The 3RW4773-0NB00 is a power semiconductor module — not a standalone soft starter, but the internal thyristor stack that handles the motor current inside a 3RW4073 frame. It's rated 600 V and 230 A, with an integrated NTC thermistor for temperature monitoring of the semiconductor junction. This is the replaceable power section of the soft starter. When a 3RW4073 unit suffers a semiconductor failure in the field, swapping this module avoids replacing the entire starter assembly — a common MRO move for panel builders maintaining Siemens SIRIUS soft starter installations.
Lifecycle and sourcing posture
Sourced through authorized distribution channels against an RFQ.
Compliance and documentation
Substance prohibitance date is 05/01/2012, indicating RoHS compliance from that date forward. The module carries the standard Siemens CE/UKCA marking for the European market.