RCD Tripping during switch over to DG from EB

[Anonymous user]

In commercial complex having multiple offices there is EB supply is provided by common transformer and power is backed by DG. Change over is happening at common panel. From where supply is going to each floor. 

On one of the floor power is given to to Main Panel.   Main panel is supplying power to various DBs for lighting, Raw power (power sockets) and computers (laptops). In each DB per phase there are RCCBs. For lighting RCCB are 30 mA, For power 100 mA & For computer it is Si type 300 mA.

Problem is – Normally all is working fine, no tripping and installation is healthy.

When changeover from EB to DG is happening then abruptly (not particular Phase /not particular DB) any 4/5 RCCBs are tripping. Some times lighting, sometimes, power, sometimes R or Y or B of any DB. 

RCCBs are checked, DBs are checked and all is fine. In fact after tripping if they are reset then it is observed they are not tripping.