Ground for three phase Wind Inverter

Re: Ground for three phase Wind Inverter

quique wrote: »

I just connected my 48V (sparking) battery bank to my wind inverter that came with the wind turbine.

It is not grounded, so we disconnected it. My question is, from what Ive seen in PV arrays, the panels are grounded in the negative conductor, the non-switched conductor.

In this case, I have 3 wires running down from my wind turbine into my inverter. How do I know which to ground?

I have the 3 wires going in on the right. I have the 2 battery bank wires (red/black) on the left. And on top, I connected a small office power strip just for testing.

Ok--Just slow down a moment...

There are lots grounds and wires here to talk about... But need to understand better before I would make any suggestions (want to keep you safe).

First, is this a pure "off grid" power system (at least the wind+battery portion) to your loads? Or is this Grid Tied capable (i.e., hybrid inverter--Does not look like it is)? Assuming this is a "pure off grid" AC inverter--Will you be using a manual/automatic transfer switch to utility power?

Regarding grounding... Typically the DC battery bank is grounded at the negative battery terminal or negative battery bus common connection. You would not ground the DC side of your system anywhere else (not at a solar array, at the wind turbine, etc.).

Some modern MPPT charge controllers offer an internal DC GFI circuit... This is a huge safety/code discussion in itself. And if you have a solar array+mppt charge controller and/or an external DC GFI circuit breaker setup--We need to know that.

You would not ground the three phase output of the wind turbine alternator ever--However, if you wanted to shut down the wind turbine (service, high winds, etc.), you can short out the three phase output of a wind turbine.

Some people/turbines do this "after" the DC rectifier--But if done here, you need to use a switch that disconnects the turbine from the battery bank, then shorts out the rectifier output (bit, in this case, it appears the rectifier is "inside" your wind inverter/controller).

Anyway, still confused.

-Bill

Re: Ground for three phase Wind Inverter

Then I would probably suggest adding a couple of surge suppressors like these to near the base of the tower--And drive a ground rod to connect to the surge suppressors:

http://www.solar-electric.com/suprde.html

If the cable from the wind turbine is buried (and/or in metal conduit that is grounded at both ends to an earth rod), that is probably enough.

If the wind turbine cable is through the air--Then I would put the suppressors at the outside wall of the home before the cable enters the home (with suppressors connected to ground rod at base of wall. I would also run a 6 awg to your home's main ground rod).

Anyway, my first take on the system design.

-bill

Re: Ground for three phase Wind Inverter

You do not ground + or - conductors in a solar array or the wiring from the array to the charge controller... The "typical" grounding for any Off Grid power system is to tie the negative battery return (negative bus) to the earth ground rod near the outside of the foundation (hopefully, the battery bank is on the inside of that same wall).

And, the DC ground rod is either the same as the AC ground rod (for main panel earth+neutral bonding), or the DC rod it tied to the AC rod with ~6 AWG cable (you want to "short" the ground rods together so that there is a solid path between all DC Returns, AC neutral, and AC+DC green wire safety grounds).

Surge Suppressors can be used from + and - on the solar array (or wind turbine, etc.) to local earth rod.

Lightning is a "radio frequency" phenomenon--And there are specific rules that you should follow for any grounding path that expected to carry lightning current.

We can talk specific grounding for your system if you wish (probably will be many thousands of words less discussion if we talk your system specifics rather than grounding generics).

-Bill

-Bill