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Automatic / Relay: Neutral Bonding?

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21 hours ago, Coulomb said:

Well, I guess that makes sense, at least.

Well it would. But I just checked on the inverter itself and got disappointed: There the 38 setting is available. In-consequent people!

21 hours ago, Coulomb said:

I think that the general lack of proper documentation is appalling. But that's what you get with Axpert level price

And they are missing a valuable sales argument.

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  • Never, EVER connect the neutral of two power sources to each other.  There is no country in the world where that is legal. Neutral bonding means a relay that connects the neutral output of the in

  • I'm confused, do you not have an earth wire running to your inverter, is that what you are saying? Definitely not legal. These regulations for inverter installs are pretty universal arou

  • Without looking at the video (sorry, time is tight), MEN (Multiple Earthed Neutral) seems to be a type of TN-C-S where there is a neutral to earth bond at the DB. That's what we have in Australia, and

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On 2021/10/27 at 9:01 PM, PowerUser said:

You don’t need 40A relay for that. 10A is enough. You can order a Weidmuller relay from Voltex:

https://www.voltex.co.za/product/weidmuller-d-series-220vac-10a-8-pin-relay-with-led-2-c0/
 

this model comes with or without LED - whatever suits you. Make sure, you order the base for it too. 
 

Running 2 inverters in parallel, I would assume, you only need to install one on the master. But rather confirm with someone familiar with parallel installations or ask SunSynk. 

Is 10A sufficient should there be a fault somewhere? 

On 2021/11/17 at 4:31 PM, Coulomb said:

In my experience, Axperts with the automatic connection of AC-out N to earth are wired like this:

file.php?id=381

Hi Coulomb, (hope I'm not hijacking this thread) I am totally off-grid with no AC-in and my AC-out Earth runs to a spike about 30m away just before it enters the house and mainDB. Everything has been running fine for years, but I'm going to be doing some work on the inverter side and was thinking of running another earth from the AC-in Earth connection to a spike closer to the inverter (PV combiner box uses this spike), for extra safety. Is this justified or will my paranoia just make things a lot less safe in the end or cause my inverter any damage due to having 2 spikes on the same earth line?

I have an axpert (clone) 5kva with 0.8pf and 145V mppt with the same N/E relay as above.

Thanks in advance

4 hours ago, jumper said:

Is this justified or will my paranoia just make things a lot less safe in the end or cause my inverter any damage due to having 2 spikes on the same earth line?

I can't see any harm in this, and it may help under certain unusual conditions.

AC-in earth and AC-out earth are of course the same thing. I assume you use the AC-in earth terminal for convenience.

Thanks for the reply

3 hours ago, Coulomb said:

AC-in earth and AC-out earth are of course the same thing.

Yeah, I figured this when I saw they are joined to each other and to the casing internally, but then I saw the N/E relays and circuits (which led me down another rabbit hole) and just wanted to be sure I wasn't going to cause anything to go haywire.

3 hours ago, Coulomb said:

I assume you use the AC-in earth terminal for convenience.

Yep, exactly, as I don't have grid power I figure I'd use that instead of shoving 2 wires in the AC-out earth.

Thanks again, much appreciated.

 

Here's a pic for reference in case anyone is interested:

AC-in and AC-out earths are joined at the casing bolt just outside the rhs of the pic

image.thumb.jpeg.4450a7048752eadc40b5453362c5e65e.jpeg

What level of current would flow through the earth/neutral bond relay? Can't the dry contact relay (from setting 38) just be directly connected between N and E? I see it is rated at 3A/250vac. Just asking 🤔

3 hours ago, JacquesVDM said:

What level of current would flow through the earth/neutral bond relay?

Normally, very little, but it has to be able to take fault current without causing a hazard. Look at the gauge of yellow/green wire in the above photo, for example. I tiny 3 A contact isn't going to cut it, unfortunately.

1 hour ago, Coulomb said:

Normally, very little, but it has to be able to take fault current without causing a hazard. Look at the gauge of yellow/green wire in the above photo, for example. I tiny 3 A contact isn't going to cut it, unfortunately.

What would you recommend size wise for a 8kW Sunsynk inverter?

4 hours ago, JacquesVDM said:

What level of current would flow through the earth/neutral bond relay? Can't the dry contact relay (from setting 38) just be directly connected between N and E? I see it is rated at 3A/250vac. Just asking 🤔

Not sure but if I look at the conditions the normally open closes it also changes state when switching between levels set by settings 12 and 13. May be different inverters use different point of operation. It could just close then the grid is on. 🤔🤔

3 hours ago, Coulomb said:

Normally, very little, but it has to be able to take fault current without causing a hazard. Look at the gauge of yellow/green wire in the above photo, for example. I tiny 3 A contact isn't going to cut it, unfortunately.

When the relay operates, it would be when the load is supplied by the inverter and the grid supply is disconnected. Where and how would a fault current flow? I can understand that if you link N and E permanently and the grid's Neutral is cut or broken, then all current (fault) would flow through the link to ground. But if it is not using the grid / battery mode there can't be current flowing through that E/N bond. Or am I missing something? 

34 minutes ago, JacquesVDM said:

When the relay operates, it would be when the load is supplied by the inverter and the grid supply is disconnected.

