Bay-O-Net fuse tracking

[thrasher]

I've been in the trade 30 plus years but saw a new one to me this week. I have many times over the years seen on the Overhead system a fuse blow but the door not drop and then voltage track on the outside of the fuse tube (especialy when it's a really old tube where the fiberglass is starting to feather). I had even seen on some of the old Westinghouse sand fuses on UG switchgear that were in an air insulated compartment that from moisture and dust that they would track. However hit a new one this week.
Got a call from a large (2000kva pad mount) seasonal consumer that they were getting wierd voltages on the middle leg of a 277/480 Y service. Serviceman went over; with no load read 283, 265, 283 to ground; they started a 10hp compressor and voltage went to 283, 235, 283. If they started something larger (50 hp augur system) voltage went 283, flickered 100-200, 283. We checked checked dip pole terminators and elbows and finally the fuses. The 140 amp bay-o-net had blown but was tracking under oil. As soon as bay-o-net holder was removed transformer started making the sound of an open phase; voltage on the center dropped to zero and stayed there. The holder ohmmed as closed but the fuse ohmmed open. The holder read a couple hundred ohms not zero but that was enough to create wierd situation. Cleaned holder replaced fuse and everything good.
Has anyone else every had an under oil fuse track after it was blown?

[reppy007]

Ive never heard of that,never have seen that happen,but if it happened once ,sooner or later it will happen again.Years from now after your retired you may recieve a call....it goes like this..... Hey Thrash,how you been doing,Ive been meaning to call but Ive been busy lately,,,but while I have you I need some advice,you see we are having voltage problems on some urd 3 phase,we cant figure it out ,so that why I called. You say.....have you checked if the bay-o-net fuses to see if one is blown......They think to themselves....it cant be that ,BUT.......:D

[Pootnaigle]

Ummm on thAT overhead check and see if the fuse is blown or melted( indicat.
ing load took it out) and they will most definitely track over specially on a barell like you desscribe but also on a brand new un ON the pad mount round here those bayonet fuses will take out a line fuse before they blow or melt. they're under oil here. I think maybe they are oversized cause they rarely blow Ive maybe seen a half dozen blow n my 39 yrs doin this stuff

[reppy007]

Ive seen many melt,but not take out any linefuse or any terminal pole fuses.

[Lineman North Florida]

Thrasher,I've seen weak link fuses in three phase padmounts do exactly what you are talking about, it's the no load situation that tends to send some people in the wrong direction as far as troubleshooting the problem.

[reppy007]

Thrasher,I've seen weak link fuses in three phase padmounts do exactly what you are talking about, it's the no load situation that tends to send some people in the wrong direction as far as troubleshooting the problem.

For some reason...when your sent in the wrong direction....that memory always sticks in your mind.....then years later you know you seen the same situation,and sometimes cant quite put a finger on it............:mad:

[thrasher]

Poot the second thing we checked was the OH fuse. The fuse was still good, under tension in the holder and the fuse tube is only about eight years old so hasn't started to feather yet. We think lightning took the bay-o-net fuse out recently and they hadn't noticed until they were testing thier equipment for thier season (the service is a cotton gin). Yes this bay-o-net fuse was under oil and the fuse link was blown but was tracking across or thru holder. Like I said first time I had seen an under oil blown fuse track.
However just because I'm the suspicious type we installed a recorder on the service to see if they are creating really high short duration spikes on thier load. Will check it after a couple of weeks.

[LAMartin.CVEC]

Mr. Thrasher, pm me please I may be able to give you some info. We had an accident/near miss a year ago or so and perhaps these things could be related.

Work safely,

L.A. Martin
Journeyman Div III
CVEC