Question

4. A separately excited de generator is rated at 172 kW, 430 V, 400 A, and 1800 rpm. Its field circuit has a total resistance Radi +Rp. Its magnetizing curve is shown in Fig. P4.1. The machine has the following characteristics: RA = 0.05 2; Rr = 20 2; Radi (a) Draw the schematic diagram of the generator. (b) If the variable resistor Radi in this generator's field circuit is adjusted to 63 2 and the generator's =0 to 300 Q; Vp = 430 V; Np= 1000 turns per pole; prime mover is driving it at 1600 rpm, what is this generator's no-load terminal voltage? (c) What would its voltage be if a 360-A load were connected to its terminals? Assume that the generator has compensating windings (d) What would its voltage be if a 360-A load were connected to its terminals but the generator does not have compensating windings? Assume that its armature raection at this load is 450 A.turns. (e) What adjustment could be made to the generator to restore its terminal voltage to the value found in part (b) (f i How much field current would be needed to restore the terminal voltage to its no-load value? (Assume that the machine has compensating windings.) (ii) What is the required value for the resistor Radi to accomplish this?

Answer 1

dc gcncY ator Spar akly cxikd TL Radj VE A RA FA VF PM a Ful loacd: Teminal voltagc- Ve= 430u 400 A Eg FL d VĻ + TAPA 430(400){ 0.05) EgFL > 4-50V Then o REtRod 4-30

(2 Thus EgAL 430 211x 18DD 60 AYmahure conlant Kニ 30 21tx800 KO. Rodj63 430 A ニ 5180み 63+20 At noload - = (0.) (5.1303) (2nx1600 60 96.39| valte E9 NL houng compeneng anding The amoter Teckon con b neglekd Vt EqTa Va So 96.351(360 x0.os) 78.351 Ultp

T amahtre Yracon i Congirlvd ( De magnehpmg ampcx fu nn 4-50 A-T Tofe Amper twn- toodx 430 A be Y duchon n omainal voheg de ho avmatur eachon (4-p) (i000x430) yedwchun(-0. 0.9989 The ig a dochon of /1 n emf generakd. (oid kmna valge) (1- V ccluchon of femnl usltage due fo demegnchAms eA fhere i? adhhone oc nd to nll thobj prdong an ampek tnma Bamm oppo to amaf mmf. Thrp n be donc by Connechng 1n Roes oih amatuc mmf. Compenehing canding Demagnchang K fuxn f Compenahng ndng AT Fcl load Cenl.

4-50 AT NT= 2T TUn 360 A jn pale 3hoe in Renej uith B Conncchng l5 tuing armahe nulliy thip omause veachon drup cer Can noload voltage Noto tminal uolluge nec d to be Yuord 1) Vt = 96.35 ualte 96.3)+ (360)fo.05) Vt TaYa Eg 4.3/V Eg= Cur Know 14.3 5(o) 6.1484 A o./11x 27x 1600 .: Ficki cumcnt Yaured to Yanc Creshorc) 6.1484 A fominal uolfug b no foad uoltag Radj -RF RF+Rad 430 Radj= -20 6.1484 Rad 4-9. 935