The Siemens 3RU2136-4BB0 is a high-performance thermal overload relay from the trusted SIRIUS 3RU2 Series, designed to provide reliable protection for three-phase motors against overload conditions, phase failure, and excessive current draw. Featuring an adjustable current setting range of 14–20 A, Class 10 tripping characteristics, and compatibility with Size S2 Siemens contactors, this relay is ideal for industrial motor control and protection applications.
The relay operates using Siemens' proven thermal overload protection principle, 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.
The Variant BB0 provides an adjustable overload release setting of 14–20 A, making it suitable for protecting motors used in pumps, compressors, conveyors, fans, HVAC equipment, manufacturing machinery, water treatment systems, and industrial automation installations. Designed for direct mounting on compatible Siemens S2 contactors, it enables compact and efficient motor starter assemblies.
As part of the Siemens SIRIUS motor protection portfolio, the 3RU2136-4BB0 supports both manual and automatic reset modes, offering flexibility for different operating requirements and maintenance procedures. The relay includes 1 Normally Open (NO) and 1 Normally Closed (NC) auxiliary contact for signaling, monitoring, and control circuit integration.
Designed with screw-type terminals for both main and auxiliary circuits, the relay ensures secure electrical connections and simplified installation. Its compact S2 frame size allows seamless integration into motor control centers (MCCs), switchboards, OEM panels, and industrial automation systems.
Manufactured according to Siemens' stringent quality standards, the 3RU2136-4BB0 delivers dependable long-term performance in demanding industrial environments where continuous motor protection is essential.
| Specification | Details |
|---|---|
| Product Name | Thermal Overload Relay |
| Part Number | 3RU2136-4BB0 |
| SKU | 3RU2136-4BB0 |
| Brand | Siemens |
| Product Family | SIRIUS 3RU2 |
| Product Type | Motor Protection Relay |
| Variant | BB0 |
| 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 |
| Number of Main Poles | 3 |
| Protection Features | Overload & Phase Failure Protection |
| Application | Industrial Motor Protection |
| Manufacturer | Siemens |
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