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Questions 29 and 30 relate to the following situation: A small power plant produ

ID: 2066835 • Letter: Q

Question

Questions 29 and 30 relate to the following situation:

A small power plant produces a voltage of 6000 volt and 150 ampere. The voltage is stepped up to 240 kilo-volt by a transformer before it is transmitted to a substation. The resistance of the transmission line between the power plant and the substation is 75 ?.

29. What is the current in the transmission line from the plant to the substation?
(a) 3.8 A (c) 6.4 A (e) 7.5 A
(b) 5.2 A (d) 7.0 A

30. What percentage of the power produced at the power plant is lost in transmission to the substation?
(a) 0.47 % (c) 0.34 % (e) 0.12 %
(b) 0.41 % (d) 0.23 %

Explanation / Answer

29.
The power generated at primary and secondary source is same.
therefore VpIp= VsIs
= 6000*150= 240000*Is
Is=6000*150/240000
Is=3.753.8
OPTION (a)

30.

power produced = Vp*Ip = 6000*150W = 900000W

power lost due to resistance = IsR2 = 3.75*75*75 = 21093.75W

%power lost = (21093.75/9000000)*100% = .0023*100 = .23%

OPTION (d)