Subject 2018 Question Paper — Government College of Engineering and T…
The 2018 Subject previous year question paper (Government College of Engineering and Technology, Jammu), with every question and its marks.
- University: Government College of Engineering and Technology, Jammu
- Course: Design of Power Apparatus
- Branch: ELECTRICAL ENGINEERING
- Year: 2018
- Paper: end-term
- Duration: 180 minutes
- Total marks: 100
Instructions
- Attempt five questions in all selecting at least two questions from each Section.
- Assume suitable data wherever missing.
- Each question carries 20 marks.
Questions
Section - A
- Q1. Determine the main dimensions, number of poles and the length of air gap of a 600 KW, 500V, 900 rpm generator. Assume average gap density as $0.6 \text{ Wb/m}^2$ and ampere conductors per meter as 35000. The ratio of pole arc to pole pitch is 0.75 and the efficiency is 91 percent. The design constrains are: peripheral speed $\le 40 \text{ m/s}$, frequency of flux reversals $\le 50$, current per brush arm $\le 400$, and armature mmf per pole $\le 7500 \text{A}$. The mmf required for air gap is 50 percent of armature mmf and gap contraction factor is 1.15. [20 marks]
- Q2. Discuss armature design of dc machine. [20 marks]
- Q3. Derive the expression for output of transformer for single phase and three phase transformers. [20 marks]
- Q4. Determine the main dimensions of the core, the number of turns and the cross section of conductors for a 5 KVA, 11000/400V, 50 HZ, single phase core type distribution transformer. The net conductor area in the window is 0.6 times the net cross section of iron in the core. Assume a square cross section for the core, flux density $1 \text{ Wb/m}^2$, a current density $1.4 \text{A/mm}^2$ and a window space factor 0.2. The height of window is 3 times its width. [20 marks]
Section - B
- Q5. Discuss choice of average flux density in air gap and ampere conductors per meter. Discuss number of stator slots, area of stator slots and length of mean turn. [20 marks]
- Q6. Determine the main dimensions, turns per phase, number of slots, conductor cross section and slot area of a 250 h.p., 3 phase, 50 Hz., 400V, 1410 r.p.m. slip ring induction motor. Assume $B_{av} = 0.5 \text{ Wb/m}^2$, $ac = 30000 \text{ A/m}$, efficiency = 0.9, power factor = 0.9, winding factor = 0.955, current density = $3.5 \text{ A/m}^2$. The slot space factor is 0.4 and the ratio of core length to pole pitch is 1.2. The machine is delta connected. [20 marks]
- Q7. Discuss design of field winding in a synchronous machine. [20 marks]
- Q8. Discuss armature design in a synchronous machine. [20 marks]