SIEMENS SIRIUS 3RU21 Thermal Overload Relay 1.8-2.5A S00 Screw Terminals 3RU21161CB0

Thermal overload relay for reliable motor protection with a current setting range of 1.8 to 2.5 A. The SIRIUS 3RU21 series offers direct mounting to contactors or screw mounting, with screw terminals for main and auxiliary circuits. It features a tripping class of 10E and includes 1 NO + 1 NC auxiliary contacts for signaling. Manual or automatic reset function provides flexibility in operation.

Advantages

Compact S00 frame size saves space in control panels. Thermal protection mechanism responds to overload conditions to prevent motor damage. Screw terminals ensure secure and maintenance-free connections. The relay operates reliably across a wide temperature range from -20 to +60 °C.

Suitable for

• Motor protection in industrial control systems
• Direct mounting on SIEMENS contactors of matching frame size
• Applications requiring manual or automatic reset
• Three-phase motor circuits up to 690 V insulation voltage

Key specifications

• Current setting range: 1.8 - 2.5 A
• Tripping class: Class 10E
• Number of poles: 3
• Mounting type: Direct mounting to contactor / Screw mounting
• Main circuit connection: Screw terminals
• Auxiliary circuit connection: Screw terminals
• Auxiliary contacts: 1 NO + 1 NC
• Reset function: Manual / Automatic
• Degree of protection: IP20 (terminals)
• Ambient operating temperature: -20 to +60 °C

Recommendations

For optimal performance, pair with a matching SIEMENS S00 contactor. Ensure proper thermal setting according to motor full load current. Use in environments within specified temperature range.