Ground for three phase Wind Inverter

quique
quique Solar Expert Posts: 259 ✭✭
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?

Attachment not found.

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.

Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    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
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: Ground for three phase Wind Inverter

    Probably need some more specific information on components. From picture I would suspect that your wind controller accepts wild a/c voltage (variable frequency) rectifies it regulates it's output for charging with a built in inverter. By the position of the "BRAKE" switch wind generator should be stopped or turning very slowly. Need to measure voltage on wires coming from wind source. With a good wind blowing. Appears that it will also, except some solar input? Need specifications from unit, Inputs and outputs? Inverter size will help you in getting the correct gauge for your battery connections and as suggested should be on the main posts and not the threaded terminals.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • quique
    quique Solar Expert Posts: 259 ✭✭
    Re: Ground for three phase Wind Inverter

    1. Yes, this is totally OFF GRID

    2. BBank negative conductor is grounded.

    3. The inverter is hybrid inverter-charger, but the charger is PWM type. It does not include a DCGFI device.

    4. The equipment does have a Brake switch for servicing which is said to cut the current coming in from the turbine.

    5. Yes the rectifier is part of the electronics in the inverter.

    My idea was to prevent lightning strikes from frying my inverter/charger. This is a 1000kW turbine rated at 48V, which is why I have a 4 - 12V battery bank.

    6. Rated battery V = 48V, Rated Wind Power = 1000W, Rated Solar input = 300W. Overdischarge shutoff V = 44V, Overdischarge Recovery Volt = 48V, OverVoltage Protection Shutoff 68V, OverVoltage Protection Recovery 66V, Floating Charge Volt 58V, Rated Output 1000VA, 120VAC, 60Hz
  • SkiDoo55
    SkiDoo55 Solar Expert Posts: 414 ✭✭✭
    Re: Ground for three phase Wind Inverter

    Do you have the connection schematics for the wind generator and inverter/charger/controller? Is there a dump load built into the unit? Would be required for when battery bank is full and no other place for produced wind energy to go. The brake switch should be shorting the inputs of the wind system when "ON" It should stop or nearly stop it in heavy winds.

    Documents should also, give you recommended wiring sizes for batteries etc., kind and capacities of protection devices, fuse/breakers.
    GT3.8 w/4600W Trina 230W, TX5000 w/5000W ET-250W, XW4024 w/1500W ET-250W, 4 L16, 5500W Gen. (never had to use) Yet!!
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    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
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • quique
    quique Solar Expert Posts: 259 ✭✭
    Re: Ground for three phase Wind Inverter

    The turbine is mounted on a pole that is fastened to the side of the building.

    I thought I needed to ground the positive conductor as you do in PV arrays.
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    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
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset