mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
230V Delta?
- Thread starter PetrosA
- Start date
- Status
MTW
Senior Member
- Location
- SE Michigan
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Last we heard, you were trying to find a job with a POCO. Care to share what POCO you are working with now that you are designing systems for?
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
Don't think POCOs would have a need for 138/240Y. From what I'm told they just start at 13,800 volts and go up from there.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Well that really answered my question!
Who are you designing systems for?
mbrooke
Batteries Included
- Location
- United States
- Occupation
- Technician
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Flicker Index
Senior Member
- Location
- Pac NW
- Occupation
- Lights
What happens if you touch the metal stuff?
kwired
Electron manager
- Location
- NE Nebraska
I was going to ask if that is what we were looking at, then saw your post.
synchro
Senior Member
- Location
- Chicago, IL
- Occupation
- EE
Yes those are wirewound resistors. Probably made by Ward Leonard based on their light olive green color.
Are there any 3 phase motors still on this system?I've been trying to wrap my head around a system I recently worked on in an old factory in York, PA. It's a 230V high-leg Delta system from what the on-site electrician explained, but the readings are unlike anything I've ever seen and I'm trying to figure out what's going on. There are three hots and a ground on site, no neutral. Phases A and C read 137V to ground, while phase B reads 157V to ground. Between any phases I get 248V. The open knife switches make it really interestingView attachment 2555618
ptonsparky
Tom
- Occupation
- EC - retired
Why wouldn’t there be? Is there something I’m missing?
PA was known for 3 wire two phase. If this is just some unused storage building, those photos on the roof could be of a scott T transformer. The voltage relationships are closer to two phase than three phase.
ptonsparky
Tom
- Occupation
- EC - retired
Ok. I have heard PA, and some areas of the North East are about the last holdouts for two phase.
PetrosA
Senior Member
- Location
- Lancaster, Pennsylvania
The primary is 3-phase, secondaries are 3-phase, and this is far enough from Philly that I really doubt there's ever been two-phase in the building. The only motor loads I saw are the elevators and a few exhaust fans, at least some of which I know are 3-phase. There are a lot of transformers throughout the facilities to provide 120V power as well, which would have included lighting and circulating fan loads. I wasn't able to get into the oldest part of the factory to see that, but the 3-phase primaries drop to that side as well.
kwired
Electron manager
- Location
- NE Nebraska
Seems to me if two phase three wire were connected like shown there would be excessive current flow through the upper and left two coils, unless there is no physical connection at the center point, which it might be trying to show that I guess.
I never have seen a 3 wire 2 phase system in the wild.
It can in theory be made with two single phase transformers off a delta 240 system.( But dont ask me how)
I have seen and worked on 5 wire two phase way back during my Philly years.
From what I recall the 3 wire variant was used in more rural areas, and the main reason building owners would keep it around is hard to replace motors like elevators (and the utility would have provided transformers when it converted to three phase).
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