We are using relay DRM570110LT and We need to switch 3A @220VDC in the output when we have a DC load. As the datasheet for this relay says, the rated switching current is 5 A, but I've been told this rated switching current is only for AC voltages. For DC voltages, the possible switching current is significantly lower (as per attached photo) and this relay can not be used for switching 3 A @ 220VDC in the output. Searching on the web, I found some solutions like connecting relay contacts in series to increase the switching capacity. But;
1- How could series-connected relay contacts result in increasing the DC current switching capacity?
2- How many contacts should I connect in series to be able to switch 3 A for a DC load? Does a general rule exist?