Abnormal connector overheating, yellowing of the casing, arcing, and a drop in insulation resistance are considered electrical failures. In severe cases, they can cause plastic melting and short-circuit tripping, posing safety risks to the entire set of equipment. Many people simply attribute overheating to product quality defects, but in reality, overload, abnormal contact, and environmental corrosion can all trigger such issues.
Current overload is the most direct cause. During selection, if the connector's rated current does not have a safety margin, long-term full load or even overload operation will cause the terminals to continuously generate heat. Contact resistance further increases with temperature, forming a vicious cycle. Continuous heating can burn the terminals and melt the plastic insulation housing, causing permanent damage. When selecting, it is recommended that the actual operating current be lower than the connector's rated value, leaving a 20%-30% margin to avoid long-term operation at extreme conditions.
Abnormal rise in contact resistance is a hidden cause of local heating at the connection. Terminal oxidation, coating damage, poor crimping, and insufficient spring contact force all increase contact resistance. Even if the overall current is within limits, heat can locally accumulate at the contact points, causing local burn marks and gradually developing into arcing faults. Some faults cannot be detected externally and require measuring the contact resistance to assess the condition.
Decline in insulation performance can also bring risks of leakage and short circuits. Connector housings and isolation walls are made of polymer insulating materials, and prolonged high-temperature exposure accelerates aging and carbonization of the insulation; after seal damage, moisture, condensation, or corrosive media entering the cavity and conductive impurities adhering between terminals reduce insulation resistance, causing leakage or interphase short circuits. External impact causing pin bending and reduced safety distance between pins also carries the risk of breakdown and short circuits.
In daily maintenance, it is necessary to observe whether the connector housing shows discoloration or abnormal odor, and to regularly test insulation and contact resistance; for humid or salt-spray environments, use products with the corresponding protection level and check the integrity of seals; never operate connectors beyond their specifications, and if terminal burn marks are found, replace them promptly to avoid continued operation with defects.