We have a 3ph set up with MP2s with an ESS. We have the system working with a changeover switch, the system operates without issues bypassing the essential loads/charging the ESS and powering the loads from the Grid. We have only run the system powering the essential loads from the ESS for 10mins at a time, it operates as expected during those tests. The 1st incident after 7 days of faultless operation and second incident after 11 days of faultless operation, Relay Test Fault. The system appears to auto run a random relay test. It fails the test and switches off, Error 11. It appears that they were #45 0x8200024 (Error Occurred GND Relay Error) and #50 0x800002 Relay Test OK PE2 Closed Error (but states Relay Test Fault in Alarm Log) errors. These errors ocur out of office hours and no one is there to reset right away. When staff return and reset system it operates. Elec Eng is sure N and E are bonded correctly and seperate between essential and non-essential boards. Without this random test we would be fine. Can we stop this test from running?