Siemens 3RU1126-4CB0 Overload Relay
The Siemens 3RU1126-4CB0 thermal overload relay is a Size S0 motor protection device with an adjustable trip range of 17–22 A and Class 10 trip characteristic. It mounts directly to a matching Size S0 contactor for compact starter assemblies.
Description
- Class 10 Trip: Protects standard motors from sustained overload.
- Adjustable Range: Sets trip current between 17 and 22 A.
- Direct Mounting: Snaps onto Size S0 contactors without wiring.
- Dual Aux Contacts: Signals trip status via 1 NO + 1 NC.
- Finger-Safe Design: Prevents accidental contact during service work.
Documentation
Technical Specifications
| Manufacturer | Siemens |
|---|---|
| Part Number | 3RU1126-4CB0 |
| Application | Protection |
| Type | Overload Relay |
| Series | SIRIUS 3RU11 |
| Size / Rating | 22 Amp Max |
| Compatibility | 3RT102 Contactors |
| Auxiliary Contacts | 1 NO + 1 NC |
| Contactor Size | S0 (direct mount to S0 contactor) |
| Connection Type | Screw Terminals |
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Description
The Siemens 3RU1126-4CB0 is a thermal overload relay from the SIRIUS 3RU1 family. It protects three-phase motors from sustained overcurrent and phase loss, with bimetal sensing on each pole and an adjustable 17–22 A trip range that lets panel builders match the relay to the motor's full-load current.
Direct mounting onto a Size S0 SIRIUS contactor eliminates flying leads and forms a compact starter. Two auxiliary contacts (1 NO + 1 NC, rated 3 A at 24 V AC-15) drop out the contactor coil on a trip and signal the fault to a PLC input or indicator lamp.
Frequently Asked Questions
What contactor does this overload relay mount to?
It direct-mounts onto any Size S0 SIRIUS contactor in the Siemens 3RT2 family, forming a compact motor starter without separate wiring between the two.
What does Class 10 trip class mean?
Class 10 means the relay trips within 10 seconds at 7.2x the set current. It suits standard motors that reach full load quickly after starting.
Can the auxiliary contacts drive a PLC input?
Yes. The 1 NC contact rated 3 A at 24 V AC-15 (1 A DC-13) can signal trip status to a PLC input or indicator lamp.
