DC Machine

If the energy conversion is from mechanical to electrical, then this machine is ...

• a) Motor

• b) Generator

• c) Alternator

• a) & c)

• b) & c)

If the energy conversion is from electrical to mechanical, then this machine is ...

• a) Motor

• b) Generator

• c) Alternator

• a) & c)

• b) & c)

If the armature is of lap winding, then the turns ratio is ...

• equal to 2

• equal to the number of poles

• equal to the number of poles divided by 2

If the armature is of wave winding, then the turns ratio is ...

• equal to 2

• equal to the number of poles

• equal to the number of poles divided by 2

In DC machines, the synchronous frequency is ...

• fixed and equal to 50 Hz

• fixed and equal to 60 Hz

• according to the problem given

How many losses exist at any DC machine?

• 2

• 3

• 4

Write the scientific names of these losses

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Answer explanation

Pcua: armature/stator copper loss & Prot: rotational/mechanical loss

In series DC machines, the terminal current is equal to ...

• a) the armature current

• b) the field current

• a) & b)

• a) minus b)

• a) plus b)

In shunt DC machines, the terminal current is equal to ...

• a) the armature current

• b) the field current

• a) & b)

• a) minus b)

• a) plus b)

At the end of the course, name 2 activities that you disliked from the whole experience?