The Siemens 3RH1921-2FA31 is a front-mounting auxiliary switch block from the SIRIUS 3RH19 series, designed to expand the control circuit capacity of SIRIUS 3RT1 power contactors and 3RH1 contactor relays in sizes S0 through S12. It features a 3 NO + 1 NC contact configuration with spring-loaded (cage clamp) terminals, providing maintenance-free, vibration-resistant connections for signaling and interlocking circuits.
Item No :
3RH1921-2FA31Order(MOQ) :
1Payment :
EXWProduct Origin :
GermanyShipping Port :
Wuhan, Hubei, ChinaLead Time :
3-5 daysWeight :
0.062kgOverview
3RH1921-2FA31 SIMATIC PLC Module
New in stock
Origin from Germany
Payment Method: TT.Western Union
Shipping Method: DHL\UPS\Fedex\EMS\Others
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| Part Number | Description | Key Difference |
|---|---|---|
| 3RH1921-2FA31 | 3NO+1NC, front-mount, spring terminal (this item) | Discontinued; remaining stock |
| 3RH1921-1FA22 | 2NO+2NC, front-mount, screw terminal | Screw terminal variant |
| 3RH1921-2FA22 | 2NO+2NC, front-mount, spring terminal | Alternative contact configuration |
| 3RH2911-2FA22 | SIRIUS 3RH2 auxiliary switch | Current platform for new installations |
| 3RT1026-1AP00 | SIRIUS 3RT1 Contactor, S0, 25 A | Compatible host contactor |
Migration Note: The 3RH1921-2FA31 was deleted without a direct replacement . For new installations or where the host contactor is also being replaced, migrate to the SIRIUS 3RH2 auxiliary switch platform and the corresponding 3RT2 contactor series.
1 × Siemens 3RH1921-2FA31 SIRIUS Auxiliary Switch Block (3 NO + 1 NC, Spring Terminal, Front-Mount)
Note: Host contactor and other accessories are sold separately.
In Stock – Ready to ship immediately
Tested – Each unit verified for functionality
Warranty Included – 12-month warranty for purchase confidence
Technical Support – SIRIUS 3RT1/3RH1 compatibility assistance available
Q1: What is the Siemens 3RH1921-2FA31?
It is a front-mounting auxiliary switch block for SIRIUS 3RT1 contactors and 3RH1 contactor relays. It provides 3 NO + 1 NC contacts with spring-loaded terminals to expand control circuit capacity .
Q2: Is this product still in production?
No. It was discontinued effective 06 October 2022 (PM500 status) and deleted without a direct replacement . It is available only through remaining stock or third-party suppliers.
Q3: What is the successor model?
Siemens specifies no direct successor. For new installations, the SIRIUS 3RH2 auxiliary switch platform (used with 3RT2 contactors) is the current replacement path .
Q4: What contact configuration does it have?
It has 3 Normally Open (NO) and 1 Normally Closed (NC) contacts .
Q5: What type of terminals does it use?
It uses spring-loaded (cage clamp) terminals, which provide maintenance-free, vibration-resistant connections without screws .
Q6: Which contactors is it compatible with?
It is designed for SIRIUS 3RT1 power contactors (sizes S0 through S12) and 3RH1 contactor relays .
Q7: Does it function as a mirror contact?
Yes. When used with 3RT1 contactors, the NC contact complies with IEC 60947-4-1 for mirror contact function .
Q8: What is the mechanical life?
Approximately 10,000,000 operating cycles .
Q9: What are the dimensions and weight?
Approximately 36.5 × 37.5 × 46 mm (W × H × D) and 0.06–0.07 kg .
Q10: What should I verify before ordering?
Always verify the exact part number (3RH1921-2FA31), confirm your host contactor is a SIRIUS 3RT1 or 3RH1 (not the newer 3RT2), and check whether remaining stock is acceptable for your maintenance requirements. For new installations, consider migrating to the SIRIUS 3RH2 platform.
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