ET ONLINE 4

1 . T h e r ot or of a 3- p h as e wo u n d r ot o r i n d u c t i on m ot o r i s p rov id e d w i t h ( a) S i n g l e p h a s e - w i n d i n g . ( b ) h e avy c op p e r or al u m i nu m b a r s p l a c e d in r ot o r s l o ts . ( c ) H e avy s h or t - c i r c u i t e d e n d r i n g s ( d ) T h r e e p h as e w i n d i n g

2 . A wo u n d r o to r i n d u c t i o n m o to r c a n b e d i s t i n g u i s h e d f ro m s qu i r r e l c ag e i n d u c ti o n m o t or by ( a) P r e s e n c e o f s l i p - r i n gs ( b ) s h a f t d i a m e t e r ( c ) L e n g th of f r am e ( d ) s i z e o f f r a m e


3 . T h e r o to r of a 3 - p h a s e i n d u c t i o n m ot or r o ta t e s i n t h e s a m e d i r e c t i o n as t h a t o f s t a t or r ot a ti n g fi e l d . T h i s c an b e e x p l a i n e d by ( a) N e w t o n s l aw s of m ot i o n ( b ) F l e m i n g s r i g ht h an d ru l e . ( c ) Fa r ad ay s l aw s o f e l e c t or - m ag n e t i c i n d u c t i o n ( d ) L e n z s l aw

4 . T h e re s u l ta nt fl u x d e ve l op e d by t h e s t at or o f a 3 - p h a s e i n d u c t i o n m ot o r i s , i f δ i s t h e fl u x d u e to o n e p h a s e . ( a) 3 δm / 2 ( b ) δm / 3 ( c ) 3 δm ( d ) ( 2/ 3 ) δm

5 . . I f t h e r o to r p f of a 3 - p h a s e I M i s 0 .8 6 6, t h e n s p at i a l d i s p l a c e m e nt b e twe e n t h e s t at o r m ag n e t i c fie l d a n d r ot o r m a gn e t i c fi e l d w i l l b e ( a) 1 50 0 ( b ) 1 20 0 ( c ) 3 0 0 ( d ) 9 0 0

6 . T h e r ot o r p owe r ou t p u t o f a 3 - p h a s e i n d u c ti o n m o t or i s 1 5 K W . T h e ro t or c op p e r l o s s e s at a s l i p 4 % w i l l b e ( a) 6 50 W ( b ) 7 00 W ( c ) 6 25 W ( d ) 6 00 W


7 . A S C I M r u n s at c on s ta nt s p e e d o n l y s o l o n g as ( a) I t s to r q u e e x a c t l y e q u al s t h e m e cha n i c a l l o ad ( b ) Tor q u e d e ve l o p e d by i t re m ai n s c o n s t ant ( c ) S t at o r fl u x r e m a i n s c o n s t a nt ( d ) I t s s u p p l y vol t a ge re m ai n s c o n s t ant

8 . A ch a n g e o f 5 % i n s u p p l y vol t a ge w i l l c a u s e ap p r oxi m a t e l y ch a n ge i n i t s t o r qu e ( a) 2 . 5% ( b ) 5 % ( c ) 2 5% ( d ) 1 0%

9 . W h e n l oa d i s p l ac e d o n a 3 - p h a s e i n d u c t i o n m o t or , i t s s p e e d ( a) i n c r e a s e s f o r s o m e va l u e an d re ma i n s c on s ta nt ( b ) r e m a i n s c o n s t ant ( c ) I n c r e a s e s ( d ) d e c r e a s e s
1 0. T h e f u l l l o ad s l i p o f a 60 H z , 12 p o l e s q u i rr e l c a ge i n d u c t i on m ot o r i s 5 % . I t s f u l l l o ad s p e e d i s ( a) 5 70 r p m ( b ) 6 00 r p m ( c ) 4 75 r p m ( d ) 5 00 r p m

1 1. T h e r at i o of s t a rt i n g t o rq u e to m a x i mu m t or q u e i s 8 0% . T h e s p e e d a t w h i ch m ax i mu m t or q u e i s 1 2% w i l l b e ( a) 1 /3 ( b ) 2 ( c ) 5 /3 ( d ) 3 /5

