Siemens 3TF4922-OXMO Retrofit-Ready Power Contactor for SIRIUS 3TF Control Systems
The Siemens 3TF4922-OXMO is a high-performance AC power contactor engineered for seamless integration into legacy SIRIUS 3TF series motor control centers and control cabinet assemblies. As industrial facilities face increasing pressure to modernize aging automation infrastructure without full system overhauls, the 3TF4922-OXMO stands out as a proven retrofit solution — offering dimensional compatibility, terminal-for-terminal wiring alignment, and coil voltage flexibility that simplifies drop-in replacement of discontinued or end-of-life contactors in the 3TF49 family.
Whether your facility is upgrading a motor starter panel, replacing a failed contactor in a SIEMENS SIRIUS control cabinet, or migrating from an older 3TF series to a more maintainable platform, the 3TF4922-OXMO delivers the electrical and mechanical compatibility required to minimize engineering rework and reduce planned downtime windows. It is rated for AC-3 duty and supports standard DIN rail or panel mounting, making it compatible with existing enclosure layouts without modification.
Upgrade Compatibility Table
| Parameter | 3TF4922-OXMO Specification | Retrofit Notes |
|---|---|---|
| Series Compatibility | SIRIUS 3TF Series | Direct replacement for 3TF49 family variants |
| Mounting Type | DIN Rail / Panel Mount | No enclosure modification required |
| Coil Voltage | AC/DC (per OXMO designation) | Verify existing coil supply voltage before installation |
| Terminal Wiring | Screw-type, standard pitch | Terminal-for-terminal compatible with 3TF49 predecessors |
| Communication Compatibility | Hardwired control (no fieldbus) | Compatible with PROFIBUS DP and PROFINET upstream controllers via hardwired I/O |
| Auxiliary Contact Block | Supports 3TX series auxiliary blocks | Confirm auxiliary contact configuration matches original wiring diagram |
| Replacement Recommendation | Replaces discontinued 3TF49 variants | Suitable for direct swap in motor starter and DOL circuits |
| Commissioning Focus | Coil voltage, contact rating, auxiliary wiring | Verify with original panel drawings before energizing |
| Warranty | 12-Month Warranty | Covers manufacturing defects; includes pre-shipment functional test |
Retrofit Planning for Existing Automation Systems
Successful integration of the 3TF4922-OXMO into an existing control system requires a structured pre-installation review. Begin by auditing the existing panel documentation — specifically the wiring diagram, terminal strip layout, and the original contactor’s coil voltage and contact rating. In most SIRIUS 3TF motor control applications, the contactor is paired with a 3RU2 or 3RB3 overload relay, and the 3TF4922-OXMO maintains the same footprint and terminal spacing to allow the overload relay to remain in place without re-drilling or re-wiring the relay side.
For systems where the contactor is controlled via a SIMATIC S7-300 or S7-400 PLC output module — such as a 6ES7 322-series digital output card — the control signal wiring to the contactor coil terminals A1 and A2 remains unchanged. Engineers should confirm the output module’s current sourcing capacity matches the coil inrush current of the 3TF4922-OXMO before commissioning. In applications using a SIMATIC ET 200S or ET 200M distributed I/O rack, the same verification applies to the remote output module driving the contactor coil.
Where the original installation included a 3TX7 auxiliary contact block or a 3TX4 surge suppressor module mounted on the contactor body, these accessories are mechanically compatible with the 3TF4922-OXMO and can be transferred directly from the old unit. This is particularly valuable in retrofit scenarios where the auxiliary contacts feed status signals back to a SIMATIC HMI panel — such as a TP700 Comfort or KTP900 Basic — and the HMI screen logic depends on specific contact state feedback. Retaining the original auxiliary block eliminates the need to reconfigure HMI tag mappings or modify the PLC program’s input address assignments.
In control cabinets where the 3TF4922-OXMO is installed alongside a SITOP PSU100S or SITOP PSU200M power supply module, verify that the 24 VDC control bus capacity is sufficient to support the contactor coil load alongside other connected devices. Overloaded control power supplies are a common root cause of intermittent contactor dropout in retrofitted panels. Similarly, if the cabinet uses a 3NP5 or 3NP4 fuse switch disconnector upstream of the contactor, confirm the fuse rating is appropriate for the motor load and the new contactor’s rated operational current.
For facilities migrating from relay-logic-based control to PLC-based automation as part of a broader modernization program, the 3TF4922-OXMO serves as a stable interim component — allowing the contactor layer to remain unchanged while the control logic is migrated from a legacy relay panel to a SIMATIC S7-1200 or S7-1500 controller. This phased approach reduces the scope of simultaneous changes and allows each subsystem to be validated independently before the next migration step begins.
Downtime Control During System Migration
Minimizing unplanned downtime is the primary concern in any contactor replacement or control system retrofit. For the 3TF4922-OXMO, the recommended approach is a like-for-like swap executed during a scheduled maintenance window. Before de-energizing the panel, photograph the existing wiring at terminals A1, A2, and all load-side terminals (1/L1, 3/L2, 5/L3, 2/T1, 4/T2, 6/T3) to create a reference record that supplements the panel drawings.
Once the panel is isolated and locked out per LOTO procedures, remove the original contactor and transfer any auxiliary contact blocks, surge suppressors, or mechanical interlock bridges to the 3TF4922-OXMO before installation. This preserves the original wiring topology and eliminates re-termination errors. After installation, perform a continuity check across all load terminals and verify coil resistance before re-energizing. A functional test — including manual actuation of the contactor and verification of auxiliary contact state changes at the PLC input module — should be completed before returning the circuit to automatic control.
For critical production lines where even a brief outage is unacceptable, consider pre-staging the 3TF4922-OXMO on a test bench with a matching coil voltage supply and a simulated load to verify operation before the scheduled swap. This pre-shipment bench test, combined with our 12-month warranty coverage, ensures that the replacement unit arrives ready for immediate installation without additional qualification delays. All units are functionally tested prior to dispatch and shipped with documentation confirming test results.
Retrofit Support FAQ
Q1: Is the 3TF4922-OXMO a direct drop-in replacement for other 3TF49 series contactors?
Yes. The 3TF4922-OXMO shares the same mounting footprint, terminal pitch, and auxiliary contact interface as other 3TF49 family variants. In most cases, the replacement can be completed without modifying the panel enclosure, terminal blocks, or overload relay. Always verify coil voltage and contact rating against the original unit’s nameplate before ordering.
Q2: Can I reuse the existing 3TX7 auxiliary contact block and surge suppressor from the old contactor?
Yes. The 3TX7 auxiliary contact block and 3TX4 surge suppressor are mechanically compatible with the 3TF4922-OXMO and can be transferred directly. This is the recommended approach to preserve HMI feedback wiring and PLC input address assignments without program changes.
Q3: What commissioning checks are required after installation?
After installation, perform a continuity check on all load and control terminals, verify coil resistance, and conduct a functional test including manual actuation and auxiliary contact state verification at the PLC input module. Confirm that the SIMATIC HMI panel displays the correct motor status before returning the circuit to automatic operation.
Q4: What does the 12-month warranty cover, and is pre-shipment testing included?
The 12-month warranty covers manufacturing defects and functional failures under normal operating conditions. All units undergo a pre-shipment functional test prior to dispatch. Test documentation is available upon request. Warranty claims are processed directly through our sales team with a typical response time of 1–2 business days.
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