diy solar

diy solar

Live Ground Shocked 5 Year Old

Hmm.... I better move on for now, but I'm thinking now that @Hedges is right on that 12.5A input to the autotransformer....

Now this will bug me until I get to the test tomorrow! 😆 I'll report back with numbers, pictures..... and idk what else. But all the data that I can easily and quickly provide!
 
timselectric said:
We are in total agreement on this.
Click to expand...

Specfically:
- MUTUAL inductance between the two halves forces the current from transferring power between L1 and L2 to be equal and both the same direction (and in N to be twice that and in the other direction), while:
- TOTAL inductance forces magnetization current (the bulk of the current in L1 and out L2) to be small, while:
- The remainder of the current in L1 and out L2 represents losses (resistive, hysteresis, eddy current, coil imbalance), which are all small.
 
ricardocello said:
This is why the Victron Autotransformer has a solenoid trip for its main breaker based on toroid temperature, not Neutral current.
Short excessive unbalances over 30A do not trip it. They claim 28A continuous depending on ambient temp.
Click to expand...

Good news/bad news.

First the good news: I've found a Square-D QO series shunt trip breaker!

QO2301021 - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in, AC shunt | Schneider Electric USA

Schneider Electric USA. QO2301021 - Mini circuit breaker, QO, 30A, 2 pole, 120/240VAC, 10kA, plug in, AC shunt.
www.se.com www.se.com

Bad news: at $256 msrp It costs about as much as the Growatt autotransformer.
Like everything Schneider, street price usually less. $120 at the slowest shipping supplier I have ever encountered:



Victron auto-transformer with 100A pass-through is a good way to go at $509

www.currentconnected.com

Victron Autotransformer - 120/240V - 32A or 100A | Current Connected

Enhance safety and efficiency with the Victron Autotransformer. Step up, step down, and balance your split phase output effortlessly.
www.currentconnected.com www.currentconnected.com

Or for similar money, pick up a used 25kVA transformer and use its 240/480V primary windings as auto-transformer. Then you can have 100% of inverter wattage feed 120V load. Just make sure breaker panel and wires can handle the current (2x the inverter current.)
 
If you want to protect at the neutral output current. A 3-phase motor starter could be cheaper. Using the center pole for the neutral.
 
timselectric said:
We agree that the 120v loads current inside the autotransformer is divided in half on the 240v feeding the autotransformer.

Were we disagree on the feed breaker size, is on how the actual loads will be presented to the breaker.

I say that it depends on how the autotransformer is connected.
In line with the feeder, I say protect the feeder. (As it will be carrying the most current)
Or "T" tapped at the loads, I say protect the neutral. (As it will be carrying the most current)
You say protect at the neutrals rating in both cases.
Click to expand...

Maybe the difference is circuit topology.

I've been saying 12.5A 2-pole breaker feeding autotransformer + loads was necessary to protect it. (e.g. only the 2-pole breaker on left of this drawing.) that's upstream breaker.

What I just realized is, if we feed the autotransformer only with 240V from source, then daisy chain off its L1/L2 to a sub-panel with backfed 25A transformer breaker, and also connect centertap of transformer to neutral bus of that panel, then autotransformer is protected. Current drawn from that panel will always have |N| = |L1 - L2|, Neither L1 nor L2 can exceed 25A so N can't exceed 25A. That allows loads to be 25A 120V on L1, or 25A 120V on L2, or 25A 240V on L1 & L2. that's downstream breaker.

While it doesn't let you run loads willy-nilly like the Victron transformer with 100A pass-through breaker, it is probably good enough for most DIY work.


1712705056701.png
 
Last edited:
ricardocello said:
Never mind! $120 is actually not awful at Gordon.
Click to expand...

No, but (sometimes) 6 month delivery time is.

Their policy is to ship next day for about $250 from any given supplier, after several weeks for smaller orders.
But if one little item is out of stock, the entire order is held back without any communications.
 
Joshua787 said:
Exactly the problem I face here in Puerto Rico. Ive called multiple electricians and as soon as i say offgrid or solar theyre turning their backs on me. This Forum has been the BEST source to fix my problem. This is my very first time posting or reading from a Forum and its been an amazing experience.
Click to expand...
When I first got started in 2019-20 buying stuff and watching Wills early videos , I didn’t have a clue what I needed to buy… . so I bought all Victron .BB and Blue Seas stuff as he was into that stuff at that point..

After I got it, 100% of the electrical companies I called to hook it up Said NO… or never called me back.. didn’t even want to talk about it…and there was no solar companies at all other than in Charlotte … 2+ hours away.

the one veteran electrician ( nice guy sorta) who said he would come out , wanted to see it “after I got it hooked up and finished” as he was unaware how to even mess with solar ..and was curious …but there would be a 85 dollar trip fee for coming out…😵‍💫.

Holy Moly ..

I decided to just dive in , learn and do it my self…
With a lot of help from many here ,it has worked out fine…

J.
 
Hedges said:
Maybe the difference is circuit topology.

I've been saying 12.5A 2-pole breaker feeding autotransformer + loads was necessary to protect it. (e.g. only the 2-pole breaker on left of this drawing.) that's upstream breaker.

