The Siemens 3RU2136-4BB00-8K is a dependable thermal overload relay from the SIRIUS 3RU2 Series, designed to provide reliable protection for three-phase motors against overload conditions, phase failure, and prolonged overcurrent operation. This relay features an adjustable current setting range of 14–20 A, Class 10 tripping characteristics, and compatibility with Size S2 contactors, making it suitable for industrial motor protection applications. The 3RU2136 family is specifically designed for direct contactor mounting and efficient motor protection in demanding industrial environments.
The relay utilizes Siemens' proven thermal overload protection technology, continuously monitoring motor current and disconnecting the motor when overload conditions persist. Its inverse-time delayed tripping characteristic helps prevent overheating, insulation damage, and premature motor failure while allowing normal motor starting currents. Siemens SIRIUS overload relays also incorporate phase-failure sensitivity for enhanced motor protection.
The Variant BB008K offers an adjustable overload release setting of 14–20 A, making it ideal for protecting motors used in pumps, compressors, conveyor systems, fans, HVAC equipment, manufacturing machinery, and industrial automation installations. Industry references identify the 3RU2136-4BB00-8K as the 14–20 A variant within the Siemens S2 thermal overload relay range.
As part of the Siemens SIRIUS motor protection portfolio, the 3RU2136-4BB00-8K supports both manual and automatic reset modes, providing flexibility for different operating requirements and maintenance procedures. The relay includes 1 NO + 1 NC auxiliary contacts for signaling, monitoring, and control circuit integration. These features are standard across the SIRIUS 3RU2 overload relay family.
Designed with screw-type main and auxiliary terminals, the relay ensures secure electrical connections and simplified installation. Its compact S2 frame size allows seamless integration into motor starter assemblies, MCC panels, switchboards, and industrial control systems.
Manufactured according to Siemens' stringent quality standards, the 3RU2136-4BB00-8K delivers dependable long-term performance in manufacturing facilities, water treatment plants, process industries, material handling systems, and infrastructure projects.
| Specification | Details |
|---|---|
| Product Name | Thermal Overload Relay |
| Part Number | 3RU2136-4BB00-8K |
| SKU | 3RU2136-4BB00-8K |
| Brand | Siemens |
| Product Family | SIRIUS 3RU2 |
| Product Type | Motor Protection Relay |
| Variant | BB008K |
| Current Setting Range | 14–20 A |
| Relay Size | S2 |
| Trip Class | Class 10 |
| Operating Principle | Thermal |
| Mounting Type | Direct Contactor Mounting |
| Main Circuit Connection | Screw Terminal |
| Auxiliary Circuit Connection | Screw Terminal |
| Auxiliary Contacts | 1 NO + 1 NC |
| Reset Type | Manual / Automatic |
| Rated Insulation Voltage | 690 V |
| Surge Voltage Resistance | 6 kV |
| Number of Main Poles | 3 |
| Protection Features | Overload & Phase Failure Protection |
| Application | Industrial Motor Protection |
| Manufacturer | Siemens |
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