Hybrid inverter doesn't work with generator

[satyricon]

Hello friends.
I have China-made 5KW hybrid inverter for 3 years -- Axioma Energy ISMPPT-BF 5000 MPPT.
It is visually similar to Axpert 5KVA inverter / Must 5KVA inverter / etc.
Also it has the same user manual and similar specs.
I guess Axioma Energy is just a localised name for Ukrainian market.

According to the manual, along with utility, it should work with generator.

I have typical 3.2kw gasoline generator with AVR.
I measured with the multimeter that generator stably produces a voltage of 230V without load and with an average load.
The frequency of the produced AC is ~52(+-0.2) Hz.
It works fine when I connect the house directly to it.

When I try to use the generator as AC source for the inverter, the inverter on the dashboard shows that the voltage grows from 250v to 310v++ in seconds and the inverter protection is triggered.

What can be the reason the inverter behaves in such weird way?
I will be grateful for any help.

 

[DThames]

I don't know, so guessing. Do you have a setting for AC input voltage?

 

[satyricon]

Hi DThames.
I have APL / UPS options in Settings Program 03.
I use Appliance option.
I tried to use UPS option, but the inverter goes down immediately after I enabled load when a generator is used as AC source.

FYI: our electrical AC grid has frequency 50hz. It works fine with both APL / UPS modes.

 

[timselectric]

The only other option I can suggest would be to connect some of your load ahead of the inverter. To help stabilize the generator output. Before the inverter sees it.

 

[satyricon]

Hi timselectric.
I tried to do that.
It just adds few more seconds while the inverter is increasing the voltage over 280v.
After that the inverter goes down.

 

[timselectric]

It sounds like your generator regulator isn't working properly.

 

[satyricon]

It sounds like your generator regulator isn't working properly.

timselectric, input AC from generator is stable 230v.
The output AC from the inverter goes over 280v.
So the inverter instead of bypass input AC from the generator, modifies it due to some reasons.

 

[timselectric]

Oh
That's definitely strange.

 

[Mattb4]

Do you have the inverter wired to house AC? Does it work properly for going into AC bypass?

 

[satyricon]

Do you have the inverter wired to house AC? Does it work properly for going into AC bypass?

Hi Mattb4.
My inverter is hybrid one.
I use it with Solar input and AC input (220v / 50Hz) from an electric utility company.
It works perfectly with utility AC.
Could the frequency of 52 Hz from the generator AC instead of 50Hz be a reason for such a weird behavior of the inverter?
Inverter's specs says that it can work with 50hz/60hz AC.

 

[Mattb4]

Yes the frequency could be out of spec so that the AIO would want to transfer to inverter supplying AC. However you report higher voltage output when running from generator and that would indicate some other problem. The only other thing that I can think of which may not matter is the wiring from your generator.

Oh wait a minute. If this is a grid tied inverter* than it may be trying to parallel with your generator. if that is the case than it likely will not work to use a generator with it.

* Should have caught the reference to Hybrid. Some folks think only grid tied with battery backup can be hybrid.

 

[satyricon]

Yes the frequency could be out of spec so that the AIO would want to transfer to inverter supplying AC. However you report higher voltage output when running from generator and that would indicate some other problem. The only other thing that I can think of which may not matter is the wiring from your generator.

The wiring is ok.
I use high-quality wire and the distance to the generator is only 15 m.
But I checked this issue even with a short wire of 4 m.

Oh wait a minute. If this is a grid tied inverter* than it may be trying to parallel with your generator. if that is the case than it likely will not work to use a generator with it.

No, I don't use it in parallel.
The utility AC is disabled/not available when I try to use the generator.

Due to missile attacks on the energy system of Ukraine, we often experience blackouts last two months.
Also because of winter / insufficient amount of sun / a short sunny day the power from solar panels are not enough.
That's why I need to use a generator.

At the evening if no electricity from the utility, I have AC from the battery.
But it has only 2200kWh capacity.
So the idea was to use generator to have AC for basic needs and to charge battery in case if battery level is low.
Then switch back to battery.

 

[Mattb4]

Edited:: Tried to find an Operators manual for your unit and if the Axpert one you mentioned is the same than my concern about the unit being a grid tie type is unfounded. so it comes back to your generator and inverter not accepting each other. Sounds like you have a faulty AIO.

