Yashwantrao Chavan Maharashtra Open University 2006 Certification TES Electric Drives - Question Paper

TES123/EE/20070817
Electric Drives
Time : 180 minutes Marks : 100
Instructions for the students :
1. All ques. are compulsory.
2. “Long ans kind ques. (LAQ)” is a supply kind ques. of 20 marks,
which require typical ans of about 60-80 lines in about 32-40 minutes.
3. “Short ans kind ques. (SAQ)” is a supply kind ques. of five marks,
which require typical ans of about 15-20 lines in about 08-10 minutes.
4. Use of non-programmable kind of scientific calculator is allowed.
5. Draw neat diagrams wherever necessary.
6. presume suitable data if necessary.


Long ans kind ques. (LAQ’s)

1. (a) Name the 4 parameters of a DC motor that a DC drive
controls. discuss the importance of feedback signal. Name
at lowest 2 sources of feedback signal in DC drive.
(b) discuss the operation of switching amplifier field current
controller. Support your ans with a simple block
diagram and waveforms.
(c) Mention the differences and similarities ranging from the
switching amplifier field current controller and the SCR
armature voltage controller.



2. (a) List 6 various kinds of braking techniques used in
electrical motors. discuss any 1 in detail.
(b) discuss the operation of four-quadrant chopper. Support
your ans with simple block/circuit diagrams. Compare it
with two-quadrant chopper.


3. (a) discuss the term V/Hz as related to AC drive. discuss its
importance.
(b) Mention the different methods of speed control of AC
induction motor. discuss any 1 in detail.


4 discuss saturable reactor in detail. How a saturable reactor can
be used with an AC motor ?

Short ans kind ques. (SAQ’s)

5. How does the 4 Phase (Magnetic sensing) BLDC motor
controller operate ?

6. Name the safety steps that 1 should follow prior to working on
a DC drive system.

7. Name the 4 areas to check when a issue occurs with an AC
inverter drive.
Where is the best place to being troubleshooting an AC inverter
drive ? Why ?

8. How a suitable reactor is used with a DC motor ?

Earning:   Approval pending.