Good. I thought it will also close with grid on and it reaches the back to grid point. Setting 12.

21 hours ago, JacquesVDM said:

Or am I missing something?

An active to earth short. If the short wins against the earth connection before the breaker breaks the circuit, then all metalwork would be live.

If the contacts are merely damaged and go high resistance, you might not notice and the whole residual current safety system is compromised. 

For an 8 kW inverter, I'd like to see several kA of fault current rating. I would also use at least 2.5mm² earth wiring, preferably 4mm² to handle about 6kA. 

It's more about the fault current rating of the relay, which might not be specified. But get one rated at 6kA to be really safe.

But my gut feeling is that 10A and 1mm² wire would suffice, with 15A and 1.5mm² safer. 

16 minutes ago, Coulomb said:

An active to earth short. If the short wins against the earth connection before the breaker breaks the circuit, then all metalwork would be live.

If the contacts are merely damaged and go high resistance, you might not notice and the whole residual current safety system is compromised. 

For an 8 kW inverter, I'd like to see several kA of fault current rating. I would also use at least 2.5mm² earth wiring, preferably 4mm² to handle about 6kA. 

It's more about the fault current rating of the relay, which might not be specified. But get one rated at 6kA to be really safe.

But my gut feeling is that 10A and 1mm² wire would suffice, with 15A and 1.5mm² safer. 

Would you be comfortable installing this?

20220621_160222.jpg

5 hours ago, Coulomb said:

An active to earth short. If the short wins against the earth connection before the breaker breaks the circuit, then all metalwork would be live.

If the contacts are merely damaged and go high resistance, you might not notice and the whole residual current safety system is compromised. 

For an 8 kW inverter, I'd like to see several kA of fault current rating. I would also use at least 2.5mm² earth wiring, preferably 4mm² to handle about 6kA. 

It's more about the fault current rating of the relay, which might not be specified. But get one rated at 6kA to be really safe.

But my gut feeling is that 10A and 1mm² wire would suffice, with 15A and 1.5mm² safer. 

So if L is shorted to E, the fault current will run to E and through the E/N bond to N on inverter? That seems logical. But if I have a RCD, any fault current flowing to E would trip it? 

19 hours ago, JacquesVDM said:

So if L is shorted to E, the fault current will run to E and through the E/N bond to N on inverter?

Yes.

19 hours ago, JacquesVDM said:

But if I have a RCD, any fault current flowing to E would trip it?

Yes, unless the N-E bond is so weak that it lets go before the RCD can break, which is unlikely.

7 minutes ago, power.esrl3 said:

I wonder if it is fine to bond E and N Deye's Load/Essential Output permanently?

You have to make sure that you don't have more than one bonding from N to E at any one installation. If you do, strange things can happen, and you can't guarantee that important things like RCDs will work, or they'll nuisance trip. It can also be a nightmare diagnosing such installations.

4 minutes ago, Coulomb said:

You have to make sure that you don't have more than one bonding from N to E at any one installation. If you do, strange things can happen, and you can't guarantee that important things like RCDs will work, or they'll nuisance trip. It can also be a nightmare diagnosing such installations.

My installation is something like this:

Inverter > External ATS > House DB

So when grid is on, everything is non essential, when grid is off, everything is essential.

So my thought is, could I just bond the Deye's Essential(aka Load) Neutral Port to a separate ground rod permantly?

1 minute ago, Coulomb said:

I think that's still asking for trouble.

Thank you so much for the advice.

My thinking was that, essential port is not used anyway and is isolated via ATS when grid is on, and only used when grid is off, so I thought I could just permanently bond the E and N on the essential port.

Ok last one sir.

See attached picture. Assume generator input is Deye's Load Output.

This is just a grab photo, as the schematics of my setup is on the other house, and this is the most I can grab from google that is identical to my setup.

Jeez, in our country, I think no installer does the neutral bonding. So this is the immediate remedy I can think of to prevent floating neutral during off grid.Grab.thumb.jpg.db4089f4c70738c1dcc6b18a48214409.jpg

4 hours ago, power.esrl3 said:

Ok last one sir.

See attached picture. Assume generator input is Deye's Load Output.

This is just a grab photo, as the schematics of my setup is on the other house, and this is the most I can grab from google that is identical to my setup.

Jeez, in our country, I think no installer does the neutral bonding. So this is the immediate remedy I can think of to prevent floating neutral during off grid.Grab.thumb.jpg.db4089f4c70738c1dcc6b18a48214409.jpg

Deye is able to signal islanding mode to a contactor/relay which is used to create the e/n bond

21 hours ago, power.esrl3 said:

See attached picture. Assume generator input is Deye's Load Output.

The problem with that is if/when the Deye connects its N out to its N in, to bypass or blend. Then you have two N to E bonds, which is bad. Eskom's N will presumably be bonded to earth in the DB somewhere. 

1 hour ago, Coulomb said:

The problem with that is if/when the Deye connects its N out to its N in, to bypass or blend. Then you have two N to E bonds, which is bad. Eskom's N will presumably be bonded to earth in the DB somewhere. 

Now I see the problem. That was an important thing you point out "N out to its N in" during bypass/blend. Thank you for clearing it out. I'll definitely use relay.

However, I found some youtube video that it is fine with TN-C-S. What say you? The topic is at 24:00

 

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