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3 phase to a 2 Phase Eg4 18kpv Inverter

Quattrohead said:
You probably need to turn that all off and wait until you have read the manual and understand what's going on. Those tiny wires are going to burn up in short order. You also need to find out what the current rating is on the tankless water heater and the pool pump.
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Good catch.
They definitely aren't capable of carrying 50a. (Breaker size)
FullNuke said:
I also have everything in the off position; battery breaker, PV and the side Off and ON; I just plugged in the wifi doggle and am able to update the firmware. Sorry I usually take caution and rather talk to Signature Solar to do step by step; with dipsticks etc...
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You don't have the correct size conductors.
The breaker should be the weakest link, not the wire.
I'm guessing that the alarm is due to voltage drop on the tiny wires.
 
Bkord said:
I work on 208 often. And I see it coming from the utility around 220. I rarely see 208. It is always higher in my area. If I see 218 on a 208 service, I consider it good.
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So one theoretical concern I have is that this will work OK at the upper tolerance range of 120/208. But this 127/220 would be the nominal grid voltage which has its own upper tolerance, which would be above the U.S. upper tolerance
 
Make sure your firmware is fully up to date as first order of priority.

I know it's sort of good money after bad, but I'd just get another, boosting your demand capacity. "It's only money", in for a penny, ... Over the long term this is going to give you a severe headache if you don't make it sane, in particular if you start re-arranging electrical panels to get stuff on the phase you need, that is not going to be free, and you will likely overload a phase. Spend a little time researching "3-phase" power, but what you are doing is sending three lower current feeds instead of one higher current one. It's likely your 3-phase is 50A or so, this means you run a smaller gauge wire , but three conductors, so you get 3X the current 50A, or 150A total vs a single 240v/150A service. This gives you THREE sources of 208v between each of the hot legs L1-L2, L1-L3, and L2-L3, but it limits each to 50A. Because of this it is unlikely you are wired to have all your high demand items on the same leg pair.
 
timselectric said:
Correct, he's only connected to one of the phases.
In a split-phase configuration. (L1, L2, N, G)
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If he has a 220V load on L2 and L3, and L2 goes through the 18kPV but L3 doesn't, and the grid drops out, the inverter will only be powering L2 and N. What will will happen?

And aren't L1 and L2 only 120 degrees apart? Shouldn't the 18kPV be told that?
 
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ricardocello said:
If he has a 220V load on L2 and L3, and L2 goes through the 18kPV but L3 doesn't, and the grid drops out, the inverter will only be powering L2 and N. What will will happen?
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Bad things will happen.
ricardocello said:
And aren't L1 and L2 only 120 degrees apart? Shouldn't the 18kPV be told that?
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the phases are 120° apart. Not two legs of one phase.
L3 & L1 is phase A
L1 & L2 is phase B
L2 & L3 is phase C

The neutral is a common center tap for all 3 phases. (In a WYE configuration)
 
Any time ANY loads are consumed on the unused line to one of the used lines, the inverter will trip.
To do this safely, in addition to correctly sizing conductors to the loads, you are going to need the second 18Kpv...
 
ksmithaz1 said:
Spend a little time researching "3-phase" power, but what you are doing is sending three lower current feeds instead of one higher current one. It's likely your 3-phase is 50A or so, this means you run a smaller gauge wire , but three conductors, so you get 3X the current 50A, or 150A total vs a single 240v/150A service. This gives you THREE sources of 208v between each of the hot legs L1-L2, L1-L3, and L2-L3, but it limits each to 50A.
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If the feed is 50A per leg x 120V x 3 legs = 18,000W
18,000W / 208V / 3 legs = 28.8A, not 50A

Two 208V loads are pulling on one 50A 120V phase, but each at a 60 degree angle.
28.8A x sin(60) x 2 = 50A
Of course if the two 208V loads are not equal, the net draw is out of phase current.
The inverters may be able to deliver more than 28.8A to a single 208V load, maybe even 50A. In which case two inverters are each delivering 6kVA but only 3kW. Their internal power dissipation probably approaches what it would have been for 6kW, lower efficiency.

