Electrical Machines Practice Test 4

1. The pitch factor, in rotating electrical machinery, is defined as the ratio of resultant EMF of a _________

2. If the current in a coil is AC, the amplitude of MMF ___________

3. What are the main problems faced by conventional DC exciters?

4. Most commercial compound dc generator are normally supplied by manufacturers as ______ compounded machines.

5. The manufacturer has mentioned a medium starting torque and 15% speed regulation. Which is the most appropriate motor for this requirement?

6. The rotating amplifiers are widely used in ____________

7. In the following applications of the dc machines, but all are not matched correctly. Choose the wrong marking.

I. DC shunt motor - Lathe machine
II. DC compound generator - Drilling machine
III. Differentially compounded generator - welding purposes

8. If the current in the coil is DC, then MMF doesn't vary with ____________

9. The flux addition is due to ______________

(i) sinusoidal distribution of mmfs
(ii) zero relative velocity between two mmfs
(iii) spatial distribution of three phases by 120°

10. A fraction pitch winding is used to reduce which of the following?

(i) amount of copper in the winding
(ii) size of the machine
(iii) harmonics in the generated EMF
(iv) cost of the machine