FAQ02202 of Solid-state Relays FAQ

NC contacts cannot be implemented for Solid-state Relays 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.

Solid-state Relays with NC contacts using depression MOS FETs have been commercially available recently mainly for applications with small signal currents.

G3VM Solid-state Relay is available from OMRON with NC contacts.