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Re: Is anyone using an arc welder with an offgrid system

Posted: Tue, 24 Sep 2019, 15:27
by doggy
Hi Jordan,
Yes, the output is totally floating (insulated) from everything else so there is absolutely no problem.
Also, my unit continues to function beautifully.
Cheers,
Dave

Re: Is anyone using an arc welder with an offgrid system

Posted: Wed, 25 Sep 2019, 07:24
by paulvk
a. Neutral link to ground.
b. Ground to existing house ground (copper stake).
NO definitely do not do this is against the rules you will have two earths on the neutral!!!!



With the newer units they have a relay for the neutral link.
If you are going to connect the inverter to a grid or generator with an existing neutral link you have to use a relay to switch the earth onto the neutral when the inverter is operating but to remove it when in by-pass and the grid or generator neutral earth is being passed through it is not allowed to have more than one earth on the neutral so only in stand alone no grid or generator with neutral link should you bond the output neutral to earth!

Re: Is anyone using an arc welder with an offgrid system

Posted: Wed, 25 Sep 2019, 08:01
by doggy
Not sure you understand my setup.

The house is bonded in the normal manner. The grid does NOT connect to the inverter in any way. In other words I am NOT using the grid input (which is not connected) nor the ATS nor the inverter's charger.

Things connected to the inverter are totally separate from things connected to the grid. So they experience the neutral bonded to ground which is copper stake at the same location as the house ground.

Regds,
Dave

Re: Is anyone using an arc welder with an offgrid system

Posted: Wed, 25 Sep 2019, 10:41
by T1 Terry
Skip the copper stake bit, that is to make a connection back to the transformer or the power generator. You have the power generator on board in the form of an inverter. If the generator is a plug in device and has a fault to the metal frame and that is sitting on the ground, the stake will make a circuit back to the generator and that will become the earth neutral link, or anyone touching the conductive body will become the earth neutral link if the are bare foot on wet ground.
If you are not going to connect to the shore power at any time then you can get your sparkie to make an earth/neutral bond after the inverter. Be very careful about connecting and earth wire to the inverter body itself unless it is in the specified spot, many inverters use a live shell inside the inverter that is isolated from the outer body, earth that and the smoke comes out big time.
Another way around the problem is to leave the system floating and fit an RVD after the inverter. These sense voltage rather than current on the earth circuit and switch the power off without any current needing to pass through the poor sod who got themselves tangled up in the active wires.
Please, keep in mind only one class 1 appliance can be safely connected to a floating supply, if that happens to be a generator plugged into the shore power socket, the RV is the first class 1 appliance in the circuit as it has the earth bonded to the conductive frame and panels. A short to the body from either line 1 or line 2 of a floating supply turns it into an earth/neutral supply and the other line becomes the active. A second appliance with a fault to the active that comes into contact with the user will not trip the circuit breaker nor will the user feel anything, but if the user also touches the conductive parts of the body work, they become another appliance with all the available current passing through them. The RCD does not see this as a fault, the user is just another appliance it needs to power.

T1 Terry

Re: Is anyone using an arc welder with an offgrid system

Posted: Wed, 25 Sep 2019, 12:30
by BaronVonChickenPants
Sorry for the thread hijack, i have started a new thread here: http://forums.aeva.asn.au/viewtopic.php?f=64&t=6226

Re: Is anyone using an arc welder with an offgrid system

Posted: Fri, 06 Dec 2019, 03:00
by Preator
You must remember 200A @24v =200*24 over a period of 20 hours this is a standard rating given for batteries is lithium, lead acid or even capacitor storage. To get to 2000w constant @ 24v your cable will be 90mm² this is a constant 84 amp draw for the duration of the draw go with a 48v blend battery Maxwell 500F 48v and 10kw minimum lead or lithium two banks parallel. The cap will buffer the rush and buffer your lithium. Always work on thru-put on the inverter so 10kva pf1 with a high response and return.