Fuses fitted incorrectly.

[Knobhead]

Anyone worked on GEC System 4 gear?

Got a phone call this morning from an old mate Dave. He’s had a switch getting hot for a while purely down to increased load. Last weekend he up rated the switch from 400 to 630A but down rated the 630A fuses to 500A. It’s a dead easy job to do, 400 & 630A units just plug in to the same frame. You can even do it with the main board still live.
The new switch was now getting hotter than the old one.
Many years ago I had shown him how to hot swap or add new switches. So he calls me.
About 30 years ago I had a board with several switches overheating so I took one out and stripped it, couldn’t find any thing wrong with the switch at all? Stripped the fuse carrier down and between the fuse lugs and the switchblade I found a hardened steel plate. The plate was supposed to be between the nuts and the fuse lugs. Told Dave just to check the fuse carrier and he found the same thing, he’d changed the fuses and put it back together the same way as he found it. I asked where did you get the new switch? “Oh it’s been in stores for god knows how long”!
Same bloody batch that got me all those years ago!
Don’t get me wrong I still think System 4 and MiniForm is fantastic gear and it’s still available. I just hope they put it together correctly now!

Fault finding by remote control, just waiting now for the bottle of VVSOP brandy to arrive!

 

[Engineer54]

Afraid i haven't worked with switchboards and the like with switch fuses for donkey's years now. Now it's withdrawable ACB's on LV switchboards which are basically the same, in terms of replacement units where frame sizes are the same. But ACBs will cover a far larger current rating in the frame sizes, than the old switch fuse frame sizes.... And as you say, withdrawable and replaceable while the switchboard remains live and in service...

 

[stansmith]

ye they are good panels ive heard them called form 4 before, very safe panels to work on as you said you can remove the equipment with the panel being live and safely, cant say ive noticed the steel plate before will keep an eye out next time. Also worked with ACBs small and large doing maintenance checking springs greasing up the contacts with contact grease. it all beats working on those bloody OCBs thats all i can say couldnt tell you how many oil changes ive done on ocbs but i hope i never have to smell that oil again lol but then again id rather change the oil in an ocb than do another transformer tbh

 

[Engineer54]

ye they are good panels ive heard them called form 4 before, very safe panels to work on as you said you can remove the equipment with the panel being live and safely, cant say ive noticed the steel plate before will keep an eye out next time. Also worked with ACBs small and large doing maintenance checking springs greasing up the contacts with contact grease. it all beats working on those bloody OCBs thats all i can say couldnt tell you how many oil changes ive done on ocbs but i hope i never have to smell that oil again lol but then again id rather change the oil in an ocb than do another transformer tbh

Form 4, is a switchboard/panel construction type format, based on sectional construction integrity/containment etc.

 

[johnboy6083]

has anybody got any documentation ect about form factors on panels? id like to have some please.

 

[johnboy6083]

if anybody does wan info about seperation ect on control panels, try this. http://www.google.co.uk/url?sa=t&source=web&cd=3&sqi=2&ved=0CC4QFjAC&url=http%3A%2F%2Fwww.racegroup.co.uk%2Fpe4.pdf&ei=EXx_TuD2KanG0QWIhZzJCQ&usg=AFQjCNGoajwEtcYvqFdqlBatb4hm9LCu2A

not sure how accurate it is, but looks like it was copied from offical books ect.

 

[Knobhead]

Stan, GEC weren’t the only ones to use the steel plates, but their the only ones I’ve ever come across incorrectly fitted from the factory. It’s worth keeping an eye out for.

As for transformer oil the wife would send me out with a full shower kit under the instructions of your not coming in here stinking of that stuff! If she knew we were doing bank holiday shutdown maintenance.

 

[Knobhead]

E54, the beauty of these you could withdraw the entire mounting frame live leaving just the bus-bars at the back. If there was any problems with the rear contacts just slam a new unit in and work on the old one at your leisure. I could change the entire shooting match in less than 5 minutes. Mind you I don’t think I could lift one on my own now.

 

[Estimator]

For separation and loads of other stuff on sw/gear try this http://gambica.org.uk/web_images//documents/Edition_1_of_Guide_to_BS_EN_61439.pdf

Or this if you don't suffer from insomnia Guide to Forms of Separation July 2011 - Guidance Documents