7/21/2019 BE 104 Paper April 2014.docx

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TRUBA GROUP OF INSTITUTES, BHOPALMID SEM-II (APRIL 2014)

Subje! N"#e$ BEE (BE-104)

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UNIT-II31 ")How the quality of core material affects the performance of the transformer? (1) b)Define Permeability and Reluctance in magnetic circuit. (1)

)Draw and explain the phasor diagram of transformer for lagging power factor Load (2)

) !"" #$ transformer has a primary winding resistance of ".% ohm and a secondary winding resistance of".""&ohm. 'he iron loss is .% #) and the primary and secondary *oltages are % #$ and +" $

respecti*ely. ,f the power factor of the load is ".-% determine the efficiency of the transformer (a/ on full

load and (b/ on half load. ()

OR

e) """0$ +"1&&%0$ transformer has been tested to determine its equi*alent circuit. 'he results of the

tests are shown below

2pen0circuit test 3hort0circuit test $245 +" $ $345 &+. $

,245 ".!% ,345 6."

P24 5 +" ) P345 ".& )

ll data gi*en were ta#en from the primary side of the transformer.(a) Draw the equi*alent circuit of this transformer referred to the low0*oltage side of the transformer.(b) 7ind the transformer8s *oltage regulation at rated conditions and (&/ ".- P7 lagging.(c) Determine the transformer8s efficiency at rated conditions and ".- P7 lagging.

UNIT-III

32 ") 9xplain why a three phase induction motor is called as asynchronous motor? (&/b)9xplain bac# emf in a D4 motor. (1)

) Deri*e the emf equation of a multi0pole D4 machine (2)

)'he frequency of the supply to the stator of an -0 pole induction motor is %" H: and the rotor frequency is +

H:. Determine (a/ the slip and (b/ the rotor speed ()

OR

e) shunt generator supplies a %" #) load at !"" $ through cables of resistance ". ohm. ,f the field winding

resistance is %" ohm and the armature resistance is "."% ohm determine (a/ the terminal *oltage (b/ the e.m.f.

generated in the armature.

UNIT-3 ")Define Doping and 7orbidden 9nergy gap. (1)

b)Differentiate between ,ntrinsic and 9xtrinsic 3emi0conductor. (1)

)9xplain 7orward ;iased and Re*erse ;iased in P< =unction Diode. (/ )Draw and explain the wor#ing of >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>..