Punjab Technical University 2005-6th Sem B.Tech Electrical and Electronics Engineering Electrical Drives and Utilization (New) 2k5 - Question Paper

ELECTRIC DRIVES AND UTILIZAION (New) EE 304 sixth Sem May 2k5

Max Marks 60

Note: part A is compulsory. Attempt any 4 ques. from part B and 2 from part C. presume any missing data.

Section A Marks two every

1.
(a) Enumerate the merits and demerits of group drive.
(b) What the properties of d.c. series motor which make it more suitable for heavy Torque applications?
(c) What kind of drives are used in lifts? provide reasons.
(d) What are the advantages of load equalization?
(e) How will you control most efficiently the heat of resistance furnace?
(f) What factors limit the option of high frequency in dielectric heating?
(g) What kind of electric supply is suitable for electric arc welding?
(h) What are the advantages of iodide coil filament gas filled lamp?
(i) What is polarization and how its bad effects on electrodeposition process can be reduced?
(j) How can the temperature inside the refrigerator be adjusted?

part B Marks five every

2. How are refrigerator, water cooler and air conditioner various tin terms of their refrigeration systems?

3. elaborate various kinds of flood-lighting installation?

4. A series motor working on 200 V takes 20 amps and runs at 1000 rpm. Armature and series field resistances are 0.1 and 0.4 ohms. At what speed will it run when a resistance of 20 ohms is placed in parallel with the armature? presume magnetic circuit to be unsaturated and torque to remain constant.

5. An insulating slab two cm thick of 150 sq. cm. in area is to be heated by dielectric heating. The power needed is 300 watts and frequency 30 MOPs is to be used. The material has relative permittivity of five and p.f. of 0.05. Determine the voltage necessary and current that will flow through the material.

6. elaborate the advantages of 25 kV a.c. system of track electrification over other systems?

part C Marks 10 every

7. With the help of a sketch discuss the working of a resistance furnace and show how the diameter and length of the heating element is designed.

8. (a) A three-phase 400 V 50 cycles per sec four pole induction motor with stator and rotor star connected has rotor resistance of one ohm. Ratio of stator to rotor turns is 1.25. If the full load slip is 4%, compute the torque developed, rotor output in h.p. and ratio of maximum torque o starting torque.
(b) elaborate the requirements of Rolling Mill drives and what kind of motors are used?

9. (a) Enumerate different factors affecting the design of indoor lighting installation.
(b) If a lamp of 200 cP is placed one metre beneath a plane mirror which reflects 90% of light falling on it, determine illumination at a point three metre away from foot of the lamp which is hung four metres above the ground.

Earning:   Approval pending.