SIEMENS
SIEMENS 3RU21161CB0 Overload Relay 1.8-2.5 A 690 V AC
Thermal overload relay protects motors at 1.8–2.5 A up to 690 V AC with auto or manual reset
- Thermal overload protection for 1.8–2.5 A circuits
- Trip Class 10 ensures fast response to overcurrent
- Direct contactor mounting simplifies panel assembly
- Screw terminals give secure, tool-friendly wiring
- Auto and manual reset modes suit varied maintenance needs
Siemens 3RU21161CB0 Overload Relay
The Siemens 3RU21161CB0 is a thermal overload relay designed for motor protection in industrial control circuits. It mounts directly to a compatible SIRIUS S00 contactor using screw terminals for secure wiring. The unit operates on three poles and includes the required thermal elements for immediate installation.
Suits panels using SIRIUS S00 contactors
This relay fits engineers maintaining or building motor starters that require a 1.8 A to 2.5 A adjustment range with Class 10 trip characteristics. It provides both automatic and manual reset options alongside 1NO/1NC auxiliary contacts for status signalling. Buyers needing a different current range, a higher NEMA size rating, or a relay without integrated thermal units should look at other models.
Adjustable range 1.8 A to 2.5 A
The decisive specification is the continuous current setting window of 1.8 A minimum to 2.5 A maximum, which must match the full-load current of the motor being protected. The 690 V AC maximum voltage rating and IEC frame size S00 define the electrical and mechanical limits of the device. Trip Class 10 determines the response speed under overload conditions.
Highlights
- Thermal overload protection for 1.8–2.5 A circuits
- Trip Class 10 ensures fast response to overcurrent
- Direct contactor mounting simplifies panel assembly
- Screw terminals give secure, tool-friendly wiring
- Auto and manual reset modes suit varied maintenance needs
Specifications
| Brand | SIEMENS |
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Questions about this item
How can I verify the 3RU21161CB0 overload relay is protecting the motor correctly after wiring it to the contactor?
With the motor running at normal load, measure phase current and confirm it sits between 1.8 A and 2.5 A; the relay should only trip if current exceeds the set value for a class 10 time-current curve.
What comes with the 3RU21161CB0 and what must I purchase separately to install it?
The relay includes its three thermal units and screw terminals for direct contactor mounting; you need a compatible SIRIUS S00 contactor, control wiring for the 1NO/1NC auxiliary contacts, and branch-circuit protection devices.
Should I choose the 1.8–2.5 A version or a different current range for my application?
Select this 1.8–2.5 A model only when the motor full-load current falls inside that window; otherwise pick the SIRIUS frame S00 overload relay whose adjustment range matches the motor nameplate amperage.
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