The 3RF3190-1AA04: The 90 A rating is the continuous load current through the semiconductor junction. At that level, the relay needs a proper heatsink — the description says 'for mounting on available cooling surfaces', meaning you bolt this directly to a metal panel or dedicated heatsink plate. Without that thermal path, the junction temperature climbs fast and you'll hit the thermal shutdown or shorten its life. The 48-460 VAC range covers common single-phase line voltages from 50/60 Hz systems, including 120 V, 208 V, 240 V, 277 V, and 400 V. The 24 VDC control input is standard for PLC or relay logic outputs, and the screw terminals accept up to maybe 4 AWG depending on the lug — check the terminal capacity in the datasheet for your wire gauge.
This SSR goes in control panels switching resistive or light inductive loads — heaters, lamps, solenoid banks, small transformers. The 22.5 mm width fits standard DIN-rail enclosures alongside contactors and breakers. Because it's a semiconductor relay, it switches silently and handles frequent cycling without mechanical wear, so it's common in temperature-control loops and process heaters where a contactor would wear out from constant on-off.