250 A solid-state motor protection with CLASS 20E trip curve
The Siemens 3RB2066-2GC2 is a SIRIUS solid-state overload relay rated for 250 A continuous current at up to 1000 V (AC-3e), making it suitable for protecting motors in the 45–160 kW range at 500 V / 50 Hz. Its CLASS 20E trip characteristic means the relay allows a 20-second overload at 7.2× rated current before tripping — matching the thermal time constant of standard AC induction motors during start-up. The electronic design provides temperature-compensated protection across -25 to +60 °C ambient, with an integrated auxiliary switch that signals the tripped state via a dedicated message output.
Mounting and wiring flexibility for panel integration
The relay mounts directly onto a contactor or as a stand-alone unit on a mounting plate, accepting busbar connections for the main circuit and solid/stranded wire up to 4 mm² for the control terminals. Dimensions of 120 mm wide × 119 mm high × 155 mm deep fit the S10/S12 frame size, and the relay can be installed in any orientation without derating.
Auxiliary contact ratings and environmental robustness
The integrated signaling contact is rated for switching loads across common control voltages: 2 A at 24 V, 4 A at 120 V, 3 A at 230 V, and 0.11 A at 220 V — covering both AC and DC control circuits. The relay withstands shock up to 15 g / 11 ms and vibration per IEC 60068-2-27 (1–6 Hz, 15 mm; 6–500 Hz, 20 m/s²), with a storage and transport temperature range of -40 to +80 °C.