What is the difference between a standard AC system and an "AC wild" system? How does the latter work?
6$\begingroup$ Welcome to aviation.se. I've never heard of "wild AC" --- can you provide a link to some example of that term being used in context? $\endgroup$– Ralph J ♦Nov 16, 2016 at 19:55
$\begingroup$ Related: Variable frequency generator on A380, and why AC generators are moving from fixed to variable frequency. $\endgroup$– minsNov 16, 2018 at 11:42
Frequency wild Unregulated AC is generated using alternators.
They were more common before constant speed drives were added to aircraft beginning in the 50's.
The alternator runs at various RPM (which varies the frequency) since it is driven by the engine.
The difference is that regulated AC is of fixed frequency. Better for motors, pumps, etc.
Unregulated AC was used for things like windshield wipers and windshield heating. DC inverters were used when regulated AC was needed.
Edit: On a plane like the ATR 72, it is indeed referred to as AC Wild.
It is used for heating the windshield, propellers, and probes. Among other systems that don't require regulated AC.
ATR notes that discuss AC Wild can be found here. (Courtesy of FreeMan.)