Originally posted by inetdog
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Ground and Neutral Wires
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Originally posted by sensij View PostI have CT's on both legs of my SolarEdge inverter's output, and whatever current it draws at night is equal on both. As far as I can tell, there is no 120 v load that uses the neutral conductor, so I can't offer any insight into why it is required.
But I wouldn't be surprised if the ethernet, cpu, LCD, etc are powered by a 120V supply - of course they should only draw 1 or 2 watts So may be hard to measure...
If you disconnect the solar input and turn on the LCD backlight you should see the power draw for it - and if you can see each leg separately, you could probably tell whether it's 120V or 240V powering the tiny DC power supply for those guys. Might be hard to measure though - possibly will only be measurable with the backlight on.Comment
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Originally posted by foo1bar View PostI believe the requirement is because of the anti-islanding circuitry - if L1-N or L2-N get out of bounds, it has to shut down.
But I wouldn't be surprised if the ethernet, cpu, LCD, etc are powered by a 120V supply - of course they should only draw 1 or 2 watts So may be hard to measure...
If you disconnect the solar input and turn on the LCD backlight you should see the power draw for it - and if you can see each leg separately, you could probably tell whether it's 120V or 240V powering the tiny DC power supply for those guys. Might be hard to measure though - possibly will only be measurable with the backlight on.
Once the DC input gets high enough they wake up and try to qualify the grid input for connection.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
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Originally posted by inetdog View PostActually, some GTIs power their electronics entirely from the DC side. They shut down completely when the PV goes away, even if the grid remains.
Once the DC input gets high enough they wake up and try to qualify the grid input for connection.Comment
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Originally posted by sensij View PostNo, the voltage is measured L1-N and L2-N. There is no ground reference provided. I just had another post go to moderation because I included the link, so just look up EKM Meter and you will see what I am using.
---Mod Note: Approved....MSEE, PEComment
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Originally posted by foo1bar View PostI know mine gets power for it's electronics from the grid - even with no panels connected (or it's real dark outside) if I push the button, the backlight lights up and it tells me "Night mode".MSEE, PEComment
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Originally posted by Sunking View PostCorrect but that does not take 120 volts to do that. Just as easily, less expensive and less complicated to do at 240.
There are many high volume (inexpensive) 120V to DC power supply.
As far as "complicated" - it's the same or less, since you're starting with a voltage that's closer to the 12V and 5V DC that is needed.Comment
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How is this thread turning into a @#$%show?
my meter is not of the type Sunking is describing, and does not require a ground. Also, the only loads I've been able to detect in the reverse direction (feeding into the meter) draw equal current on both legs of the 240 V supply, supporting Sunking's belief that the inverter's internal loads will run on 240 V, not 120 V. The loads I have been able to see are associated with the startup and shutdown of the inverter each day. So far, the wattage when it is fully settled into night mode is below the detectability of the meter, although I will attempt to reconfigure it to get a better measurement. It is possible to turn the screen on at night, so I don't think it is depending on the presence of DC power from the array to operate.
If the goal is to answer "what is the purpose of the neutral in a GTI", I'm not sure we have made any progress toward figuring it out for the last couple pages of this thread.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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Originally posted by sensij View PostHow is this thread turning into a @#$%show?
If the goal is to answer "what is the purpose of the neutral in a GTI", I'm not sure we have made any progress toward figuring it out for the last couple pages of this thread.
No more need be said, IMHO.SunnyBoy 3000 US, 18 BP Solar 175B panels.Comment
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Originally posted by inetdog View PostCurrent production GTIs for 120/240 volt utility service which have a 240V output are required by the UL listing criteria to measure the L1-N to L2-N balance as part of their anti-islanding circuitry.
No more need be said, IMHO.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
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Originally posted by sensij View PostHow is this thread turning into a @#$%show?
my meter is not of the type Sunking is describing, and does not require a ground. Also, the only loads I've been able to detect in the reverse direction (feeding into the meter) draw equal current on both legs of the 240 V supply, supporting Sunking's belief that the inverter's internal loads will run on 240 V, not 120 V. The loads I have been able to see are associated with the startup and shutdown of the inverter each day. So far, the wattage when it is fully settled into night mode is below the detectability of the meter, although I will attempt to reconfigure it to get a better measurement. It is possible to turn the screen on at night, so I don't think it is depending on the presence of DC power from the array to operate.
If the goal is to answer "what is the purpose of the neutral in a GTI", I'm not sure we have made any progress toward figuring it out for the last couple pages of this thread.
The question is why does this inverter require the neutral wire?
--Mod Note: When your first post is diverted to moderation, posting again will not help.
Meanwhile your question about why the inverter requires a neutral has been answered.Last edited by inetdog; 06-02-2015, 04:43 PM.Comment
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Originally posted by foo1bar View PostI disagree - I think it's likely less expensive at 120V.
There are many high volume (inexpensive) 120V to DC power supply.
Originally posted by foo1bar View PostAs far as "complicated" - it's the same or less, since you're starting with a voltage that's closer to the 12V and 5V DC that is needed.
Stop and think about any modern Laptop or PC power supply. They work at 50/60 Hz, from 90 to 260 volts and anything in between.MSEE, PEComment
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Originally posted by SunEagle View Post--Mod Note: When your first post is diverted to moderation, posting again will not help.
Meanwhile your question about why the inverter requires a neutral has been answered.MSEE, PEComment
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Not so sure your meter does not require a ground. Unless it is Double insulated, UL, with a Polarized plug, it is required to have a Equipment Ground Conductor.MSEE, PEComment
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Originally posted by sensij View PostHow is this thread turning into a @#$%show?
My meter is not of the type Sunking is describing, and does not require a ground.
Not so sure your meter does not require a ground though. Unless it is Double insulated, UL, with a Polarized plug, it is required to have a Equipment Ground Conductor.MSEE, PEComment
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