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As the line inductance increases, the transmission capacity
Increases
Decreases
Remains same
Insufficient data
Decreases
Transmission capacity, often represented by the Surge Impedance Loading (SIL), is inversely proportional to the square root of the line inductance. Therefore, an increase in line inductance directly leads to a reduction in the power transfer capability of the transmission line.
Transmission capacity, often represented by the Surge Impedance Loading (SIL), is inversely proportional to the square root of the line inductance. Therefore, an increase in line inductance directly leads to a reduction in the power transfer capability of the transmission line.
SIL=ZcтАЛV2тАЛ тАФ Surge Impedance Loading formula
ZcтАЛ=CLтАЛтАЛ тАФ Surge impedance of a lossless line
The power handling capacity of a long transmission line is governed by its surge impedance ZcтАЛ=CLтАЛтАЛ. Since SIL=ZcтАЛV2тАЛ, substituting the impedance gives SIL=V2LCтАЛтАЛ. As inductance L increases, the denominator of the square root term increases, thereby decreasing the overall SIL capacity.
Transmission line inductance is a function of conductor spacing and radius.
Higher inductance increases the line reactance (XLтАЛ=2╧АfL), causing higher voltage drops.
SIL is the power delivered by a line to a load resistance equal to the surge impedance.
Compensating for high inductance (using series capacitors) is a common method to increase capacity.
Inductance helps in limiting fault current magnitudes.
Lower inductance design allows for higher power flow.
High inductance leads to increased reactive power consumption.
Excessive inductance limits the steady-state stability limit of the system.
HVAC Transmission lines
Power system stability analysis
Transmission lines are typically operated near their SIL to maintain voltage stability.
Option A is incorrect because increasing inductance increases the reactive voltage drop, reducing stability limits.
B is correct тАФ As the line inductance increases, the surge impedance increases, which leads to a decrease in the surge impedance loading (SIL) capacity of the transmission line.
Remember that inductance and capacitance act in opposition regarding power flow: increasing inductance decreases capacity, while increasing capacitance (or adding shunt compensation) improves capacity.