1 2. T h e t or q u e - s l i p ch a r ac t e r i s t i c o f p o l y p h a s e i n d u c t i on m o to r b e c o me s a l m o s t l i n e a r a t s m al l va l u e s of s l i p , b e c au s e i n t h i s r an g e o f s l i p s ( a) T h e r ot or re s i s t an c e i s e q u al t o th e s t at o r r e s i s t a n c e . ( b ) T h e r ot or re s i s t an c e i s e q u al t o th e r ot o r r e ac ta n c e ( c ) T h e e ff e c t i ve r o t or c i rc ui t re s i s t an c e i s ve ry l ar g e c o m p ar e d t o th e r ot o r r e ac ta n c e ( d ) T h e r ot or re s i s t an c e i s e q u al t o th e s t at o r r e a c t an c e

1 3. I n a p ol y - p h as e s q u i r re l c a ge i n d u c t i on m ot o r i n c r e a s e d s ta r t i n g to r q u e c a n b e o b ta i n e d by ( a) I n c r e a s i n g t h e f re qu e n c y o f o p e r at i o n ( b ) u s i n g a d o u b l e c a g e r o to r ( c ) u s i n g d e e p b ar ro t or s ( d ) I n c r e a s i n g t h e nu mb e r of p o l e s

1 4. c o gg i n g o f i n d u c t i o n m o to r s o c c u r s at ( a) l ow vol t ag e an d w h e n t h e nu mb e r of s t a to r t e e t h a n d r o t or t e e t h ar e n ot e q u a l ( b ) l ow vol t ag e an d w h e n t h e nu mb e r of s t a to r t e e t h a n d r o t or t e e t h ar e e q ua l ( c ) h i g h vol t ag e an d w h e n t h e nu mb e r of s t a to r t e e t h a n d r o to r t e e t h ar e e q ua l ( d ) h i g h vol t ag e an d w h e n t h e nu mb e r of s t a to r t e e t h a n d r o to r t e e t h ar e n ot e q u a l

1 5. I n i n d u c t i on mo t or s , t h e s h o r t - c i r c u i t t e s t i s t e s t ( a) s t a to r r e s i s ta n c e ( b ) n o - l o ad ( c ) o p e n - c i rc u i t ( d ) b l o cke d r ot o r

1 6. S t ar - d e l t a s t ar t i n g i s e q u i val e nt t o a u to - t r a n s f o rm e r s t ar t i n g w i t h t ap p i n g . ( a) 3 3. 3 ( b ) 8 3 ( c ) 5 7. 7 ( d ) 5 0

1 7. W i t h D O L s t ar t o f an i n d u c ti o n m o t or t h e h e a ti n g d u r i n g a c c e l e r a ti o n o f i n e r ti a l o ad i s p r o p o rt i o n al to ( a) S t or e d k in e ti c e n e r g y ( b ) e l e c tr o m a gn e t i c p owe r d e ve l op e d o n r ot o r ( c ) s l i p at m a x i mu m t or q u e ( d ) M a x i mu m t or q u e

1 8. S u p p l y f r e q u e n c y c ont r ol i s g e n e r a l l y aff e c t e d w i t h c o n s t ant ( a) s u p p l y vo l ta ge V ( b ) V * f ( c ) V / f ( d ) V * 2f

1 9. T h e r e l at i ve s p e e d b e twe e n s t a to r a n d r o to r fi e l d s , i n a n i n d u c t i o n m o to r i s e q u al to ( a) Z e ro ( b ) s l i p s p e e d ( N s +N r ) . ( c ) s y n ch r on o u s s p e e d , N s . ( d ) S l i p s p e e d ( N s - N r ) .

2 0. I n a s e l f e x c i t e d i n d u c t i on ge n e ra t or , t o ke e p t h e f re q u e n c y o f g e n e r a te d vol t a ge c o n s t ant w i th t h e i n c r e a s e i n l o a d , t h e s p e e d of th e i n d u c t i o n m ach i n e s h o u l d b e ( a) m a i nt a i n e d m o r e t h a n t h e r a te d s y n ch r on o u s s p e e d ( b ) d e c r e a s e d ( c ) m a i nt a i n e d l e s s t h a n t h e r a t e d s y n ch r on o u s s p e e d ( d ) i n c r e a s e d
ANS:A,B,B,D,A ,C,B,D,C,A ,B,A,C,B,C ,B,D,A,C,B.