Ground and Neutral Wires

[sensij]

The non-socketed meters are generally used when it is not necessary to seal the connections to prevent unauthorized access. Although they do support sealing too.

Yes, the covers of the terminals are lockable, and there is a thin wire that will break if the device is opened from the backside. I put the meter in myself and have no authority that requires it, so I have full control over how it is set up and whatever data can be extracted from it. I'll be reconfiguring the pulse outputs to get 0.625 Wh resolution soon, which will give much better resolution for the low power consumption overnight. Another wrap or two through the CT may still be required to pick up all the idle mode consumption though.

[foo1bar]

I 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.

I 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.

[inetdog]

I 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.

Actually, 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.

[foo1bar]

Actually, 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.

I 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".

[Sunking]

No, 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....

Sensi in any meter can or cabinet N-G are bonded together. By law and design Watt Hour meters must use a Ground Reference for Grounded systems, or Phase to Phase Reference for Open Delta.

[Sunking]

I 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".

Correct but that does not take 120 volts to do that. Just as easily, less expensive and less complicated to do at 240.

[foo1bar]

Correct but that does not take 120 volts to do that. Just as easily, less expensive and less complicated to do at 240.

I disagree - I think it's likely less expensive at 120V.
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.

[sensij]

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.

[inetdog]

How 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.

Current 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.

[sensij]

Current 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.

But you said that in post #5. Look at all the fun we've had since then!

[SunEagle]

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.

The inverter that is being used by the OP is a Solectria 7600TL. According to the installation manual you are required to bring in the Neutral wire from your main power panel and terminate it to the Inverter N or neutral terminal.

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.

[Sunking]

I disagree - I think it's likely less expensive at 120V.
There are many high volume (inexpensive) 120V to DC power supply.

How so? It cost more to add a Neutral circuit requiring current and a fourth terminal costing the manufacture more money, and the consumer having to add the 4th wire.

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.

It is still more complicated adding the additional circuit requirements to pick off 120 volts when 240 is already there. With SMPS higher voltage is always preferred and really makes no difference what the voltage ratio is.

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.

[Sunking]

--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.

Tell me please. I would like to know.

[Sunking]

How is this thread turning into a @#$%show?

my meter is not of the type Sunking is describing, and does not require a ground.

Calm down Sensi. All I said is Neutral i snot needed or required for a watt or watt hour meter.

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.

[Sunking]

How is this thread turning into a @#$%show?

My meter is not of the type Sunking is describing, and does not require a ground.

Calm down Sensi. All I said is Neutral is not needed or required for a watt or watt hour meter. I never said your does not.

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.