 

[satyricon]

I think my inverter is hybrid one, it doesn't allow to export an energy to the grid.
There were models which allow that, but it's not mine.
It can work with/without battery.
Even manual and specs have no any information about the possibility to export an energy.

 

[DThames]

I am thinking of ways to perform some troubleshooting that will give additional information.

If the inverter is on but there is no load on the inverter, when you apply power from the generator, the battery should charge. Have you tested like this with no load on the inverter?

Also, many all in one (AIO) type inverters will allow the charge from the AC to be reduced so that you don't overload the generator. Have you made changes to the charge settings to see if that changes the behavior?

You said that if the generator had another load on it that the problem takes a little longer to show up. During this time, the inverter output voltage is going from a normal 220v-230v up to >280v How long does that take? Do you have a switch in place between the generator and the inverter? If so, once the voltage starts up, if you disconnect the generator, does the voltage go back to normal?

 

[schmism]

what are the specs on your battery? Are you attempting to use this batteryless?

 

[schmism]

When I try to use the generator as AC source for the inverter, the inverter on the dashboard shows that the voltage grows from 250v to 310v++ in seconds and the inverter protection is triggered.

A note in this video reminded me of this post.

voltage gain due to abnormal resistance.

 

[DThames]

A note in this video reminded me of this post.

voltage gain due to abnormal resistance.

In the case of this post, the use is having the issue even without a load on the inverter. Yes, what the video says is a fact, if there is an effort to deliver X watts or X amps back down the AC line. My grid tie micro inverters are pushing about 250v while I have 245v back at the house.

 

[timselectric]

In short.......
A voltage drop at the end of a run.
Can also be seen as a voltage rise at the beginning of the same run.

 

[Yukko]

I've just registered to share some details about running these inverters. I'm from Ukraine as well as the topic starter. When RU started to attack energy infra we one by one got 4 x Must ph18-5048 vhm systems + batteries. That was almost the only available option at that time because Victron's prices skyrocketed and other cheaper inverters were out of stock.

I'm running a UA copy of the Chinese generator, it is called Dnipro M here. It has AVR (automatic voltage regulator) on board and all home appliances run just well when the power supplied directly from the generator.

So, after several tests on my own system, it turned out that the only possible option to charge batteries from the generator is to use GEN mode in the AC input voltage range program (it can be either program 02 or 03 in different models of these inverters). All other modes failed for me.

Still, I was able to switch the load and battery charging to the generator several times in APL mode after fine-tuning the frequency (but it is hard to repeat as the generator without loads generates frequencies different from 50Hz, so you need to manually adjust it all the time). Check out the generator, it has an adjustment screw that either loosens or tightens the engine revolution control system, as a result, adjusts the frequency.

Depending on the generator model fine-tuning the engine RPMs with that screw can help and you can run even in APL mode and switch between the grid and generator to charge the batteries, at least I've found several reports on the Internet people run on default values (APL) in their inverters and supply power from generators just fine. Your inverter will likely show you the frequency even if it does not switch the load to the generator. So you will not need a separate tester socket for this operation.

Another possible issue reported by the users of similar inverters is they can be phase-dependent. Generators generate 2 phases. 1 phase per wire. In case an inverter looks for Neutral wire, but gets a phase, you need to ground one phase by connecting it to the earth wire (green and yellow) of your house. Do not connect a grounded neutral to the phase connector of the inverter even if it can run when neutral and phase swapped.

All my tests in GEN mode were completed with one neutral wire earth grounded, but the first test was completed without connecting neutral to the grounding earth, so I supplied the inverter with 2 phases over phase and neutral wire. This test run in GEN mode was OK, all loads were fed from a generator and batteries were charging, but somehow I failed to switch to the grid in GEN mode after running loads from the generator with an ungrounded neutral wire. The inverter showed '[08] Inverter bus voltage is high' and started to beep. It forced me to spend some 15 minutes to rewire the system and run more tests.

An important disclaimer. All Ukrainians need to have some knowledge of electricity these times, but I'm not an electrician and have no special knowledge. So run all experiments at your own risk! Remember, electricity can be deadly! As an example, grounding neutral wire of the generator to the common protective earth wire can be deadly if the earth wire breaks or is disconnected, in this case you will get a phase from the generator on the metal frames of all your grounded appliances.

An important disclaimer #2. DO NOT breathe the air 5m around the running generator when for example adjusting RPMs and frequency. Generators exhaust CO, a human deadly gas when inhaled. Use a special CO detector near your gen to have early CO gas warnings.