What is it called when the 60hz line power becomes something else?

<What do you believe the frequency changed to ? (nominal 60Hz, right. <Well, anything from 50Hz to 70Hz (say) would be no problem at all). Id sueggest if you average 0hz(no power!) and 60 hs you may get someting inbetween. However the 0hz state must not exceed 8-10 cycles or you will no question get power fail. ;) Likely the power supplies dropped out whe the line voltage got below 88v. Most of those supplies will regulate down to that. However if there is also a dropout at 88V it will stop regulating as there will not be enough stored energy in the caps to hold it up. FYI: 400hz not only gets you smaller transformers it also reduces the size of the filter caps needed to remove the ripple from the rectifiers. The size and weight difference is significant when you combine the two. Allison