The Siemens 3RF3190-1AA02 is a 1-pole SIRIUS 3RF31 solid-state relay in a 22.5 mm wide housing, rated for 90 A continuous load current with a control voltage range of 24-230 V AC / 24 V DC. For a 90 A continuous load, the panel feeder and overcurrent protection must be coordinated to that value, and the relay requires a cooling surface (heatsink or panel metal) to dissipate the on-state losses at that current.
Screw terminals accept the power and control wiring. The relay is designed for mounting on available cooling surfaces — meaning the panel builder must provide a metallic mounting plate or dedicated heatsink to conduct heat away from the SSR baseplate; without adequate thermal management, the 90 A rating cannot be sustained. This is a common point where a replacement SSR gets undersized if the original heatsink is lost or damaged.