Author - Australiantroubleman

Submitted By - Australiantroubleman A few years ago I was sent to a large multi transformer distrubution substation feeding a large shopping centre.

They had uprated one of the transformers from 1000kva to 1500kva, the switchgear was old truck type oil filled circuit breakers with old disk type overcurrent relays protecting the transformers.

It was my job to commission the new transformer phase it out and put it on load.

I carefully inspected the new work it looked ok earths connected elbow type connections on the transformer looked ok to me ,

I then made the transformer ready for service was about to energise it when i thought to myself that the circuit breaker position was very close to the new elbow connections , i also checked the overall condition of the substation tripping batteries .
They where in poor physical condition although they had the correct voltage reading when tested.

I decided that i didnt want to stand next to the circuit breaker while closing it as if a fault occurred i would wear the arc on my back and the old circuit breaker / protection relay combination didnt inspire me with much trust, my way of thinking is a fuse is always a fuse but a circuit breaker has many reasons not to function at times, so my trust was being further diminished.

I tied some warning tape into the circuit breaker handle and cleared the substation of all workers , I copped a ribbing for this "you wimp"  "dont you trust my work" wheres your balls "from the guys , but i persisted.

Three times the tape fell off the circuit breaker handle as i tried to  close it remotely, the guys where laughing their heads off , i finally taped the tape into the handle with insulation tape .

I then pulled the tape the circuit breaker closed and BOOOOMMM!!! there was a huge explosion from one of the new elbows . The old circuit breaker did eventually trip but the fault energy and noise scared the crap out of us , luckily we where all out of harms way and only suffered some ringing in the ears and almost filling of our underwear .

Once the smoke cleared we checked out the damage . the elbow was not correctly installed and had flashed over to ground , the fault energy was quite large as the circuit breaker was slow to clear and the fault level was very high due to being close to alarge  town substation.

So i had the last laugh the guys couldnt believe that i really didnt know it was going to fail.

So gut feeling and experience saved us from injury this time.