Primary utility circuits

[sparks1]

What are primary voltages used in Massachusetts(Cape Cod area) for residential over head, pole mounted , utility transformers?

Are these transformer primary circuits single phase or three phase in a residential developments?

What size KVA transformers are normally used?

 

[lile001]

Re: Primary utility circuits

This is not specific to Cape Cod, however generally residential overhead is supplied by 4160V or newer 12KV single phase lines, and the transformers are often 50KVA or less single phase. Your local power company will be able to give you the real lowdown on your particular area. There is an engineer who probably knows every foot of these lines.

--Lawrence

 

[charlie]

Re: Primary utility circuits

I really thought someone from that area would answer you. I am betting that my answers will fit even Provincetown.

What are primary voltages used in Massachusetts(Cape Cod area) for residential over head, pole mounted, utility transformers?

Most electric utilities use the 15 kV class for distribution (12.47 kV, 13.2 kV, 12 kV, 13.8 kV, etc.) and are getting rid of the 4.16 kV in the old areas of town. Some 23 kV and 34.5 kV is used for distribution but it is not very common.

Are these transformer primary circuits single phase or three phase in a residential developments?

1?, 2?, and 3? are all used. We have to maintain balance on our main line primary circuits. However, only a single phase is used to feed any one transformer.

What size KVA transformers are normally used?

Most utilities use 50 kVA transformers but for one or two customers, we will install a 25 kVA.

 

[physis]

Re: Primary utility circuits

2?

 

[charlie]

Re: Primary utility circuits

Sam, I am talking about taking the primary distributions system into a subdivision. An electric utility can take 1, 2, or 3 wires of primary into a subdivision. These are usually taken overhead along the perimeter of a subdivision and risers to take the phases underground into the distribution transformers.

In order to keep the distribution system balanced, I may take one phase from riser pole #15 and two phases from riser pole #18 and loop all three phases through the subdivision. I would use only a single phase to pick up any single transformer. All three phases would then loop back to riser pole #22 to complete the loop. After the loops are designed, I will pick an open point in the electrical center of each loop in order to place LAs. The loops would feed from both directions and if a cable fails, a trouble man could switch the faulted portion of the cable and have everybody back into service in about ? hour.

The above description is the way we do URD design. Some electric utilities use a radial system and do not loop the underground back to the second riser pole.

To answer your question, we do not use a two phase system for anything but we do use two phases.

 

[physis]

Re: Primary utility circuits

2?'s

There I go again acting like I'm correcting you.

That sounds strange. Are you running single phase transformers from 2 phases 120? apart?

 

[charlie]

Re: Primary utility circuits

No Sam, I am running a single phase transformer from the phase to neutral, going to another location and running a different single phase transformer from the other phase to neutral. Even though all three phases or two phases are used, it will all be served as single phase loads.

 

[physis]

Re: Primary utility circuits

Well there's nothing strange there then.

 

[charlie]

Re: Primary utility circuits

I agree.