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<=KNEC Diploma in Electrical and Electronics Engineering Module II: Electrical Power Generation, Transmission and Protection past paper July 2021
i)With aid of a diagram explain the varley loop method of locating an earth fault in underground cables.
ii)Derive an expression for the distance of the fault from the test end in (i).
ii)Derive an expression for the distance of the fault from the test end in (i).
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Questions List:
1. Explain the generation of electrical power in reference to diesel power station
2. State one function of each of the following parts of the power station in a(i). (I) air intake system; II) lubricating system.
3. Draw a labelled schematic diagram of a nuclear power plant.
4. Explain the significance of high load factor in an electric power generation station
5. Distinguish between peak and base loads of a power station
6. Define 'power factor' as used electrical power systems
7. Explain the effect of low power factor on each of the following: (I) transmission line (II) transformers, (III) switch gear.
8. Explain two methods used to meet increased kilowatt demand on a power station
9. State two properties of overhead line insulators
10. Illustrate how overhead line conductors are attached to each of the following types of insulators: (I) pin - type; (II) suspension type.
11. List two performance tests carried out on insulators before being used on overhead lines
12. Explain two effects of short circuits in a power system
13. Distinguish between fusing current and, fusing factor as used in switch gears
14. List any two types of circuit-breakers
15. Illustrate each of the following reactors in a power system: (I) tie-bar reactors; (II) feeder reactors.
16. Figure 1 shows a generating station having two alternators A and B operating at a common base of 100 MVA. Determine the amount of short circuit MVA due to a fault at point F.
17. State two factors that determine the total cost of power transmission
18. Figure 2 shows an illustration of Kelvin's law. Copy the graph and name the curves labelled 1, 2 and 3. Indicate the position of the most economical cross-sectional area of a transmission conductor
19. Figure 3 shows cross-sectional views of various types of underground cables. i)Identify the cables x, y and z. (ii) List three methods of installing underground cables
20. i)With aid of a diagram explain the varley loop method of locating an earth fault in underground cables. ii)Derive an expression for the distance of the fault from the test end in (i).
21. State two effects of lightning strokes
22. Explain two factors that determine whether a structure requires protection against lightning
23. List two metalwork associated with electrical installation which may require cathodic protection
24. Explain two precautions undertaken in order to prevent corrosion
25. Explain 'temporary installation'.
26. State two IEE regulation requirements regarding temporary installations
27. Outline three conditions likely to cause electric shock at a building site
28. Explain each of the following as used in building services: (i) water supply, (ii) water treatment.
29. State two: (i) merits of using conduit wiring system; (ii) IEE regulation requirements of the wiring in (ii).
30. Define each of the following terms as used in illumination: (i) brightness; ii)illuminance.
31. Explain the significance of the spacing to height ratio in the design of a lighting scheme
32. i)Draw a labelled diagram of a carbon filament lamp. ii)State two disadvantages of the lamp in c(i) when compared to an arc lamp
33. Two lamps each of 500 W with a lamp efficiency of 25 lumens per watt are mounted on two lamp posts 10 m apart. The posts have different heights of 3 m and 4 m respectively. Determine the illumination at a point mid-way between the lamp posts.
34. A three phase overhead transmission line has conductors of diameter 1.2 cm, arranged at the corners of an equilateral triangle of 3 m side. Determine the capacitance of each line conductor
35. Figure 4 shows a schematic diagram of a PVC sheathed electrical installation. Draw the wiring diagram such that (i) S1 controls lamp L1 : (ii) S2 controls lamps L2 and L.3 independently; (iii) socket outlets are connected in radial;
36. A consumer takes a peak load of LKW at a power factor of cos. He is charged at a rate of Shar per kVA of maximum demand. He then improves his power factor to cos, by installing a bank of capacitors which cost him Sh y per KVAR per annum. Show that the consumer's most economical power.
1. Explain the generation of electrical power in reference to diesel power station
2. State one function of each of the following parts of the power station in a(i). (I) air intake system; II) lubricating system.
3. Draw a labelled schematic diagram of a nuclear power plant.
4. Explain the significance of high load factor in an electric power generation station
5. Distinguish between peak and base loads of a power station
6. Define 'power factor' as used electrical power systems
7. Explain the effect of low power factor on each of the following: (I) transmission line (II) transformers, (III) switch gear.
8. Explain two methods used to meet increased kilowatt demand on a power station
9. State two properties of overhead line insulators
10. Illustrate how overhead line conductors are attached to each of the following types of insulators: (I) pin - type; (II) suspension type.
11. List two performance tests carried out on insulators before being used on overhead lines
12. Explain two effects of short circuits in a power system
13. Distinguish between fusing current and, fusing factor as used in switch gears
14. List any two types of circuit-breakers
15. Illustrate each of the following reactors in a power system: (I) tie-bar reactors; (II) feeder reactors.
16. Figure 1 shows a generating station having two alternators A and B operating at a common base of 100 MVA. Determine the amount of short circuit MVA due to a fault at point F.
17. State two factors that determine the total cost of power transmission
18. Figure 2 shows an illustration of Kelvin's law. Copy the graph and name the curves labelled 1, 2 and 3. Indicate the position of the most economical cross-sectional area of a transmission conductor
19. Figure 3 shows cross-sectional views of various types of underground cables. i)Identify the cables x, y and z. (ii) List three methods of installing underground cables
20. i)With aid of a diagram explain the varley loop method of locating an earth fault in underground cables. ii)Derive an expression for the distance of the fault from the test end in (i).
21. State two effects of lightning strokes
22. Explain two factors that determine whether a structure requires protection against lightning
23. List two metalwork associated with electrical installation which may require cathodic protection
24. Explain two precautions undertaken in order to prevent corrosion
25. Explain 'temporary installation'.
26. State two IEE regulation requirements regarding temporary installations
27. Outline three conditions likely to cause electric shock at a building site
28. Explain each of the following as used in building services: (i) water supply, (ii) water treatment.
29. State two: (i) merits of using conduit wiring system; (ii) IEE regulation requirements of the wiring in (ii).
30. Define each of the following terms as used in illumination: (i) brightness; ii)illuminance.
31. Explain the significance of the spacing to height ratio in the design of a lighting scheme
32. i)Draw a labelled diagram of a carbon filament lamp. ii)State two disadvantages of the lamp in c(i) when compared to an arc lamp
33. Two lamps each of 500 W with a lamp efficiency of 25 lumens per watt are mounted on two lamp posts 10 m apart. The posts have different heights of 3 m and 4 m respectively. Determine the illumination at a point mid-way between the lamp posts.
34. A three phase overhead transmission line has conductors of diameter 1.2 cm, arranged at the corners of an equilateral triangle of 3 m side. Determine the capacitance of each line conductor
35. Figure 4 shows a schematic diagram of a PVC sheathed electrical installation. Draw the wiring diagram such that (i) S1 controls lamp L1 : (ii) S2 controls lamps L2 and L.3 independently; (iii) socket outlets are connected in radial;
36. A consumer takes a peak load of LKW at a power factor of cos. He is charged at a rate of Shar per kVA of maximum demand. He then improves his power factor to cos, by installing a bank of capacitors which cost him Sh y per KVAR per annum. Show that the consumer's most economical power.
