Thanks so much guys, the feedback is awesome
and much appreciated as usual. I am leaving quite a bit out since i was just concentrating on what condition would trigger the need to disconnect/switch ntrl sources. From the feedback im seeing where everyone is getting hung up. The ATS will work...
More details please. Im not asking for anyone to redesign this for me but am looking for pointers in the right direction if you can. I’ve torn into this a few times, just looking for extra eyes.
“If my critics seen me walk on water they would say its because i cant swim”
- M.T.-
No argument there, i agree. Its not ideal for sure as this is primarily a retrofit im tearing into that was previously designed.
“If my critics seen me walk on water they would say its because i cant swim”
- M.T.-
Thanks so much guys for the feedback. For clarity i put together a rough sketch of the system so everyone sees the application. Let me know if this clears things up.
“If my critics seen me walk on water they would say its because i cant swim”
- M.T.-
@waross & @wcasey thanks so much! The utility transformer is Delta-Y, Grounded. We will be pulling the XFMR neutral to the main swgr where everything will be commonly bonded. (The remote ATS and Gen grounds will tie their grounds to main swgr as well). We do have 120/277 L-N loads for controls...
Good afternoon,
Im working on a distributed generation application where i will need to disconnect the neutral when switching from utility power to generator power. We have a bonded neutral to ground source (utilty transformer NTRL will be bonded to ground inside of the switchgear it feeds) and...
@wcasey using your formula above if the subtransient reactance(xd”) is 0.140 p.u. then the formula is 10(1/.140)
(1/.140) = 7.14
10(7.14) = 71.4
Would this number need to be multiplied by the rated current to get fault value?
“If my critics seen me walk on water they would say its because i...
Thanks wcasey! That confirms alot and yes we will be connecting to the grid. They have not responded on fault current just yet.
“If my critics seen me walk on water they would say its because i cant swim”
- M.T.-
Good Evening,
Im assisting our senior engineering group on designing a substation that will be powered by engine/gen sets. Im hitting a wall on designing the switchgear and associated transformers. Whats a reliable way to size my switchgear based on the generator data? And whats a reliable way...
Good morning team,
Looking for a quick refresher on transformer selection and how it correlates to fault current contribution to a grid. Is there a major benefit in selecting a delta-delta or delta-wye or wye-delta or wye-wye when trying to limit the fault contribution. Im seeing more...
@palletjack we have already paid them hundreds
of thousands of dollars. Please provide a technical response next time
“If my critics seen me walk on water they would say its because i cant swim”
- M.T.-
Thanks guys, @Casey i only pulled a small sample size for about a month and all three phases have the same characteristics. When trended the primary voltage with no gen connected resembles a richter scale or a polygraph of me saying i like my wifes meatloaf. In this particular case the utility...
Thanks everyone, as always i appreciate the support and expertise. This is all awesome. The DER i am referencing above is purely generators, there is no inverter in the system. We are going from primary through a 12.47/.48 Y-Y grounded XFMR to Switchgear to generators and back so to speak. And...
@waross i was FINALLY able to do a trend on the primary while the generator is not running and the voltage is erractic. Just over the last month its fluctuated 16V with lowest at 474 and highesr at 490. They are doing alot of switching on this line
“If my critics seen me walk on water they...
Thanks @wcasey, we will have means for the utility to trip the system offline in the case of a fault but of course that does not wave the requirement for secondary protection. This is great feedback.
@cranky yes this will be a grounded Y-Y transformer. We will be adding differential protections...
Looking for confirmation on zero sequence philosophy as it pertains to Distributed Energy Resources. I am converting a site with multiple meters to a singular main primary PCC/primary service point. I am creating the protection scheme which is pretty much done but was told im still lacking zero...
Line to Line voltages are not blinking at all. They stay steady at 480 +\- 2 to 3 volts.
@wcasey it really does look that way but voltage is steady.
“If my critics seen me walk on water they would say its because i cant swim”
- M.T.-
Just want to start off by thanking everyone for chiming in on this. I was able to gather some additional data today and found that voltages are stable line to line and line to neutral on all (3) phases when the issue occurs. However current, kW, and kVar are irratic. Ive attached some screen...
@jghrist its a phase imbalance that occurs when synching to the grid for export.
@waross the generator is looking at the wye side. From the drawing it does not show solid ground and also the Xfrm is at 5% impedance in lieu of the recommeded 6% per IEC 60076-5. Also, yes we are a long distance...
