Neutral/earth bridging method.

[Derlyn]

When bridging the neutral and earth on the inverter output during islanding mode, there are basically 2 ways of doing it and achieving the same result.

Which is the correct way and why ?

A. Use a normally open contact on the relay and energise the relay coil from the inverter output. Or.

B. Use a normally closed contact on the relay and energise the relay coil from the inverter input.


Edited 08.06am.

Ok, stupid question. Must be B. Inverter output is always there, whether in islanding mode or not so the relay will remain energised permanently.

[Isetech]

This is the reason both a relay and permanent bond are not the correct way to do it.

They are both just as dangerous and why, not having SABS approval in place prior to dumping these products in SA.

These units are not designed for the SA market and wouldnt have reached the SA shelves if there was still SABS approval required. I am surprised nobody has challenged the sale of these products.

To make matters even worse, the manufacturer just tells everyone they should do it as per the countries regulations.

So right now, anything goes and that is why people dont really care much for SANS regs.

If you decide to go with the relay and it fails, you are creating an even more dangerous environment for the user.

If this ever went to court, it would make for a really interesting court case, who would be responsible if someone was killed?

The manufacturer for dumping what some would be regarded as a dangerous product, I doubt them telling you on a youtube video to connect as per your countries regulations would cut it.

The supplier for selling this product without a a detailed document highlighting the dangers of these products?

The DOL for not taking steps to investigate these products and creating regulations to ensure the product is safe to install.

The installer who is not provided with a legal approved document clearly stating the dangers of this product and a detailed approved method to make it safe?

The fact that this subject is even being discussed on social media is a clear indication that there is a problem, so honestly If I were you I wouldnt worry to much about the a NO or NC relay, either way it is not safe until the inverters are designed and approved for sale in SA, with the required modifications to make them safe.

When bridging the neutral and earth on the inverter output during islanding mode, there are basically 2 ways of doing it and achieving the same result.

Which is the correct way and why ?

A. Use a normally open contact on the relay and energise the relay coil from the inverter output. Or.

B. Use a normally closed contact on the relay and energise the relay coil from the inverter input.


Edited 08.06am.

Ok, stupid question. Must be B. Inverter output is always there, whether in islanding mode or not so the relay will remain energised permanently.

[GCE]

This is the reason both a relay and permanent bond are not the correct way to do it.

They are both just as dangerous and why, not having SABS approval in place prior to dumping these products in SA.

These units are not designed for the SA market and wouldnt have reached the SA shelves if there was still SABS approval required. I am surprised nobody has challenged the sale of these products.

To make matters even worse, the manufacturer just tells everyone they should do it as per the countries regulations.

So right now, anything goes and that is why people dont really care much for SANS regs.

If you decide to go with the relay and it fails, you are creating an even more dangerous environment for the user.

If this ever went to court, it would make for a really interesting court case, who would be responsible if someone was killed?

The manufacturer for dumping what some would be regarded as a dangerous product, I doubt them telling you on a youtube video to connect as per your countries regulations would cut it.

The supplier for selling this product without a a detailed document highlighting the dangers of these products?

The DOL for not taking steps to investigate these products and creating regulations to ensure the product is safe to install.

The installer who is not provided with a legal approved document clearly stating the dangers of this product and a detailed approved method to make it safe?

The fact that this subject is even being discussed on social media is a clear indication that there is a problem, so honestly If I were you I wouldnt worry to much about the a NO or NC relay, either way it is not safe until the inverters are designed and approved for sale in SA, with the required modifications to make them safe.

So who is responsible when a CB welds in the closed position, or an Earth leakage unit does not work ?

[GCE]

When bridging the neutral and earth on the inverter output during islanding mode, there are basically 2 ways of doing it and achieving the same result.

Which is the correct way and why ?

A. Use a normally open contact on the relay and energise the relay coil from the inverter output. Or.

B. Use a normally closed contact on the relay and energise the relay coil from the inverter input.


Edited 08.06am.

