024engineer
Member
What would happen if the H2 bushing was grounded on the primary side of a 3 phase Unground Wye-Delta bank while energized? What is the voltage between ground and the H2 bushing?
Wye-Delta H2 floating
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
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- Electrical Contractor
Engineer, welcome to the forum! 
Ungrounded supply? In theory, the only effect would be to fix the voltages of the other lines and the neutral to ground. The two lines would be the L-L voltage, and the neutral would be the L-N voltage.
If you mean when floating, it approximately equals the L-N voltage, due to capacitance to earth. However, that high impedance means very little current capacity. Enough to shock in most cases.
wirenut1980
Senior Member
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- Plainfield, IN
024engineer
Member
Still questioning?
Still questioning?
So would each leg simply gain a reference to ground and nothing more or would it cause a short circuit to earth?
Still questioning?
So would each leg simply gain a reference to ground and nothing more or would it cause a short circuit to earth?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
The first grounding would become the earth reference, but no current would flow. Another grounding becomes a short, and the resultant current depends on the pathway impedance (and source voltage, of course.)
An intentional, low-impedance connection between one conductor and the EGC system assures operation of a fuse(s) or breaker upon a line-to-grounded-surface contact. People protection depends on GFCI devices.
wirenut1980
Senior Member
- Location
- Plainfield, IN
Oh, I think I understand the original question now. Since there is current flowing on the neutral there will be some voltage on it with respect to remote earth (ground). Typical values of this voltage I have measured (assuming the primary neutral is intact) range from less than 1 V to around 10 V. There would be no short circuit to earth from connecting the H2 bushing to ground.
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