[RE-wrenches] Conext SW 4024 with bad firmware

[Hugh Piggott]

hi Lou,

I don’t wish to contradict this version of events but if true then it will make the inverter unsuitable for most generators.  Here is another scenario I have seen a few times that looks similar but can be fixed.

The inverter charges the battery etc. and decides to turn off the generator.  It disconnects.  It may or may not have its own “cool down” time for the generator.  It then tells the generator to stop.  At this point the generator control circuit may decide to run a further cool down period.  Meantime incoming AC voltage is still visible to the inverter.  The inverter may then decide that it is obliged to connect to this running generator.  After any chosen “warm up period” it may go ahead and synch with the running generator and start to draw power just before and during the point where fuel is shut off and it dies.  This causes power quality problems and errors in some inverters.  Maybe better firmware could fix this.  Victron inverters are designed to disconnect on a falling voltage every time, and they do so gracefully.  With SMA inverters and Outbacks it’s better avoided.

The best fix for this is to make sure that the generator does not have its own cool down period.  If you can access and edit this parameter in the generator this is best.  Another fix is to set a longer warmup time in the inverter software but this can cause issues where the generator is being started to meet a high load.  In the case of an SMA inverter you can get a fix to it using “genman mode”.

I just wonder if you have witnessed the process and checked whether the generator’s own built-in cool down period could be the cause.

cheers
Hugh

> On 30 Dec 2016, at 00:43, Lou Russo <lou at spreesolarsystems.com> wrote:
> 
> Thanks to all for the input and suggestions, it is much appreciated. Just to be clear about the situation, the inverter has already made the AC transfer, which goes smoothly. The AC IN light is off. At this point the generator is unloaded and there is no battery charging happening. The inverter is carrying the loads.  From what Schnieder tells me is that the software is telling the inverter to follow the Hertz of the generator until it's below 40 Hertz. 
> 
> I do believe that manual start is best as it keeps the user in tune with system. It is what I do at my own home. Unfortunately most clients want the autostart and don't want to think about it. This is typically not deal breaker for me and I will push a client only so far on it. In this particular situation the system is 500 ft away from the home. So the autostart is mandatory. 
> 
> 

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