Siemens 3RN2000-2AA30 Thermistor Motor Protection Relay, 17.5 mm, Spring-Loaded Terminals, 1 CO Contact, AC/DC

The Siemens 3RN2000-2AA30 thermistor motor protection relay is a precision-engineered device designed to provide reliable thermal monitoring for electric motors. Housed in a compact 17.5 mm enclosure, this relay is optimized for space-saving integration into control cabinets. It utilizes advanced thermistor technology to detect overheating, ensuring that motors are protected from thermal damage during operation. With its versatile AC/DC power supply compatibility and robust spring-loaded terminals, it offers a dependable solution for maintaining the longevity and safety of industrial motor systems.

Advantages

This motor protection relay stands out due to its compact design, which allows for high-density mounting in modern control panels. The inclusion of spring-loaded terminals significantly reduces installation time and ensures a vibration-resistant connection, which is critical in industrial environments. By monitoring the temperature directly via thermistors, the device provides a more accurate assessment of the motor's thermal state compared to traditional current-based protection methods. Its universal AC/DC voltage range further enhances its flexibility, allowing it to be used in a wide variety of electrical configurations without the need for multiple device variants.

Suitable for

• Industrial automation systems
• Motor control centers
• HVAC equipment and pump systems
• Conveyor belt drives
• Machinery requiring continuous thermal monitoring

When it may not be suitable

This device is specifically designed for use with PTC thermistor sensors embedded in motor windings. It is not suitable for applications that require direct current monitoring or overload protection based on current measurement alone. Furthermore, it should not be used in environments that exceed the specified operating temperature range or in hazardous areas without appropriate protective enclosures.

Key specifications

• Width: 17.5 mm
• Connection type: Spring-loaded terminals
• Output: 1 changeover (CO) contact
• Supply voltage: AC/DC
• Function: Thermistor motor protection

How to use

Installation should be performed by qualified personnel in accordance with local electrical regulations. The relay is designed for mounting on a standard 35 mm DIN rail. Connect the PTC thermistor sensor leads to the designated input terminals on the device. Ensure that the control circuit is wired to the changeover contact to trigger the motor shutdown or alarm signal when an over-temperature condition is detected. Verify that the supply voltage matches the specifications before energizing the unit.

What to consider before purchase

• Ensure your motor is equipped with compatible PTC thermistor sensors.
• Check the available space on your DIN rail to accommodate the 17.5 mm width.
• Verify that the control voltage matches your existing system requirements.
• Confirm that the spring-loaded terminal type is compatible with your wiring standards.

Usage recommendations: Regularly test the functionality of the relay during scheduled maintenance intervals to ensure the motor protection circuit remains operational and that the thermistor sensors are correctly detecting temperature changes.