Super Bowl Blackout Caused By Defective Protective Relay

New submitter wilby writes "Power company Entergy New Orleans says the Super Bowl blackout was caused by device designed to prevent power outages. A device designed to improve the Superdome electrical system reliability instead caused it to shut down dramatically during Super Bowl 47. [The company] said testing traced the source of the problem to an 'electrical relay device' it had installed in December to protect Superdome equipment in case a cable failure occurred between the company's switchgear and the stadium."

Re:Seems like system failures

[the eric conspiracy]

That's why I stopped using UPS's on my home computers. I was having more failures caused by the UPS's than if I didn't have them in my system.

I think the turning point was when journaling file systems came to Linux.

Re:The TL;DR

[cblguy2]

Circuit breaker was not "miscalibrated". The protective relay (which is separate from a breaker) possibly had a setting in it that was too low. Protective relay settings are based on time curves (which are plotted on logarithmic paper). For, say, 300 amps, it trips after 10s or 100s of seconds of continuous operation past the setting. For 10,000 amps, it may after .03 seconds (or you may have an instantaneous setting, or a definite time delay based on cycles). That kind of curve. If the load was drawing so much current, for so long of time, then yes, it will send a command for the circuit breaker to trip. Anyhow, it's easy to screw up a protective relay setting - and yes, I've done it. That's why relay settings are always checked by a second engineer as well, just to make sure you didn't miss something. IAAPE (I am a protection engineer, and a P.E.), though we don't use S&C relays (Schweitzer here).

Re:The TL;DR

[Anonymous Coward]

You are being pedantic to make yourself feel important. Sure they may not be part of the racked out breaker for high voltage breakers (4160, 13.8kv, and above), but in those cases the relays are associated with the breaker and include it in their designation (51-bkr designation, 86-breaker designation, 27-breaker designation, etc.). The control logic for those breakers will usually be in the breaker cubicle and the relays will usually be mounted on the front or with the control logic. For lower voltage breakers you will have a relay cabinet and control power fuses that feed the breakers and certain relays mounted into the breakers (so that even when you rack them out, the relays come along). 99% of breakers that you deal with will be this variety. 0.9% will be the more complex variety above. and 0.1% will be complex enough that control logic is done in different cabinets like you describe (for example, nuclear plant protective logic or for extremely high voltage like 345kv breakers where you want all of the logic controlled in a switchhouse). How does this apply? 99.9% of the 'breakers' will be housed in one integral cabinet or have a relay cabinet in the same bus housing. An operator will call it a 'breaker'. An electrical tech will call it a 'breaker'. An engineer when communicating with anybody else will call it a 'breaker'. Only an engineer when communicating with another engineer would ever be pedantic enough to point out that the relay isn't part of the breaker. For everyone using it, it is. Why an engineer talking to the general public on Slashdot feels the need to point out the difference is unknown. Perhaps this engineer feels under appreciated?