Electrical engineering Technical Awareness Questions and Answers.

Electrical engineering Technical Awareness Questions and Answers.

01. A simple method of increasing the voltag of a DC generator is

to increase the speed of rotation.

SOLUTION 
Generated voltage is directly proportional to speed. 
Generated voltage
can be increased by increasing speed of rotation.

02. For speeds higher than 3000 r. p. m.
the single phase motor used is

universal motor

SOLUTION
Full-load speeds of universal motors are from 7000 r.p.m. To 10, 000 
r.p.m.

03. The most commonly used material for insulators of overhead transmission lines

porcelain

SOLUTION
Porcelain is mechanically stronger than glass. Further, it gives less trouble from leakage and it is less affected by
temperature variations.

04. With the increase in the values of voltage and power factor, the cost of transmission line conductor

decreases.

05. following generating plants has the minimum operating cost..

hydro-electric plant.

06. The e. m. f. of a DC generator depends on

Speed.

07. Efficiency of Electrical furnaces are about

60-80% and rest heat get waste.

08. What is the maximum distance between
the two successive cleats?

0.6 m.

SOLUTION 
The distance between two successive cleats is 0. 6 m. The life period of this wiring is 3 months minimum and maximum10 to 15 years.

Cleat wiring system is a temporary wiring system therefore it is not suitable for domestic premises.

09.Which of the following devices can be used to test the windings of an inductor for continuity?

Ohmmeter.

10. Magnetic lines of force coming from a magnet

can not intersect at all.

11. The relative permeability of paramagnetic material is

greater than unity.

12. Minimum number of flip flops required to construct BCD counter is

Answer:- 4.

13. A potentiometer type instrument is used for measuring displacement, the response is

Linear.

14. The material used in high frequency
transformer core is

Ferrimagnetic.

SOLUTION
Due to high spontaneous magnetization and insulator property ferrimagnetic
material used in high frequency transformcore to reduce eddy current losses.

15. Hay's Bridge is used for

measurement of unknown inductances in terms of capacitors.

16. The most popular configuration of BJT used is

CE.

SOLUTION
As CE (Common Emitter) has highest current gain and voltage gain and
moderate input and output resistance, so it is used widely.

17. At O°k the conductivity of n type
semi-conductor is

nearly zero.

SOLUTION 
at O ° k there will be no free charge carriers available for conduction of current so,
conductivity will be nearly zero and semiconductor will act as an insulator.

18. EHT cables have rating of

33 kv to 66 kv

SOLUTION
ST cables : Super-tension cables with a rating of between 22kv to 3kv.

EHT cables : Extra high-tension cables with a rating of between 33kv and 66kv.

Extra super voltage cables : with a
maximum voltage rating beyond 132kv.

19. To measure very low resistance values the instrument used is

Kelvin's double bridge method.

20. Thyristor are used in HVDC transmission just to improve

Rating of voltage

SOLUTION
In HVDC transmission, the purpose of Thyristor is to increase the voltage rating.