What it is and what it does
The Siemens 3RB3113-4NB0 is a SIRIUS solid-state overload relay in Size S00, designed for motor protection in control panels. It monitors motor current and trips the contactor on overload, with a thermal current rating of 1.25 A. Trip class is field-adjustable between 5E, 10E, 20E, and 30E, letting you match the relay to the motor's thermal capacity and starting characteristics. Mounted directly on a contactor (contactor mounting), it saves panel space and keeps wiring clean. The screw terminals accept 0.5 to 4 mm² solid or 0.5 to 2.5 mm² stranded wire.
Key ratings and what they mean for fit
The upper current setting max is 3.5× the set value, and the minimum trip condition is motor current below the lower setting. This provides a wide adjustment band for real-world motor FLA. Operating temperature range -25 to +60 °C with full temperature compensation; storage and transport -40 to +80 °C. Vibration resistance per IEC: 1-6 Hz/15 mm, 6-500 Hz/20 m/s², 10 cycles.
How it compares to the 3RB3133-4UB0
The 3RB3133-4UB0 is a different variant within Size S00. The 3RB3113-4NB0 is rated 1.25 A thermal current with adjustable trip classes 5E, 10E, 20E, and 30E. Verify motor FLA against the setting range before substitution.