Neutral/earth bridging method.

[Dave A]

There is a simple way of knowing when there is no Neutral/Earth bond, in other words detecting lack of the bond.

I am wondering if there is any way that I can commercialize the solution, getting tired of others making money off my ideas over the years, and even get them phoning me to get my thoughts on how to solve their problems, and never even getting anything for it, but they get paid handsomely for "solving the problem"

There is already a product intended to protect installations from floating neutral issues that detects an excessive voltage difference between neutral and earth. It is meant to be installed behind an earth leakage unit and protects the installation by causing the earth leakage unit to trip. I was thinking of something similar for this N-E bridging relay issue, but with a fault indicator light as signal.

(I quietly wonder how many people with this new unit installed will be sitting there repeatedly trying to reset their earth leakage unit when this floating neutral protection device is activated because there is no indicator signal that it has been activated...)

[Isetech]

If the neutral earth is that important, it should be done internally on all inverters and shut down the inverter automatically, with a built in fail safe mechanism, It should never be done externally, nor switched on the app.

But hey I dont know what all the fuss is about on social media, if it was as dangerous as people make it out to be, the DOL would have published a formal document preventing the sale of these inverters in SA.

Unfortunately it is going to take a death of a few people for anyone to issue a formal statement.

Just remember the method you use is compliant until a formal statement is released. So if it takes another 5 years for the powers that be to issue a formal statement, your COC for the relay or permanent bond is still compliant.

There is a simple way of knowing when there is no Neutral/Earth bond, in other words detecting lack of the bond.

I am wondering if there is any way that I can commercialize the solution, getting tired of others making money off my ideas over the years, and even get them phoning me to get my thoughts on how to solve their problems, and never even getting anything for it, but they get paid handsomely for "solving the problem"

[Isetech]

You wonder why people dont fit ELU on inverter circuits

You actually dont need a special device, or internal components, you just need to fit the device designed for public safety.

There is already a product intended to protect installations from floating neutral issues that detects an excessive voltage difference between neutral and earth. It is meant to be installed behind an earth leakage unit and protects the installation by causing the earth leakage unit to trip. I was thinking of something similar for this N-E bridging relay issue, but with a fault indicator light as signal.

(I quietly wonder how many people with this new unit installed will be sitting there repeatedly trying to reset their earth leakage unit when this floating neutral protection device is activated because there is no indicator signal that it has been activated...)

[GCE]

If the contactor is correctly sized for the neutral earth bond the chances of failure are extremely low - the same way that if a CB is sized correctly failure is low.

If the contactor fails then the ELU will not work which according to statements made above should be tested regularly and so the fault would be picked up.

How does the house owner test to ensur that his CB has not welded / failed - Is that not the same as the contactor ?

How does he test to see that the eskom supply has not lost earth neutral bridge due to theft/burnt connection , over head line fault etc - That has been going for years

I have mentioned it previously that the regs are written we need to comply - Not if you dont agree then make lots of noise on social media until it becomes so clouded in mystery that people purposely start ignoring the regs and so things never improve - same has euro socket

[Isetech]

The comment about the ELU has nothing to do with the contactor/relay, if you do a permanent bond and fit an ELU on the input side of the inverter it will trip.

You reply highlights why it is important to have the bridge done internally using a fail safe method.

[Derlyn]

The comment about the ELU has nothing to do with the contactor/relay, if you do a permanent bond and fit an ELU on the input side of the inverter it will trip.

7.16.4.5 makes it illegal to supply an inverter through an ELU on it's input side.


7.16.4.5 The neutral shall not be earthed beyond any earth leakage unit.

[Isetech]

Only if the bond is permanent, nothing wrong with installing an ELU if a relay is used. the neutral is only earthed when in islanding mode.

7.16.4.5 makes it illegal to supply an inverter through an ELU on it's input side.


7.16.4.5 The neutral shall not be earthed beyond any earth leakage unit.