The Siemens 3RU2146-4HB00-8K is a reliable thermal overload relay from the SIRIUS 3RU2 Series, engineered to provide effective protection for three-phase motors against overload conditions, phase failure, and excessive current draw. Designed for industrial motor control applications, this relay features an adjustable current setting range of 36–50 A, Class 10 tripping characteristics, and compatibility with Size S3 contactors. The relay is intended for direct contactor mounting and provides dependable motor protection in demanding industrial environments.
The relay operates using Siemens' proven thermal overload protection principle, continuously monitoring motor current and disconnecting the motor when overload conditions persist. This helps prevent overheating, insulation damage, reduced motor life, and costly downtime while improving operational reliability. Siemens SIRIUS overload relays are designed for current-dependent motor protection and phase-loss detection.
The Variant HB008K incorporates a thermal inverse-time delayed overload release with an adjustable setting range of 36–50 A, making it suitable for protecting motors used in pumps, compressors, conveyor systems, fans, HVAC equipment, manufacturing machinery, and process automation applications. The model belongs to the S3 relay size family and is designed for seamless integration with compatible SIRIUS contactors.
As part of the Siemens SIRIUS motor protection portfolio, the 3RU2146-4HB00-8K supports both manual and automatic reset modes, allowing users to configure protection according to plant operating requirements and safety procedures. The relay includes integrated 1 NO + 1 NC auxiliary contacts for trip indication and control circuit integration. Similar S3-frame variants in the 3RU2146 series share these core features.
The device is designed with screw-type terminals for both the main and auxiliary circuits, ensuring secure electrical connections and simplified installation. Its compact S3 frame size enables easy integration into motor starter assemblies, MCC panels, and industrial control systems.
Featuring a Class 10 trip characteristic, the relay provides rapid protection for standard motor starting applications while minimizing nuisance tripping during normal operation. It also offers phase-failure sensitivity, helping protect motors from damaging single-phasing conditions.
Manufactured according to Siemens' stringent quality standards, the 3RU2146-4HB00-8K delivers dependable long-term performance in manufacturing facilities, water treatment plants, process industries, material handling systems, HVAC installations, and industrial automation projects.
| Specification | Details |
|---|---|
| Product Name | Thermal Overload Relay |
| Part Number | 3RU2146-4HB00-8K |
| SKU | 3RU2146-4HB00-8K |
| Brand | Siemens |
| Product Family | SIRIUS 3RU2 |
| Product Type | Motor Protection Relay |
| Variant | HB008K |
| Current Setting Range | 36–50 A |
| Relay Size | S3 |
| Trip Class | Class 10 |
| Operating Principle | Thermal |
| Mounting Type | Contactor Mounting |
| Main Circuit Connection | Screw Terminal |
| Auxiliary Circuit Connection | Screw Terminal |
| Auxiliary Contacts | 1 NO + 1 NC |
| Reset Type | Manual / Automatic |
| Number of Main Poles | 3 |
| Protection Features | Overload & Phase Failure Protection |
| Application | Industrial Motor Protection |
| Manufacturer | Siemens |
No reviews yet.