Siemens 3RN2012-1BW30 Thermistor Motor Protection Relay, 24-240V AC/DC, Screw Terminals

The Siemens 3RN2012-1BW30 thermistor motor protection relay is a robust industrial component engineered to monitor motor temperatures by evaluating resistance changes in integrated thermistors. This device ensures operational safety by detecting overheating conditions and triggering a protective response, thereby preventing potential motor damage in demanding industrial environments. Its versatile design supports a wide supply voltage range, making it compatible with various control system architectures.

Advantages

This relay offers exceptional reliability through its precise temperature monitoring capabilities, which are essential for maintaining the longevity of electric motors. The inclusion of two changeover contacts provides flexibility in control circuit design, allowing for multiple signaling or shutdown configurations. Furthermore, the use of secure screw terminals ensures a stable and vibration-resistant connection, which is critical for long-term performance in industrial settings. The wide-range power supply simplifies inventory management and installation by reducing the need for multiple device variants.

Suitable for

• Industrial motor protection systems
• Monitoring temperature in heavy-duty machinery
• Automation control panels requiring thermal feedback
• Applications where motor overheating poses a risk to equipment

When it may not be suitable

This device is specifically designed for use with PTC thermistor sensors and will not function correctly with other types of temperature sensors like thermocouples or RTDs. It is not intended for direct motor control of high-current loads without an intermediate contactor or relay.

Key specifications

• Supply voltage: 24-240V AC/DC
• Contact configuration: 2 changeover contacts
• Connection type: Screw terminals
• Function: Thermistor motor protection

How to use

To install the relay, mount it onto a standard DIN rail within the control cabinet. Connect the PTC thermistor sensor leads to the designated input terminals on the device. Wire the output contacts into your motor control circuit to ensure that the motor is de-energized when the relay detects an over-temperature state. Ensure all screw terminals are tightened to the manufacturer's specified torque to maintain a secure electrical connection.

What to consider before purchase

• Verify that your motor is equipped with compatible PTC thermistors.
• Ensure the control voltage matches the 24-240V AC/DC range.
• Check available space in your control cabinet for DIN rail mounting.

Usage recommendations

Regularly test the relay functionality during scheduled maintenance to ensure the thermal protection circuit remains active and responsive to simulated fault conditions.