The Siemens 5SY4203-7CV is a 2-pole miniature circuit breaker (MCB) with a C-curve trip characteristic rated at 3 A. Its interrupting capacity is 15 kA at 400 V — that is the maximum fault current it can safely clear without welding its contacts or rupturing the case, which matters when the available fault current at the panelboard exceeds the standard 10 kA level common in residential-grade MCBs.
Deployment and panel integration
The 2-pole width (2 module spaces, ~36 mm) fits the same cutout as any Siemens 5SY-series or SENTRON 3RV/5SY family breaker — no adapter plate needed for a retrofit into an existing Siemens panelboard.