What type of UPS to put on a generator.

[BillP]

I have 4 UPS of the Back-UPS Pro type, when I switch on the power supply of my generator, these do not stop switching to mains battery, I have set their sensitivity to a minimum but this does not change nothing. The 4 UPS have the same problem and phenomenon.
By cons on the sector no problem
Could you tell me about the type of UPS that I could install, so that I no longer have this problem.
Thank you all

[Brad_C]

It depends on what your generator is. If it's an inverter then you shouldn't have an issue. If it's a conventional rotating machine then you'll potentially have constant issues as minor load variations cause the frequency to walk around as the machine tries to govern its speed. You'll also see voltage variations per load.

Both of these conditions cause the UPS to see the mains as "outside tolerance" and will switch to and from battery as things move around. I've used a rotating machine and in inverter with my Smart-UPS(s) and  BackUPS, but had to make sure there was a fairly constant load on the rotating machine to keep the load stable.

Some cheaper conventional generators also have some "AVR" circuitry which can cause a distorted waveform while regulating the output voltage and there is almost no hope of getting those to work well with a UPS.

I love my little 3KVA Chinese inverter genny. It runs all the gear via 2 UPS (SU2200 & SUA3000), bot both switch to battery when I try and run the coffee machine at the same time due to the cycle controlled heater causing awful distortion of the mains waveform.

[BillP]

Thank you for your reply.
This confirms my doubts, I have a GENYX G5000DT-2 generator.
I wonder if it was not possible to put a regulator at the outlet, in order to avoid the problem.
Or if it does not work, simply bypass the inverters on operation with the generator is also a solution.
thank you so much

[Brad_C · Accepted solution]

On 1/3/2020 5:05 PM, Jean Luc said:

I have a GENYX G5000DT-2 generator.

From my limited searching it appears to be one of the more conventional rotating machines with AVR. The AVR tends to produce relatively awful mains waveforms on top of the fluctuating frequency. So you might be somewhat out of luck.

On 1/3/2020 5:05 PM, Jean Luc said:

I wonder if it was not possible to put a regulator at the outlet, in order to avoid the problem.

Can't think of anything that would work off the top of my head short of a full on-line UPS. I have no experience with the APC line of on-line UPS.