The B-curve (3–5× In magnetic trip) means it will hold through moderate inrush from resistive loads and lighting ballasts but will trip faster on a hard short than a C-curve would, giving better selectivity with downstream fuses or smaller MCBs. The 2-pole configuration switches both phase conductors simultaneously, which is standard for single-phase AC circuits derived from a transformer or for DC circuits where both poles need isolation. At 3 A it protects small control transformers, signal power supplies, or lighting circuits — not motor or heater loads.
Siemens 5SY4203-6CC11 MCB 400V 10kA 2-pole B 3A railway
MPN5SY4203-6CC11
Siemens 5SY4203-6CC11 miniature circuit breaker, 400 V, 10 kA interrupting capacity, 2-pole, B-curve, 3 A, railway applications.
Source DocumentedChannel stated on listing & quote
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Worldwide DispatchDHL/FedEx — transit quoted per order
Independent China distributor & sourcing agent· Listing updated Sep 2026
Product details
Frequently asked questions
What is the 5SY4203-6CC11 used for?
It is a miniature circuit breaker for railway applications, rated 400 V, 10 kA interrupting capacity, 2-pole, B-curve, 3 A — used to protect control transformers, signal power supplies, and lighting circuits in rolling stock or trackside panels.
Where can I buy the 5SY4203-6CC11?
This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time.
MPN
5SY4203-6CC11