I think you're correct it "limits each to 50A", just can't support all three at once 50A. Assuming the inverter is happy with reactive loads.
 
ricardocello said:
If he has a 220V load on L2 and L3, and L2 goes through the 18kPV but L3 doesn't, and the grid drops out, the inverter will only be powering L2 and N. What will will happen?

And aren't L1 and L2 only 120 degrees apart? Shouldn't the 18kPV be told that?
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Since they have wiring diagrams for 2 or 3 units in a 3 phase arrangement, I'm guessing that should not really be problematic, but it's a point well explored. The problem as I see it is you're going to end up overloading one phase, kind of defeats the purpose, draw all your juice from L1-L2, the other two have nothing. Might attract attention from the power company as well when you are in bypass.
 
Hedges said:
If the feed is 50A per leg x 120V x 3 legs = 18,000W
18,000W / 208V / 3 legs = 28.8A, not 50A

Two 208V loads are pulling on one 50A 120V phase, but each at a 60 degree angle.
28.8A x sin(60) x 2 = 50A
Of course if the two 208V loads are not equal, the net draw is out of phase current.
The inverters may be able to deliver more than 28.8A to a single 208V load, maybe even 50A. In which case two inverters are each delivering 6kVA but only 3kW. Their internal power dissipation probably approaches what it would have been for 6kW, lower efficiency.

I think you're correct it "limits each to 50A", just can't support all three at once 50A. Assuming the inverter is happy with reactive loads.
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Man, you really are trying to make me look all this sh*t back up aren't you? It get's really fuzzy after 40+ years. @timselectric works with this stuff every day, I'm sure he can confirm one way or the other, but I'm pretty sure when it comes to the 208, you can pull 50A from each leg, subject to the normal 80% rules. Looking into some lower end DCFC installs, they generally spec 208/50A or 240/150A service to support a 25KW unit. Since Neutral is bound to each leg, your saying you only get 2/3 of the potential because it's shared, and not 180 degrees out from only one? So 120v is different? As we head into the weeds, ...
 
ksmithaz1 said:
Man, you really are trying to make me look all this sh*t back up aren't you? It get's really fuzzy after 40+ years. @timselectric works with this stuff every day, I'm sure he can confirm one way or the other, but I'm pretty sure when it comes to the 208, you can pull 50A from each leg, subject to the normal 80% rules. Looking into some lower end DCFC installs, they generally spec 208/50A or 240/150A service to support a 25KW unit. Since Neutral is bound to each leg, your saying you only get 2/3 of the potential because it's shared, and not 180 degrees out from only one? So 120v is different? As we head into the weeds, ...
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He misunderstood the situation, inverter ONLY outputs single phase on two legs of the panel, so, 50A each 120V leg, or 50A across L1L2 combined...
Only get out around 10,800W at 216V
 
I still say running against only one phase is going to cause issues eventually. Every time *I* do dumb sh*t like this it *always* ends up biting me in the rump at the worst possible time, and whatever I need to make it work is only available at the Lowes/Home Depot 1/2 way across town. YMMV.

The 18KPV seems to support a full 3P with only two inverters, I really don't grok what they are doing to make the magic work for the 3rd phase, be that as it may, $5K seems like cheap insurance, to get something to a fully supported configuration all the way around.
 
There's nothing wrong with having backup on only part of a service.
I'm almost positive that the only thing that is 3-phase on the property is the service. All loads are most likely single phase. Either 120v or 208v (126/218).
And for clarity on the other conversation. A 50a service will provide 50a on any single leg, or combination of legs.
 
A split-phase inverter with two independent 120V inverters can just have a timing signal to make them 120 degrees apart, or 180 degrees apart.
Then two such inverters could provide 3-phase and have a spare leg left over. Likely doubles up current on one leg. I'd rather have it in phase (or 180 degrees out of phase if your name isn't Tim), wired so the four legs are good for both 120/208Y and 120/240V split-phase. The split phase would be good for split-phase grid or generator input.
 
timselectric said:
There's no such thing as 2 phase.
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Well, there is, but no one works with that much.

However, two of three phases plus a neutral is very close to what 2 phase is, which is two feeds 90 degrees out of phase with each other. 2 phases (plus neutral) of a 3 phase feed are only 60 degrees out of phase, but they will still do all the things that a "true" 2 phase feed will do (i.e. run induction motors without starting capacitors.)
 
