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Comment by walshemj | Hacker News Reader

I thought that halon systems where supposed to have interlocks so that they could physically not go off if anyone was in the room.

The dinosaur pen batteries seem to have been done on the cheap though - dont understated how the power coming back took out the UPS though.

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The power came back at the same time as the generators came on. I guess this doubled the, uh, voltage, and threw the phase off... yeah.

Edit: clearly the problem was that too much amperage was pushed! :)

You don't just connect the two in series :-) In fact the best practice is not to switch from your backup supply back to mains automatically just in case the power goes out again.

How its should work is mains or your gas turbine are used to charge the batteries the power is always coming from your battery room.

I am not sure this was best practice in 1987. We learned a lot from incidents not entirely unlike this one and I went through one catastrophic power failure (that took down more than 1000 machines in the late 1990s) due to a cascade problem between the multiple "redundant" power sources.

One of the machines refused to come back and we got a call from operations asking where (physically) was the box within the datacenter. It was inside a Cubix blade-like (we didn't call them blades at the time) chassis.

It's best practice according to my 1948 GPO telecommunications handbook power always comes from the batteries.

There is an interesting write up on the register about how a London based colo facility does its UPS here

http://www.theregister.co.uk/2014/02/21/city_lifeline_london...

I agree it's the only sane approach, but I have seen a lot of insanity in computing. It's not impossible telecom best practices were ignored for data processing until it became obvious computers are every bit as critical as telephones.

If you abruptly change the speed of a generator (like when it breaks), a huge voltage peak comes from it.

Absolutely not. Purge systems like this WILL go off if they are not bypassed. Typically you have a short amount of time to hit the 'don't purge me, bro' button, before the system dumps.

They're designed to protect critical hardware, not people.

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