Siemens 3UB8123-4DW2 Solid State Overload Relay

The Siemens 3UB8123-4DW2 Solid State Overload Relay is a three-pole, solid-state motor protection device in the ESP200 family, designed to replace traditional bimetal relays by monitoring motor current and trip behavior to prevent overload in three-phase systems. Rated for 5.5 to 22 A on the main circuit and compatible with voltages up to 600/690 VAC, this model (catalog 48ATD3S00, part number 3UB8123-4DW2) provides fast electronic protection with adjustable trip settings to match motor full-load amperage and startup characteristics. The unit is a 3-pole device sized for direct mounting on a backplate or used as a standalone protection block, with the main circuit terminals and a separate auxiliary circuit offering screw-terminal connections, enabling straightforward wiring in control panels. Reset options include manual or automatic reset, and Siemens' ESP200 interface supports integration with motor starters and soft starters, making it suitable for industrial drives, conveyors, fans, and pumps where compact, reliable overload protection is essential.