( s ) ⋅ ( sL) = R( sL)(sC ) I ( s ) s 2 LC + ( R + R1 ) sC + 1 = s 2 RI ( s ) ( R + R1 ) 1 s+ s2 + L LC p. 148, Solution 123: Change line 1 as follows: The power input to the speaker is V2/R = (30)2/8 = 900/8 = 112.5 W. The speaker output is (112.5 W)(0.15) = 17 W. S:\COMMUN\WEBTRANS\ELE ERRATA July 03.doc ERRATA for Electrical and Computer Engineering Sample Questions and Solutions REV 0: lower right corner of first page (errata posted November 15, 2002) Morning Questions p. 19, Question 102: Reword the second paragraph as follows: A small computing system costing $50,000 is installed initially. A second computer is installed 2 years later to handle additional production needs, also at a cost of $50,000. Each unit requires a maintenance cost of $10,000/year of operation. p. 25, Question 111: Reword the question and change the figure as shown: The transfer function v(s )/i(s ) for the circuit shown in the figure below is: C R1 i (s ) R L v (s ) p. 41, Question 138: Reword the question as follows: The one-line diagram below represents three single-phase transformers connected in a delta-wye arrangement and rated for the line-to-line voltages indicated as shown below. The turns ratio of individual single-phase transformers is most nearly: Power Questions p. 116, Question 504: In the first sentence, change the edition of the National Electrical Code® (NEC) to 2002. Change the second sentence to read as follows: The minimum size THWN copper conductors rated at 75°C installed in conduit required to serve a continuous duty 230-V 10-hp single-phase induction motor and non-continuous 1-kW resistance heater on a circuit operating at 240-V single phase are: p. 117, Question 505: Change the edition of the National Electrical Code® (NEC) to 2002. 1 p. 117, Question 506: Change the edition of the National Electrical Code® (NEC) to 2002. Change the first sentence to read: You have sized branch-circuit conductors supplying a 3-phase squirrel-cage induction motor in accordance with the 2002 edition of the National Electrical Code®. p. 118, Question 507: Reword the question as follows: A 3-phase transmission line is rated 65 kV and 24 MVA. The line impedance is 50 Ω/phase. Assuming the line-rated values are also the base values, the per-unit impedance is most nearly: p. 131, Question 529: Change the edition of the National Electrical Code® (NEC) to 2002. p. 131, Question 530: Change the edition of the National Electrical Code® (NEC) to 2002 in Option C. p. 133, Question 533: Change the edition of the National Electrical Code® (NEC) to 2002. p. 136, Question 537: Change the figure as shown: 2 Morning Solutions p. 151, Solution 135: Change lines 2 and 3 as follows: P.F. = 0.80 8,000 kW S load = = 10,000 kVA 0.80 Qload = 10,000 2 − 8,000 2 = 6,000 kvar Electronics, Controls, and Communications Solutions p. 165, Solution 504: Add “…and resulting in an ‘OR’.” to the end of the sentence. Power Solutions p. 179, Solution 504: Change the first line to read: 10-hp load is 50 A × 1.25 = 62.5 A (NEC® Table 430.148, NEC® Article 430.22 (A) Change the next-to-last line to read: Select #4 copper (NEC® Table 310.16) p. 180, Solution 505: Change the Table to 430.151(B). p. 180, Solution 506: In the first paragraph, change the NEC® Article to 430.52(c) and the Table to 430.52. In the third paragraph, change the Article to 430.22 (A). In the fourth paragraph, change the Article to 430.110 p. 186, Solution 530: In the first paragraph, change the NEC® Article to 460.9. In the third paragraph, change the NEC® Article to 460.8 (c) exception. In the fourth paragraph, change the NEC® Article to 460.9. p. 186, Solution 533: Change the NEC® Article to 250.56. p. 187, Solution 537: Change the second line to read: The time dial setting for 3.6 × at 0.9 sec = 2 p. 187, Solution 538: Change the NEC® reference to 240.3 (D). 3