Solid-state overload relay, 50–200 A, Class 20
The Siemens 3RB1056-2FG0 is a solid-state overload relay in the 3RB10 series, rated 50–200 A with a Class 20 trip curve. The S6 variant includes mounting rails for direct attachment to a 3RT105 contactor or for separate mounting on a 35 mm standard DIN rail. Class 20 means the relay allows a 600% overload for up to 20 seconds before tripping — standard for general-purpose motor starting where the load doesn't require a faster trip (e.g., pumps, fans, compressors). The solid-state design eliminates the bimetal drift found in thermal relays, giving more consistent repeatability across ambient temperature swings inside a panel.
The S6 variant ships with mounting rails for direct attachment to a 3RT105 contactor — no separate bracket needed for a combined motor starter assembly. For standalone use, the same rails clip onto a 35 mm standard DIN rail, so the relay can be positioned anywhere in the panel, not just paired with its contactor. The 50–200 A range covers a wide motor FLA band; verify the actual motor nameplate current falls within the adjustable trip range of this specific unit. Class 20 is typical for standard induction motors driving centrifugal loads — not for high-inertia loads that need a longer acceleration curve (Class 30) or for short-stall protection (Class 10).