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Test #2

# Test #2 - a f/M 11.14.05 EE 4420 Name Merriam ﬁeﬁm-Ar...

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Unformatted text preview: a f/M 11.14.05 EE 4420 Name: Merriam . . ﬁeﬁm-Ar. .. MID—SEMESTER TEST No. 2 Solve the numerical problem (question 6) and answer 3 out of 5 theoretical questions. Question #1 (2 points) a) Draw the torque-speed characteristic of induction machine in the entire speed range and Show on speed axis the 3 modes of operation. What is the rotor frequency in each mode? '_ b) Draw the equivalent circuit for motor operation showing wﬁon of ﬂow of power components. w 4.23 7H7”; 10\$; 4:. irovhv—gh Mews 1 WWW“ T GEMEﬂﬁWC-‘a J ﬁML Question #2 (2 points) a) List the methods, which are applied to speed control of induction motors. Which of these methods can be applied to control the speed of squirrel-cage, which — to slip ring motors only. Explain why. b) Using the torque-speed characteristics describe the variable ﬁequency method with constant magnetic maximum torque. Question #3 (2 points) a) Specify the methods that are used to start the induction motors. Which ones of them are applied to slip-ring and which ones —— to cage motors. b) Describe in details (using torque-speed and current-speed characteristics) starting of slip-ring motors. Does the motor develop any starting torque when the total rotor resistance equals zero? Explain why. Question #4 (2 points) Draw the torque-speed characteristics: - For 3 different rotor resistances - For 3 different supply voltages - For 3 different supply frequencies if: a) The supply voltage V1 = const, b) The V1/f1 = const T. 73123157: 64??” \Juureczvﬁs \/ hbr jaw; 5L 5mm ‘nn‘h' “‘3 “1 ’ IF w, m]. Hmnm __ H: VI-‘(UMT (IMM-q‘ n‘lr \L muss]. \I E“ rrommpr “ H“ n\‘I jN‘F-i' (ONsT 0'5! “Lin Question #5 (2 points) 1) Draw the phasor diagrams that show alternating and elliptic magnetic ﬂuxes represented by two circular ﬂuxes. 2) Specify the conditions for generating of rotating (elliptic) magnetic ﬁeld and circular magnetic ﬁeld. 3) Write the values of the rotary speed of the magnetic ﬂux for 2, 4 and 6 magnetic poles of the stator winding if is supplied with 60 Hz frequency. 0,. 1.35: _ mom F3 ' f (3 9:2 EEO-zeourrn 2L 72‘” 0 F N P if . {8° F pie #213". I190 rpm \> ALTEEumlrdb, MBC‘JIJETIL 1w; ELLIPT‘C. MAC—ME;er 1:th kw .. it FM [9145 -' Fm. 5mm) Cosiut.\ @1933 -' a imgnmuthi taut ‘3'.“(6IMD Z) COND‘T’DNé FDﬂ QVENEEMNG, Fo'lﬂﬂub MAGMEWC We L0 ..— gHDuLD MRUE AT LaHsT "L IN [N95 DigpLhLE—D 1N SPACE ,— TH’Esr w OWL N 15 womb gg snowmen #39 AC Cuﬂﬂ-ENT S SHrFTEO NTIME I'F l5 [Jo-T THE“) FT 19 ALTEKNMNG; MAC: tiff—U9 it'uRCLE‘ M (M Made smmevﬁucﬁc umoudcqc ELciPTIc: -I -' Hue mo 94MMEmrcAc, SMPPU‘f 4/4 Question #6 (4 points) A 15 hp, 208 V, 60 Hz, Y-connected, 6-pole induction motor has a slip of 0.05 when operating at full load condition. Its mechanical power losses are negligible. 21) Find the rotor Speed 11, rotor frequency f2 and the full load torque. (1 p.) b) Determine the power crossing the air-gap, power losses in the rotor winding and the motor ideal efﬁciency (PM = Pug ). (1 p.) c) Find the starting current and the starting torque if the motor is supplied by the rated voltage and its per phase equivalent circuit parameters are: R1 = 0.2 Q, R; = 0.12 (1, X51 = 0.41 9, X; = 0.41 S) , Xm =15 Q (ignore the 11:3 current) (2 p.) Ci 3 n5 2 5 ’2°( éaﬁ~ [ZoOr I P I c, ' m ‘ nae“ [loo-I ' : 3 5 6' ﬂ . - n l as " ) IDS ‘ 3200 V ' T= 4137 i ' re - Nu : “LIOFPn \/ :.= w - E \$2; 6?: ‘- [MAG-ﬂ: 3H2 /// T: 2%“: [90(5wa FL 7mm 72:1 Cut-m ‘ ?3.7,\/M \/ ‘5 ' {’5 P T 31:: J Fm W 737 S ILS.G(. 055' ans l/ #70:, _. IZWG /// (DH- stwsymm =383.w ﬁkt EFF : a) Q\:‘ 1Y5; ﬁb‘é Afr MW {Us , . : _ Lg: LESLIE” ITAH’ a?!” “grasp.” 74“, gm?! ‘ ‘ I a . .1151"?- *J'”0 gl‘ﬁr {9&5 (I? §l{,ud\ A.‘LW+ZT.%-~733”‘SM '—————F—"’H__' -——-""_’ —‘ """' J _' \l'i ill—ﬂ!“ ‘ r i .9 [mi Hewibl- “i. 03% .\1_ idvu-i I7 ; f.lS.HLl Vat-‘1 Wad .\ am .. ‘J’ C Jrzitur lingo 53.0%ng 70.42:: r at H ‘ : I20“ \[xoh ‘ Q: t 'Lk “:- \ E\:"L-\ SAM f .H b J Vi 11-0 5.0 I'ST : E;— '. 2 .4 i U3“: \$065” (9350 \/ (3; ST.- le CM” ( . Ezo no _ J. 2 T: I n W 5 W 1 . 7,61] 7;. A 4T xi}? I 4 El; ‘. BIL“ 4,“: “47.7! 73.7 t/ ‘5 5 I1 { 1:197 73):}: A] 5 f {3— 91m” [82% “r” ‘\ 1 I T m 3 ( J / “’2 2 (“mm T ﬁr” ’ “ ““““““““““ ”’ “ff—w 229 N M 5 Wﬁ “S ‘2 54an M— ...
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Test #2 - a f/M 11.14.05 EE 4420 Name Merriam ﬁeﬁm-Ar...

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