Determining if a circuit breaker is functioning correctly requires a comprehensive verification process involving three steps: visual inspection, functional testing, and electrical testing. The core objective is to confirm its reliable tripping capability under overload or short-circuit conditions and its stable power supply under normal operating conditions.
Visual Inspection and Condition Check (Initial Screening)
Observe the casing condition: Check the circuit breaker for cracks, burn marks, deformation, or a burnt smell. Check for loose or oxidized terminals. Obvious damage may indicate malfunction.
Check indicator lights and handle position:
Green light on → Circuit is powered normally
Red light on or flashing → Tripped or faulty (e.g., short circuit, leakage)
Handle in "OFF" position → Disconnected, requires manual reset
Check nameplate parameters: Confirm that the rated current (e.g., C16, C20) matches the circuit load to avoid overload operation.
Mechanical and Functional Testing (Operational Verification)
Manual Operation Test
Repeatedly operate the switch handle to check for smoothness and any jamming.
After tripping, it should lock in the "disconnect" position and not automatically spring back.
Button Test Verification (For Residual Current Circuit Breaker)
Press the "T" (Test) button; the circuit breaker should trip immediately. Test monthly to ensure the residual current protection function is effective.
Closing Stability Test
After closing, connect a normal load and observe whether it trips without cause. Frequent malfunctions may indicate an abnormality in the internal tripping mechanism.
