We have a 480V3P4W PG&E DELTA pump service at an orchard. The only device connected to it is a 100HP submersible pump, nothing else. We've been asked to provide low voltage for a chemical pump to clean the irrigation lines. We are proposing a 3kva Delta to Wye transformer with a new (deep) ground rod. The transformer will be NEMA 3 or 3R, concrete pad mounted. We are anticipating a standard Delta to Wye connections to furnish 120VAC to the chemical pumps, which will start when the irrigation pump starts. Are we looking at any problem(s).
3kva Transformer connection, Delta 480V3P4W to WYE 208-230/120
- Thread starter rhfii
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- Semi-retired engineer
why do you need delta to wye xfmrs to get 120 VAC?
what the heck is a "deep" ground rod?
personally I would use a single phase 480-240/120 V xfmr to feed the 120VAC pump with two normal ground rods. unless you have 3 chemical pumps in which case maybe a 3 phase solution makes some kind of sense. kind of depends on how much current the chemical pumps draw.
what the heck is a "deep" ground rod?
personally I would use a single phase 480-240/120 V xfmr to feed the 120VAC pump with two normal ground rods. unless you have 3 chemical pumps in which case maybe a 3 phase solution makes some kind of sense. kind of depends on how much current the chemical pumps draw.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Me too. 3 phase is overkill for just a little chemical feed pump. I'd just get a 3kVA (assuming you need that big) single phase xfmr and if it won't fit in the box, use a wall mount encapsulated outdoor version and hang it on the side or the back of your pump controller.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
I didn't read the paper, but how do they distinguish between the depth factor contributory to the lowered resistance from simply the increased area of contact between a longer ground rod and the earth?
Sorry for the tongue-in-cheek about the "deep" ground. 8' vs 10' The ground is very dry.
This is a 10,000 tree orchard with a three zone irrigation system pumping water from a 700' well. At this point the exact configuration of the chemical/descaling equipment is not known but we think there will be a series of pumps of moderate volume. Also, there is no 120/220 power at this site, none. The owners would like to have some electric capacity for maintenance, security and what-ever. That is the reason for the larger configuration and there is no need for a "stinger" phase.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
Yeah I don't know, I was wondering that. Obtaining a low resistance connection to earth is an academically interesting topic to me, but that article really overstress how important it is and what that accomplishes
I wouldn't call it nonsense. There are some good points and if you are dealing with sensitive electronic equipment in outdoor installations there is concern with the adequacy of grounding in some arid and semi-arid locations.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
- Occupation
- Electrician
iceworm
Curmudgeon still using printed IEEE Color Books
- Location
- North of the 65 parallel
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- EE (Field - as little design as possible)
ef -
You are familiar with IEEE Emerald Book ?
1100-2005 - IEEE Recommended Practice for Powering and Grounding Electronic Equipment
If you are having trouble sleeping, it is a pretty good read.
You are familiar with IEEE Emerald Book ?
1100-2005 - IEEE Recommended Practice for Powering and Grounding Electronic Equipment
If you are having trouble sleeping, it is a pretty good read.
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