What I just realized is, if we feed the autotransformer only with 240V from source, then daisy chain off its L1/L2 to a sub-panel with backfed 25A transformer, and also connect centertap of transformer neutral bus of that panel, then autotransformer is protected. Current drawn from that panel will always have |N| = |L1 - L2|, Neither L1 nor L2 can exceed 25A so N can't exceed 25A. That allows loads to be 25A 120V on L1, or 25A 120V on L2, or 25A 240V on L1 & L2. that's downstream breaker.

While it doesn't let you run loads willy-nilly like the Victron transformer with 100A pass-through breaker, it is probably good enough for most DIY work.


View attachment 208294
Click to expand...
Yep. Lol. This is the direction I was starting to think. 👍
 
Hedges said:
Maybe the difference is circuit topology.

I've been saying 12.5A 2-pole breaker feeding autotransformer + loads was necessary to protect it. (e.g. only the 2-pole breaker on left of this drawing.) that's upstream breaker.

What I just realized is, if we feed the autotransformer only with 240V from source, then daisy chain off its L1/L2 to a sub-panel with backfed 25A transformer, and also connect centertap of transformer to neutral bus of that panel, then autotransformer is protected. Current drawn from that panel will always have |N| = |L1 - L2|, Neither L1 nor L2 can exceed 25A so N can't exceed 25A. That allows loads to be 25A 120V on L1, or 25A 120V on L2, or 25A 240V on L1 & L2. that's downstream breaker.

While it doesn't let you run loads willy-nilly like the Victron transformer with 100A pass-through breaker, it is probably good enough for most DIY work.


View attachment 208294
Click to expand...
This is were I was. Because of how the Growatt autotransformer is wired. Input and output, instead of "T" tapped at the loads panel.
 
timselectric said:
That's fine,
Except that the grey wire in the drawing, between the inverters and transformer, should be black. So that it's not confused with a neutral.
Click to expand...
That’s fine? I’m confused, in his drawing he has L2 going into neutral busbar. In my set up I have L2 going into a 30a breaker which feeds phase 2 on my left panel.

Did I do something wrong?
 
Hedges said:
I think the comments laid it out pretty clearly. But commenters aren't authoritative, just as we forum members aren't.

"I've heard them called "slash rated". The lower rating is phase to ground voltage, the higher is phase to phase. As Bird dog said, the issue comes up in wanting to use the high leg on a 3P4W delta for a single phase 208v load; the breaker has to have a phase to ground rating of at least 208v, which a slash rated breaker does not."

"120/240V Slash rated breakers are suitable for 1Φ or 3Φ loadcenters, where the highest voltage to ground is 120V and the max voltage phase to phase is 240V. Also used in 120/208V 3Φ 4W Wye systems.



240V Straight rated breakers are suitable for 1Φ or 3Φ loadcenters, where the highest voltage to ground is 240V and the max voltage phase to phase is 240V. Such as in a Center tapped delta system, where the wild leg is 208V to ground.


Most 3P breakers come standard with a straight 240V rating.
2P units can come either way, normally slash rated, but straight rating is required if your connecting to a 208V wild leg.


BR240H is an example of a 2P unit with a straight rating, for use on a center tapped delta system."
Click to expand...
Moot point, since slash breakers wont fit in a high leg panel...
 
What is a "high leg panel"?
How is it different from any QO 3-phase panel?
 
Joshua787 said:
That’s fine? I’m confused, in his drawing he has L2 going into neutral busbar. In my set up I have L2 going into a 30a breaker which feeds phase 2 on my left panel.

Did I do something wrong?
Click to expand...
Good catch.
You're absolutely right.
I missed that, thanks.
That drawing is all kinds of wrong.
 
Come to think of it. I have never specified slashed or non slashed breakers, when ordering.
I just order the brand, number of poles, and voltage level. (250v or 600v)
Maybe one or the other breakers are a special order thing?
 
 
Hedges said:
What is a "high leg panel"?
How is it different from any QO 3-phase panel?
Click to expand...

It's an ordinary 3-phase panel fed from a 240V "high-leg delta" utility feed.

The neutral is fed, not from the midpoint of the phase triangle, but from the
center-tap of one (the "lighting") pair of phase legs. So while those two
are at 120V from neutral, the third ("high") leg is at 208V.

By convention the high leg is wired to the middle (B of A-B-C)
feed of the panel, coming out on the second, fifth, seventh, etc.
row of breaker positions. You can feed 120 V circuits from A or C,
240V circuits from any pair (but usually A and C), and three-phase
from all three as usual.

You can usually spot a high-leg panel because it has 120V
circuits but the B leg positions do not have them, but only a
3-gang breaker or blank.

(High-leg color code is supposed to be orange.)
 
You must log in or register to reply here.

Similar threads

Y
Off Grid shed connected to RV getting shocked
Replies
16
Views
476
yettieu
Y
J
Ground for Multiplus inverter
Replies
13
Views
435
John.DS99
J
TheFlumph
Ground neutral bond location.
Replies
9
Views
414
timselectric
T
C
Main Panel Amp Limit?
Replies
5
Views
197
Cmy
C
O
1st time anything solar.
Replies
2
Views
157
offthetop04
O
Back
Top