The Siemens 3RU2136-4KB0 is a premium thermal overload relay from the renowned SIRIUS 3RU2 Series, engineered to provide dependable protection for three-phase motors against overload conditions, phase failure, and excessive current draw. Designed for industrial motor control applications, the relay features an adjustable current setting range of 62–73 A, Class 10A tripping characteristics, and compatibility with Size S2 Siemens contactors.
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 incorporates phase-loss sensitivity, helping minimize motor heating during single-phasing conditions.
The Variant KB0 is designed for direct mounting on Siemens S2 contactors, including compatible SIRIUS 3RT2037 and 3RT2038 contactors. With an adjustable current range of 62–73 A, it is ideally suited for protecting motors used in pumps, compressors, conveyor systems, fans, HVAC equipment, manufacturing machinery, and industrial automation installations.
As part of the Siemens SIRIUS motor protection portfolio, the 3RU2136-4KB0 supports both manual and automatic reset modes, providing flexibility for various industrial applications and maintenance procedures. It includes 1 Normally Open (NO) and 1 Normally Closed (NC) auxiliary contact for trip indication, signaling, and control circuit integration.
Designed with screw-type terminals and a compact S2 frame size, the relay ensures secure electrical connections and seamless integration into motor starter assemblies, MCC panels, switchboards, and industrial control systems. Its robust construction delivers reliable long-term performance in demanding industrial environments.
| Specification | Details |
|---|---|
| Product Name | Thermal Overload Relay |
| Part Number | 3RU2136-4KB0 |
| SKU | 3RU2136-4KB0 |
| Brand | Siemens |
| Product Family | SIRIUS 3RU2 |
| Product Type | Motor Protection Relay |
| Variant | KB0 |
| Current Setting Range | 62–73 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 Loss Protection |
| Application | Industrial Motor Protection |
| Manufacturer | Siemens |
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