[RE-wrenches] Generator Overvoltage Troubleshoot

Tue Jan 14 10:58:02 PST 2025

Jim:

I am familiar with this case having worked with you on it.  The client is
an off-grid public school and reliability is very important to avoid
disruption of curriculum.  Various factors (tree cover on the site, maximum
needs occurring during winter, proximity to the ocean creating frequent
overcast and environmental constraints) will make it extremely difficult to
ever provide enough PV to cover the energy budget.  Therefore this system
will always rely on generator input.  If the generator fails power will go
out and school is disrupted.

The school needs two generators to provide reliable power.  I suggest a
second, new generator, appropriately sized is the best solution.  With a
new generator it is unlikely that generator caused problems will continue.
At least you can test with a second generator.

At the very least, provisions should be made to install a permanent power
feed from the parking lot so a portable backup generator can be quickly
deployed.  With those provisions, a rental generator will allow you to test
the inverters with another genset.

I am not in favor of rebuilding generators for critical reliability
applications unless the mechanical and electrical systems are both
rebuilt.  Field repairs are typically less reliable than a new unit.

William

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985

*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Dana Orzel via RE-wrenches
*Sent:* Saturday, January 4, 2025 4:47 PM
*To:* RE-wrenches
*Cc:* Dana Orzel
*Subject:* Re: [RE-wrenches] Generator Overvoltage Troubleshoot

I’ve chimed in on this connection before I have an Onan 20 KW an  analog
unit - 25 years old and I had it completely rebuilt prior to moving to
Idaho and then after a couple of years, the voltage got really unstable. I
dealt with ASAP they got me a they got me a replacement new not ORM voltage
regulator that has been absolutely perfect

Here is their phone number these guys were super super helpful.

(717) 274-9396

Dana Orzel

C: 208.721.7003

E- dana at solarwork.com

On Jan 3, 2025, at 1:52 PM, Darryl Thayer via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

Here is my two cents I had a similar over voltage. It was caused by the
generator. It helped to put a load on the generator, I put on a 500 watt
resistance load, it helped but in the end the generator was replaced.  Good
luck.

On Fri, Jan 3, 2025, 8:17 AM Jim Gowdy via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

Hi all,

     I need some help with a generator overvoltage troubleshoot.  I'm
working on an outback offgrid system that consists of 2 x Radian GS8048a, 1
x MATE3S controller, 1 x FM 80 charge controller, 1 x 55kw single phase
propane AC cummins generator, about 4kw of solar *not sufficient enough to
keep up with the load, and 24 x 4v Rolls batteries series/paralleled to
make 48v.  The generator was rebuilt and the batteries replaced about a
year ago and since then, the generator has been faulting due to
overvoltage.  I had help and first found that the MATE needed calibrating
so that was done, but the generator still was faulting.  I found changing
the AC Input Charging from 30a to 20a seemed to work.  I put a power
monitor on the generator output and found that, with the AC Input Charging
set at 30a, noticed that there was a voltage spike up to 300+V at about a
70a draw.  The generator company put a load bank on and verified the
generator may not be at fault and the problem is after the generator.  Has
anyone encountered a problem like this and have suggestions?  I've attached
a PDF with a timeline of what I've done for troubleshooting so far.

-- 

Jim with Gowdy Electric

Cambria, Ca 93428

business  805 927 2630

cell  805 975 5279

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