have any in your area?

[reppy007]

How many of you have or havent worked on an urd loop that was fed off the circuit which was energized 19.9 and was stepped down to 7200 by stepdowns all on one pole,does it pose any problems as far as your concerned.....pros and cons ?

[T-Man]

We converted to 14.4/24.9 and when the main line went past an 8 kv URD subdivision we stepped down out on the main line and fed the URD from there. The problem came when we only fed half of the subdivision from each voltage. The bridging point in the URD would be out of phase and if you closed there you blew fuses on the risers if you were lucky. So we marked that bridging point in the field and on the operating maps in the control center.

[reppy007]

Thats a new one on me big T.....Two different voltages on the same loop.....wonder how common that is?

[reppy007]

Its not too common here ....but the one's Im talking about is like 6 poles in a row that are paralleled with 167kva stepdowns....so when the loop goes out you have to figure if one is bad,your usually going to have to change the limiter and find the trouble on the loop itself.Now if you happen to have two faults on the loop you feel like you just won the lotto :D

[Pootnaigle]

U MM WEHADDA13 TO 34.5 STEP UP RUNNIN A SMALL ADDITION overhead n hada major prollem with guys that knew the area to be 13 n when changin a pot they wud use one wound for 13 n it didnt werk too good

[reppy007]

U MM WEHADDA13 TO 34.5 STEP UP RUNNIN A SMALL ADDITION overhead n hada major prollem with guys that knew the area to be 13 n when changin a pot they wud use one wound for 13 n it didnt werk too good

Funny that lineman grow big balls when the voltage is steped down and those same balls srink when the voltage is stepped up.

[T-Man]

Thats a new one on me big T.....Two different voltages on the same loop.....wonder how common that is?

It's not common reppy, but during the cut over to the higher voltage and the distance on the main line between down feed risers into the existing urd loop, once in a while one riser gets cut over a day or two before the other and the bridging point has the same phase and voltage but different angular displacement and can not be closed. So when the time comes there is a short outage set up where the old riser is opened, load dropped and the bridging point is closed. Then, when the last riser is cut over to the new voltage with step down , they can phase and close in the open bridging point now at the first tub off the riser and then open the original bridging point and the system is being fed as before. They correct the maps and signage that indicate irregular phase displacement in the field location.

[reppy007]

More than once ,usually after a flood Ive been behind lineman that would shoot the fuse feeding a step-down when theres transformers in a low area down the street....now the problem was that these transformers happened to be livefronts.....underwater and all....and many of times that would cause the transformers to be damaged on the inside,as far as Im concerned stepdowns are more sensitive than other transformers.This happened twice in an area that I was sent to many of years ago,twice in the same hour....I wondered,where do they get these guys ....did they actually think it would hold?

[rob8210]

I worked at one utility that would build an underground loop then feed it one phase from one end and a different phase from the other end! Same voltage though.

[Lineman North Florida]

I worked at one utility that would build an underground loop then feed it one phase from one end and a different phase from the other end! Same voltage though.What could possibly be a good reason for them to want do that?

[reppy007]

Im with ya LNF.....Ive always thought having them both on the same phase was the rule of thumb and not the thumb of rule :D

[rob8210]

There was no valid reason it just was. It was an unusual place many odd ways of doing things.

[trigger]

You would be able to swap load if needed. Balancing feeders.

[Lineman North Florida]

You would be able to swap load if needed. Balancing feeders. In my opinion if that's their reason for having a 2 different phases in an open point transformer, then the potential bad outweighs the good, there are a whole lot of other ways to balance the load on feeders rather than setting somebody up with a dual phase loop.

[T-Man]

In my opinion if that's their reason for having a 2 different phases in an open point transformer, then the potential bad outweighs the good, there are a whole lot of other ways to balance the load on feeders rather than setting somebody up with a dual phase loop.

I'm with ya on that LNF, too much of a chance to close into opposite phases. Even if you get orders to switch that over, it would have to include a section outage on a clear day to change it over to the other phase. Which sounds simple enough but actually is a lot of horsing around obtaining outages from the customers dropping them then running to the other end closing and picking them up again, checking if everyone is on again (they mess with circuit breakers when the power goes out)

It's not you Rob, it's the system you spoke of.

[reppy007]

There R other ways to balance a feeders load....why not swap phases feeding overhead laterals....wonder why some places see that practice as being ok....beats me:nightmare:

[lewy]

Having an out of phase condition is never ideal, but there are situations where it is used as a backup for emergency purposes. It should be well taged in the field as well as at your control room.

[reppy007]

I guess while we are discussing urd I have to ask,and maybe Ive asked before what was the distance of the longest loop you have ever worked on?Here we have several long loops but one that comes to mind was a 12kv loop that was around 5,000 feet long....split with deadfronts,livefronts and a couple of submergeables.