ELECTRICAL ENGINEERING QUESTION ANSWERS- 05/10/20016

1. Which of the following is an open loop control system ?
(a) Metadyne
(b) Ward leonard control
(c) Stroboscope
(d) Field controlled D.C. motor
Ans: (d) Field controlled D.C. motor

2. Which of the following statements is correct for a system with gain margin close to unity or a phase margin close to zero ?
(a) The system is relatively stable
(b) The system is highly oscillatory
(c) The system is highly stable
(d) None of the above
Ans: (b) The system is highly oscillatory

3. A current density of _____ is ilsed for large power transformers with forced circulation
of oil or with water cooling coils
(a) 1.5 to 2.5 A/mm2
(b) 5.4 to 6.2 A/mm2

(c) 4.0 to 5.0 A/mm2
(d) 3.5 to 4.5 A/mm2
Ans: (b) 5.4 to 6.2 A/mm2

4. A voltage of about 200 V can be measured
(a) a D.C. potentiometer in conjunction with a volt ratio box
(b) directly by a D.C. potentiometer
(c) a D.C. potentiometer in conjunction with a known resistance
(d) none of the above
Ans: (a) a D.C. potentiometer in conjunction with a volt ratio box

5. The effect of error damping is to
(a) provide larger settling lime
(b) reduce steady state error
(c) delay the response
(d) any of the above
 Ans: (b) reduce steady state error

6. In induction motors, the length of air gap in kept as small as mechanically possible is
order to have
(a) low power factor
(b) high over load capacity
(c) high power factor
(d) any of the above
Ans: (c) high power factor

7________ is not a final control element.
(a) Control valve
(b) Electro-pneumatic converter
(c) Potentiometer
(d) Servomotor
Ans: (c) Potentiometer

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