[RE-wrenches] Outback VFX input voltage cycling

Mon Dec 29 21:25:53 PST 2008

jay peltz wrote:
> Hi Kirpal,
>
> I understand and have sure seen lots of "fixed" generators that we not 
> fixed.
> The guy who sells most of the generators I use used to be at Stanford 
> labs, smart guy.
>
> I agree but I have never seen this type of problem, that is "fixed" by 
> turning on a few lights.
>
> And to be clear, this isn't to allow the generator to connect, it 
> connects just fine, but once connected the AC voltage will rise  quite 
> quickly and then once it goes above the max input setpoint the 
> inverter kicks it out of course.
>
> I just don't understand how turning on a few lights would stop this 
> from happening?
>
> jay 
> peltz power
>
>
I can sorta see how this pre-loading the generator could work... Maybe...

If the generator is already fairly well loaded down, it's not as 
susceptible to having to regulate and change RPMs
so much when another, smaller load like a charger is added to it.

Jay, what do you mean when you say the AC voltage will rise ?  You mean 
the generator voltage rises when it gets loaded ?
OK then, maybe Kirpal's method might just work for that.

Also, inductors tend to filter better with more current.   Remember the 
old SW ??  It did the same thing.  The more load you gave it, the
smoother the little steps were.  Related ?...   I have no idea, but it 
sounds good to me, that is, if there is an inductor somewhere in the 
circuit.

boB

> On Dec 29, 2008, at 8:07 PM, Kirpal Khalsa wrote:
>
>> Hi Ron, Jay and all.......It is easy to blame the generator because 
>> it is usually the generator causing the problem.........One thing 
>> that we have run into on occasion is that the generator has been 
>> re-adjusted and tuned up but that the generator repair person does 
>> this only at an idle load.....We now always make sure that when our 
>> customers are having their generators tuned up that also included in 
>> the tune up is that the generator is able to hold its voltage and 
>> frequency at a minimum of 3/4 of the rated load capacity........This 
>> has solved a few of our generator  connection issues...........just 
>> one idea.....
>> Might be worth while to test the generator under these parameters as 
>> this would affect the the acceptance by the VFX.....
>> Cheers,
>> Kirpal
>>
>> On Mon, Dec 29, 2008 at 6:14 PM, jay peltz <jay at asis.com 
>> <mailto:jay at asis.com>> wrote:
>>
>>     HI Christopher,
>>
>>     I don't know if this is similar.
>>
>>     I have a stacked 3648 unit, running in parallel at 120v.  Being
>>     fed from a 240v generator with a X-240 as stepdown.  Generator is
>>     a Onan 8.5kw.  ( don't ask why its a long story)
>>
>>     Unit did work OK for about 2 yrs.
>>
>>     When you start the generator, the inverter will connect, AC
>>     voltage will rise until the inverter kicks out the generator and
>>     the cycle repeats.
>>
>>     Now here is where it gets weird, if you turn on a few lights (
>>     could be incandescent or CFL's) and I mean like 150 watts worth,
>>     and then turn on the generator it will work OK.  Won't have the
>>     AC spike. But a small motor spike, such as a Rotozip etc will
>>     kick out the generator, and then it starts again.
>>
>>     Turning down the AC input AAC rating doesn't help, unless you
>>     turn it down a lot.
>>     The generator has a new board and was tested out as OK.  
>>
>>     If you run the house directly from the generator no problems. You
>>     can run large loads no problem.
>>     If you run the house directly from the inverter all is good.
>>
>>     Only issue is with genny/inv interface.
>>
>>     Of course its a 2.5 hr drive each way.  
>>
>>     Do you think this is a related problem?
>>
>>     thanks,
>>
>>     jay
>>
>>     peltz power
>>     On Dec 29, 2008, at 10:41 AM, Christopher Freitas wrote:
>>
>>>     Ron –
>>>
>>>      
>>>
>>>     Tech support is open today and should be able to help you
>>>     troubleshoot this in a step-by-step process that will discover

>>>     the root problem. 
>>>
>>>      
>>>
>>>     I am a bit confused by the descriptions of the events and have
>>>     the following questions and comments: 
>>>
>>>      
>>>
>>>     When you tested just the inverter without the generator running
>>>     – you stated that there was a noticeable flicker every 20
>>>     seconds – did you also notice that the yellow "AC INPUT" light
>>>     would blink and then turn solid momentarily?  This usually
>>>     indicates that there is a cross connection of the inverter's AC
>>>     output with the AC input wiring – which can be caused by many
>>>     different problems (nicked or chewed wires, water filled
>>>     junction box or conduits, miswiring of a 240VAC load, etc. – or
>>>     an internal problem with the inverter).  In a nutshell – the
>>>     inverter is "seeing" its own AC output at its AC input – so it
>>>     connects and then tries to charge from itself – which causes the
>>>     AC output voltage to decrease – and then it drops the AC source
>>>     for another 20 seconds – over and over…
>>>
>>>      
>>>
>>>     When the generator was connected to the inverter – was the
>>>     varying AC input voltage viewed on a digital test meter or on
>>>     the MATE's display?   The voltage display on the MATE will vary
>>>     until the inverter has actually connected to the generator since
>>>     the inverter is not locked onto the frequency of the generator. 
>>>     The fluctuation of the AC voltage on the MATE is more pronounced
>>>     if the frequency of the generator is way off from the 60hz
>>>     nominal.  Check the voltage and the frequency at the inverter's
>>>     AC input terminals with a good quality true-RMS meter with the
>>>     generator running but not connected. 
>>>
>>>      
>>>
>>>     e a situation where two (or more) things are going on
>>>     simultaneously.  My approach would be to continue to isolate
>>>     components and run several different tests on all components.  
>>>
>>>     Good luck 
>>>
>>>     Drake 
>>>
>
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