We have an installation with Axperts running 3-phase (1x Axpert 5kVA per phase) and we are experiencing intermittent "E60 Power Feedback Protection" error which shuts down the inverter outputs. We have tried changing out the inverter which was tripping up to no avail. Since we've changed out inverter  the fault has occurred on two separate phases/inverters on separate occasions. One inverter will display error and all 3 will stop supplying loads but PV still feeds battery.

The fault only occurs when inverters are in line mode (bypass) and is switching back to PV/battery mode - and the fault does not manifest every time it switches,  it gets it right about 50% of the time.

I understand the inverter is sensing a PV feedback situation and it's designed not to allow this but why does it require a full manual reset to function normally again and why does this only seem to manifest on this one 3-phase installation and never in single phase installs (that I've seen)?

Does anyone know what could be the cause of this and offer a solution?

On 2019/03/27 at 3:52 AM, PeterP said:

"E60 Power Feedback Protection"

The fault only occurs when inverters are in line mode (bypass) and is switching back to PV/battery mode

Actually, the firmware only checks for this error when in battery mode. So it must be happening immediately after it switches to battery mode from line mode.

On 2019/03/27 at 3:52 AM, PeterP said:

the fault does not manifest every time it switches

In main firmware 73.00, the fault will occur when the instantaneous output power is < -2000 W, or < -1200 W 4 times in a row, 10 ms between checks.

Interestingly, it does not perform this check when in SIG [ edit: was SNG ] output mode, but it has no checks for whether it is in three phase mode or paralleled mode. It seems to me that exactly 3 machines in 3-phase mode is much the same as three single phase machines running separate loads. That is, unless you have actual 3-phase loads, phase to phase as opposed to phase to neutral.

I suppose if you have a significant inductive 3-phase load, like a 3-phase motor, you could get some instantaneous power back to the bus. Do you have such a load?

 

On 2019/03/27 at 3:52 AM, PeterP said:

I understand the inverter is sensing a PV feedback situation

PV? This seems to be about pulling power from the AC output. 

Quote

and it's designed not to allow this but why does it require a full manual reset to function normally again

This is classed as a fault. Some faults are resettable (on the fly), others not. 

Quote

and why does this only seem to manifest on this one 3-phase installation and never in single phase installs (that I've seen)?

That's because there is a check for SIG output mode; if so, the firmware doesn't even check for reverse power. I don't understand why that test is there.

My wild guess at this stage is that your 3-phase motor load has too low a power factor. Can you estimate the power factor of your loads?

Edited October 31, 20214 yr by Coulomb
"SNG mode" -> "SNG output mode", SNG →SIG

My other thought is why this only happens immediately after switching from line to battery mode. Is your line voltage significantly different to 230 V? If it's much more like 220 or 240 V, you might experiment with changing the inverter output voltage to one of those values.

See Changing the output voltage with the POPV command.

1 hour ago, Coulomb said:

My other thought is why this only happens immediately after switching from line to battery mode. Is your line voltage significantly different to 230 V? If it's much more like 220 or 240 V, you might experiment with changing the inverter output voltage to one of those values.

See Changing the output voltage with the POPV command.

this could be it - the line voltage is always hovering around 240 V (236 - 243 V)... will try this - thanks!

6 hours ago, Coulomb said:

I suppose if you have a significant inductive 3-phase load, like a 3-phase motor, you could get some instantaneous power back to the bus. Do you have such a load?

That's my thinking as well.Power out on the one phase and back in on the other 🙂

49 minutes ago, plonkster said:

Power out on the one phase and back in on the other 🙂

Ah! Another possibility. Perhaps a neutral is high resistance, and some of the power going out on two phases is returning via the third phase instead of the neutral. Assuming you have mostly phase to neutral loads (more star than delta).

Just trying to figure out the direction of that power flow. I guess it has to depend on the relative loads; if the loads were exactly equal, then there would be no neutral current anyway. It seems to me that whichever phase had the lightest load would get power fed back into it.

Still stuck with this one - there are no 3-phase loads on the 2 sites where I have this problem. Only response from Voltronics is that it must be a load.

Any one have a suggestion as to how one would identify the load causing the feedback? Tried doing Utility to switch to SBU on the one site with a cranky fridge and voila - it displayed E60 error - tried to repeat the feat x3 with no E60 error......not sure what to do.

Edited November 7, 20196 yr by PeterP

8 minutes ago, PeterP said:

not sure what to do

If you have no 3-phase loads, and not even a 3-phase outlet anywhere, you could try changing all the inverters to SNG output mode, instead of 3-phase. So the outputs will all be in phase with their inputs, and they will act independently instead of with one master calling the shots. My reading is that fault code 60 (error 60) can't happen in SNG output mode. It means that when you change a setting on one inverter, you'll have to manually change it on the others.

Oh, that brings up another possibility. Maybe there is a "phase rotation", and you need to swap two inverter output modes, say the 3P2 and 3P3 units. They might be expecting the other units to have the opposite phase angle to what they do (expecting say -120°, and finding +120° say). As I type this, I can't see how this would cause the backfeeding error, but it might be worth trying.

We are running it in SNG output mode for the time being and this works in terms of negating the E60 Error - but then we lose part of our monitoring systems functionality which the clients paid for.....our monitoring system supplier thinks this can be overcome by changes to the software but it's not high on their priority list to fix

I am having a similar issue but the system that I have installed is just a single AXPERT unit (5kva) running in SNG mode. By my reading of the manual this shouldnt be possible? Has anyone seen this situation before? Only unusual load is a golf cart charger, could it be that?