The Siemens 3RH1921-1KA02 is a second laterally mountable auxiliary contact block from the Siemens SIRIUS accessory range, designed for compatible SIRIUS 3RT1 contactors in sizes S6 to S12. It provides 2 normally closed (2 NC) instantaneous auxiliary contacts and uses 10 mm screw-terminal connections. Siemens identifies this article as a second lateral auxiliary switch according to DIN EN 50005.
The 3RH1921-1KA02 is used to add additional auxiliary switching capability to compatible large-frame Siemens contactors.
It provides extra contact paths for control and signalling functions without changing the main switching function of the contactor.
Typical applications include:
Contactor status feedback
Electrical interlocking
PLC input signals
Control-circuit logic
Machine sequencing
Auxiliary signalling
Motor-control circuits
Industrial automation
The 3RH1921-1KA02 provides 2 normally closed auxiliary contacts.
Both contacts are instantaneous and can be used for control, interlocking and monitoring circuits.
Typical applications include:
Electrical interlocking
Contactor status feedback
PLC monitoring
Auxiliary signalling
Machine-control logic
Relay circuits
Safety-related control functions where the complete system is appropriately designed
The available Siemens catalog identifies the article as a 2-pole, 2 NC auxiliary switch.
A major feature of the 3RH1921-1KA02 is that it is the second laterally mountable auxiliary contact block.
It is designed for right- or left-side mounting on compatible Siemens SIRIUS contactors. Siemens lists this second lateral auxiliary-switch family for 3RT1.4 through 3RT1.7, covering the relevant S6 to S12 sizes.
This is useful where additional auxiliary contacts are required after a first lateral auxiliary block has already been installed.
The 3RH1921-1KA02 is intended for compatible SIRIUS 3RT1 contactors in sizes S6 to S12.
The accessory is especially suitable for large contactors used in high-power industrial motor-control systems.
Typical applications include:
Large motor starters
Heavy-duty industrial machinery
Conveyor systems
Pumps
Compressors
Large fans
Production lines
Industrial automation panels
The exact compatibility should be checked against the complete contactor article number before installation.
The 3RH1921-1KA02 uses a 10 mm screw connection, providing a practical connection method for the auxiliary control circuit.
This connection format is suitable for industrial panel builders and maintenance teams working with large-frame contactors.
The product is specified according to DIN EN 50005 for its auxiliary-contact arrangement.
The standardization of auxiliary-contact designation helps simplify control-circuit identification and integration in industrial contactor assemblies.
The 3RH1921-1KA02 can be used to expand the control and feedback functionality of compatible large SIRIUS contactors.
The two NC auxiliary contacts can be used for electrical interlocking, status feedback and motor-control logic.
The contacts can provide auxiliary status information to PLC digital inputs where the electrical ratings are suitable.
The NC contacts can support machine sequencing, interlocking and control logic.
The lateral mounting arrangement is suitable for high-power contactor assemblies where additional auxiliary contacts are required.
The auxiliary contacts can provide additional signalling and feedback paths in automated industrial equipment.
The 3RH1921-1KA02 is suitable for OEM machine manufacturers, electrical panel builders, automation integrators and industrial maintenance professionals working with large SIRIUS contactors.
Its 2 NC configuration, second lateral mounting position and screw-terminal connection make it useful when additional auxiliary contact functionality is required on S6 to S12 contactor assemblies.
Siemens SIRIUS auxiliary contact block
Article number 3RH1921-1KA02
Second laterally mountable auxiliary switch
2 NC auxiliary contacts
2-pole configuration
Suitable for S6 to S12 contactor sizes
Suitable for compatible 3RT1.4 to 3RT1.7 contactors
Right- or left-side lateral mounting
10 mm screw-terminal connection
DIN EN 50005 configuration
Suitable for electrical interlocking
Suitable for PLC feedback
Suitable for industrial automation
2 NC contacts: Provides two additional normally closed switching paths.
Second lateral position: Allows additional auxiliary contacts to be installed when required.
Left/right mounting: Provides flexibility in large contactor assemblies.
S6–S12 compatibility: Designed for large Siemens SIRIUS contactors.
Screw connection: Supports practical industrial panel wiring.
Interlocking support: NC contacts are useful for suitable electrical interlocking circuits.
PLC feedback: Can provide contactor-status information to automation systems.
Compact lateral design: Adds auxiliary functionality without requiring a separate external relay.
The Siemens 3RH1921-1KA02 is a practical solution for adding two instantaneous NC auxiliary contacts to compatible SIRIUS large-frame contactors.
As a second laterally mountable auxiliary block, it is particularly useful when additional auxiliary switching capacity is needed on S6 to S12 contactors. Siemens' catalog specifically identifies the device as a second 2-pole lateral auxiliary switch for these contactor sizes.
For OEMs, panel builders and automation integrators, it provides additional interlocking, feedback and signalling capability while maintaining the existing contactor assembly.
SB Smart supplies Siemens industrial electrical and automation products across Faridabad, Gurgaon/Gurugram, Delhi NCR, Haryana, Noida, Punjab, Mumbai and all major cities across India.
Major delivery locations include:
Faridabad
Gurgaon/Gurugram
Delhi
Delhi NCR
Noida
Greater Noida
Haryana
Punjab
Mumbai
Pune
Ahmedabad
Bengaluru
Hyderabad
Chennai
Kolkata
Jaipur
Chandigarh
Lucknow
Indore
Surat
Vadodara
Nagpur
Coimbatore
And other major cities across India
It is a Siemens SIRIUS second laterally mountable auxiliary contact block with 2 NC contacts for compatible large-frame contactors.
It provides 2 normally closed auxiliary contacts.
It means the block is designed as the second auxiliary switch installed laterally on a compatible SIRIUS contactor.
It is designed for compatible Siemens 3RT1 contactors in sizes S6 to S12, including the relevant 3RT1.4 to 3RT1.7 range.
Yes. Siemens lists the second lateral auxiliary-switch configuration for right- or left-side mounting.
It uses a 10 mm screw-terminal connection.
They can be used for electrical interlocking, PLC feedback, signalling, control logic and machine sequencing.
No. It is an auxiliary contact block; the main load is switched by the compatible contactor.
Yes. It is intended for compatible S6 to S12 SIRIUS contactors used in large industrial switching applications.
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 | 3RH1921-1KA02 |
| Product Type | Auxiliary Contact Block |
| Contact Configuration | 2 NC |
| Number of Poles | 2 Pole |
| Mounting Position | Second Laterally Mountable |
| Compatible Contactor Sizes | S6 to S12 |
| Terminal Type | Screw Terminals |
| Mounting Method | Side Mount |
| Electrical Function | 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 |
No reviews yet.