Can we load Altivar sofstarters ATS480 or ATS490 relay output by greater voltage than 30V DC? If so, how much current can we switch off e.g. at 110V DC?

Datasheet declares max 30V DC that can be switched off by ATS480/ATS490 relays. Switching off DC current is more demanding than switching off AC. It is due to electric arc that does not automatically disappear. In AC switching, current crosses zero value every 10ms, so electric arc disappear and may reappear if the contact surface is still hot and emitting electrons and when contacts are still close to each other (not yet fully open). In DC switching, the current never crosses zero value naturally. So the only method to cut electric arc in DC current is to move away the contacts during relay switching off to a distance that is greater that distance needed for electric arc to flow. We say that arc voltage must be greater than operating voltage in the circuit (otherwise el. arc will never be extinguished). In case of external relay, we usually put 2, 3 or more contacts in series to increase arc voltage, but this cannot be done with ATS48 built in relay.

To answer question about how much current can be switched off by ATS480/ATS490 relay, I can provide datasheet of 3 relay manufacturers that can be used in ATS480/ATS490. Selection of exact type purely depends on manufacturing process, for example which of the relays are available at the moment.
In any case, all 3 manufacturers show that switching off DC current at 110V DC is possible providing that the load is resistive and the current is not greater than:
aprox 0.45A in Tyco and siemens type
aprox 0.3A in Hongfa.
Curves from datasheets attached.

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