ECN Forum Forums Technical Discussion Electrical Theory and Applications Rattling conduit

I live a few blocks from a neighborhood distribution substation with step-down transformers, circuit breakers and voltage regulators feeding three overhead circuits. On occasions when there's a fault (usually due to falling tree limbs in a storm) I'll sometimes hear a loud, distinctive 60Hz "groan" from the sub, simultaneous with my lights dimming or going out.

Bump again...

Keep the stories coming!!

Albert, a POCO friend was in a substation during an earthquake once...he said the combined noises from the transformers going into overload from the faults, the breakers reclosing repeatedly and worst of all, watching the solid tubular bus work deflect was almost scary enough to make him retire!!

He was quite uncomfortable going into substations for a while after that incident.

Never been in a substation during an earthquake (don’t get them in Scotland thanks)

But I have been in a hydro station when one of the sets was brought on line a fraction out of phase. Needles to say when a set stalls just for that fraction of a second the whole building shook, that combined with the bang was something I will never forget. Nearly needed to change my shorts

Tongland power station

We were servicing a 4160 to 480 1500KVA pad mount xformer, and when we turned the power back on an operator had left the control switch for a 200 HP motor in the hand position (no PB, just a HOA) and when my helper slammed in the second cut out, the motor went to single phasing and the noise the 4160 overhead started making was intense. It seemed to travel down the overhead distribution lines untill the breaker tripped. Never before or after have I heard a sound quite like that.