Input RCD tripping 80 secs after AC is applied.
I have 2x 5.5kW ecco inverters in parallel (single phase), batteries and PV. This has been running in grid tied mode without problem for several months.
After a short grid outage a few days ago, I discovered that the single 30mA input RCD had tripped and each time I reset the RCD it would blow 80 seconds after resetting.
My installer has returned, inspected the installation, tested and confirmed the RCD is within limits. It is no longer possible to connect to the grid using the normal startup procedure as the RCD blows every time.
From a shutdown this is what happens:
Turn On Battery
Turn On Inverter (Silver Button on left hand side)
Wait for 'Normal' LED to light (can take up to 5 minutes)
Turn On AC – 80 seconds later the RCD trips.
Turn on PV
My installer has found a workaround to enable the inverters to connect to the grid using this startup sequence which does not trip the RCD.
Turn On Battery
Turn On AC
Turn on PV
Turn On Inverter (Silver Button on left hand side)
Wait for 'Normal' LED to light (can take up to 5 minutes)
Unfortunatly the workaround does not help in the event of a power outage. Any interruption of AC trips the RCD 80 seconds later.
The 80 secs delay is the time the inverter allows before energising the internal contactor connecting the LOAD and GRID circuits. However I dont currently have anything connected to the GRID terminals.
This has only recently started happening. Firmware was updated to the latest about a month ago.
Does anyone have any suggestions on what the issue could be. I could be waiting months for any support from SS.
That's what i would do.
And as i've said, you have two options, EMI causing RCD to trip, or you really have high differential current on startup (sunsynk transformerless topology has high differential current on startup with some solar panels (DC and AC side is not isolated so panels act like capacitors))