The somewhat condescending answer of the EOR:
Gary,
There is no problem, the wye/delta is a typical installation.
Thanks
xxxxx
So we went to the manufacturer:
Please see the response below from our Consulting Specialist. However, this question really should have been posed to the Engineer of...
Well, I asked the question, I thought I posted it in here but I do not see it:
This is how I phrased my question:
MY QUESTION:
I believe this is my last question with respect to the now Delta/Wye transformer(s). Should there be any concern for ferroresonance? I will accept a simple no...
JG - it appears it becomes more of an issue at voltages aboe 12kv, yes? I think I saw a thread on it in here, I will go find it before I say or ask something not necessary.
No, I will ask one, wha does "remote" mean #3 below)
QUOTE FROM MIKE HOLT FORUM
To recap, the following issues combine to...
I do not know how to do quotes in here, sorry.
jghirst"One problem with feeding a delta-wye transformer with cable is the potential for ferroresonance if one phase is open."
I will read the thread referenced, especially since I do not know what ferroresonance is nor its impact when fuses are...
itsmoked: I am on overload as it is, I could never do what you guys do.
A few of you mentioned 25kv insulation, is this no longer a need? The spec is 15kv.
gary
gare
It is out!
Thanks a LOT!!!
Changed T1 to Delta/Wye, added EGC, it is MUCH nicer :-)
garehttp://files.engineering.com/getfile.aspx?folder=f00f7cc7-411f-4d39-8982-d8c24f3ee199&file=E1_1_0_032009NEW.pdf
Thanks jg and Bill, we have been told that a complete new single line with all necessary details is coming out tomorrow. I also appreciate that I probably do not need to contact PG&E as the new transformer should take care of the potential back-feed issues.
gare
jghirst: PG&E does not want to "own" a bunch of 12kv wiring on the premises and the homeowner does not want PG&E to enter any further into the property as is necessary.
I somewhat appreciate the difference of opinion on the shield landing, ONLY because it means an electrician should not be...
Does the local utility ever have an interest in what the next transformer down line from their transformer is, as well as what protective devices are being used? Might they have based their transformer design on what is being fed versus what they are providing?
gare
QUOTE:
Oh, good, it wasn't Portland General Electric. Pacific Gas and Electric is generally PG&E. PGE would not accept a 480V grdY-12kV delta transformer connected to a 480V service. I don't know if PG&E will or not. If the PG&E service transformer that provides the 480V is a grdY-grdY...
QUOTE:
Generator; The sketch appears to show the generator neutral bonded to ground at the generator. If this is done you must use a 4 pole transfer switch and switch the neutral. END QUOTE
We are using an ASCO 7000 4-pole transfer switch per the EOR.
QUOTE: Then, when running on the...
No loads. I have only heard that the local utility provider felt the demand was too low for them to provide the 12 kv as a metered feed, therefore they mandated the installation of a step-down xfmr to 480. After the meter, they do not seem to care what the end user does with it.
gary
gare
I uploaded a pdf of the single line and the details referenced from other dwgs. Clouds are my comments/questions to the EOR.
garehttp://files.engineering.com/getfile.aspx?folder=9eebfd26-b3af-4eaa-bed4-aab741cfb6cd&file=SingleLineW_DetailsRev6.pdf
Thanks waross, we are waiting to see what the final changes will be before anything else is said. I hope they have accepted the invitation to at least view this thread.
gare
QUOTE davidbreach:
As a utility we would not accept a customer installing a grounded wye (source)-delta (load) transformer without extensive protection on the wye side to trip the transformer off line should there be any ground fault on the utility system. END QUOTE
How on earth could any one...
Thanks jghrist.
I want to honor the spirit of the forum, seeking/providing great information without the ever present liability issue in the back of someone's mind. At the same time, credit rightfully belongs to those who expense their knowledge, in this case at no cost to others.
I will wait...