RTU 2016 Question Paper Semester VIII Electrical and Electronics Engineering Electric Drives And Their Controls

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v,-\ B.Tech. Vm Semester (M ain/B ack) Exa min ation,,4.priVMay 2016
& Electrical and Electronics Engineering
rd 8EX2A Electric Drives & Their Control
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Comrnon With 8EE2A

Time : 3 Hours Maximum Marks : 80
Min. Passing Marks : 24

Attempt any five questions, selecting one question from each unit. All questions
carry equal marks. (Schematic diagratns must be shown wherever necessary.
Any data you feel missing suitably be assumed and stated clearly.)
Units of quantities ttsed/calculated must be stat'ed clearly

Unit - I
1. a) What is the concept of steady state stability explain. Also comment on the
stability of the operating pointA,B,C,D in the given plot of speed v/s motor
and load torques

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b) Drive the equivalent values of drive pararneter
1) For loads with rotatioqal motion
ii) For loads with translation motion

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OR
1. a) Explain the concept of load equalization
b)' Explain the speed torque convention an<l multiquardrant operation of electrical
drive with ansuitable examPle
Unit - II
2. a) Explain the following breaking method for D.c. series and separately excited
motors
i) DYnamic breaking
ii) Plugging
A 200v r-o.s e, 2000 rpm shunt motor has the armature and field
resistance
b) is constant at
of 0.5 and 4009 respectively. lt drives a load whose torque
drops to
,atedmotor to.qil. calculated motor speed if the source voltage
- r75V
OR
resis'tance ,)
2. a) A200y g75 rpm,l50A separately excitecl dc molor has an armaturewith an AC
of 0.06 o. Itls fed from a single phase fully controlled rectifier
calculate
source uotrug" of 220Y,50 tlz assuming continuous cpnduction
1) Firing angle for rated motor torque and 750 rpm
I ii) Motor speed far a:1600 and rated torque
b) Explain the chopper control of seperately excited dc motors for
l) Motoring control
ii) Regenerative braking control
Unit - III
3. a) Explain the any four methods of starting of an lnduction motor drive

b) A2200V,2600kW 735 rpm, 5ltz,and 8 pole 3 pha^se squirrel cage induction
motor' hur the foliowing parameter referred to the stator
; R, = 0.075f) fil = 0,1O X" = 0,45f) X,l = 0.5-cQ stalor winding is
delta connected
,t
\t
andconsistsoftwosectionconnectedinparallel
Calculate starting torque and maximurn torque as a ratio of rated
torque'
D
ii) What will be the value of nraximum line current and torque during starting
if the part winding method of starting is employed

OR
3. a) A 400V star connected 3 phase 6 pole 50 LIZ induction motor has following
parameterreferredtothestator
PCtl4rlrvLvr lvrvrrvr R" = R)ri' =- 1o x .S = --X 1 = 2A r

for regenerative braking operation of the motor determine
D Maximum overhauling torque it can hold and range of speed for
safe
operation
ii) Speed at which it will hold an overhauiing load with a torque of 100 N-m
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converter (vsr) control for an
of voltage source
hi)
w Discuss the operation
' InJuction motor drive

Unit - IV

4. ExPlainthofollowing control
a) Static'o'o' resistance
t) ituti" kramer drive
oR
4. Explainthefollowing
a) StiP Power recovery
Ul Stator scherbius drive ,""
Unit - V
o t.
a) Regenerattvof sYnchron
us moror with VSI
i) Pv""u*it braking
.
OR
trt\

Explainthefollowing
' .. Sortrse Invsrter(CSD
motor using Current
a) Control of 'y"In'onus

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