The Siemens 3RU2136-4JB0 is a reliable thermal overload relay from the trusted SIRIUS 3RU2 Series, designed to provide effective protection for three-phase motors against overload conditions, phase failure, and prolonged overcurrent operation. The relay features an adjustable current setting range of 45–55 A, Class 10A tripping characteristics, and is designed for direct mounting on Siemens Size S2 contactors, making it ideal for industrial motor control and protection applications.
Built on Siemens' proven thermal overload protection technology, the relay continuously monitors motor current and disconnects the motor when overload conditions persist. Its inverse-time delayed tripping characteristic helps prevent motor overheating, insulation damage, and premature equipment failure while allowing normal motor starting currents. The relay also provides phase-failure sensitivity to help protect motors during single-phasing conditions.
The Variant JB0 is intended for contactor mounting and is suitable for protecting motors used in pumps, compressors, conveyor systems, fans, HVAC equipment, manufacturing machinery, and industrial automation installations. Its compact S2 design enables efficient integration into motor starter assemblies and control panels.
As part of the Siemens SIRIUS motor protection portfolio, the 3RU2136-4JB0 supports both manual and automatic reset modes, offering flexibility for maintenance and operational requirements. 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 main and auxiliary terminals, the relay ensures secure electrical connections and dependable long-term performance in demanding industrial environments. With a rated insulation voltage of 690 V and an operating temperature range of -40°C to +70°C, it is well suited for a wide range of industrial applications.
| Specification | Details |
|---|---|
| Product Name | Thermal Overload Relay |
| Part Number | 3RU2136-4JB0 |
| SKU | 3RU2136-4JB0 |
| Brand | Siemens |
| Product Family | SIRIUS 3RU2 |
| Product Type | Motor Protection Relay |
| Variant | JB0 |
| Current Setting Range | 45–55 A |
| Relay Size | S2 |
| Trip Class | Class 10A |
| 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 |
| Operating Temperature | -40°C to +70°C |
| Protection Features | Overload & Phase Failure Protection |
| Application | Industrial Motor Protection |
| Manufacturer | Siemens |
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