Q: What’s the difference between AC and DC?

A: The difference between AC and DC systems is how the power moves through the lines. AC reverses polarity or “oscillates”, positive to negative and back again, 60 times per second. The polarity of DC does not oscillate and remains constant or “static” like the current flowing from a battery.

Q:  What is the difference between AC transmission lines and DC transmission lines?

A: Power can be transmitted using either alternating current (AC) or direct current (DC). All modern power systems use AC to generate and deliver electricity to customers through transmission lines and then through distribution lines to where it is needed. DC is typically used for point-to-point bulk power transmission over long distances. A converter station is required at each end of the line to convert AC electricity to DC electricity for transmission and then convert it back to AC electricity for distribution to customers on the AC power grid. DC transmission lines have several advantages over AC,  they experience less line loss, have lower line and tower costs and require a smaller right-of-way. However, DC lines also need high-cost special equpipment to convert power to DC and then back to AC.