Siemens 3TF4922-OXMO Replacement for SIRIUS 3TF

Product Overview

Siemens 3TF4922-OXMO Replacement for SIRIUS 3TF: Seamless Transition & Legacy System Upgrade

When your existing SIRIUS 3TF series contactor reaches end-of-life or becomes difficult to source, the Siemens 3TF4922-OXMO provides a proven, drop-in replacement path that preserves your panel wiring, control voltage architecture, and auxiliary contact configuration. Designed for 3-pole heavy-duty AC switching applications, this contactor is widely deployed in motor control centers (MCCs), switchgear panels, and distributed control system (DCS) output stages where reliable coil actuation and long mechanical life are non-negotiable.

Industrial facilities running legacy Siemens SIMATIC S5 or early SIMATIC S7-300 PLC output modules frequently rely on the 3TF49 series contactors as the final switching element in their digital output (DO) chains. When migrating from an S5-115U or S5-135U controller to a modern S7-1500 or ET 200SP distributed I/O architecture, the 3TF4922-OXMO can remain in place as the load-side actuator, eliminating the need to re-engineer the power circuit during the control-layer upgrade. This dramatically reduces panel modification time and minimizes production downtime during cutover.

For plants operating Siemens SIRIUS 3RA1 combination motor starters or 3RV2 motor protection circuit breakers upstream of the contactor, the 3TF4922-OXMO integrates directly into the existing busbar and terminal block arrangement. The coil voltage and auxiliary contact (NO/NC) pinout remain compatible with standard 3TF-series mounting dimensions, meaning the 3SB3 pushbutton station wiring and 3TX7 surge suppressor accessories already installed in the cabinet do not require replacement. Engineers can reuse existing 3RT2 series wiring diagrams as a reference baseline, adjusting only for any coil voltage differences between the legacy unit and the replacement.

In DCS environments built around Siemens SIMATIC PCS 7 or third-party systems using PROFIBUS DP or PROFINET I/O for field device communication, the 3TF4922-OXMO operates as a conventional hardwired output load. Its control interface connects to the digital output card of the remote I/O station — such as an ET 200M IM153-2 or ET 200S interface module — without requiring any fieldbus configuration changes. This makes it an ideal candidate for partial retrofit projects where the field wiring infrastructure is retained while the control hardware is modernized.

Physical installation follows the standard DIN rail or panel-mount footprint of the SIRIUS 3TF49 frame size. The contactor’s screw-clamp main terminals accept the same cable cross-sections as the predecessor unit, and the auxiliary contact block arrangement on the front face is compatible with standard 3TF-series add-on contact modules. For applications requiring electronic overload protection, the 3RU2 or 3UA52 thermal overload relay can be directly coupled to the 3TF4922-OXMO without an adapter, preserving the compact assembly profile within the control cabinet.

Power supply compatibility is straightforward: the OXMO coil designation indicates an AC operating coil, and the rated control supply voltage should be verified against the existing panel design before installation. In mixed-voltage panels where 24 V DC control circuits coexist with AC power switching, a 3TX7 RC suppressor or varistor module is recommended across the coil terminals to protect the PLC digital output card from inductive kickback — a best practice already standard in most SIRIUS 3TF installations.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful migration from a legacy motor control or power switching system to a modernized architecture typically involves more than a single contactor replacement. When upgrading a panel built around the 3TF4922-OXMO, procurement teams commonly source the following components in the same project scope:

The Siemens 3RV2 motor protection circuit breaker is frequently replaced alongside the contactor when the upstream protection device has also reached its service life. Paired with the 3TF4922-OXMO, the 3RV2 forms a coordinated Type 2 combination starter that meets IEC 60947-4-1 short-circuit coordination requirements without additional fusing. For the overload protection function, the Siemens 3RU2 electronic overload relay direct-couples to the contactor frame and provides class 10 or class 20 trip characteristics suitable for standard induction motor loads.

