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Generator grounding

Discussion in 'Off Grid Living' started by SpikeandKari, May 25, 2016.

  1. SpikeandKari

    SpikeandKari Monkey

    Hi, new user here so if I've posted in the wrong place please be gentle!

    I live in Spain and am installing a 3kw solar system. Much more than my domestic needs but I need to pump water from a borehole to keep an orange grove alive. I am using SMA gear and during the installation and ploughing my way through six manuals which repeat information with nuggets of new stuff to keep you on your toes I find that there is a requirement to tie neutral on the 240V AC to ground. No problem with that but it means that the neutral side of the backup generator will also be tied to ground. So my question is: Is it normal to ground the neutral on a normal alternator based gen set? I have used a multimeter on the gender and find AC on BOTH live and neutral relative to ground which makes me think this is a non starter. Any input much appreciated. Ta, Spike
    Motomom34 likes this.
  2. azrancher

    azrancher Monkey +++

    In Spain you have a completely different electrical system, so it depends. Was your SMA and Generator built for European power, which was 20 years ago, a 240VAC with no neutral, or green wire (safety ground), or were they built for a neutral that is bonded to the separate ground back at the power entrance panel?

  3. BTPost

    BTPost Old Fart Snow Monkey Moderator

    There is 240 Single Phase 50Hz which is the Eu Standard, then there is 120/240 Split Phase 6o Hz which is the North American Standard... I suspect you are 240 Single Phase 50Hz, and therefore you would bond One side of your 240 to Ground, and your Safety Ground, to Ground, via Grounding Rod. Most likely you would make a single Bonding Point at the Incoming Distribution Point (Breaker Box) and NOT at the Genset. You would add a Safety Ground Only at the Genset. via Grounding Rod, and run a Safety Ground Wire back to the Distribution Box Safety Ground....
  4. Cruisin Sloth

    Cruisin Sloth Special & Slow

    Both above are correct IF !!
    What are your SMA numbers & generator numbers or point me to the link of your equipment please.
    Im working with a Auzi dude that were stacking a parallel SW & I know some of the Euro systems voltages and tricks .

    BUT before I say anything , I need the real items of what were working with . If it is made in USA , the part you are reading might not apply, sometimes usa thinks its the center of the world & forgets is pretty small compared with country's of thousands of years old rather than just 300 .


    EDIT Bonding of a leg to make it the neutral / ground base IS to be done only in one panel /zone to stop a loop or a field circle that can cause power waves .

    So before we go any further , I need more specs.
    Last edited: May 25, 2016
  5. SpikeandKari

    SpikeandKari Monkey

    Thanks to you both for your replies. My answer here is going to be a little full (and therefore probably very boring) so casual browsers may want to stop here! The generator is Spanish, a 3.0 KW peak, 2.6 KW rated gasoline model by Genergy at www.genergy.es it looks like a conventional alternator model with electronics monitoring/controlling output. It is producing 233 V at 52 Hz under moderate loads. The outlet is the standard European outlet which is non polarised so I have taken off the fascia to trace positive and negative. Bizarrely I get 90 V AC from positive to ground and 30V AC from negative to ground but I suspect this is because the AC is floating relative to ground. The SMA boxes I am using are a Sunny Boy 3000 TL which is a PV inverter normally used for grid feed in and a Sunny Island 3.0M which is a battery charger inverter. The system will use 12 200w PV panels connected in series to fire the PV inverter which will connect to the output grid of the battery inverter. During the day this will have a water pump connected to the stand alone grid with excess energy charging the batteries. At night the battery inverter will power the house just to be complete the batteries are 4 Rolls 290 AH ATM connected in series at 48 Volts .

    So I need to form a single earthing point as in
    The TNS off grid with generator schematic is relevant. So when the generator is connected in my case literally by plugging in the cord which I will fit with a polarised plug the neutral from the generator will see a direct connection to ground. Maybe all of this is normal and OK but I don't want my introduction to off grid living starting with a very expensive bang! Thanks for your help guys. Spike
  6. techsar

    techsar Monkey++

    My first thought is that if you did this test without a (resistive) load on the circuit, the generator (which appears to be an inverter-type) may not be triggered to output "normal" power. Hook an incandescent light or a small heater up and see what sort of voltages you experience with a load on the circuit. I suspect your findings will be different.

    ...and Welcome!
    Cruisin Sloth likes this.
  7. Cruisin Sloth

    Cruisin Sloth Special & Slow

    A Forum run by Enthusiasts of MidNite Solar - Index

    Post this question on this site , Nigel is very good in this area & my wife needs to translate Spanish for me . ..
    Im thinking Grounded Gen set if your not Grid - tied ..Not sure till I read the Genset specs .
    But I have a poke into that site for Nigel (Spanish reader also) .
    If I can get it translated , I reply when Im sure.


    I found this , but no specs :
    <h2 align="center">JACA</h2> <h4 align="center">3000W 230V</h4> <h4 align="center" style="color:#FFF">ARRANQUE ELECTRICO</h4>
    Last edited: May 26, 2016
  8. SpikeandKari

    SpikeandKari Monkey

    Thanks! Will do both and post what happens for the record and thanks for the welcome!
  9. Cruisin Sloth

    Cruisin Sloth Special & Slow

    I chatted with Nigel today & he is fluent in Spanish & an sparky .
    E-mail him & he's ready to help , just make sure you have all the serial #'s and info for him , This is his Job .
  10. SpikeandKari

    SpikeandKari Monkey

    Hi Sloth and thanks for your help, would you be so kind as to post the link for Nigel again? I have managed to get the answer from the Spanish support people for grounding the generator, it was 'OK if really necessary on the neutral line' so that's done but no improvement on battery inverter behaviourr, still throws an error on connecting the Genset. SMA have no generator spec in their shipped docs but I have found a 'whitepaper' (whatever the hell that is) on generator comparability issues with the Sunny Island inverter. It looks like I will need to ask about much more complex issues than just grounding. Thanks for your help, Spike
  11. azrancher

    azrancher Monkey +++

    Whitepaper, ah yes the technical american term for an Information Paper.... comprende'

  12. SpikeandKari

    SpikeandKari Monkey

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