﻿ Virtual Labs - DEI

## QUIZ - 2

1. Ratio of Xd/Xq for cylindrical alternator is ------- Xd/Xq of salient pole machine
• greater than
less than
Equal to
None of the above

2. Steady state direct axis reactance is ---------- transient direct axis reactane
• greater than
less than
Equal to
None of the above

3. In an hydro alternator, if Xd=1.15 then the value of Xq will be approximately
• 1.75
15
0.75
0.075

4. In Salient pole alternator the rotor diameter is -------- its length
• greater than
lesser than
Equal to
None of the above

5. While conducting slip test, the synchronous machine runs at a slip ‘s’ and stator supply frequency ‘f’, the frequency of
1. voltage induced across open field terminals
2. envelope of the armature terminal voltage
3. envelope of the armature current, and
4. armature current
will be respectively
• sf, sf,sf and f,
sf, f, sf and f
f, sf, f and sf
f, (1-s)f,(2-s)f and sf

6. When a synchronous motor is running at synchronous speed, the damper winding produces
• Damping toruqe
Eddy current torque
Driving torque
No torque

7. The reactance of any machine is ------------- proportional to relucatance of flux path and ---------- proportional to square of number of turns
• inversely, directly
directly, inversely
directly, directly
inversly, inversly

8. The armature reactance of salient pole synchronous machine
• is equal to Xd
is equal to Xq
varies between Xd and Xq
none of the above

9. The ratio of Xd to Xq in salent pole machine varies in the range
• 0.66 to 0.7
0.3 to 0.0.5
0.9 to 1.0
1.0 to 1.5

10. By which test synchronous machine can be recognised as cylindrical or salient pole type?
• Slip Test
Static Test
Open circuit Test
Short circuit Test