Ok, stupid question. Must be B. Inverter output is always there, whether in islanding mode or not so the relay will remain energised permanently.

Most inverters have an output to operate the contactor

[Derlyn]

Thank you brother.

As always, a most comprehensive reply.

This particular inverter has a dry contact but is only for low battery.

The inverter has a sticker on it saying "South African Version".

I have not yet started it up yet, but will do so in a day or 2 and take readings. Who knows, maybe a bridge is not necessary on this unit. It's a Luxpower 5 Kw off grid inverter.

I will report back in a day or two's time.

Have a super day.

[Isetech]

We are talking about changing the state of a power supply, which could potentially create a dangerous environment, which might not be detected for weeks, month or years. I am sure you are aware that dangerous things require a fail safe mechanism or at least have some means of identifying that the relay has failed or arced closed.

If we have to fit some form of indications when the inverter is feeding the essential supply, a failed relay or permanent bond should be monitored. I am sure I have read that a permanent bond is dangerous, well I am sure a failed relay is just as if not more dangerous.

In my opinion, it should be fitted with a mechanism that is fail safe and shuts down the inverter until the danger is repaired.

By the way it clearly states on the ELU (the one I am holding my hand) "push monthly". Do you fit a label indicating that the relay should be checked daily to prevent injury if the relay fails ?

From my experience a CB would require a dead short or extremely high current to arc the contacts closed. If the cause of the fault is still connected you would attend to the problem.

So who is responsible when a CB welds in the closed position, or an Earth leakage unit does not work ?

[Isetech]

Some Sunsynk inverters are NRS 097 approved. (copied from the 12 kw 3 phase unit) no mention of the protection level class I or class II.


Certifications and StandardsGrid RegulationIEC 61727,IEC 62116,CEI 0-21,EN 50549,NRS 097,RD 140,UNE 217002,OVE-Richtlinie R25,G99,VDE-AR-N 4105EMC/Safety Regulation IEC/EN 61000-6-1/2/3/4, IEC/EN 62109-1, IEC/EN 62109-2

Some even have class I protection (copied from and 8 Kw installer manual) but no mention of NRS approval.

Protection Level Class I.

[Andrew_van_Zyl]

I always installed a contactor and selected "Signal islanding mode" before. Installed a 8kW Sunsynk this week and was surprised to find PE/N bond taken care of internally.

[Sparks]

According to SANS neutral and earth may not be bonded after the point of control. After an installation I isolate the grid and take readings and if my readings are true I do not install a relay, I leave it as is. Relays often fail so unless you are going to test it on an ongoing basis you will end up with problems.

[Sparks]

Exactly, I am glad to see I am not the only one who is not happy about the current state of affairs. Well said.


"This is the reason both a relay and permanent bond are not the correct way to do it.

They are both just as dangerous and why, not having SABS approval in place prior to dumping these products in SA.

These units are not designed for the SA market and wouldnt have reached the SA shelves if there was still SABS approval required. I am surprised nobody has challenged the sale of these products.

To make matters even worse, the manufacturer just tells everyone they should do it as per the countries regulations.

So right now, anything goes and that is why people dont really care much for SANS regs.

If you decide to go with the relay and it fails, you are creating an even more dangerous environment for the user.

If this ever went to court, it would make for a really interesting court case, who would be responsible if someone was killed?

The manufacturer for dumping what some would be regarded as a dangerous product, I doubt them telling you on a youtube video to connect as per your countries regulations would cut it.

The supplier for selling this product without a a detailed document highlighting the dangers of these products?

The DOL for not taking steps to investigate these products and creating regulations to ensure the product is safe to install.

The installer who is not provided with a legal approved document clearly stating the dangers of this product and a detailed approved method to make it safe?

The fact that this subject is even being discussed on social media is a clear indication that there is a problem, so honestly If I were you I wouldnt worry to much about the a NO or NC relay, either way it is not safe until the inverters are designed and approved for sale in SA, with the required modifications to make them safe. "