Siemens 48FC31AA3 Relay

The Siemens Furnas 48FC31AA3 relay is a three-pole melting‑alloy thermal overload relay designed to protect three‑phase motors in Furnas/Siemens Innova starter configurations. Part of the Series C family, it uses a melting‑alloy mechanism to trip the circuit when excessive current and thermal load are detected, providing direct motor protection in industrial control panels. It is intended for mounting on Size 2 Innova starters and supports Innova frame sizes 14, 17, 18, 22, 25, 26, 30, 32, 36, and 37, making it a compatible component for a wide range of standard motor starters. Manufactured under the Furnas Electric Co. brand and marketed within the Siemens portfolio, the 48FC31AA3 is commonly employed in applications such as conveyors, pumps, and fans where reliable overload protection helps prevent motor damage and unplanned downtime. The three-pole design provides balanced protection across all three supply phases, helping ensure controlled motor protection and coordinated operation with associated contactors and overload relays.