Assignment_8 Solution

Assignment_8 Solution - ELECTRICAL ENGINEERING DEPARTMENT...

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Unformatted text preview: ELECTRICAL ENGINEERING DEPARTMENT California Polytechnic State University BB 255 Assignment #8 Problem #1 At a location in USA, it is necessary to supply 300 KW of 50—Hz power. The only power source available operate at 60-Hz. It is decided to generate the power by means of motor—generator set consisting of synchronous motor driving a synchronous generator. How many poles should each of the two machines have in order to convert 60—HZ t0 50-Hz power? Problem #2 A 2400-V, IOOO-KVA, 0.8—PF—lagging, 60—Hz, 4-poles, delta—connected synchronous generator has a synchronous reactance of 1.1 Ohms and an armature resistance of 0.15 Ohms. At 60-Hz, its friction and windage losses are 20 KW, and its core losses are 15 KW. The field circuit is adjustable over the range from 20 to 200 Q. The OCC oft is generator i sho‘ m in Figure P5=l, page 338 {4th edition) or Figure P6-l, page 353 (3rd edition). a. How much field current is required to make the no—load terminal voltage equal to 2.4 KV? b. What is the internal generated voltage of this machine at rated load conditions? 0. How much field current is required to make the terminal voltage equal to 2400 V when the generator is running at rated conditions? (1. ' How much power and torque must the generator’s prime mover be capable of supplying? Problem #3 Assume that the field current of the generator of problem 2 has been adjusted to a value of 4.5 A. a. What will the terminal voltage of this generator be if it is connected to a delta- connected load with an impedance of 24145°Q ? 1). Sketch the phasor diagram of this generator. 0. Now assume that another identical delta-connected load is to be paralleled with the first one. What happens to the phasor diagram of the generator? “W hat is the new terminal voltage after the load has been added? 0 XIILn+m 14-1.. .+. .4- .4- m' ] 4- '4— .. _' '_ I y 1... vv ucu LLLhSL [)6 (110116 LG ICStOIC thC LCuulfiai voltage LO 1L3 Oflgifiar 'vaiufi.’ p: or Problem #4 A 480-V, 60-HZ, 4—p01e, Y—connected synchronous generator rated at 300« KVA and 0.9 PF lagging. Its armature resistance is 0.02 Ohms The core losses of this machine at rated conditions are 7 KW, and the friction and Windage losses are 8 KW. The open- and short-circuit characteristics are shown in the Errata Sheet under error 7. a. What is the saturated synchronous reactance of this generator at rated armature current? b. What is the unsaturated synchronous reactance of this generator at rated armature current? c. What is the internal generated voltage of this generator under rated conditions? d. What field current does this generator require to operate at the rated voltage, current, and power factor? e. What is the voltage regulation of this generator at the rated current and power factor? f. If this generator is operating at the rated conditions and the load is suddenly removed, what will the terminal voltage be? g. What are the electrical losses of this generator at rated conditions? h. If this generator is operating at the rated conditions, what input torque must be applied to the shaft? i. Determine the efficiency of the generator under rated conditions. 2m. __ «r a: m a? Hun . mpg __ Lw a. (w a ma... M, M ode __ (5 r __ mm 0 1% mm o : I. M0 e 5 MN. _ = __ mam commaquU muamcmmcw m w E .mmm .oZ @fiflgkfimfigmm mm Efigineefs Computation Pad N0. 9'37 811E 2%? E31135 QTLER‘E 2402: V 50 #2:- )(5 2’ H .2- 1000 {CW} 4..de9 2“ :6'15-JL 0 8p; A 4a.”?! = 204:“) gm: 6th Ea. T745 -L- Ea(Pq, +jX5) .3 24mg." + I37Z:E‘f¥7a(o.15 +} U) z 25)! £5: \/ 2 \ —3' 1 : 3004.303?) 69.15,)” + 15 +20 :3 8143 7 KW 7",, g. 3553700 :— un’ié Mm 701 2514:5623 Engineer’s, Computaé‘ion Pad Na. 93'? 8%1E é? EETflEflTLERGJ 11/2. 4-) (3.57 :. 2217.5 /"”’55 \/ III—— :5 —« fmkcgwj XS C) [aacis I “ I. I w (pan/4109] O V l .279" _..———--— l2— L‘i‘é ° 0.2; an +/2 45 I 2139/ 1;. V4) 2’," 2.30éZ90 fag, Via/$5 Hrs-:3 \‘J a :41) 5 I _........ __._..... Ema. commafircuw mummcficw w W. a E .03 gmmfimmfim mm g g H - mmmmgm_._,_w_m a i I ! NO. 93? 811E? é? SSTflEIQTiEW) Engineer‘s Computaiicn Pad E £ 0“? I’Hfj Pa W? «9152— 4—7M/c. Boo,va 43:0,: :7 KM a) find X5 “hawk”; 3:43. - Smi' IQ = 350/”? ._. 3a.? F} mks fixg-fa 550% sec: I; :2 0.3;}. From 0C6; a. :: 650V L-L z'z X5 = 7650 :2 [0452,91‘ *4 gage-8) / lo) $V0‘M A'W'JQP [like Ea =é50 V L-L X5 : 65o ’ J; L mm 37350.9) 0‘" A” C) £43 at *”4(P€LHXS) _.; 1.775} M 7&4; rfi'g‘f A I /L—-- 1- vw (a 35,3e5 '39 a“) 1'" I (PH/rt? r] r/v-1 a \/ bat-L :43 L97 7/ = 791-3 v l mmimmm, . _ Red. = $7414 Open Circuit Characteristic 1200 1100 1000 Open-circuit voltage, V an 8 I 400 L 300 200 100 00 0.! 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 [.1 1.2 1.3 1.4 L5 FieidcurrenLA (a) Shari Circuit Characteristic 1600 1200 5. 5 I § Armatm'e current, A 0 i ‘ - i L n n I: n u u . . u.u mu Field current, A (b) } .__. m- m 05? 1") 2) cm (7) ... . (3 ":l m ( RD "U 93 00 CD 93 5.] :J "U F: O E ('D B c3‘ ,_._. ‘r—‘ E 5'3 5 -: (D r-s (D 53. w 1-!- m 3 O (‘D a. F3 O 00 “{O S} :3 :1. c—h LT‘ (D m ‘4 D E O :5 O 5: m 10. Page 470, Problem 7—20 ((1), the holding the infinite bus is 460-V. Engineer‘s Cornpu‘iaiicrr‘: Pad NO. 93? 811E é? §§TfiE§E3TLER® ...
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This homework help was uploaded on 04/07/2008 for the course EE 255 taught by Professor Shaban during the Fall '05 term at Cal Poly.

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Assignment_8 Solution - ELECTRICAL ENGINEERING DEPARTMENT...

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