The Siemens 3RU2126-1HB0 is a high-performance thermal overload relay from the trusted SIRIUS 3RU2 Series, engineered to provide dependable protection for three-phase motors against overload conditions, phase failure, and prolonged overcurrent operation. Featuring an adjustable current setting range of 3.5–5 A, Class 10 tripping characteristics, and compatibility with Size S0 Siemens contactors, this relay is ideally suited for industrial motor control systems, motor starter assemblies, and automation applications.
Built using Siemens' proven thermal tripping technology, the relay continuously monitors motor current and responds to overload conditions using an inverse-time characteristic. This helps prevent motor overheating, insulation damage, and costly equipment downtime while permitting normal motor starting currents. Integrated phase-failure sensitivity enhances protection against single-phasing conditions and improves overall system reliability.
The Variant HB0 offers an adjustable overload release setting of 3.5–5 A, making it suitable for protecting small and medium-sized motors used in pumps, fans, compressors, conveyors, HVAC systems, packaging equipment, machine tools, and industrial automation machinery. Its compact S0 frame size allows direct mounting onto compatible Siemens contactors, reducing installation time and panel space requirements.
The relay includes 1 Normally Open (NO) and 1 Normally Closed (NC) auxiliary contact for trip indication, signaling, and control circuit integration. It supports both manual and automatic reset modes, providing flexibility for different operational and maintenance requirements.
Designed with durable screw-type terminal connections and manufactured to Siemens' stringent quality standards, the 3RU2126-1HB0 delivers long-term reliability and consistent motor protection in demanding industrial environments.
| Specification | Details |
|---|---|
| Product Name | Thermal Overload Relay |
| Part Number | 3RU2126-1HB0 |
| SKU | 3RU2126-1HB0 |
| Brand | Siemens |
| Product Family | SIRIUS 3RU2 |
| Product Type | Motor Protection Relay |
| Variant | HB0 |
| Current Setting Range | 3.5–5 A |
| Relay Size | S0 |
| Trip Class | Class 10 |
| Operating Principle | Thermal |
| Mounting Type | Direct Contactor Mounting |
| Main Circuit Connection | Screw Terminal |
| Auxiliary Contacts | 1 NO + 1 NC |
| Reset Type | Manual / Automatic |
| Rated Insulation Voltage | 690 V |
| Number of Main Poles | 3 |
| Protection Features | Overload & Phase Failure Protection |
| Application | Industrial Motor Protection |
| Manufacturer | Siemens |
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