1.   Describe the key features of dc and ac motors:-

2.   Describe the main methods of starting A.C motors

3.   Describe the advantages and disadvantages of star delta starting

4.   How can the speed and direction of a three phase synchronous motor be controlled

5.   Describe the main factors affecting the selection of an electric motor

6.   Give an example and explanation of the information on a typical motor nameplate.

7.   You have been asked to source a motor ( and starter) capable of powering an escalator; The following information is to be used:-

a)   Angle of escalator = 30deg

b)   Rise = 8m

c)   Each tread = 0.4m

d)   Each tread could have 1 person ( assume 75kg per person)

e)   The escalator rises from bottom to top in 20 seconds

f)    Assume 2kW of load due to friction

g)   The motor will operate in a continuous mode in an ambient temperature between 10 and 30 deg C. The maximum temperature increase is 70 deg C