As the most commonly used short-circuit protection device in today's power distribution systems and electronic control circuits, air circuit breakers, in various models and specifications, dominate the market. Their advantages over traditional short-circuit protection devices like fuses are well known to many of us, so I won't elaborate here. However, in actual use, air circuit breakers may trip sporadically in some situations. Because there's no obvious fault in the system, and these intermittent faults often leave us, as electricians, feeling overwhelmed. So, what are some possible causes of these circuit breaker malfunctions in daily work? Today, we'll briefly analyze the possible causes.

First, incorrect circuit breaker model selection.
This situation often occurs when using the DZ47 series miniature air circuit breaker. A typical example is when some companies use a C series civilian version of the circuit breaker instead of a D series power version when controlling power loads. As a result, when the power load experiences conditions not found in residential systems (such as sudden load changes or frequent short-duration starts), the C-series circuit breaker will trip. Therefore, when selecting an air circuit breaker, be sure to ensure the model is compatible with the operating environment!

Second, Improper Circuit Breaker Specifications
This situation often arises when the circuit breaker selection specialist fails to fully consider the actual load conditions. For example, in a motor control circuit, they focus only on the motor's rated current while ignoring objective factors such as the motor's starting conditions and starting current. As a result, the selected circuit breaker capacity may be insufficient for the motor's operation (the circuit breaker capacity is only slightly greater than the load current), leading to sporadic circuit breaker tripping. This situation is most common on the main circuit breaker responsible for the line.

Third, Hidden Faults in the System
Common fault types in this situation include: loose connections, soft insulation breakdown, transient fluctuations in grid quality, and overloads. Because these faults are often subtle and deceptive, they are often overlooked.

 In addition to the three common fault causes mentioned above, other factors that may cause air circuit breakers to trip sporadically include: failure to replace the corresponding circuit breaker in a timely manner to accommodate load expansion (often overlooked); high-power electromagnetic interference (for example, a high-power inverter without a filter reactor); improperly set circuit breaker setting values; and aging circuit breakers due to long-term use.