Inverters shutting down on motor start

[jff6791]

I have an EGuage monitor on my dual inverter grid tied system and am seeing one or both inverters shutting down and re-starting when a pool filter pump comes on. The arrays have to be at 50% or more for this to happen. Has anyone else noticed this with similar motor starting like HVAC compressor, etc?

[Mike90250]

It seems odd to me, but maybe it's a Power Factor issue, and the imbalance gets so high the inverters freak out and reset.

i could see a hi resistance feed line from the grid, but if the inverters are cranking out power, the grid contribution should be minimal. Do you get or can you record any error message ?

[jff6791]

thanks. I had the utility check out the service drop and the guy pulled the meter and ran some checks with a switchable load/monitor device and it checked fine. Also applied it at panel with same result. I'll see if any errors show on the inverter displays next time they are re-starting. This is just a 1 HP 240 volt single speed pump and doesn't create a lot of flicker when starting.

[thejq]

All grid tied inverter has a safety mechanism to shut down when the grid goes down. I think your inverter is either too sensitive or the voltage drop is too big when the pump starts. You can do some measurements yourself if you know what you're doing to debug the problem.
1. the best way is to get a scope (or spectrum/signal analyzer) and hook up the probes to inverter inputs (you will most likely need attenuators so you don't blow up the equipment), set it to 60 Hz (assuming you're in the US) and monitor the zero span voltage. Record the voltage drop when starting the pump and check with the spec or call the manufacture.
2. an alternative is use a high precision digital multi-meter, but because the number changes so fast, it might be hard to see. But doing it a couple of times should give you a good idea.

Once you root caused it, we can try figuring out the solution.

[thejq]

thanks. I had the utility check out the service drop and the guy pulled the meter and ran some checks with a switchable load/monitor device and it checked fine. Also applied it at panel with same result. I'll see if any errors show on the inverter displays next time they are re-starting. This is just a 1 HP 240 volt single speed pump and doesn't create a lot of flicker when starting.

I think our posts just crossed. So what do you mean by "checked fine" and "with same result". "Fine" as in no voltage drop? and "same" as in the inverter shuts down when a load is applied?

[jff6791]

I think our posts just crossed. So what do you mean by "checked fine" and "with same result". "Fine" as in no voltage drop? and "same" as in the inverter shuts down when a load is applied?

He was switching a 20 amp load alternately on each leg and the drop was 1-2 volts which they deem acceptable. This was late in the evening so the arrays were almost down to zero output but they didn't go into shutdown.