Siemens Thermistor motor protection relay, 2C/O, 24-240VAC/DC Part number 3RN2012-1BW30

Product Overview

The Siemens 3RN2012-1BW30 is a SIRIUS 3RN2 thermistor motor protection relay designed for monitoring motor windings via thermistor sensors. It supports automatic, manual or remote reset functions and features two change-over auxiliary contacts for interfacing. The unit is DIN-rail mountable in a 22.5 mm wide housing and offers advanced protection functions including short-circuit and open-circuit detection in the sensor circuit, wire-break monitoring and error memory.

Key Features

• Thermistor motor protection relay from the Siemens SIRIUS 3RN2 series
• Compact 22.5 mm width standard evaluation unit for DIN-rail use
• Rated control supply voltage from 24 to 240 V AC/DC
• 2 change-over auxiliary contacts (2 CO) for signaling or interlock applications
• Automatic, manual and remote reset modes selectable
• Wire-break and short-circuit detection in the thermistor sensor circuit
• Non-volatile error memory for fault history retention
• ATEX approval for use in hazardous environments (depending on specific variant)

Technical Specifications

• Product Series: SIRIUS 3RN2
• Article Number: 3RN2012-1BW30
• Control Supply Voltage (Us): 24 … 240 V AC/DC
• Width: 22.5 mm
• Number of Auxiliary Contacts: 2 change-over
• Reset Modes: Automatic / Manual / Remote selectable
• Protection Functions: Motor winding thermistor monitoring, wire-break detection, short-circuit detection
• Mounting: DIN-rail (35 mm) mountable, screw terminals
• Operating Ambient Temperature: –25 °C … +60 °C
• Storage/Transport Temperature: –40 °C … +85 °C

Compliance & Certifications

• Designed and manufactured by Siemens according to SIRIUS series motor protection standards
• Complies with IEC/EN regulation for motor protection relays (including wire-break and short-circuit monitoring)
• ATEX certified variant available for use in hazardous areas

Applications

Ideal for motor protection systems using thermistor sensors (PTC/thermistor) in applications such as pumps, compressors, conveyors and general industrial motors. It provides reliable monitoring of motor winding temperature and sensor faults, enabling early shutdown or alarm before damage occurs.