The 10 kA breaking capacity at 400 V AC means this breaker can safely interrupt a fault current up to 10,000 A without welding its contacts or cascading failure upstream — adequate for most secondary distribution panels in rail vehicles and wayside cabinets where the prospective short-circuit current stays under that threshold. The D-curve (10–20× In magnetic trip) is deliberately slower than B or C curves, so it won't trip on the magnetizing inrush of a 24 VDC power supply or a contactor coil; that's why it's the standard choice for rail auxiliary loads.
Siemens 5SY4408-8CC11 MCB, 400V 10kA 4P D 8A, Railway
MPN5SY4408-8CC11
Siemens 5SY4408-8CC11 miniature circuit breaker, 400 V 10kA, 4-pole, D-curve, 8 A, for railway applications.
Sourced new & surplus through independent channelsAuthenticity-screened · ESD-safe packingListing updated Aug 2026
Product details
Frequently asked questions
What is the breaking capacity of the 5SY4408-8CC11?
It is rated for 10 kA at 400 V AC, which is the maximum fault current it can safely interrupt.
Where can I buy the 5SY4408-8CC11?
This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at the time of quote.
What does the D-curve mean on this MCB?
The D-curve trips magnetically at 10 to 20 times the rated current (80–160 A for this 8 A breaker), making it suitable for loads with high inrush such as transformers, contactors, and DC power supplies in railway applications.
MPN
5SY4408-8CC11