Utility upgrade from 4.16kv to 13.8kv.

[rian0201]

Utility upgrading happened to the utility company i have worked before, back in my place, they first proposed it based on the load density, load growth in the coming years, distribution losses, economic costs, losses vs replacement costs, etc.

I was once worked in the planning department, the management in the end will be the deciding factor, they were only looking for the losses, as the government imposes penalties for exceeding power loss quotas.

However, it depends on what objectives the utility has.

It could also be that they cannot increase the price the energy cost, so they upgrade the system to increase in price per kwh with the energy commission or govt approval.

We will never know what that utility from question has, you better go ask them. But for sure, there will be no full disclosure.




Sent from Mars

 

[peter d]

nice pics. There is a two pole platform down the road with pretty big units on it, Ill take a picture of it next time I go by. I know I have seen some absurd singles around but cant recall any specifics or their location. You have me on the lookout now.

You can let me know the address and I'll check in out.

 

[mivey]

NG does not offer them anymore as a new service, you get wye or you get nothing.

Our way or the highway, eh?

The only delta services that still exist are to mills and the odd machine shop or industrial building that had their service installed many decades ago. These installations are few and far between now as the mills are being demolished or converted into apartments.

Industrial facilities liked the delta. Ungrounded for reduced outage risk as well. Filters zero sequence currents also. Not all bad.

 

[mbrooke]

Our way or the highway, eh?

Industrial facilities liked the delta. Ungrounded for reduced outage risk as well. Filters zero sequence currents also. Not all bad.

Explain

 

[mivey]

Explain

Secondary ground faults don't produce primary neutral current. Other things will, but for the most part no neutral current.

Yd also helps with harmonics.

 

[mbrooke]

Secondary ground faults don't produce primary neutral current. Other things will, but for the most part no neutral current.

Yd also helps with harmonics.

But how does that effect the POCO or the customer?

 

[peter d]

Our way or the highway, eh?

When it comes to NG, that is pretty much the case.

Industrial facilities liked the delta. Ungrounded for reduced outage risk as well. Filters zero sequence currents also. Not all bad.

Good point, they were ungrounded delta. I've been in a few of those old mills and there are transformers everywhere inside to make 120, 208 or whatever they needed. I think I have seen exactly one high leg delta service. They were extremely uncommon.

 

[mivey]

But how does that effect the POCO or the customer?

Customer has higher L-G fault current (at least near transformer). Utility can coordinate better for ground faults because secondary ground faults don't pass through. Fewer turns makes it more economical. Utility doesn't get the customer 3rd harmonics on the system. Delta can producd traditional 120/240 voltages. Can operate (at reduced capacity) even with the loss of one transformer (with primary grounded). Can handle unbalanced loading better.

 

[rian0201]

Our way or the highway, eh?

Industrial facilities liked the delta. Ungrounded for reduced outage risk as well. Filters zero sequence currents also. Not all bad.

But fault location would be somehow difficult, and it requires higher insulation for line ground.

Motors for example should have their line to ground insulation to line to line.

 

[electrofelon]

LOL! Id certainly be interested.

Well I snapped a few pictures today, and was all excited to one up you, but upon closer inspection realized you have me beat. All I could come up with is 3 500's on a platform, fisher-price stuff :rant: I'll keep looking.....

 

[peter d]

Well I snapped a few pictures today, and was all excited to one up you, but upon closer inspection realized you have me beat. All I could come up with is 3 500's on a platform, fisher-price stuff :rant: I'll keep looking.....

That's clearly National Grid in New York state. National Grid New England never puts large transformer on platforms like that. :happyno:

 

[iwire]

That's clearly National Grid in New York state. National Grid New England never puts large transformer on platforms like that. :happyno:

We had two set ups like that at RPP but they were private and likely dated from the 60s.

 

[mbrooke]

Well I snapped a few pictures today, and was all excited to one up you, but upon closer inspection realized you have me beat. All I could come up with is 3 500's on a platform, fisher-price stuff :rant: I'll keep looking.....

Still eye candy to me Thanks

 

[peter d]

We had two set ups like that at RPP but they were private and likely dated from the 60s.

No doubt, I have never seen that kind of construction in NG/Narragansett territory, and believe me, I'm always looking.

 

[truck41trouble]

Here is a picture of a common setup here in Ny ( orange county). 3 500kva autotransformers to change a grounded wye feeder to a ungrounded delta system. There is a 4th cutout on the neutral from the wye system, which is normally open. We only close the neutral when hotting up the circuit to reduce resonance. Actually I've only done this once as the utility I work for doesn't use this setup. You can also seen this on a single phase system. I know this has nothing to do with this thread, but something you all may or may not have seen before. Happy holidays!

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[truck41trouble]

In response to my last post, not sure why the picture didn't upload.

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[electrofelon]

Here is a picture of a common setup here in Ny ( orange county). 3 500kva autotransformers to change a grounded wye feeder to a ungrounded delta system

Interesting. Why do they need to do that? Maybe they refed an old line with a newer one? If the secondary is ungrounded, the transformers couldn't be connect as autos though... unless by "ungrounded" you just mean no neutral.

 

[truck41trouble]

The secondary is grounded but only to the rod at the pole. There is no service neutral on the secondaries and the transformers are 2 bushing transformers. In this case im not sure why this system is warranted or why they didn't just upgrade the whole feeder to wye. This is a dead end feeder that runs for 8 miles feeding homes, without any interconnections to other systems. The one time I installed a bank like this it was a single phase delta and it was just easier to drop in the 3rd line.

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[mbrooke]

The secondary is grounded but only to the rod at the pole. There is no service neutral on the secondaries and the transformers are 2 bushing transformers. In this case im not sure why this system is warranted or why they didn't just upgrade the whole feeder to wye. This is a dead end feeder that runs for 8 miles feeding homes, without any interconnections to other systems. The one time I installed a bank like this it was a single phase delta and it was just easier to drop in the 3rd line.

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Back then many POCOs only ran 3 wires and every pole pigs was P-P connected.

 

[electrofelon]

The secondary is grounded but only to the rod at the pole. There is no service neutral on the secondaries and the transformers are 2 bushing transformers. In this case im not sure why this system is warranted or why they didn't just upgrade the whole feeder to wye. This is a dead end feeder that runs for 8 miles feeding homes, without any interconnections to other systems. The one time I installed a bank like this it was a single phase delta and it was just easier to drop in the 3rd line.

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Maybe its different jargon between nec and utility, but you said "autotransformers" so the secondary wouldn't be a separately derived system and would maintain the ground reference of the feeding system. Am I misunderstanding?