In panels where the control voltage distribution is being reorganized during the retrofit, the Siemens SITOP PSU100S 24 V DC power supply is a common addition, providing a regulated 24 V DC rail for the PLC I/O modules and coil control circuits. Where the existing wiring uses legacy terminal blocks, engineers often upgrade to Siemens SIRIUS 8WH DIN rail terminal blocks to standardize the cabinet wiring and improve long-term maintainability.

For projects that include a PLC control layer upgrade, the Siemens SIMATIC S7-1500 CPU or a compact S7-1200 controller is typically selected as the replacement for obsolete S5 or early S7-300 hardware. The digital output signal from these controllers drives the 3TF4922-OXMO coil through the existing panel wiring without modification. Where remote I/O is required, an ET 200SP IM155-6 PN interface module with a compatible digital output module provides the PROFINET-connected DO channel that actuates the contactor.

HMI integration is another common element of the modernization scope. The Siemens SIMATIC HMI KTP700 Basic panel is frequently specified alongside the control upgrade to provide local operator visibility of contactor status, motor run/stop commands, and fault acknowledgment — replacing older OP7 or OP17 operator panels that are no longer supported. Finally, for applications requiring signal isolation between the PLC output and the contactor coil circuit — particularly in high-noise industrial environments — a Phoenix Contact or Weidmüller signal isolator relay module is inserted in the control circuit to protect the PLC output card.

Retrofit Guidance FAQ

Q: Can I reuse the existing panel wiring when replacing the contactor with the 3TF4922-OXMO?
A: Yes. The 3TF4922-OXMO shares the same main terminal screw-clamp arrangement and cable entry dimensions as other 3TF49-frame contactors. In most cases, existing cable lugs and ferrules can be reused. Verify the torque specification for the main terminals (typically 4–6 Nm for this frame size) and re-torque all connections after installation.

Q: Is the coil voltage compatible with my existing control circuit?
A: The OXMO suffix designates an AC coil. Before installation, confirm the rated control supply voltage on the nameplate matches your panel’s control voltage (commonly 110 V AC or 230 V AC). If your panel uses 24 V DC control, a different coil variant is required — contact us to confirm the correct suffix for your application.

Q: Will the 3TF4922-OXMO work with my PROFIBUS DP or PROFINET I/O system?
A: Yes. The contactor is a hardwired load device and is protocol-agnostic. It connects to the digital output terminal of any I/O module regardless of the fieldbus protocol used by the controller. No fieldbus configuration changes are required.

Q: Does the physical footprint fit my existing cabinet cutout and DIN rail position?
A: The 3TF49 frame size has a defined mounting footprint. If you are replacing a unit of the same frame designation, the DIN rail position and adjacent component clearances will be maintained. If replacing a different frame size, verify the dimensional drawing against your cabinet layout before ordering.

Q: Can I couple my existing 3RU2 overload relay directly to the 3TF4922-OXMO?
A: Yes. The 3RU2 and 3UA52 overload relays are designed for direct coupling to the 3TF49 contactor frame without an adapter plate. The combined assembly maintains the compact footprint required for high-density MCC installations.

Q: What programming changes are needed after replacing the contactor?
A: None, in most cases. The 3TF4922-OXMO is a hardwired switching device. The PLC program logic, I/O address mapping, and HMI tag configuration remain unchanged. Only the physical device in the panel is replaced.

Warranty Assurance

Every Siemens 3TF4922-OXMO unit supplied by TOPNLMS is covered by a 12-month warranty from the date of shipment. Prior to dispatch, each unit undergoes outgoing inspection including coil actuation verification, contact resistance measurement, and visual inspection for mechanical integrity. Units that do not meet specification are quarantined and not shipped.

In the event of a warranty claim, TOPNLMS provides replacement support with priority processing for customers experiencing production downtime. Our after-sales response target is within 1 business day for warranty inquiries submitted by email. Replacement units are dispatched from our Xiamen warehouse, with express shipping options available for urgent requirements.

For procurement teams requiring documentation, we can provide a test report, packing list, and commercial invoice with each shipment. Long-term supply agreements and blanket purchase orders are supported for customers with recurring MRO requirements.

To place an order or request a compatibility consultation, contact our technical sales team:

📧 [email protected]
📞 +86 18359293191