Transformer protection breaker in the SIRIUS 3RV2 family
The Siemens 3RV2421-4DA10-Z W97 is a size S0 circuit breaker from the SIRIUS 3RV2 motor starter protector family, specifically configured for transformer protection. Its A-release is adjustable 18-25 A, and the N-release (magnetic short-circuit trip) is fixed at 400 A, sized to handle transformer inrush without nuisance tripping while protecting the secondary winding from sustained overloads. This variant uses screw terminals and carries standard switching capacity. It ships in a multi-unit pack of 12 pieces, which is the packaging quantity — the same part number applies to each individual breaker within the bundle.
RoHS compliance is documented since October 1, 2009. The REACH Article 33 declaration notes the presence of lead titanium zirconium oxide (CAS 12626-81-2) above 0.1% w/w — this is a standard disclosure for certain ceramic components in the breaker arc chamber and does not affect normal handling or installation.
The S0 frame size is a standard DIN-rail mount footprint common across the SIRIUS 3RV2 range. The screw terminals accept copper conductors typical for motor and transformer branch circuits up to 25 A. The multi-unit pack (12 units) is intended for panel builders or MRO planners stocking a common transformer-protection breaker across multiple machines — each unit is individually functional, not a linked assembly.