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Siemens Overload Relay: Thermal Protection, 3 Poles, 1NO/1NC, Frame Size S0 - IEC Thermal Overload Relays
SiemensIEC Thermal Overload Relays

Siemens Overload Relay: Thermal Protection, 3 Poles, 1NO/1NC, Frame Size S0

The SIEMENS Overload Relay is an IEC thermal overload relay with integrated bimetallic elements, designed for frame size S0 and compatible with SIRIUS contactors. It features a 1NO/1NC auxiliary contact form, screw…

SKU 3G-OTH-39802

Brand
Siemens
Item
Overload Relay: Thermal Protection, 3 Poles, 1NO/1NC, Frame Size S0
Category
IEC Thermal Overload Relays
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Technical Specifications

Siemens
Manufacturer Part Number
3RU21261HB0
Type
1NO/1NC, Frame Size S0, 5.5 A – 8 A
Poles
3
Frame Size
S0
Compatible Contactors
Frame Size S0
Auxiliary Contact Form
1NO/1NC
Maximum Voltage Rating
690V AC
Phase Loss Sensitivity
No
Thermal Units Required
None (Relay Includes Integrated Bimetallic Elements)
Terminal Connection Type
Screw Terminals
Compatible Contactor Series
SIRIUS
View Full Spec Sheet

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Siemens Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The SIEMENS Overload Relay is an IEC thermal overload relay with integrated bimetallic elements, designed for frame size S0 and compatible with SIRIUS contactors. It features a 1NO/1NC auxiliary contact form, screw terminals, and a maximum voltage rating of 690V AC, with no phase loss sensitivity. This 3-pole relay covers a current range of 5.5 A to 8 A (MPN 3RU21261HB0).

Frequently Asked Questions

What is the SIEMENS 3RU21261HB0 overload relay used for?

The SIEMENS 3RU21261HB0 is an IEC thermal overload relay used to protect motors from overcurrent and phase imbalance. It integrates bimetallic elements for thermal protection and is designed for frame size S0, compatible with SIRIUS contactors. Typical applications include industrial motor control panels, conveyors, pumps, and compressors.

What are the specifications of the SIEMENS 3RU21261HB0 overload relay?

The SIEMENS 3RU21261HB0 is a 3-pole thermal overload relay with a current range of 5.5 A to 8 A. It features 1NO/1NC auxiliary contacts, screw terminals, a maximum voltage rating of 690V AC, and no phase loss sensitivity. It includes integrated bimetallic elements and is compatible with SIRIUS contactors in frame size S0.

Where to buy the SIEMENS 3RU21261HB0 overload relay worldwide?

You can source the SIEMENS 3RU21261HB0 overload relay worldwide through 3G Electric, a global industrial equipment distributor. We handle full logistics, customs clearance, and delivery to your location. Contact us for availability and lead time; we supply genuine Siemens components for industrial applications.

How to select the correct SIEMENS overload relay for a motor?

To select the correct SIEMENS overload relay, match the relay's current range to the motor's full-load current. For the 3RU21261HB0, the range is 5.5 A to 8 A. Ensure the frame size (S0) matches your contactor series (SIRIUS). Use screw terminals for wiring. Always consult the motor nameplate and Siemens documentation for proper coordination.

Used in

Common applications for Siemens
District cooling plants — LME73 + RWF55 for condenser-water modulation
Inflight catering and food-processing steam boilers — LMG22 with SQN90 air-fuel cross-damper
Hospital steam-plant redundancy — LME41 with QRA2 UV flame detection for dual-fuel boilers
Semiconductor fab process heat — LME23 and SKP55 gas valves on hot-oil heater skids
Container-terminal reefer-deck heating — LMG22 retrofit onto legacy burner racks

Siemens Products

3G Electric supplies Siemens iec thermal overload relays. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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SIEMENS Overload Relay: Thermal Protection, 3 Poles, 1NO/1NC, Frame Size S00, 0.18 A – 0.25 A (MPN 3RU21160CB0). Key specifications — Brand: SIEMENS; Auxiliary Contact Form: 1NO/1NC; Compatible Contactor Series: SIRIUS; Terminal Connection Type: Screw Terminals; Frame Size: S00; Maximum Voltage Rating: 690V AC; Phase Loss Sensitivity: No; Thermal Units Required: None (Relay Includes Integrated Bimetallic Elements).
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SIEMENS Overload Relay: Thermal Protection, 3 Poles, 1NO/1NC, Frame Size S00, 0.35 A – 0.5 A (MPN 3RU21160FB0). Key specifications — Brand: SIEMENS; Auxiliary Contact Form: 1NO/1NC; Compatible Contactor Series: SIRIUS; Terminal Connection Type: Screw Terminals; Frame Size: S00; Maximum Voltage Rating: 690V AC; Phase Loss Sensitivity: No; Thermal Units Required: None (Relay Includes Integrated Bimetallic Elements).
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SIEMENS Overload Relay: Thermal Protection, 3 Poles, 1NO/1NC, Frame Size S00, 0.35 A – 0.5 A (MPN 3RU21160FB0). Key specifications — Brand: SIEMENS; Auxiliary Contact Form: 1NO/1NC; Compatible Contactor Series: SIRIUS; Terminal Connection Type: Screw Terminals; Frame Size: S00; Maximum Voltage Rating: 690V AC; Phase Loss Sensitivity: No; Thermal Units Required: None (Relay Includes Integrated Bimetallic Elements).