FAQ02202 of Solid-state Relays FAQ

NC contacts cannot be implemented for SSRs with triac or thyristor outputs without a drive power supply.

To form NC contacts, the semiconductor used for output must be normally closed (NC) and a depression transistor is required.

SSRs with NC contacts using depression MOS FETs have been commercially available recently mainly for applications with small signal currents.

SSR G3VM is available from OMRON with NC contacts.