Effect of Inductive Loads On Inverters

Q&A and troubleshooting
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1

Is there any effect when running three phase motors on Victron devices?
I encountered an issue where 3*10KVA Quattro inverters are connected in a three phase set up to power a poultry farm, which has mostly three phase motors and fans.
Accessing the loads physically per phase, they are all below the inverters’ power rating.
The GX device also shows that the loads are around 4-5kW per phase.
But the most interesting thing is that, the inverters shut down on overload when consumption get to around 4kW per phase.
How can a 10KVA inverter shutdown on 4-5kW load? It is abnormal.

At a point, we thought maybe, the problem was from any of the loads so we had to put off all loads and switch them one by one to monitor which specific one is triggering the overload, but it appears that none of them were the problem. The overload alarm comes if the total consumption attain 9kW and above, thus, 4-5kW per phase.

Another thing we realized is that, measuring the current drawn by the loads per phase, we had 40A, 39A and 37A respectively. This implies that the inverters are actually giving their maximum power and the GX device is not displaying the correct readings.
Also, the inverter is to call in grid when the load gets to 8kW. With the presence of grid, even if the GX device is not displaying the correct reading, the inverter should have switched to grid without going on overload.
We even changed the GX device but the issue persist.

Is there anything I need to know with regard to running inductive loads on Victron products?

Attached is a video for perusal.

Any help will be greatly appreciated.

2

When running motors from inverters, you need to be aware of 2 things:

  1. Start up surge. Motors which are direct on line have start up of ~6 times the motor rated current. (3 phase motors with star -delta starters also have a large current spike when they switch from star to delta).
  2. Power factor: Motors tend to produce a significant lagging power factor, where the current is NOT in phase with the voltage. This reduces the consumed kW, but the kVA is still high.
    In your case, it seems to be the latter problem. You do need to remain within the inverters kVA limit: Most modern inverters are capable of producing full current output at any phase angle relative to the voltage, standard requirement for generators and utilities is that the power factor (Cos phi, where phi is the phase angle between the current and the voltage) is >0.8
    So the Cerbo in reporting kW is measuring active (in phase) power, but The overload alarm is reacting to peak current in the inverter. This is completely normal.
    Solution:
    A) Use power factor correction capacitors on each fan, or as a single unit close to the inverters.
    B) Add more inverter capacity.