Magnum MS4448 PAE generator high volt ac problem

grizzley · December 2018

I am running into an issue with my inverter/charger sensing a high voltage ac and therefore it will not use my genertor to charge my batteries when needed. We have two Magnum MS 4448 PAE inverter/chargers with a ME-RTR router and a ME-AGS generator stater. As a generator we have an LPG Generac Guardian 10K. It ususlly worked for the past years. Sometimes I would get a "High Volt AC" warning when the generator turns on but after a oil change etc the problem would go away if the generator warmup time was set long enough ( I have it set for 120sec)

This time I am running into an issue and I can not seem to figure out how to correct it. I just had my generator services 40 weeks ago. When my system calls for the generator to start the unit starts and I immediately get a flashing red light on the ME-RTR and a message of "High Volt AC" well before the generator has completed its warmup cycle. I know the generator after the warmup is generating "good" voltage because after the system shut itself down do low voltage and came back on (obviously not ideal or desired) there was no warning light and the system started charging from the generator through the MS 4448 PAE inverter/charger.

Did I forget something or are there setting I need to check or is there a workaround other than crashing the system. I tried to contact Magnum but they no longer have after hours/weekend support teams. Any help would be appreciated.

grizzley · December 2018

Sorry, just noticed that I have a typo. The generator was serviced 4 weeks (one month) ago not 40.

mcgivor · December 2018

Things to check would be the actual voltage output of the generator, versus acceptance voltage of the inverter, if default perhaps a wider acceptance may be programmable. In leu of the above try plugging a resistive load, space heater for example, to the generator before connecting AC input to the inverter, open circuit voltage may be higher than qualification requirements, the load may stabilize the voltage to a lower value, which the inverter may accept.

grizzley · December 2018

thank you for your response mcgivor.

I have not been able to find anything where the acceptable tollerances could be set. I was hoping for something like this but if it is there I did not see it but perhaps someone in this forum knows these units well and has an idea where to look. The generator is hardwired into the system so I can not plug or unplug it. I know the load stabilizes during warmup and that is why I set the warmup time to 2 minutes. This has worked in the past.

mcgivor · December 2018

Looking at the manual, the input voltage acceptance range is 60 -140 volts which is quite a wide range, frequency 50-70 Hz, is the generator 60Hz in North America ?

grizzley · December 2018

Yes it is. It has worked for years without issues as long as the generator was serviced. So that is why I am stumped that it is now causing these issues. I installed the system in 2012. Could this be a degenerative aging issue? And if so any ideas how to check for it?

mcgivor · December 2018

Do you have a means of reading the frequency, the service may have increased or decreased the engine speed setting which would alter frequency, just trying to connect the dots, worked fine before but not after.

BB. · December 2018

Also, check the AC input on the input terminals to EACH Inverter...

It does happen that neutral (or even L1/L2/etc.) connections become loose (thermal cycling, vibration from genset), corroded (water traveling down cable jacket to connections), etc. Also look for signs of heating (browned insulation, color changes to metal hardware caused by excessive temperature (frequently cause by a poor/high resistance connection due to loose screw/wire nut/corrosion)....

Have you noticed any issues were some lights may flash brighter for a moment (when some other load cycles) or similar. That can be the result of poor electrical connection somewhere.

For example, you may see correct 120/120/240 VAC at the input of one AC inverter... A different voltage at another inverter (paralleled connections)--Like 90/150/240 between L1 to N, L2 to N, L1 to L2 (poor connection somewhere).

Frequency could be an issue... Many Kill-a-Watt type power meters and newer DMMs include a frequency counter...

For a Utility connected inverter, typically 60 Hz +/- 1 Hz... For generator connections, typically 60 Hz +/- 5 Hz (or more).

-Bill

mcnutt13579 · December 2018

Without knowing exactly the voltage and frequency that the generator is actually making, all else is useless. Figure that out first. Changing the oil does not have anything to do with what the generator puts out.

Is this a capacitor regulated unit or does it have a voltage regulator? My first reaction would be to dial it down some, if possible. If it puts out a proper 120v indicated on the meter, and the inverter still complains, drop the generator to 110v and see what happens.

grizzley · December 2018

Thank you for your responses. I will try to respond to each of your questions below.

I currently do not have the ability to check the frequency. I will see that I can get a meter that does.

On first glance the connections seem solid and I don’t see any signs of browning or the like but will have to do a more thorough inspection.

The main cables from the generator to the inverters are buried in conduit. Near the inverters the line from the generator is split and two sets of wires go one to each inverter. They are set up as in the Magnum instructions as master and slave.

Question: does any know if the sensing of the incoming power is done by both or just the master? Since we installed the system we have never changed which is the master and which the slave. So the master would have done the bulk of the work. So not sure if there could be wear and tear issues.

Not sure if the general guardians are capacitor or voltage regulated. Have to find out.

Since you all recommend to check voltage and frequency do you have any recommendations for a meter. Preferably one that captures the extremes, since the inverters seems to sense immediately.

mcnutt13579 · December 2018

Fluke, Fluke, Fluke. I have owned a lot and used a lot more of colleagues on job sites. There really is a big difference. I don't know of any other I would trust.

Something in the 80 series or 115 range is most common.

I have a significant number of inverters (not Magnum but similar) reporting voltage a lot higher than the Fluke says. I trust the Fluke explicitly. If there is a problem like you have, I increase the voltage acceptance of the inverter [if possible] rather than decrease the voltage of the generator which I know to be OK.

I would be interested to know if the Generac is capacitor regulated. Look in the box under the control panel for either a big aluminum capacitor or an active voltage regulator which is a block that has fins, a single adjustment, and a red light. I have one unit in the field that has capacitor regulation and the Outback system reports significantly higher voltage than reality. I wonder if the wave form is fooling with the inverter.

grizzley · December 2018

Update:

My electrician had taken precise measurements when he had serviced the backup generator a month ago and he passed them along with previous data onto me. So when I was able to talk to a service tech at Magnum and they wanted to give me the same spiel as always "it is your generator providing to much power" I was able to give them the precise data.

After that she wondered about the time delay and if we had programmed it in, which we have. She then suggested to check the one more item, which she thought my trigger the warning just by sensing the initial start of the generator. Although not obvious to me in the Magnum ME-RTR menu under Setup -> Charger is a menu point called "Low VAC Dropout" . Mine was set to 90V which she said was to tight as the low value also sets a upper range point. She recommended to set it to 60 to open up the upper range to cover any excessive voltage the generator may produce on the initial start.

It seems to work right now and I hope this solves the issue. Thank you again for all of your suggestions.

Magnum MS4448 PAE generator high volt ac problem

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