5sj43 Siemens Miniature Circuit Breaker

The Siemens 5SJ43 Miniature Circuit Breaker is versatile and designed for reverse feed connections. These IEC-compliant miniature circuit breakers prioritize safety with touch protection as per EN 50274 standards. They feature visible indicators for both the ON and OFF/trip statuses and can be easily mounted on a DIN rail (35 mm).

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Features of 5sj43 Siemens Miniature Circuit Breaker

  • Tripping Characteristic Explanation: The anticipated tripping behavior, especially the expected trip time of the desired MCB, is determined by its I-t tripping characteristic.
  • Two-Tiered Tripping Systems: Aligned with the existing overload release system using bimetal and the short-circuit release system with a magnet coil, the I-t tripping characteristic path comprises two distinct sections:
    • The Overload Section (Thermal)
    • The Short Circuit Release Section (Magnetic)
  • Overload Section Details: The overload section of the curve defines the trip behavior associated with the bimetal element.
  • Short Circuit Release Section Details: The short circuit release section of the characteristic curve explains how the short circuit coil releases.
  • Tripping Characteristics Importance: Depending on the equipment in use and the operational patterns of connected loads, it’s crucial for the MCB to trip during short circuits to ensure effective short circuit protection. These specific tripping behaviors are standardized as per IS/IEC 60898-1.
  • Tripping Characteristic B: Tripping occurs when the current is between 3 to 5 times the normal full load current (3-5 x In). MCBs with ‘B’ characteristic react swiftly to short circuits and are ideal for safeguarding incandescent lighting and socket outlet circuits in residential and commercial settings where surge-related trips are less likely.

Specification of 5sj43 Siemens Miniature Circuit Breaker

Standards IS / IEC 60898-1 : 2015
Tripping characteristic B / C
Rated voltage Un V AC 240 / 415
Current Rating A 6 – 63
Operational voltage V AC





264 / 456

Rated breaking capacity Icn kA 4.5;6
Insulation coordination

•        Rated insulation voltage

•        Degree of pollution for overvoltage





250 / 440

2 / III

Handle end position, sealable Yes
Degree of protection IP20
CFC and silicone-free Yes
Conductor cross-sections mm2

•         Solid and standed

•         Finely stranded,

with end sleeve


0.75 … 25

0.75 … 25


•        Terminal tightening torque




2.5 … 3

Line load reversibility Any
Service life on average, with rated load 20 000 actuations
Ambient temperature °C -25 … +55, max. 95 % humidity,

storage temperature: -40 … +75