The Siemens 3RF3190-3AA06 is a 1-pole SIRIUS 3RF31 solid-state relay rated for 90 A continuous at 48-600 VAC, controlled by 24 VDC. It comes in the 22.5 mm wide housing common to the SIRIUS family, with ring cable lug connections intended for mounting on a customer-supplied heatsink or panel surface. At 90 A, this SSR handles substantial resistive or moderate inductive loads — think large heater banks, industrial ovens, or motor starters where you want silent, maintenance-free switching. The 48-600 VAC range covers most global line voltages from low to nominal 480 VAC three-phase.
But note the ring cable lug connection — this isn't a spring-cage or screw-clamp terminal block. You need to land ring lugs on the studs, which is a bit more time on the panel build but gives a gas-tight connection that won't vibrate loose on a pump skid. The packaging dimensions (104 x 44 x 48 mm) give you the shipping envelope, but the real installation clearance is the 22.5 mm DIN slot plus airflow above and below for the SSR's heat dissipation. Because this relay has no internal heatsink — it's designed to be mounted on a cooling surface you provide, like a panel backplate or dedicated heatsink profile.
What the key rating means
The 90 A rating is the continuous on-state current at the rated voltage. For motor loads, you'd typically derate — a 90 A SSR might switch a 50-60 HP motor on 480 VAC, but the real limit is the thermal management. Without adequate heatsinking, that 90 A will quickly exceed the junction temperature. Out here in the grease, I've seen guys bolt these to a painted panel and wonder why they trip — the mounting surface is part of the circuit.