191. A single-phase transformer is feeding a lagging load. What will be the effect on t he voltage regulation of the transformer if
     (i) an inductor is connected in parallel to the load
     (ii) a capacitor is connected in parallel to the load The regulation will

1. 1. decrease in both the cases.

   
   
   

   2. increase in both the cases.

   
   
   

   3. increase in case (i) but decrease in case (ii).

   
   
   

   4. decrease in case (i) but increase in case (ii).

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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192. The magnetic core of a certain material is operated at constant flux density. If core losses measured at 50 Hz and 75 Hz are respectively 2000 W and 3375 W, the hysteresis and eddy current losses of the core at 100 Hz would respectively be

1. 1. 2500 W, 2000 W

   
   
   

   2. 2000 W, 2500 W

   
   
   

   3. 3000 W, 2000 W

   
   
   

   4. 2000 W, 3000 W

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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193. A torroidal ferromagnetic ring is uniformly wound with copper wire of certain turns. A dc voltage V1 is applied across the winding to cause a uniform flux density in the ring. If linear dimensions of the ring, number of turns and length of a mean turn are doubled without changing gauge of the wire, then dc voltage required to be applied across then new winding to produce same flux density will be

1. 1. V₁ /2

   
   
   

   2. V₁

   
   
   

   3. 2V₁

   
   
   

   4. 4V₁

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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194. In electromechanical energy conversion device shown in the given figure, instantaneous values of armature induced emf, bus bar voltage and armature current are respectively e, v and i, T_e, T_a and ω_r represent external torque, armature developed torque and angular velocity of shaft respectively. Assume that given directions of parameters in the figure are positive. If device is working generating mode, then
     

1. 1. all parameters will have the positive direction

   
   
   

   2. e, υ, T_e and ω_r will have negative direction and others will remain in positive direction

   
   
   

   3. T_a and i will have negative direction and others will remain in positive direction

   
   
   

   4. T_e and ω_r will have negative direction and others will remain in positive direction

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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195. The developed electromagnetic force and/or torque in electro-mechanical energy conversion systems act in a direction that tends to

1. 1. increase stored energy at constant m.m.f.

   
   
   

   2. decrease stored energy at constant flux

   
   
   

   3. decrease co-energy at constant m.m.f

   
   
   

   4. decrease stored energy at constant m.m.f.

   
   
   

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1. View Hint View Answer Discuss in Forum

   In the eletro-mechanical energy conversion system,
   Mechanical energy output = electrical energy input – increase in stored energy
   ∴  F_ƒdx = i dλ − dW_ƒ
   where, F_ƒ = torque developed
   λ = flux linkages
   W_ƒ = stored energy
   If flux is constant, then
   dλ = 0
   ∴  F_ƒdx = – dW_ƒ
   

   ⇒ Fƒ = −	dWƒ
   	dx

   
   From the above relation, torque developed will be in opposite direction of stored energy,

   Correct Option: B

   In the eletro-mechanical energy conversion system,
   Mechanical energy output = electrical energy input – increase in stored energy
   ∴  F_ƒdx = i dλ − dW_ƒ
   where, F_ƒ = torque developed
   λ = flux linkages
   W_ƒ = stored energy
   If flux is constant, then
   dλ = 0
   ∴  F_ƒdx = – dW_ƒ
   

   ⇒ Fƒ = −	dWƒ
   	dx

   
   From the above relation, torque developed will be in opposite direction of stored energy,

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