We have installed a 12kw 3 phase inverter with a Freedom Won 20/16 battery. No solar panels are installed.

All has been working well for over a month but suddenly the inverter disconnected from the Grid supply (even though grid supply was available) resulting in the batteries being run flat. The installation is in a remote location without internet connectivity, so we were not aware of the disconnection.

 

We were unable to restart the installation as the inverter would always disconnect the Grid when it started up as it tried to draw power from the grid to recharge the batteries.

 

We were eventually able to start recharging the batteries by changing the charge current down to 20 amps. By playing with this setting, we were able to get this up to 40amps (+-2kw). The batteries are now at 100%.

 

Whenever we try to draw more than 2kw from the grid (for either charging the batteries or for the AC load) the inverter disconnects the grid and reverts to batteries.

 

If the load is below 2kw it will work fine.

 

Some more information:

 

There is only one load on the entire system - a 3 phase 4kw pump. This pump runs fine directly from grid. When trying to run through the inverter, the inverter disconnects from grid - this is always above 2kw. The electrician has checked the voltages and frequencies on all 3 phases and although the one phase's voltage is lower than the other 2 phases, it still seems to be within limits (see attached picture of voltages). There is no discernible voltage or frequency drop (when looking at a multi-meter) on any of the phases when the inverter draws load from the grid (by either starting the pump or charging the batteries). I have attached some other pictures of the inverter settings also (note that battery charge current is set low to 40A as any value higher and the inverter disconnects from the grid).

 

 

Any ideas as to why the inverter is disconnecting from the grid above 2kw?

 

 

I'm no expert but have the same inverter with Sunsynk 10kwh battery. Just comparing settings to mine:

1. I have "activate" ticked on Batt type settings screen.

2. "Grid signal" also ticked on Batt charge screen.

Not sure if that will help.

On 2023/03/13 at 4:42 PM, Steve Farnaby said:

There is only one load on the entire system - a 3 phase 4kw pump. This pump runs fine directly from grid. When trying to run through the inverter, the inverter disconnects from grid

The startup current of your 4kW pump most likely exceeds the capabilities of the 12kW inverter.

6 minutes ago, P1000 said:

The startup current of your 4kW pump most likely exceeds the capabilities of the 12kW inverter.

He can set the discharge amps up from 200A to the inverters max of 240A? maybe worth a try .

11 minutes ago, P1000 said:

The startup current of your 4kW pump most likely exceeds the capabilities of the 12kW inverter.

Yep, when no grid each phase limited to 4kWh on that inverter

2 minutes ago, ZaydS said:

Yep, when no grid each phase limited to 4kWh on that inverter

kWh? Are you sure about that? What are you trying to say? (keep in mind that a 4kW pump will almost certainly have a 3 phase motor)

Edited March 16, 20232 yr by P1000

5 minutes ago, P1000 said:

kWh? Are you sure about that? What are you trying to say? (keep in mind that a 4kW pump will almost certainly have a 3 phase motor)

My bad. Not a sparky. Meant kw. If 4kw pump splits the draw per phase then probably not an issue.

 

I should rather not comment😇

Edited March 16, 20232 yr by ZaydS

Interestingly, on this inverter you can draw 6kW on a single phase, but you cannot exceed 12kW on all phases.

However, the startup current of an induction motor is usually 5-7x the running current.

11 minutes ago, P1000 said:

Interestingly, on this inverter you can draw 6kW on a single phase, but you cannot exceed 12kW on all phases.

However, the startup current of an induction motor is usually 5-7x the running current.

So, no limit of 4kw per phase when grid is down?

What you do need to try is starting the pump against a shut off head, if a centrifugal pump. Once running you can then open the discharge valve. The type of pump (centrifugal, progressive cavity, etc) will also influence the starting amps.