I was watching a YT video recently where they said something along the lines of “AC current is too inefficient for long distance power transmission, so xyz project needs DC power” and then moved on. I (from my vague memories 20 years ago of school) thought that AC had less loss and inefficiencies. What am I missing/what did I tune out in school?
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Times changed and tech advanced
AC is easy to change between voltages. Take a hunk of iron, coil two wires around it. Congratulations you now have a transformer! This was feasible in the early 1900s
Converting DC voltages to other DC voltages requires either a DC motor feeding a DC generator, or *semiconductors*
The motors and generators would be insanely large and when deciding on AC or DC they didn’t yet know about semiconductors so they opted for AC so they could convert voltages
Modern times let us use large semiconductor DC-DC converters and inverters at the end to get the AC our devices want
AC has losses on transmission lines due to real wires having capacitance and inductance which while being apparent power, they suck additional real current from the generators which gets impacted by the wire resistance. The skin effect also comes into play on really big power lines, AC current only travels down to a certain depth so really high current connections have multiple (3/4/5) wires in a shape because a single super thick wire wouldn’t carry any current in the middle. DC doesn’t have this problem, you’re only worried about resistance, no other weird effects
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