A dc separately excited motor has constant field current. The armature is fed fr

CuriousTab

CuriousTab

Home Aptitude

Discussion

Home ‣ Electronics and Communication Engineering ‣ Power Electronics See What Others Are Saying!

Question
A dc separately excited motor has constant field current. The armature is fed from a single phase supply through a full converter. When a = 0, speed is 500 rpm. If a = 45�, the speed is likely to be
Options
A. about 350 rpm
B. about 250 rpm
C. about 175 rpm
D. about 125 rpm

Correct Answer

about 125 rpm

Explanation

Average output voltage ? cos a and therefore reduced to 0.707 of the value for a = 0. Speed is nearly proportional to voltage.

More questions

1. The power requirements of a DRAM in active and stand by modes is about
Options
A. 350 mW and 5 mW respectively
B. 350 mW each
C. 5 mW each
D. 350 mW and 100 mW respectively

2. The different access methods which permit many satellite users to operate in parallel through a single transponder without interfering with each other as
Options
A. Frequency Division Multiple Access (FDMA)
B. Time Division Multiple Access (TDMA)
C. Code Division Multiple Access (CDMA)
D. All of the above

3. Match the following:

	List I		List II
A.	T (Reflection coefficient) = 0	1.	(Z_L - Z_o)/(Z_L + Z_o)
B.	T = - 1	2.	Z_L = Z_o
C.	T = + 1	3.	Z_L = 0
D.	- 1 < T < + 1	4.	Z_L = ?

Options
A. A-2, B-3, C-4, D-1
B. A-2, B-4, C-1, D-3
C. A-1, B-2, C-3, D-4
D. A-3, B-2, C-4, D-1

4. Assertion (A): Ferromagnetic materials possess ferromagnetic properties only when temperature is less than paramagnetic curie temperature.
Reason (R): For a ferromagnetic material for T > ?_f.
Options
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true but R is false
D. A is false but R is true

6. A two branch parallel circuit has a 20 ? resistance and 1 H inductance in one branch and a 100 ?F capacitor in the second branch. It is fed from 100 V ac supply, at resonance, the input impedance of the circuit is
Options
A. 500 ?
B. 50 ?
C. 20 ?
D. 5 ?

8. An amplifier has a large ac input signal. The clipping occurs on both the peaks. The output voltage will be nearly a
Options
A. sine wave
B. square wave
C. triangular wave
D. (a) or (c)

9. In the figure shown, A₁, A₂, A₃ are identical Ammeters. If A₁ and A₃ read 5 and 13 A respectively, reading of A₂ will be
Options
A. 8
B. 13 A
C. 18
D. 12 A

Comments

There are no comments.

More in Electronics and Communication Engineering: