Siemens 3RN2 Thermistor Relay for Motor Overheat Protection

Product Description

Product Overview

The Siemens 3RN2 thermistor motor protection relay is a compact evaluation unit designed for reliable motor temperature monitoring.
It evaluates signals from PTC thermistors or bimetallic switches and protects motors against thermal overload conditions.
Moreover, the device supports a wide control voltage range from 24 V to 240 V AC or DC.
Therefore, it integrates easily into diverse industrial control panels and global power systems.

Technical Specifications

• Product Series: Siemens 3RN2

• Product Type: Thermistor motor protection relay, standard evaluation unit

• Monitoring Method: PTC thermistors or bimetallic temperature switches

• Supply Voltage: 24–240 V AC/DC

• Reset Mode: Automatic reset

• Contact Configuration: 2 changeover contacts (DPDT)

• Contact Rating: Suitable for control and signaling circuits

• Electrical Isolation: Yes

• Mounting Type: DIN rail mounting

• Terminal Type: Screw terminals

• Enclosure Width: 22.5 mm

• Dimensions (L × W × H): 91.6 × 22.5 × 100 mm

• Operating Temperature: –25 °C to +60 °C

• Net Weight: 0.174 kg

• Product Lifecycle: Active product

• Compliance: RoHS compliant, WEEE take-back applicable

FAQ

Q1: What types of sensors can the 3RN2 relay monitor?
It supports PTC thermistors and bimetallic temperature switches commonly installed inside motor windings.

Q2: Does this relay require manual reset after a trip?
No, it features automatic reset once the monitored temperature returns to a safe range.

Q3: Can the relay operate with both AC and DC control voltages?
Yes, it accepts a wide control voltage range from 24 V to 240 V AC or DC.

Q4: How is the relay mounted inside a control cabinet?
It mounts directly onto standard DIN rails and connects using screw terminals.

Q5: What visual indicators are available for diagnostics?
Two LEDs indicate power readiness and trip status for fast operational assessment.