One-sentence answer: AC charging guns are exposed to rain, condensation and insertion/withdrawal wear outdoors over the long term. Water ingress at any point among the terminal cavities, the mechanical lock cavity and the cable outlet inside the gun head can cause electric leakage and short circuits. Using the CTS Sentinel A28 differential pressure leak detector to compare a master part with the part under test allows cavity-by-cavity plugging and cavity-by-cavity judgment, making it suitable for 100% inspection in batches on charging gun assembly lines.
The L, N and PE terminal cavities, the mechanical lock cavity and the signal cavity are independent of one another, each isolated by seals. Water ingress in any one cavity makes the whole gun non-conforming, so testing must be done cavity by cavity.
The front and rear housings compress the sealing ring via screws or snap fits. Batch-to-batch tightening torque variation can leave the sealing ring locally under-compressed, forming local leak paths.
A charging gun is a part users plug and unplug every day. Repeated latch actuation and accidental drops can permanently deform the housing and sealing ring. Factory testing is the only quantifiable interception point.
High-power liquid-cooled charging guns integrate cooling channels in the gun body. The water circuit and the electrical cavity must be strictly isolated, so the number of test objects goes from one to two.
Sealing locations:
Consequences of leakage: moisture entering the terminal cavities lowers insulation, corrodes terminals, and causes short circuits or leakage alarms during charging, directly threatening user safety. Water entering the cable outlet can also spread along the core wires to the charging pile side, causing more serious faults.
Charging guns are multi-cavity, medium-volume, high-volume workpieces, and the volumes of different cavities vary considerably:
The specific rating is determined by the product standard and customer requirements. Air tightness testing cannot replace the immersion test specified by the standard. A reasonable division of labor is: air tightness testing is used for piece-by-piece 100% inspection on the production line to quickly screen out process defects; IP rating verification is done by sampling and immersion confirmation according to standards such as IEC 60529. The two have different purposes and complement each other.
It is recommended to plug and test each cavity separately. Although inflating the whole gun at once is faster, when it fails you cannot tell which cavity is the problem, and rework can only be done by disassembly and inspection. Cavity-by-cavity testing with the A28's multiple test programs lets you state the failed cavity directly, significantly shortening rework time.
Yes. The liquid-cooling channels and the electrical cavity must be isolated from each other, and both cavities should be treated as independent test objects. If only the electrical cavity is tested, leakage on the channel side will carry coolant into the electrical cavity during use, posing the same risk as moisture ingress.
For sealing tests of AC charging guns, the key is to intercept the process defects of each multi-cavity structure separately before shipment. The CTS Sentinel A28 achieves stable judgment through differential pressure comparison. Combined with a gun-insertion simulation fixture and 32 test programs, it is suited to cavity-by-cavity 100% inspection and failed-cavity localization on charging gun assembly lines.
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