Siemens 3RW4434-6BC44 Replacement for SIRIUS 3RW44

Product Overview

Siemens 3RW4434-6BC44 Replacement for SIRIUS 3RW44: Smooth Transition Upgrade Solution

Upgrading or replacing a legacy soft starter in an active production line demands zero-compromise compatibility. The Siemens 3RW4434-6BC44 is a high-performance SIRIUS 3RW44 series soft starter rated at 132 kW / 400 V, designed for demanding motor control applications in industrial automation, pump stations, compressor systems, conveyor drives, and fan control panels. Whether you are retiring an end-of-life 3RW30, 3RW40, or earlier 3RW44 variant, or replacing a failed unit in a live control cabinet, this module delivers a direct, low-disruption migration path with minimal rewiring and no PLC program changes.

The 3RW4434-6BC44 integrates seamlessly into existing SIRIUS control architectures. Its standard 3-phase main circuit terminals maintain the same wiring footprint as predecessor models in the 3RW44 family, allowing field engineers to swap the unit without modifying cable routing or terminal block assignments. The built-in bypass contactor eliminates the need for an external bypass relay, reducing panel space requirements and simplifying the control cabinet layout during retrofit projects.

For sites running Siemens S7-300 or S7-400 PLCs with PROFIBUS DP communication, the 3RW4434-6BC44 supports optional communication modules that plug directly into the soft starter, enabling parameter read/write, fault diagnostics, and remote start/stop commands without additional gateway hardware. Sites migrating from hardwired control to PROFIBUS or PROFINET architectures can retain their existing S7 program logic while adding soft starter diagnostics to the SCADA layer. The 3RW4434-6BC44 is also compatible with the SIRIUS 3RT2 contactor family for upstream isolation switching, and pairs naturally with 3VL or 3RV circuit breakers already installed in the same panel.

During a typical retrofit, engineers replacing an older 3RW3036 or 3RW4036 unit will find that the 3RW4434-6BC44 occupies a slightly larger DIN rail footprint due to its higher power class, but the control terminal layout (24 V DC auxiliary supply, thermistor input, relay output, and enable signal) remains functionally equivalent, reducing commissioning time significantly. The integrated motor thermistor evaluation circuit (PTC/NTC) eliminates the need for a separate 3RN1 thermistor relay in most retrofit scenarios, freeing up additional panel space.

Power supply compatibility is straightforward: the 3RW4434-6BC44 operates on 380–480 V AC main voltage with a 24 V DC control supply, matching the standard control voltage used across most Siemens SIRIUS control panels. No additional power supply modules or voltage converters are required when migrating from same-series predecessors. The unit’s soft ramp-up and ramp-down parameters are configurable via the integrated operator panel or via the optional 3RW44 PC tool, allowing engineers to replicate the acceleration profiles of the replaced unit without modifying the upstream PLC motion sequences.

For facilities managing a broader migration from legacy distributed control systems, the 3RW4434-6BC44 fits naturally alongside other SIRIUS components such as the 3SK1 safety relay, 3UF7 SIMOCODE motor management system, and 3RA6 compact starter combinations. When the migration scope includes I/O expansion, the ET 200SP distributed I/O system can be added to the same control cabinet without conflicting with the soft starter’s communication interface, providing a scalable path toward a fully networked motor control center.

Procurement teams sourcing this unit as an emergency replacement will find that TOPNLMS maintains ready stock of the 3RW4434-6BC44, with same-day dispatch available from our Xiamen warehouse. Each unit undergoes pre-shipment functional verification, and all orders are covered by a 12-month replacement warranty from the date of delivery.

Compatibility Comparison Table

Seamless Upgrade Solutions

A complete soft starter migration rarely involves a single component. When replacing the 3RW4434-6BC44 in a live motor control center, engineers typically address the surrounding system simultaneously to ensure long-term reliability. The 3RT2045 SIRIUS power contactor is commonly installed upstream for main circuit isolation, while the 3VL3725 circuit breaker provides coordinated short-circuit protection rated for the 132 kW load class. For sites adding PROFIBUS communication to the soft starter, the 3RW44 PROFIBUS DP communication module plugs directly into the unit without additional wiring.

