Chapter 2 Review

Welcome to your Chapter 2 Review

1. Transformer cores are made up of:
2. Transformer core losses:
3. Core loss consists of:
4. Exciting current is:
5. Why are transformer laminations insulated from one another?
6. The flux density in a transformer core increases if: (pick the true statements)
7. An increase in line voltage of 25 percent on a 50 KVA transformer will have what results? (pick the true statements).
8. The basic transformer flux equation is:
flux density = Epri x 108 / 4.44 x  f  x A x  Npri
You are designing a transformer to be used on a 480V 60 Hertz line and your first design has a flux density of 100,000 lines per square inch. This is 25 per cent too high for the grade of steel you have to use. How can you change your design to get the right flux density?
9. In the design described in question #8, what will the flux density be if the core area is increased by 25 per cent?
10. What should be done to the corrected design in question #8 to make it suitable for a 240 volt line at the same kVA?
11. Pick the true statements:
12. Transformer sound is affected by which of the following? (pick the true statements)
13. Which of the following will cause a transformer to run hotter? (pick the true statements)
14. Calculate the flux density in a transformer (use the equation under question #8) that has a 480V 60 Hertz primary, 10 square inches of core area and 225 turns: