Siemens Thermistor motor protection relay, screw, 2 c/o, 24VAC/DC Part number 3RN2011-1BA30

Product Overview

The Siemens 3RN2011-1BA30 is a thermistor motor protection relay from the SIRIUS 3RN2 series. It monitors motor temperature via PTC thermistor sensors and trips reliably when overheating is detected, protecting motors against thermal overload as well as open or short circuit in the sensor circuit. Compact at 22.5 mm width, it is suitable for control panels requiring safe temperature-based protection.

Key Features

• Thermistor protection relay for motor temperature monitoring
• Evaluates PTC thermistor sensor signals directly
• Compact 22.5 mm housing — space-efficient panel installation
• 2 change-over relay contacts (DPDT) for switching and signalling
• Status indication LEDs for READY / TRIP
• Manual or remote reset after trip
• Detects thermistor open/short circuit and sensor failure
• Galvanic isolation between control and sensor circuits

Technical Specifications

• Article Number: 3RN2011-1BA30
• Type: Thermistor motor protection relay
• Control Supply Voltage: 24 V AC/DC
• Relay Output: 2 change-over (DPDT)
• Width: 22.5 mm (DIN-rail mount)
• Protection Function: Overtemperature monitoring via PTC sensors
• Sensor Fault Detection: Open/short circuit monitoring supported
• Insulation Voltage: approx. 300 V
• Surge Withstand Voltage: approx. 4 kV
• Protection Rating: IP20 (requires enclosure)
• Reset Method: Manual or remote reset input
• Service Life: Designed for long electrical and mechanical endurance typical of SIRIUS relays

Compliance & Standards

• Meets IEC/EN standards for thermistor-based motor protection
• Galvanic separation ensures safe circuit interfacing
• Available for use in industrial environments, including enhanced protection when used with approved PTC sensors

Applications

Suitable for overload and overtemperature protection of three-phase motors in pumps, conveyors, compressors, fans, processing machines or equipment operating under intermittently heavy load conditions. Commonly used where precise thermal monitoring is required beyond standard overload relays, especially in harsh duty or low cooling environments.