Siemens SIRIUS 3RN2 Thermistor Motor Protection Relay
Primary Specifications (3RN20101CW30)
| Parameter | Value |
|---|---|
| Base Product Number | 3RN20101 |
| Series | SIRIUS 3RN2 |
| Function | Overtemperature |
| Reset Feature | Automatic Reset |
| Mounting Type | DIN Rail |
| Operating Temperature | 25°C ~ 60°C |
| Encapsulation | Bulk |
| Package | Bulk |
| RoHS | ROHS3 Compliant |
| Product Status | Active |
The seed unit is a 1NO+1NC output relay with automatic reset, designed for direct PTC thermistor sensor input. Bulk packaging ships without retail-style individual wrapping. Operating range spans 25–60°C ambient; DIN rail mounting accommodates standard TS35 profiles.
Output Contact Variants Across SIRIUS 3RN2 Family
The Siemens SIRIUS 3RN2 thermistor protection relay series shares a common PCB footprint and sensor input circuitry across all variants. Contact arrangements differ by suffix:
| MPN | Contact Arrangement | Encapsulation | Reset Type |
|---|---|---|---|
| 3RN20101CW30 | 1NO 1NC | Bulk | Automatic |
| 3RN20101CA30 | 1NO 1NC | Bulk | Automatic |
| 3RN20101BW30 | 2CO | Box | Automatic |
| 3RN20101BA30 | 2CO | Bulk | Automatic |
| 3RN20102CW30 | 1NO 1NC | Box | Automatic |
| 3RN20102BW30 | 2CO | Box | Automatic |
| 3RN20102CA30 | 1NO 1NC | Box | Automatic |
| 3RN20102BA30 | 2CO | Box | Automatic |
| 3RN20121BW30 | 2CO | Bulk | Manual |
CW/CA suffixes denote 1NO+1NC; BW/BA suffixes denote 2CO (two changeover contacts). The 3RN20121 base number incorporates manual-reset logic versus the standard automatic-reset variants. Units differ only in package style (Bulk vs Box) and contact configuration—all share the same DIN rail form factor, sensor input, and 25–60°C rating.
Application Notes
Thermistor motor protection relays monitor PTC sensors embedded in motor windings. The 3RN20101CW30 accepts PTC input and switches its output contacts upon overtemperature fault detection, interrupting the motor contactor coil circuit. Automatic reset restores output once temperature falls below the release threshold. Panel builders should verify sensor compatibility (PTC characteristic must match relay trip curve) and confirm contact rating sufficiency for the driven load.