MCB: Assembled Right, Tested Right, Then Shipped

Small in size, but the first line of defense in terminal distribution — that's the miniature circuit breaker (MCB). Across its DZ47, DZ30 and related series, ChengXi Electric follows standardized assembly plus unit-by-unit testing, so every breaker trips reliably under overload or short-circuit conditions.

Assembly

• Contacts & arc chamber – precisely positioned so the arc is broken and extinguished quickly during tripping.
• Bimetallic strip & electromagnetic release – handle overload (delayed trip) and short-circuit (instant trip) protection; assembly clearance is tightly controlled.
• Housing & terminals – high flame-retardant PC housing, terminals properly crimped to prevent overheating from poor contact.

Testing

• Trip characteristic test – every unit is powered up to verify trip times under overload and short-circuit conditions match the rated curve (B/C/D type).
• Insulation/dielectric withstand test – checks insulation between housing and internal circuitry to rule out leakage risk.
• Mechanical operation check – manual open/close cycles to confirm the handle operates smoothly and fully.
• Leakage-specific test (DZ47LE, etc.) – simulates 30mA/50mA leakage current to verify trip sensitivity.

Assembly and test data are recorded for every batch, so each breaker leaving the factory isn't just visually inspected — it's proven to work.