The Siemens 3RH1921-1EA11 is a first laterally mountable auxiliary contact block from the Siemens SIRIUS 3RH19 accessory range, designed for compatible 3RT1 contactors. It provides 1 normally open (NO) and 1 normally closed (NC) instantaneous auxiliary contact, with screw-terminal connections and a compact 2-pole design. Siemens currently lists this article as an active product.
The accessory is designed to expand the control, feedback, signalling and interlocking capability of compatible large-frame Siemens contactors without changing their main power-switching function.
The 3RH1921-1EA11 provides additional auxiliary switching paths for industrial control and automation circuits.
These auxiliary contacts can be used for:
Contactor status feedback
PLC input signals
Electrical interlocking
Control-circuit logic
Machine sequencing
Auxiliary signalling
Motor-control circuits
Industrial automation
Siemens identifies this product as a first lateral auxiliary switch for 3RT1 contactors.
The 3RH1921-1EA11 provides:
1 NO + 1 NC
Both contacts are instantaneous auxiliary contacts.
This combination provides flexibility for applications where both normally open and normally closed signals are required from the same contactor.
Typical uses include:
Contactor ON feedback
PLC monitoring
Electrical interlocking
Auxiliary signalling
Machine sequencing
Status indication
Control-system feedback
Relay logic
Siemens' product data confirms one instantaneous NC contact and one instantaneous NO contact.
A key feature of the 3RH1921-1EA11 is its first lateral mounting position.
It is designed to mount on the side of compatible Siemens 3RT1 contactors and forms part of the lateral auxiliary-switch system for larger SIRIUS contactors. Siemens identifies the product specifically as a first laterally mountable auxiliary switch.
This arrangement is useful where additional auxiliary contacts are required without occupying the front auxiliary-contact position.
The 3RH1921-1EA11 is intended for compatible Siemens 3RT1 contactors, including applications covering sizes from S0 through S12. Siemens product data identifies compatibility with 3RT10, 3RT12, 3RT145, 3RT146 and 3RT147 contactor families.
This makes the accessory suitable for a wide range of industrial motor-control contactors.
Typical applications include:
Large motor starters
Heavy-duty machinery
Conveyor systems
Pumps
Compressors
Fans and blowers
Production lines
Industrial automation panels
The exact compatibility should always be checked against the complete contactor article number before installation.
The 3RH1921-1EA11 uses screw-terminal connections for the auxiliary circuits. Siemens specifies a screw connection design for the product.
This provides a familiar wiring method for electrical panel builders and maintenance teams.
The product is also identified with a 10 mm screw connection in Siemens-related product documentation.
Both contacts of the 3RH1921-1EA11 are instantaneous.
The auxiliary contacts follow the switching state of the associated contactor without an intentional timing delay.
This makes the accessory suitable for:
Immediate contactor feedback
Interlocking
Status indication
PLC monitoring
Machine-control logic
Auxiliary signalling
The 3RH1921-1EA11 can expand the auxiliary control functionality of compatible Siemens SIRIUS contactors.
The NO and NC contacts can provide contactor-state feedback and additional motor-control signals.
The auxiliary contacts can be connected to PLC digital inputs for monitoring the operating state of the contactor.
The 1 NO + 1 NC configuration can support machine sequencing, interlocking and control logic.
The lateral mounting arrangement provides an organized way to add auxiliary switching capability to compatible contactors.
The additional contact paths can provide feedback and control signals within automated industrial equipment.
The 3RH1921-1EA11 is suitable for OEM machine manufacturers, electrical panel builders, automation integrators and industrial maintenance professionals working with Siemens SIRIUS contactors.
Its 1 NO + 1 NC configuration, first lateral mounting position and screw-terminal design make it useful for applications requiring additional auxiliary control functionality.
Siemens SIRIUS 3RH19 auxiliary contact block
Article number 3RH1921-1EA11
First laterally mountable auxiliary switch
1 NO + 1 NC auxiliary contacts
Instantaneous contacts
2-pole configuration
Screw terminals
10 mm screw connection
Suitable for compatible 3RT1 contactors
Suitable for S0 to S12 applications
Suitable for PLC feedback
Suitable for electrical interlocking
Suitable for machine-control applications
Suitable for industrial automation
1 NO + 1 NC contacts: Provides both normally open and normally closed auxiliary switching paths.
First lateral mounting: Adds auxiliary functionality to the side of compatible contactors.
Wide compatibility: Suitable for applicable Siemens 3RT1 contactor sizes.
Instantaneous operation: Auxiliary contacts follow the operating state of the connected contactor.
Screw terminals: Provides a familiar industrial wiring method.
PLC integration: Supports contactor-status monitoring.
Interlocking support: NC contact can be incorporated into suitable interlocking circuits.
Compact lateral arrangement: Adds auxiliary functionality without requiring a separate external relay.
The Siemens 3RH1921-1EA11 provides a practical solution for adding one instantaneous NO and one instantaneous NC auxiliary contact to compatible Siemens SIRIUS 3RT1 contactors.
As a first laterally mountable auxiliary switch, it is useful where additional feedback, signalling or interlocking contacts are required while keeping the main contactor assembly compact and organized. Siemens currently lists the article as an active product.
For OEMs, panel builders and automation integrators, it provides an effective way to expand auxiliary contact functionality in industrial motor-control and automation systems.
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It is a Siemens SIRIUS first laterally mountable auxiliary contact block with 1 NO and 1 NC instantaneous contacts for compatible 3RT1 contactors.
It provides 1 normally open and 1 normally closed contact.
Yes. Both contacts are instantaneous auxiliary contacts.
It identifies the accessory as the first laterally mountable auxiliary switch in the compatible SIRIUS contactor arrangement.
It is designed for compatible 3RT1 contactors, including the applicable S0 to S12 range and specified 3RT10, 3RT12, 3RT145, 3RT146 and 3RT147 families.
Yes. It uses screw-terminal connections, with Siemens-related documentation identifying a 10 mm screw connection.
They can be used for PLC feedback, signalling, electrical interlocking, contactor monitoring, control logic and machine sequencing.
No. It is an auxiliary contact block; the main load is switched by the compatible contactor.
Yes. It is designed for compatible 3RT1 contactors across S0 to S12 applications, making it suitable for a wide range of industrial control assemblies.
You can explore the Siemens product range at SB Smart for Siemens auxiliary contact blocks, contactors and other industrial automation products.
| Specification | Details |
|---|---|
| Product Name | Auxiliary Contact Block |
| Manufacturer | Siemens |
| Series | SIRIUS |
| Order Code | 3RH1921-1EA11 |
| Product Type | Auxiliary Contact Block |
| Contact Configuration | 1NO + 1NC |
| Number of Poles | 2 Pole |
| Mounting Position | First Laterally Mountable |
| Compatible Contactor Sizes | S6 to S12 |
| Terminal Type | Screw Terminals |
| Mounting Method | Side Mount |
| Electrical Function | Signaling, Monitoring & Interlocking |
| Suitable For | Siemens SIRIUS Contactors |
| Industrial Application | Yes |
| Mechanical Life | Long Service Life |
| Electrical Durability | Industrial Grade |
| Brand | Siemens |
| Condition | New & Genuine Product |
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