The inspection of plug and socket mainly includes the following aspects:
1.Appearance inspection
2.Dimension inspection
3.Electric shock protection
4.Grounding actions
5.Terminal and end
6.Socket structure
7.Anti-aging and damp-proof
8.Insulation resistance and electric strength
9.Temperature rising
10.Breaking capacity
11.Normal operation (life test)
12.Withdrawal force
13.Mechanical strength
14.Heat resistance test
15.Bolt, current-carrying component and the connection
16.Creepage distance, electric clearance, distance of penetrating insulation sealant
17.Abnormal heat resistance and flame resistance of insulating material
18.Anti-rust performance
Main Quality Problems
1.Unreasonable Product Structure
It’s required by standards that the socket and adaptor plug bush assembly shall be of the enough elasticity to make sure the contact pressure to plug pin is sufficient. Therefore, it shall pass the test of withdrawal force.
For some unqualified products, the distance between two clamping pieces of plug bush, it’s not possible to clamp the plug pin and the withdrawal force is too low and even not at all. The consequence is leading to poor contact when using it, and electrical appliances cannot work normally and the temperature rising is out of limit and leading to seriously heating. In addition, for some sockets, the distance between the bottom surface of plug bush and plugging surface is too small, while the clearance between socket and the plugging surface of plug is relatively large, which cannot realize the fully plugging and is easy to result in electric shock accident.
For the rewirable plug, moving socket and rewirable adaptor, it’s required by standards that there shall be components fixed by soft wire. However, some products are not, leading to that the soft wire cannot be clamped and is easy to be pulled out. It’s also required by standards that the grounding plug bush and intermediate plug bush of the moving socket and rewirable adaptor shall be locked and can be dismantled by using tools only after disassembling the socket. However, the plug bush of some products can be dismantled by hands.
In addition, there are a fairly large number of products equipped with earth pole plug bush but without wiring terminal, and user cannot connect them with conducting wire. What’s more, there are earth pole jacks on the panel while there is no grounding plug bush on the base. The grounding plug pin or intermediate plug pin of some plugs can be replaced to the incorrect position. In this way, user will connect the wrong conducting wire, leading to burning the appliances or making it cannot work normally.
2.Not Passing the Flame Resistance Test for Insulating Material
It’s required by standards that the material of plug and socket shall be of the flame retardation performance. In the flame resistance test, some inferior product materials exceed the specified limit when burning, and continue burning and cannot be extinguished for 30s after removing the glowing filament. This kind of product will lead to the consequence out of control in case of firing.
3.Nonstandard Sign
The common problem is lack of model sign and power supply symbol (~): incorrect grounding symbol, the product is marked with “E” or “G” while the national standard is required to mark with “” (There is a misunderstanding for manufacturer that they consider the grounding symbol has been changed as “” in standards. Actually, the grounding symbol specified by standards is still the “”. The adaptor products are required to be marked with the symbol of “MAX (or maximum)” to identify the rated current and / or power, but most of products are not marked. In addition, the symbols of “250V-10A”, “10A-250V”, “10A~250V” and the similar are not conforming to the standard requirements. The sign specified by standards shall be durable and clear and the signs on screen printing and paper label of some products can be easy to be removed.
4.Large Terminal Problem
Some products have no wiring terminal, for example, the plug pin of rewirable plug is just drilled with holes simply without bolts and there is thread on plug pin. The rewirable adaptor just adopts tin soldering to weld the conducting wire core onto the plug bush. Some rewirable plugs, rewirable moving sockets and rewirable intermediate adaptors use the threaded clamping terminal, but when applying the specified torque to tighten the bolts, the bolt threads or connector threads will be damaged. In this way, user cannot connect with wires when using it or it will lead to poor contact after wiring. During the using process, the terminal is heating seriously. Once the wire core falling, it may cause short circuit and lead to electric shock accident to personnel.
5.Unqualified Electric Shock Protection
For some unqualified products, when plug is plugging with the fixing socket, the live plug pin of plug can be contacted by test finger. Any of plug pin of plug can plug in live plug bush of socket and adaptor when other plug pins are in accessible status.
Post time: Mar-10-2022