Siemens SIRIUS Soft Starter, 3RW3 and 3RW4 Series

A range of Siemens Soft Starters from the 3RW30 and 3RW40 ranges. These starters are used to start three-phase induction motors with reduced torque and reduced starting current, in both simple or standard applications.

The starters have been developed to enable the soft run-up and slow-down of DC motors. They help the mechanical power transmitting elements of the machine at the start by reducing the starting torque and efficiently protect the network from dangerous spikes through reduced power consumption. Through the continued increase of the motor voltage, the network, the motor and load are optimally protected against voltage overload. The 3RW Soft Starters are small, inexpensive and can be easily combined with the SIRIUS contactors, power switches and overload relays.

SIRIUS 3RW40 Soft Starters have all the same advantages as the 3RW30 Soft Starters including soft start and soft stop and internal bypass. At the same time they come with additional functions, i.e. selectable solid-state motor overload, intrinsic device protection and adjustable current limiting, as well as a new patented two-phase control method (Polarity Balancing) that is unique in this rating range.

Application areas include, fans, pumps, building/construction machines, escalators, transport systems, air conditioning systems, ventilators, assembly lines, compressors and coolers and operating mechanisms.

• Electronic motor overload protection, adjustable current limit
• Improve the performance by retrofitting with fans
• Soft starting and soft stop
• Stepless starting
• Reduction of current peaks
• Avoidance of mains voltage fluctuations during starting
• Reduced load on the power supply network
• Reduction of the mechanical load in the operating mechanism
• Considerable space savings and reduced wiring compared with mechanical reduced voltage starters
• Maintenance-free switching
• Applicable standards: IEC 60947-2 and UL/CSA E143112
• Available in 3RW3 and 3RW4 versions