A few pages back Andy D posted a link to "Flying Squirrels and Unspun Gyros", an excellent 10 min talk by Mike Christian (then of Yahoo) about how these systems can fail & yes, power issues are a high factor.
OTOH, the more complicated you make your failsafe protection systems the more failure modes you have (rather like AB...
)
Sometime turning it all back on immediately can make a bad situation a great deal worse.
https://www.youtube.com/watch?v=iO2z3ttlpi4
Very much worth watching if you want to educate yourself a bit (I learned some new things), rather than just cursing the Spaniards.
[And I've also written enough code to know that there'll always be an edge-case that only turns up every 20 years...]