Does the phase angle make a difference to the individual inverters creating the Y legs? I guess it might affect the ratio between the kVAs induced into the inverters and the kW sent to the loads.
 
billvon said:
Well, there is, but no one works with that much.

However, two of three phases plus a neutral is very close to what 2 phase is, which is two feeds 90 degrees out of phase with each other. 2 phases (plus neutral) of a 3 phase feed are only 60 degrees out of phase, but they will still do all the things that a "true" 2 phase feed will do (i.e. run induction motors without starting capacitors.)
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Not quite.
Yes 2 phase did exist (and still does in a couple locations). But they were independent of each other. As in two sets of two conductors. (No shared conductors) which is why it was mostly abandoned when 3-phase replaced it.
Two legs of 3-phase (with or without a neutral) is just one (single) phase of the 3. The 3 phases are 120° of timing from each other. You are confusing legs (conductors) with phases.
I explained this in post #56 of this thread.
 
timselectric said:
There's no such thing as 2 phase.
You either have single phase, 3 phase, or split phase.
The EG4 18kpv is a split-phase hybrid AIO.
If your service is 120v/208v 3 phase. You can connect the 18kpv to one of the phases.
You can not combine phases, in any way.
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Single phase 208! Only two legs or 2 phases are used out of the 3-phases. In the main panel, L3 is omitted. Is not an actual 3-phase configuration within the property. It's WYE (Star) configuration
 
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carsantini said:
Single phase 208! Only two legs or 2 phases are used out of the 3-phases. In the main panel, L3 is omitted. Is not an actual 3-phase configuration within the property. It's WYE (Star) configuration
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Two legs is single phase.
Add a center tapped neutral and you have split-phase.

L3 + L1 = phase A
L1 + L2 = phase B
L2 + L3 = phase C
 
timselectric said:
Two legs is single phase.
Add a center tapped neutral and you have split-phase.

L3 + L1 = phase A
L1 + L2 = phase B
L2 + L3 = phase C
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In the USA, pretty much all big apartment complexes and buildings are feed 120/208 (only 2 phases or legs and a neutral) L3 is omitted.

In these settings, the buildings are often supplied with a three-phase wye (Y) system, but only two of the three phases (L1 and L2) plus a neutral are typically used to provide power for the individual apartments. This results in the following voltage relationships:

• L1 to L2 = 208V (line-to-line voltage)
• L1 to Neutral (N) = 120V (line-to-neutral voltage)
• L2 to Neutral (N) = 120V (line-to-neutral voltage)

L3 is omitted.

In this configuration, the third phase (L3) is not used in the individual apartment units, which means you effectively have a single-phase service derived from a three-phase system. This is common in many larger residential buildings because it allows for efficient power distribution while still providing the standard voltages needed for household appliances and lighting.

So, in conclusion individual apartments does not have 3-phase system with 3 legs, its a single phase 120/208v system.
 
Supervstech said:
He misunderstood the situation, inverter ONLY outputs single phase on two legs of the panel, so, 50A each 120V leg, or 50A across L1L2 combined...
Only get out around 10,800W at 216V
Click to expand...
Does this means the EG4 18k can work in 120/208 enviroment?
 
carsantini said:
In the USA, pretty much all big apartment complexes and buildings are feed 120/208 (only 2 phases or legs and a neutral) L3 is omitted.

In these settings, the buildings are often supplied with a three-phase wye (Y) system, but only two of the three phases (L1 and L2) plus a neutral are typically used to provide power for the individual apartments. This results in the following voltage relationships:

• L1 to L2 = 208V (line-to-line voltage)
• L1 to Neutral (N) = 120V (line-to-neutral voltage)
• L2 to Neutral (N) = 120V (line-to-neutral voltage)

L3 is omitted.

In this configuration, the third phase (L3) is not used in the individual apartment units, which means you effectively have a single-phase service derived from a three-phase system. This is common in many larger residential buildings because it allows for efficient power distribution while still providing the standard voltages needed for household appliances and lighting.

So, in conclusion individual apartments does not have 3-phase system with 3 legs, its a single phase 120/208v system.
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Correct
But the 3 phases are equally distributed through the different apartments.
First apartment L1,L2, N
Second apartment L2, L3, N
Third apartment L3, L1, N
And so on.....
 
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