Inverter Install Compliance

[deejaypsy]

Hi Bergie. I have been checking what the regulations say & based on this have come up with a diagram. Could you possibly let me know if this would pass a coc.
http://www.power.edisplays.co.za/changeover.html

Hi Tonye,
Just a question...
Why are you feeding your mini DB with a breaker that is on your main DB's EL, as the mini DB has its own EL anyway.

[deejaypsy]

Sorry Deejatpsy, I missed your reply until now.

I haven't been through your control circuit completely but it looks way overcomplicated, I'd go with separate RCD's for the essential and non-essential then redesign it much simpler. Even better if the essential circuits are only supplying lighting and computer equipment and other ClassII appliances then make the sockets red dedicated and do away with the RCD entirely on the essential ccts.

Hi Andy,
I have since modified my design to include a 2nd EL solely for the use of the critical equipment and am in the process of redesigning the control circuit to simplify it as suggested.

[bergie]

hi tonye

your diagram looks good . i do it the same way. deejay is correct though the mini db supply breaker shouldnt be on the main dbs earth leakage relay.
i use a modular changeover switch and install it in the mini db.
as you mentioned , the customer can choose to leave it on inverter but be limited with total current or changeover to eskom and have full load.

[Tonye]

My bad. have changed diagram


One problem I had, was the inverter has a floating neutral on output side. Voltage tests between live & earth 110v, between neutral & earth 110v.
Earth leakage on Mini DB showed an earth fault and would not trip.
After consulting with an electrical engineer who stated the neutral needed a reference point, I connected the neutral to main earth on the output side of the inverter.
Bingo, problem solved

[deejaypsy]

My bad. have changed diagram


One problem I had, was the inverter has a floating neutral on output side. Voltage tests between live & earth 110v, between neutral & earth 110v.
Earth leakage on Mini DB showed an earth fault and would not trip.
After consulting with an electrical engineer who stated the neutral needed a reference point, I connected the neutral to main earth on the output side of the inverter.
Bingo, problem solved

Ah hah!
This solves a problem i have been finding of an earth fault not tripping the EL.
So the solution is to earth the neutral on the load side(output) of the inverter?
This makes sense.
Thanx for the input.
The inverters i have installed are line interactive inverters so no changeover switch is required. It switches automatically on mains fail, but even when Eskom is available it runs in bypass mode, still supplying the critical load with power at the rated maximum size of the inverter...

[Tonye]

Glad I could help.

[Tonye]

My inverters are also line interactive. The reason for running through the changeover switch is to allow the client to turn off
Equipment which may overload the inverter.

[Tonye]

Ah hah!
This solves a problem i have been finding of an earth fault not tripping the EL.
So the solution is to earth the neutral on the load side(output) of the inverter?
This makes sense.
Thanx for the input.
The inverters i have installed are line interactive inverters so no changeover switch is required. It switches automatically on mains fail, but even when Eskom is available it runs in bypass mode, still supplying the critical load with power at the rated maximum size of the inverter...

Just completed an installation. Pulling my hair out. Earth leakage keeps tripping when running on inverter
mode. Apparently their are different types of earth leakage units.
Type AC, sensitive to alternating current only
Type A, sensitive to alternating current and/or pulsating current with DC components.
Don't know if you have also experienced this.

[DieterT]

Nice job!

Like the trunking you used and the way it has the curve into the flush mounted DB, very neat.
I had no idea there was AC & A type earth leakages. Would the A type earth leakage have a difference with tripping on the inverter?

Normally we just implement a connection box at the output of the inverter/generator with a neutral bar inside and do a earth neutral connection and label it on the box.
This is also the point where we bring our earth spike into the installation, so kind off kills 2 birds with one stone + being able to safely earth the alternative supply.

[Tonye]

Nice job!

Like the trunking you used and the way it has the curve into the flush mounted DB, very neat.
I had no idea there was AC & A type earth leakages. Would the A type earth leakage have a difference with tripping on the inverter?

Normally we just implement a connection box at the output of the inverter/generator with a neutral bar inside and do a earth neutral connection and label it on the box.
This is also the point where we bring our earth spike into the installation, so kind off kills 2 birds with one stone + being able to safely earth the alternative supply.

Hi Dieter,
Thanks for the compliment. The trunking is quite expensive but comes with all types of accesories,
making a neat job. I was also not aware of different types of earth leakage units.
Type AC should be fine on Pure sine wave inverters and Type A should work on Modified sine wave inverters. I will be doing further tests and let you know the outcome