Embarrassed to ask...been a while:
Any issue with installing a 2-pole brkr. for a single phase inverter
in a (residential), 3 phase, 120/240VAC, DELTA, panel?
Any two legs of the three OK for PV?
:thumbs up:
I am sure POCO would rather not have you pulling full normal load on the 120/240 winding while at the same time feeding back power on another phase. It would just make their imbalance worse. Also the pot or pots for the high leg might not have the current capability for full inverter power if they are scaled only for a fraction of the overall demand.
On the other hand, if the normal service load is mostly three phase, then going with just one single phase inverter may not be acceptable regardless of which phase you put it on.
That's exactly how an open delta with a lesser-rated stinger than its complimentary lighter transformer should be configured. There is no phase-to-phase balancing in these cases, only loading issues... but phase-to-neutral balancing is still desired, preferred, recommended, etc....One thing I saw there that I had never seen anywhere before was that the facility's fused disco had different sized fuses in it; the high leg (B phase, I am pretty sure) had a fuse that was half or less the size of the other two. When I saw that I figured (correctly) that CPS was not going to worry about the imbalance.
That's exactly how an open delta with a lesser-rated stinger than its complimentary lighter transformer should be configured. There is no phase-to-phase balancing in these cases, only loading issues... but phase-to-neutral balancing is still desired, preferred, recommended, etc.
Yes, or at least that's how it worked out for me in the example I posted. Another benefit was that installing the system that way saved money - two pole instead of three pole switch, single phase instead of three phase AC combiner, fewer conductors, smaller conduit, etc.So assuming the utility has no concern, it better to group every inverter across the A-C phases, and avoid the high leg altogether?
I'd avoid the high leg altogether... and for these open delta systems with small stinger transformer, there's no advantage to going 3 phase with the PV system.So assuming the utility has no concern, it better to group every inverter across the A-C phases, and avoid the high leg altogether?
Given loads on the A & C phases dominating the system, and dissimilar fuses/transformers to match, I can certainly see how it is an advantage to build it this way. Plus, any single phase inverter can be connected at that position, and it will look no different to the inverter than a standard residential 1-phase grid.
You certainly don't want phase-to-phase balancing, if the consequence is that you overload the high leg service equipment, that may be ampacity limited.
I'd avoid the high leg altogether... and for these open delta systems with small stinger transformer, there's no advantage to going 3 phase with the PV system.
Many POCOs limit the size of residential PV systems according to the usage on their meter, so I'd wager she would qualify for a pretty big system.I appreciate the very thoughtful responses.
I will sit down and digest it all with references in hand when the time comes: mainly, a signed contract.
Most of the terms were above my head. My experience with non -resid. wiring being limited to vague recollections of the terms, "Wye", "Delta" and "stinger" (sounded cool) and something about square root of 3 or 2 being a factor in ampacity calculations on certain legs. More or less......
Interesting house though...she is an artist with a normal house BUT a HUGE, industrial-sized 400A full closet sized service gear...for glass-melting kilns.
All the stabs should be 240V to each other...... so i figure i'll find the two of the three stabs that are 240 V to each other and snap on my pv brkr there?