If Line A is a 100 mile transmission line and Line B is a 10 mile transmission line both lightly loaded, how much MVAR will line A contribute to the bus?

In analyzing the contribution of Line A to the bus in terms of reactive power (measured in MVAR), it is essential to consider the relationship between the length of a transmission line and its impedance, as well as the loading conditions. Given that both lines are lightly loaded, the longer Line A, spanning 100 miles, will have a greater total reactive power due to its longer length and associated impedance.

Transmission lines inherently have capacitance and inductance that affect their performance in terms of reactive power. The total MVAR contribution from a transmission line is influenced by its length; a longer line typically presents a higher capacitance and can thus provide more reactive power to the system. In this case, Line A's length and low loading conditions suggest that it will indeed contribute a substantial amount of reactive power, likely exceeding the contribution of Line B significantly.

Consequently, the conclusion that Line A will contribute more than 3.2 MVAR is aligned with the principles of transmission line theory, where longer lines exhibiting similar voltage conditions tend to offer greater reactive support to the bus. Thus, the appropriate choice reflecting this analysis is that Line A's contribution will be more than 3.2 MVAR.