Control cabinet I/O expansion is frequently handled by the ET 200SP IM 155-6 PN interface module paired with standard digital I/O modules, allowing the soft starter’s run/fault signals to be integrated into the plant SCADA without modifying the main PLC rack. Where motor protection is being upgraded simultaneously, the 3UF7010 SIMOCODE pro C motor management unit can replace legacy overload relays and provide enhanced diagnostics over PROFIBUS. For panel builders standardizing on a common control voltage rail, the SITOP PSU100S 24V/10A power supply provides a stable 24 V DC bus for the soft starter control circuit and auxiliary relays.

Sites migrating from older hardwired control panels to structured wiring often install 3RK1901 AS-Interface flat cable connectors or 3RA6120 compact starter combinations for lower-power auxiliary motors in the same cabinet. Signal isolation between the soft starter’s analog output and the PLC analog input card is best handled by a SIEMENS 7NG3212 signal isolator, particularly in environments with high electrical noise from variable frequency drives operating nearby. Finally, for HMI integration, a SIMATIC KTP700 Basic Panel provides a straightforward operator interface for soft starter parameter display and fault acknowledgment without requiring a full SCADA deployment.

Retrofit Guidance FAQ

Q: Can I replace a 3RW4036 with the 3RW4434-6BC44 without rewiring the main terminals?
A: The main terminal layout differs between the 3RW40 and 3RW44 series due to the higher power class. A wiring review is required, but the control terminal pinout (24 V DC, enable, thermistor, relay output) is functionally equivalent, minimizing control circuit changes.

Q: Will my existing S7-300 PROFIBUS program work with the 3RW4434-6BC44?
A: Yes, provided you install the optional PROFIBUS DP communication module. The GSD file for the 3RW44 series is available from Siemens and integrates directly into STEP 7 or TIA Portal without requiring program restructuring.

Q: Does the integrated bypass contactor eliminate the need for an external 3RT2 contactor?
A: For standard applications, yes. The integrated bypass handles the transition from soft-start to full-voltage run mode. An external isolation contactor upstream is still recommended for safety and maintenance isolation per IEC 60947-4-2.

Q: How much panel space does the 3RW4434-6BC44 require compared to a 3RW4036?
A: The 3RW4434-6BC44 is physically larger due to its higher power rating. Verify available DIN rail length and vertical clearance before installation. The integrated bypass and thermistor evaluation offset the space increase by eliminating external components.

Q: What communication protocols are supported?
A: The base unit supports hardwired control. PROFIBUS DP is available via plug-in module. PROFINET and Modbus RTU are not natively supported on this model; a gateway device would be required for those protocols.

Q: Can the ramp parameters from the old unit be transferred?
A: Ramp-up time, ramp-down time, and current limit settings are configurable via the integrated operator panel or the 3RW44 PC tool. Document the existing unit’s parameters before removal and replicate them during commissioning.

Warranty Assurance

Every Siemens 3RW4434-6BC44 unit shipped by TOPNLMS is covered by a 12-month replacement warranty from the date of confirmed delivery. Prior to dispatch, each unit undergoes a pre-shipment functional check including control voltage verification, terminal integrity inspection, and packaging integrity review. In the event of a confirmed unit defect within the warranty period, TOPNLMS will arrange a replacement shipment or issue a full refund — whichever the customer prefers — without requiring return of the defective unit in most cases.

Our standard lead time for in-stock units is 1–3 business days for international express shipment from Xiamen, China. Emergency same-day dispatch is available for orders confirmed before 14:00 CST. All shipments include a commercial invoice, packing list, and certificate of origin for customs clearance. For bulk procurement or project-based orders requiring multiple units, staged delivery schedules and reserved stock arrangements are available upon request.

For technical pre-sales support, compatibility verification, or after-sales warranty claims, contact our engineering team directly:

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