3 ms·
I love reading about problems like these, it's great that Amazon is forthcoming about them. There's always some new wrinkle. E.g. in this case, in normal opera
by PhantomGremlin 10y ago
I love reading about problems like these, it's great that Amazon is forthcoming about them. There's always some new wrinkle.
E.g. in this case, in normal operation, power from the utility power grid spins a flywheel. When the grid fails, the flywheel provides a holdover until Amazon's diesel generators can start.
But in this failure the voltage from the grid sagged, rather than going away completely. The breaker isolating the flywheel from the grid didn't open quickly enough. So power from the flywheel was sent out to the grid. It didn't succeed in powering the grid for very long. Oops.
- smegel 10y agoThere's a reason why electrical engineering students are usually the smartest people at uni (I wasn't one of them but was often in awe).
- JorgeGT 10y agoSomething else must have failed or was not properly configured, because backup Diesel generators should kick-in after 2-15 seconds of voltage drop, regardless of the flywheel. The flywheel is used in critical systems to cover only that <1m gap.
- jbg_ 10y agoAmazon addresses that in their report. Each UPS is fed by generator power and grid power. Because the UPSes had been forced to try to supply the grid, and because they are giant spinning weights that you really don't want to go wrong and kill someone or destroy property, they did a safety inspection before powering them back up, which meant a delay before the facility could be supplied by generator power.