ECET EEE 2009-2

1.Waveform of output voltage of a single phase bridge inverter is

A. Purely sinusoidal
B. Triangular
C. Square wave
D. Trapezoidal

Answer : Square wave
Explanation:-

2.The output voltage of an inverter for driving ac motor should have

A. both amplitude and frequency variable so as to maintain the ratio of two constant
B. both amplitude and frequency variable independently
C. only amplitude variable
D. only frequency variable

Answer : both amplitude and frequency variable so as to maintain the ratio of two constant
Explanation:-

3.A cyclo converter is a

A. phase angle changer
B. frequency changer
C. waveform changer
D. amplitude changer

Answer : frequency changer
Explanation:-

4. In a seperatley excited dc motor controlled by a singe phase full converter device, under continuous armature current condition, average armature voltage is given by

A. Vm/π cosα
B. Vm/π(1+cosα)
C. 2Vm/(1+cosα)
D. 2Vm/π cosα

Answer : 2Vm/π cosα
Explanation:-

5. 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 likely to be

A. about 350 r.p.m
B. about 250 r.p.m
C. about 175 r.p.m
D. about 125 r.p.m

Answer : about 125 r.p.m
Explanation:-

6.In a GTO, anode current begins to fall when gate current

A. is negative peak at time t = 0
B. Is negative peak at t = storage period Ts
C. Just begins to become negative at t = 0
D. Is negative peak at t (ts + fall time)

Answer : Is negative peak at t (ts + fall time)
Explanation:-

7.In d.c chopper, if 'T' is chopping period, then output voltage can be controlled by varying

A. T, keeping T on constant
B. Ton, keeping T constant
C. Cannot be controlled
D. T, keeping Toff constant

Answer : Ton, keeping T constant
Explanation:-

8. The 8051 micro controller has a total of _______ pins for I/O operations

A. 4
B. 8
C. 16
D. 32

Answer : 32
Explanation:-

9. The program status word of 8051 micro-controller is _____ bit register

A. 2
B. 4
C. 8
D. 16

Answer : 8
Explanation:-

10.A current of 10 A is passed through a resistance of 100Ω for hour the energy consumed is

A. 1 kwh
B. 100 kwh
C. 10 kwh
D. 50 kwh

Answer : 10 kwh
Explanation:-