A Victron Multigrid 24/3000 is used as a grid back up.
A 30mA differential relay is used at its output.
The relay trips with no obvious reason.
a) Whenever the unit switched from inverter back to mains on (i.e. when grid exists again)
After this tripping the relay is armed to operation and works normally but on (b) below.
b)for no reason and at irregular intervals. The relay if armed does not trip again but after some random hour.