Corner Grounded Delta Madness

[brian john]

the chance of getting shocked is slim

AHHH but get between the ground and a phase (other than the grounded conductor/phase) and the potential is higher that in a properly installed Wye.

 

[LarryFine]

AHHH but get between the ground and a phase (other than the grounded conductor/phase) and the potential is higher that in a properly installed Wye.

Well, due to the lack of a solid ground connection, there is certainly the potential for a higher-than-secondary potential due to either induction or internal/external primary-to-secondary faults.

 

[iwire]

The potential is higher because the potential is higher.

A corner grounded Delta or an ungrounded delta with a ground fault will supply line to line voltages, line to ground.

480 Volt Wye to ground is 277 volts.

480 corner grounded Delta to ground is 480 volts or 0 volts if your lucky.

 

[rattus]

Who said that?

Who said that?

AHHH but get between the ground and a phase (other than the grounded conductor/phase) and the potential is higher that in a properly installed Wye.

Who said, "The risk of getting shocked is slim"?

 

[brian john]

Thanks again for all the insight, especially winnie, rattus and brian. Please allow me to summarize my thoughts on this corner grounded topic. First, if one phase is intentionally grounded the load will still see this as a three phase supply. Secondly, if one were to touch an enclosure that was bonded with said grounded conductor, the chance of getting shocked is slim because the equipment's potential is very low because it is bonded to the frame of the transformer, ges, and connected to one of the transformer's windings and will open the ocpd when one of the ungrounded conductors shorts to ground. Thirdly, in an ungrounded system, one should not get shocked by touching properly grounded equipment that contains a single fault because it's potential is also kept low due to being bonded, via the equipment ground, to the frame of the transformer and grounding electrode system. However, because there is no connection to the source the ocpd will only open when a second fault occurs. Is what I have stated above correct?

FROM mark32


I just took this thought to the next level

 

[rattus]

For Mark:

For Mark:

FROM mark32


I just took this thought to the next level

Mark, to obtain significant current, one must have a closed loop containing a source. Grounding one corner of the delta does not form a loop. Now, as has been said, if you close the loop by inserting your bod between one of the other two legs and ground, you should call 911. Better still, have someone else call.

 

[mark32]

I got ya rattus, what I meant by "Getting shocked is slim" is the theory that if one touches an enclosure/equipment that was bonded by the grounded conductor, that which in this case also feeds a motor, that the person should not get shocked if they were to find themselves between another piece of grounded equipment and said enclosure. Certainly, getting between a hot and this grounded phase could ruin one's day.

 

[brian john]

MArk: I understood what you were saying, I was just expanding on this.

 

[rattus]

I got ya rattus, what I meant by "Getting shocked is slim" is the theory that if one touches an enclosure/equipment that was bonded by the grounded conductor, that which in this case also feeds a motor, that the person should not get shocked if they were to find themselves between another piece of grounded equipment and said enclosure. Certainly, getting between a hot and this grounded phase could ruin one's day.

It's like the little birdies that roost on the HV lines. Since their little feets are so close together, there is virtually no potential between them, and they just twitter their lives away.

But then, there are the big birdies, e.g., eagles, that built nests atop poles and sometimes get fried when their wings touch two hots. The poco has to build special platforms for their aeries so that does not happen.

 

[mark32]

No no, that's cool Brian, I liked what you added to this thread. That last post was just to clarify I am very much aware of the dangers if a body were to make contact with hot and ground. I've learned a lot on this forum this week, this site is invaluable. I feel smarter already, Mark

 

[LarryFine]

Who said, "The risk of getting shocked is slim"?

Um, Ben Franklin, while holding a kite string?