ELE2601 - Electrical Engineering II test 2 Memo 2021.

ELE2601 test 2 2021-07-23



QUESTION 01

1.1 State 7 disadvantages of low power factor. (7)
1.2 Discuss 3 causes of low power factor. (3)


Answer

1.1

i. High KVA rating of equipment√
ii. Less amount of active power√
iii. Large voltage drops in alternators√
iv. Large copper losses√
v. Poor voltage regulation√
vi. Reduced handling capacity of systems√
vii. Increasing size of conductors√

1.2

i. Single or three phase induction motors√
ii. Arc lamps, electric discharge lamps and industrial heating furnaces√
iii. High Magnetization current due to varying load on the power system√




QUESTION 02 (Resonance)

2.1 A coil is supplied from an A.C source that is represented by the following equations for voltage
and current:
𝜋
𝑒𝐿 = 296,985 sin(315𝑡 + )𝑉
7.2
𝜋
𝑖𝐿 = 5.303 sin (315𝑡 − )𝐴
12

2.1.1 Calculate the resistance and inductance of the coil. (8)

2.1.2 Calculate the power factor of the circuit. (2)

2.1.3 If series capacitance is added to bring resonance to the circuit across the same supply, determine
the corresponding expression for the instantaneous value of the current. (9)



TOTAL [19]




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https://www.coursehero.com/file/104026788/ELE2601Online-Major-test-2-Memo-2021-1pdf/

, This study source was downloaded by 100000836267798 from CourseHero.com on 09-04-2022 07:23:21 GMT -05:00


https://www.coursehero.com/file/104026788/ELE2601Online-Major-test-2-Memo-2021-1pdf/