Siemens 3RW4426-1BC35 SIRIUS Soft Starter

The Siemens 3RW4426-1BC35 is a three-phase digital soft starter from the Siemens SIRIUS 3RW44 series, designed for reduced-voltage starting and soft stopping of three-phase AC induction motors. This Siemens 3RW4426-1BC35 uses thyristor phase-angle control to ramp motor voltage gradually, limiting inrush current and lowering mechanical shock on couplings, pumps, fans and conveyor equipment. The Siemens 3RW4426-1BC35 is a widely used spare part for maintaining and retrofitting legacy Siemens motor control cabinets.

The Siemens 3RW4426-1BC35 features an integrated bypass contactor that bypasses the thyristors after the motor reaches full speed, cutting heat loss during continuous operation. It supports both inline and inside-delta wiring configurations for higher motor current coverage. Built-in protective functions include overload, phase loss, SCR over-temperature, locked rotor and supply undervoltage protection to safeguard both the soft starter and the connected motor. The local display and keypad on the Siemens 3RW4426-1BC35 allow parameter tuning, runtime monitoring and fault code reading. It supports Modbus RTU communication for connection to PLC, HMI and SCADA systems for remote control and status monitoring. Users can adjust initial voltage, ramp-up time, ramp-down time and pump stop profiles to eliminate water hammer.

This Siemens 3RW4426-1BC35 adopts compact cabinet-mounted construction and complies with industrial EMC standards to resist electromagnetic interference in factory electrical rooms. The Siemens 3RW4426-1BC35 has flexible class settings for motor overload protection such as Class 10, Class 20 for different load duty cycles. Its control logic and hardware specifications follow the original SIRIUS 3RW44 platform, so saved application parameters can be retained after direct replacement to reduce commissioning time. The unit is fitted with screw terminals for stable wiring connections.

The Siemens 3RW4426-1BC35 is commonly deployed on centrifugal pumps, blowers, material conveyors and compressors in water treatment, mining and general manufacturing lines. Replacing a faulty soft starter with the Siemens 3RW4426-1BC35 quickly restores gentle motor start-stop operation and reduces mechanical wear on driven machinery. As a mature member of the SIRIUS 3RW44 range, the Siemens 3RW4426-1BC35 provides dependable current-limited starting control for users maintaining existing Siemens low-voltage motor control systems. ESD precautions should be followed while handling the Siemens 3RW4426-1BC35 to protect internal thyristor and control circuit components.