HMMMMMMMM.......... I work (now) with high power motor drives and generator controls........ 800V bus, 200 HP output, 480 to 600V AC, that sort of stuff....
YES BY GOLLY I DO have one hand out of trouble when I have to do certain things, like probe around with the power on..... (technically it's illegal.... OSHA etc, but you gotta do what you gotta do sometimes).
So do all the other engineers and techs I have worked with when doing similar stuff, and they are all still around annoying the rest of us......
Otherwise I shut down power and move the meter lead.....
I have personally seen people who did NOT do that get shocked halfway into next week. So far I have not had to use that CPR class, thankfully........
But it won't do much good if your shoes are not good insulators......
Well yeah I'm not saying get into gear with both hands and start probing around. You have to know WHAT YOU ARE LOOKING AT and know what you are doing.
Jerrold you weren't sitting on one hand everytime you worked on an SVT head, lets get real. You knew exactly what you are looking at and where not to stick a hand. When YOU MOVE the clip on lead you can flip the thing off.
I used to be a dealer for a motor control manufacturer and the largest unit I ever commisioned was a pair of 150 HP units.
They were pretty cool, the motors would make full torque at 1RPM. That however would rattle the whole building BOOM BOOM BOOM as each phase clicked by, we only did that once.
The FET's in those controllers were as big as your fist.
Also the check list for startup was like 10 pages in the manual and when you were done going through the checklist, the last thing was stand back and flip the go switch... Pretty interesting. back in 1988 the price for a blown fet was about $1250 each if I remember correctly. It was not something you wanted to do.
That explosion in miami was really something. We were doing a control system in the MARRIOT INFLIGHT KITCHEN in 1980. Thats where the meals for airlines are prepared. They leave the Marriot building in the trucks you see that jack up next to the airliners.
Well the remodel of this kitchen had a new power service going in. There was a pair of electricians working in the power room, both finisihing up two different panels. Because it was about 85 degrees and 85% humidity and the air wasn't up yet the guys were working in shorts, tennis shoes with no socks and no shirts.
The main guy finished up his panel and it was time to light up the main. What nobody knew was there had been some shipping damage to this monster service panel. Apparently the bus bars for the three phase were now cocked in the box and were closer at the bottom than they should have been.
I wasn't in the room, but he had the front of the panel off and heated it up. The arc started at the bottom like across a human hair of some crap that wasnt seen and flashed up melting the bus bars as it went.
The UV light that was given off, like a giant arcwelder. Gave the second man facing the other panel severe sunburn all over his back and legs to the point of blisters.
The guy who was in front of the panel. I saw him sitting on the curb outside waiting for the ambulance, holding his arms out and bent up at the elbows. The flesh just hanging loose from the bones completely cooked. It was ready to fall off just like a well cooked set of ribs. 1st Second and third degree burns everywhere and no hair.
I have a lot of respect for power.
BOB
Cats do have 9 lives.
.
