Technical Specifications

Main Features and Advantages

Versatile Contact Configuration and Compatibility: The Siemens 3RH1921-1HA22 provides a balanced set of 2 NO and 2 NC auxiliary contacts, offering maximum flexibility for implementing diverse control logic, from simple status indication to complex interlocking schemes . Its design is tailored for the SIRIUS modular system, ensuring seamless integration with a wide range of Siemens 3RT1 motor contactors, from the compact Size S0 to the larger Size S12 . This broad compatibility across the Siemens contactor family makes the Siemens 3RH1921-1HA22 a versatile asset for standardizing control panel designs.

Superior Reliability and Durability: Engineered for long-term performance in demanding industrial environments, the Siemens 3RH1921-1HA22 boasts an impressive mechanical service life of 10 million switching cycles and an electrical endurance of 200,000 cycles under AC-15 load conditions . This exceptional durability minimizes the need for frequent replacements, reducing downtime and maintenance costs. With a rated insulation voltage of 690V and a surge voltage resistance of 6kV, the Siemens 3RH1921-1HA22 offers reliable operation and protection against electrical disturbances, safeguarding critical control circuits .

Tool-free Installation and Maintenance: The Siemens 3RH1921-1HA22 features a simple, yet secure, snap-on mounting mechanism that allows it to be installed or removed quickly without the need for specialized tools . This design significantly speeds up panel assembly and simplifies field replacements. Up to one 4-pole auxiliary switch block, such as the Siemens 3RH1921-1HA22, can be fitted to the front of a compatible contactor . The use of reliable screw terminals ensures robust and maintenance-friendly wiring, suitable for various conductor cross-sections .

Application Field

The primary application for the Siemens 3RH1921-1HA22 is in industrial motor control, where it is used to expand the auxiliary contact functionality of motor contactors and contactor relays . It provides essential additional contacts for implementing control interlocks, which can prevent machinery from operating in unsafe conditions, and for providing status feedback to programmable logic controllers (PLCs) and human-machine interfaces (HMIs) . In a typical motor starter panel, the Siemens 3RH1921-1HA22 would be used to signal that a motor has successfully started, provide a contact for an emergency stop circuit, or create a seal-in circuit for a latching relay.

In the broader context of automation systems, the Siemens 3RH1921-1HA22 is vital for expanding the I/O capabilities of a control system without the need for additional digital input modules . It is frequently found in switchgear and distribution panels, pump and fan control systems, and conveyor control systems. For industries such as automotive manufacturing, food and beverage processing, and material handling, the Siemens 3RH1921-1HA22 provides a robust and cost-effective solution for auxiliary switching tasks. Its compatibility with Siemens SIRIUS components ensures that it can be deployed in both new equipment and as a replacement part for maintaining existing systems, offering a reliable solution for a wide spectrum of industrial automation and control requirements .