Design of Electrical Machines Practice Test 1

1. For a DC machine, the armature slot pitch is 35mm and the diameter is 0.2m. What is the number of armature slots for the machine?

2. What is the property of insulating materials?

Increases the unwanted flow of current

Allows the unwanted flow of current

Decreases the unwanted flow of current

Prevents the unwanted flow of current

3. What is a commutator in DC machines?

mechanical device which reverses the current direction between the rotor and external circuit

mechanical device which allows the current flow between the rotor and external circuit

electrical device which allows the current flow between the rotor and external circuit

electrical device which reverses the current direction between the rotor and external circuit

4. How many classifications of magnetic materials are present?

5. What is the total number of design steps available for the commutators in DC machines?

6. High conductivity materials are used in electrical machines.

True

False

7. What is the condition for choosing the armature current/parallel path in armature design?

<200 ampere for lap winding, >200 ampere for wave winding

> 200 ampere for both lap and wave windings

< 200 ampere for both lap and wave windings

>200 ampere for lap winding, <200 ampere for wave winding

8. How should the conducting materials be in terms of malleability and ductility?

highly malleable, less ductile

less malleable, less ductile

less malleable, highly ductile

highly malleable, highly ductile

9. How many classifications of overhead line insulators are there?

10. Given Z=228 conductors, number of coils C=38 for a DC machine. What is the turns/coils ratio?