[RE-wrenches] Generac QT series

Tue Jul 14 06:18:02 PDT 2015

I suggest you get a Fluke 435 and put it on the Generac output. I would
expect this to be a power factor problem, the inductive nature of the
transformer is reacting with the alternator of the generator and shifting
the phase angle of the current with respect to the voltage, causing heating.
If you have a device such as the Fluke, you can see the phase relation of
current and voltage. With the oscilloscope, you are only seeing the voltage
waveform. The waveform you are showing is not a problem, the THD is pretty
small and the transformer will damp the higher harmonics anyway.
Try adding a resistive load to the generator in parallel with the Magnum,
that will help to correct the power factor. You can play with capacitance
once you can measure the power factor.

On Tue, Jul 14, 2015 at 9:01 AM, Mac Lewis <maclewis1 at gmail.com> wrote:

> Hello wrenches,
>
> Last December I posted about a Magnum 4448 and a Generac 22 kW generator
> that aren't working well together.  The symptom was that the Magnum
> transformer would overheat very quickly, even at very low charge rates (<2A
> DC).  We have verified 120/240 VAC operation of the generator.
>
> We were able to get up to the site with an oscilloscope and see if we
> could find anything out.  I've attached some photos of the oscilloscope
> output.  I don't have anything to compare it to, so I'd like to see if
> anyone has some insight into why this may be occurring.
> The 4 photos are as follows (all photos L1-L2):
> 1.  Generator Waveform No Load: Unloaded Generator Voltage Waveform
> 2.  Charger 1st Connected: AC Input Voltage waveform immediately after
> charger connects
> 3.  Steady State Operation Editted: AC Input Voltage waveform after about
> 10 seconds, this waveform continues until transformer overheats (in about 2
> minutes)  Note the disturbances.
> 4.  Zoomed In Ripple: Closer view of the disturbances noted in #3.
>
> We have tried replacing the Magnum with an identical unit, and we had the
> same issue.  We also tried a Honda 6500 with atrocious voltage and
> frequency regulation and it worked fine with the Magnum.  Since I did not
> sell him the generator, the easy out is to replace the generator.  However,
> there is some custom exhaust duct work and it will be much more expensive
> to replace the generator than to try a new inverter.
>
> I think that over all it is preferable for the client to replace the
> inverter/charger with a different brand.  I have no problem doing that
> except that I'd like to be relatively sure that this is anomalous behavior
> between the Magnum and the Generac and not a generator issue.  What are the
> chances that I'd have the same issue with a different inverter?  What might
> cause this?  All voltage and frequency measurements have been perfect with
> the Generac.
>
> Your comments or thoughts are appreciated.
>
> Thanks
>
>
>
> On Tue, Dec 16, 2014 at 11:15 AM, RE Ellison <reellison at gmail.com> wrote:
>
>> If memory serves me correctly and this is the off grid Generac they are
>> available as a 120 volt and it takes a new breaker and rewiring to get 120
>> / 240 out of them
>>
>> I run into this in the past they actually had it wired for 240 into a
>> balancing transformer to feed 120 into the inverter
>>
>> We could've just left it at 120 volt
>>
>> Later,
>> Bob ellison
>>
>>
>> Bob Ellison
>>
>> On Dec 16, 2014, at 11:33 AM, "Baxter, Gary" <gbaxter at sensata.com> wrote:
>>
>> Hi Mac,
>> Jay just had the same issue and it was 120v from the gen instead of
>> 120/240. The inverter was charging using half the windings causing it to
>> Overtemp.
>>
>>  Check the 60A breakers on the side of the inverter. Also make sure to
>> remove the wires from the input terminal block before measuring voltage as
>> the inverter will make 120v look like 120/240v at the terminals.
>>
>>  If the generator is 3 Phase it won't work with this inverter unless you
>> only use one leg. This will work but you will need to turn the charge rate
>> to 50% in order to prevent Overtemp. Sometimes it works as high as 70%.
>>
>> Gary Baxter
>> Product Manager
>> Magnum/Dimensions
>>
>> On Dec 15, 2014, at 12:12 PM, Mac Lewis <maclewis1 at gmail.com> wrote:
>>
>>   Hi jarmo,
>>
>> We have verified this is split phase 120/240. My multimeter gets 120 L-N
>> and 240 L-L.
>>
>> Thanks
>> On Dec 15, 2014 10:25 AM, <Jarmo.Venalainen at schneider-electric.com>
>> wrote:
>>
>>> Hi:
>>>
>>> The Generac QT02224GNAX ships as a three-phase 120/208 VAC.  I believe
>>> the Magnum is a 120/240 VAC.
>>>
>>> JARMO
>>>
>>> _____________________________________________________________________________________
>>>
>>> * Jarmo Venalainen*  |  * Schneider Electric **  |  Solar Business*  |
>>>   *CANADA*  |   *Training & Development Specialist - Senior*
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>>>
>>>   From: Mac Lewis <maclewis1 at gmail.com>  To: RE-wrenches <
>>> re-wrenches at lists.re-wrenches.org>,  Date: 12/15/2014 05:52 AM  Subject: [RE-wrenches]
>>> Generac QT series  Sent by: "RE-wrenches" <
>>> re-wrenches-bounces at lists.re-wrenches.org>
>>> ------------------------------
>>>
>>>
>>>
>>> Hello wrenches,
>>>
>>> We have a newly installed system that has a 22 kW Generac Quiet Source
>>> QT02224GNAX with a Magnum MS4448-PAE.  When we start the generator, the
>>> Magnum's internal transformer temperature climbs to overtemp (240F) within
>>> a 2 minutes.  The batteries are being floated at the time, and haven't seen
>>> more than 5A coming out of the generator.  We swapped the Magnum out, and
>>> we have the exact same issue.  We then got a job-site gas generator 6500W
>>> and ran it.  No problem whatsoever.  The problem appears to be with the
>>> Generac, or with the interaction between the Generac & the Magnum.  I
>>> didn't have a scope on site but the fluke multimeter doesn't detect
>>> anything wrong with the voltage or frequency coming from the Generac.
>>>
>>> Has anyone had issues with the Generac QT?  Anyone paired one with a
>>> Magnum PAE before?  I want to get my scope up there and look for triplen
>>> harmonics, but I'm not sure how to filter these out.  Any references on how
>>> to effectively do that is appreciated.
>>>
>>> Thanks in advance
>>>
>>> --
>>>
>>>
>>>
>>> Mac Lewis
>>>
>>> "Yo solo sé que no sé nada." -Sócrates
>>>
>>>
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>
>
> --
>
>
>
> Mac Lewis
>
> *"Yo solo sé que no sé nada." -Sócrates*
>
> _______________________________________________
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-- 
Chris Mason
NABCEP Certified Solar PV Installer™
Solar Design Engineer
Generac Generators Industrial technician

www.cometsolar.com <http://www.cometenergysystems.com>
264.235.5670
869.662.5670
Skype: netconcepts
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