hardworker
Senior Member
Corner Grounded Delta that has 240vt and 240vt and 0vt on the three phases. Is there a transformer to convert this to 208vt three phase?
Corner Grounded Delta 3 Phase
- Thread starter hardworker
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winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
Don’t let the corner ground delta intimidate you.
with a delta you always check voltages L-L, because that’s what matters. So you have 240,240,240
with Y you can check voltages to a common point and across the Y
hardworker
Senior Member
The phases are 240 and 240 and zero.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
How did you measure these voltages?
ptonsparky
Tom
- Occupation
- EC - retired
You are checking voltage to the grounded phase? Why do you expect it to be anything other than 0?
ptonsparky
Tom
- Occupation
- EC - retired
A to B = 240
B to C = 240
A to C = 240
(C being the grounded phase for this example)
C to C should = 0
B to C = 240
A to C = 240
(C being the grounded phase for this example)
C to C should = 0
winnie
Senior Member
- Location
- Springfield, MA, USA
- Occupation
- Electric motor research
To add to the above:
A to G = 240
B to G = 240
C to G = 0
The C phase is a full current carrying conductor powering the load. It is simply at 0 V to ground because it is intentionally grounded.
Jon
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
The need to would be rare, but why do you want to covert to 208v? I would think, in most cases, it would be cheaper to just replace the 240 delta transformer.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Those are the Line - Ground voltages. As others have pointed out the Line - Line voltages are all 240V.
It is a good practice to mention both points you are using when making voltage measurements
Depends on the kVA of the existing 240 equipment and how that might need to be converted to 208. Might be more economical to just order 240V equipment and use whats there.
ggunn
PE (Electrical), NABCEP certified
- Location
- Austin, TX, USA
- Occupation
- Consulting Electrical Engineer - Photovoltaic Systems
Right. You connect the ground to neutral on the 208Y/120V secondary.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Areas of concern converting a corner ground to a wye include:
In a properly installed corner grounded system, the corner conductor should be white or gray.
Corner grounded systems often employ 2 pole circuit breakers and distribution panels which would need to be replaced.
hardworker
Senior Member
Thanks for the link. I am checking with them. I think they have what I need.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
That's probably the most common usage for a 240D-to-208Y transformer
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