Design of Electrical Machines Practice Test 7

1. What is the bar type current transformer?

primary winding consists of a rod of suitable size and material

primary winding consists of a bar of suitable size and material

secondary winding consists of a rod of suitable size and material

secondary winding consists of a bar of suitable size and material

2. What is the formula for total number of turns in the magnet coils?

total number of turns = mmf per coil + current

total number of turns = mmf per coil * current

total number of turns = mmf per coil / current

total number of turns = mmf per coil - current

3. What is the formula for the breadth of the ac machine?

breadth = 6 / 0.01 * inner diameter of frame

breadth = 6 – 0.01 * inner diameter of frame

breadth = 6 + 0.01 * inner diameter of frame

breadth = 6 * 0.01 * inner diameter of frame

4. What is the work of the frame of dc machines?

to reduce the flux

to carry the current

to carry the flux

to reduce the voltage

5. What is the use of the turns compensation in current transformer?

to increase the phase angle error

to increases the ratio error

to reduce the ratio error

to reduce the phase angle error

6. What is the meaning of stiffness?

ability to withstand the weight of the rotor

ability to withstand unbalanced magnetic pull

ability to withstand the weight of rotor and unbalanced magnetic pull

ability to transmit the power

7. What is the additional usage of the presspahn material used as insulation material?

to reduce the losses

to protect secondary winding conductor from mechanical damage

to protect secondary winding conductor from electrical damage

lamination

8. How is the reluctance of the interleaved corner related with the magnetizing current?

reluctance of the interleaved corner is indirectly proportional to the square of the magnetizing current

reluctance of the interleaved corner is indirectly proportional to the magnetizing current

reluctance of the interleaved corner is directly proportional to the square of the magnetizing current

reluctance of the interleaved corner is directly proportional to the magnetizing current

9. What is the range of current density in the windings of the current transformer?

1-3 A per mm²

2-3 A per mm²

0.5-2 A per mm²

1-2 A per mm²

10. What is the relation of the diameter of the shaft in the bearings to the diameter under the armature?

diameter of the shaft is lesser than the diameter under the armature

diameter of the shaft is equal to the diameter under the armature

diameter of the shaft is very much greater than the diameter under the armature

diameter of the shaft is greater than the diameter under the armature