Stator Relay, what is it and what does it do ?

Got an alternator checked out at the parts store this weekend and they say the stator relay is bad. So my question is what is it and what does it do ? Just curious. Thank goodness for warranty parts.

 

bttt

 

Never heard of it. There's a stator & diodes. Maybe they said your stator "really" is bad.

 

either way what the hell does it do ?