# Expert Answers

1. (a) A short 3 phase 11 kV line delivers a load of 4.1 MW, 2.6 MVAr lag.

If the series impedance of the line is (7.2 + j12.1) /ph, calculate the sending end voltage and load angle

(a) At load, active power = 4.1MW

(b) Develop the receiving end performance chart for the above line and load to a 3-phase power scale. (Use a scale of 10 mm = 1000 V and 30 mm = 4.1 MW.)

4. Using the chart you produced in Question 3, determine:

the real and reactive power when

(i) the transmission angle remains unaltered and the sending end voltage is increased by 28%

(ii) the original sending-end voltage is reduced by 15% and the transmission angle increased by 9°. (Use the same scale as that for Question 3 (b))

(b) the real power limit for the sending voltage in (ii) above (i.e. when reduced by 15%).

If the series impedance of the line is (7.2 + j12.1) /ph, calculate the sending end voltage and load angle

(a) At load, active power = 4.1MW

(b) Develop the receiving end performance chart for the above line and load to a 3-phase power scale. (Use a scale of 10 mm = 1000 V and 30 mm = 4.1 MW.)

4. Using the chart you produced in Question 3, determine:

the real and reactive power when

(i) the transmission angle remains unaltered and the sending end voltage is increased by 28%

(ii) the original sending-end voltage is reduced by 15% and the transmission angle increased by 9°. (Use the same scale as that for Question 3 (b))

(b) the real power limit for the sending voltage in (ii) above (i.e. when reduced by 15%).

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