Jumpering 3 Phase Units

[mainline]

I know I am probably going to get a lot of input on this so here it goes. At my utility we have a large number of CSP 3 phase units. When we do make ready for an outage we will jumper out all three high side taps just above the primary bushing. We use 15kv mechanical jumpers and the highest voltage we do it on is 12470. Once we have the jumper in place we cut the taps and leave the stub with the jumper in place. The jumper head is typically covered with a blanket. When we go to de-energize the unit, secondary breaker is opened, the secondary side is tested to be sure that it is open, the high sides of the mechanical jumper are removed and put on a parking stands. We then proceed with the outage. What I am curious about is how many utilities allow jumpering out x-frmrs. For those of you who don't use units, the clearances are tight. Alright have at it guys.

[lineman345]

:confused: Why would you, jump it out if your taking it off line?
Is there 2 men in the air?
I will jump out tap on a single phase xfmr but not on a 3 phase
stacker your asking for trouble.
Remove one tap an clear it or put on your stand off,an repeat
on other two.

[mainline]

We due this before the outage in order to shorten the duration of the actual outage. We will transfer the phases up onto the new pole, build the bank, and do as much work as possible prior to the outage itself. I am not saying that this is necessarily the best practice, but we have been doing it for a long time. We usually do this with two men in the air, but it would not be out of the question for one man to do it.Thanks for the input.

[Pootnaigle]

CSP transformers have been discontinued by many utilities because they have a propensity to explode when they fault. I personally dont trust em werf a crap. Had one blow the lid off one nite and wrap it around an opposing phase .............talk about gettin dark quick. If someone had been up there with it they wouldnt stand a chance. I also fail to see much of an advantage to mac em out since yer gonna hafta kill em later anyway,, wouldnt take much longer to do the hole deed dead if you rotated and marked the secondary.Or am I missing sumpin?

[md2]

I would not mac out a 3 phase bank unless it was absolutely necessary and if I had too i would try to use a cutout. I've worked on some properties were they won't hook up a CSP without using a cutout...that way if the coil does go you don't drop the line or have a big bang. either way not a bad idea

[lewy]

If everything is tight after you have dropped load why not just cut out the high side leads with sticks & then install switches for the new bank.

[tramp67]

That's been a pretty routine thing with the contractors I've worked for, keeping the bank hot while moving the phases to a new pole. If I understand you correctly, you are just macking out the high side leads so you have enough length to move the primary to your new pole without an outage, then you build and test the new bank. When you are ready to cut over to the new bank, you open the secondary breakers on the pots, remove the secondary leads to eliminate possibility of backfeed to the high side, and then remove the primary jumpers. You aren't making any changes to the existing CSP's themselves until you open the secondary breakers. If you are concerned about failure of the pots when you open the breakers, you could attach cutouts or current limiting fuses to the primary between the conductors and the macs. Pretty simple to attach a hotline clamp to either the top of a cutout or to a current limiting fuse, and a short piece of #4 solid on the bottom to attach the macs to. The biggest mistake I see people make is not putting the end of the mac right next to the transformer bushing, then it gets too floppy when you cut out the stinger. BLW.:D

[wtdoor67]

I would rig some cutouts. Heavens! CSP's are crummy.

[THE KID]

Use temporary cutouts that hang on the line and has a tit coming off to put your hot line clamp on.

[LEAFMAN]

In our area we don't have any banks without cutouts and we have changed out all csp tanks. Just trouble waiting to happen

[SBatts]

In our area we don't have any banks without cutouts and we have changed out all csp tanks. Just trouble waiting to happen

What company uses CSP's in banks?? The utility needs new management or engineers?

HL&P did that in the 1960's and then found out about CSP's and main feeder line trouble and went back and hung cutouts on any CSP on any feeder circuit.

[mainline]

Not many utilities use CSPs in banks, what I was refering to was a CSP 3 phase unit, different animal altogether. Tramp has it nailed as to what we do. I do agree though it is a crappy practice, I was curious to see how wide spread it is. Thanks for the input everyone.

[Edge]

That's been a pretty routine thing with the contractors I've worked for, keeping the bank hot while moving the phases to a new pole. If I understand you correctly, you are just macking out the high side leads so you have enough length to move the primary to your new pole without an outage, then you build and test the new bank. When you are ready to cut over to the new bank, you open the secondary breakers on the pots, remove the secondary leads to eliminate possibility of backfeed to the high side, and then remove the primary jumpers. You aren't making any changes to the existing CSP's themselves until you open the secondary breakers. If you are concerned about failure of the pots when you open the breakers, you could attach cutouts or current limiting fuses to the primary between the conductors and the macs. Pretty simple to attach a hotline clamp to either the top of a cutout or to a current limiting fuse, and a short piece of #4 solid on the bottom to attach the macs to. The biggest mistake I see people make is not putting the end of the mac right next to the transformer bushing, then it gets too floppy when you cut out the stinger. BLW.:D


yeah Tramps got it spot on...

I personally would use CLF's they clear faster than a cut out and have the added benefit of not having the "KABLAMMO!!!"

thats some dangerous shit your working with there bro... try to talk your company into 21st century...

and what ever you do... do it safe

Edge

[CPOPE]

Use temporary cutouts that hang on the line and has a tit coming off to put your hot line clamp on.

This was a good suggestion! Good tool to pick up load ir clear cutouts off crossarm while maintaining fuse protection on the jumper.

Web links to the catalog cut and instructions follow.

http://www.hubbellpowersystems.com/powertest/catalog_sections/PDF_hotline/2313_1_2.pdf

http://www.hubbellpowersystems.com/powertest/literature_library/pdfs4lib/operating-instructions/P600-1981revD.pdf

[tramp67]

yeah Tramps got it spot on...

I personally would use CLF's they clear faster than a cut out and have the added benefit of not having the "KABLAMMO!!!"

thats some dangerous shit your working with there bro... try to talk your company into 21st century...

and what ever you do... do it safe

Edge

CLF's (current limiting fuses, ie. K-mates) in series with temp cutouts would be my preference, but like you say, Edge, much less chance of the "KABLAMMO!!!" with the current limiting fuses. Some utilities use the CLFs in conjunction with cutouts on their conventional transformers for the safety of their linemen. Best location for normal use seems to be when they are installed directly into the primary bushing, less problem of them blowing from wildlife contact.

[Tsplice]

:mad::confused:We have a few of these "triplex"tubs still in service.But for the most part,we have elimitated the light blinking,outage causing,headache inducing,pieces of junk!As for jumpering these things out?You my friend have more balls than brains,I must say.As close as things are together on these things,I personally would not take such a chance,just for a difference of a few minutes on an outage tickett!

[mainline]

If you read my posts, I think you will find I never said it was a great idea. We don't just go up there whirling jumpers around either. Lots of rubber is used, but I agree it is not a great idea.