Terminal plastic insulation materials and conductive parts is directly related to the quality of the terminal, which determines the insulation performance of the terminal and electric conductivity. Any one terminal failure will lead to the failure of the whole system engineering. Is the painful lessons in this respect at home and abroad is very profound.

Prevention is purpose, analysis is the foundation. In a sense, the prevention of failure is more important than the analysis of the failure. It to make sure the quality and reliability of the terminal has more realistic significance.

Should be at terminal blocks from the use of point of view, function is: must make the conduction of conduction, reliable contact. Insulation parts shouldn't conduction insulation must be reliable. Terminals of the common fatal fault form has the following three:

1. Poor contact

Terminals within the metal conductor is the core of the terminal part, it will come from external wires or cables voltage, current or signal to the corresponding contact element matching connector. So the contact structure must have a good, stable and reliable contact retention and good electrical conductivity. Due to the unreasonable contact element structure design, material selection error, the mold is not stable, processing out-of-tolerance size, surface roughness, plating surface treatment such as heat treatment process is unreasonable, improper assembly, storage conditions and improper operation, will be in contact with a contact part of the cause poor contact and cooperate with the parts.

2. Defective insulation

Insulator's role is to keep contact with a correct position, and make the contact element and contact element, insulation between contact element and shell. So the insulation parts must have excellent electrical performance, mechanical property and formability. Especially with high density, miniaturization of the widespread use of terminals, the effective wall thickness is more and more thin insulator. The insulation materials, precision injection mold and molding process, such as more stringent requirements are put forward. Due to the insulator surface or within the metal tailings, surface dust, flux, such as pollution of be affected with damp be affected with damp, organic material deposition and harmful gas adsorption film with surface water membrane fusion to form ionic conductive channel, absorption of moisture, mold, insulation aging, can cause short circuit, leakage, breakdown, low insulation resistance insulation fault phenomenon.

3.Fixed bad

Insulators insulation effect not only, also usually provide accurate outstretched contact for protection, and at the same time also has the installation position, the function of the lock is fixed on the device. Fixed bad, light person affect reliable contact cause instantaneous power, serious is the disintegration of products. Refers to the disintegration of terminals in close state, due to the material, design, technology and so on reasons for structure between plug and socket caused by unreliable, abnormal separation between pin and socket, will cause control system and signal control in power transmission interrupted serious consequences. Unreliable due to design, select material errors, incorrect molding process, heat treatment, mould, assembly, welding process of poor quality, such as fixed assembly does not reach the designated position, etc can cause adverse.

In addition, due to the coating peeling, corrosion, bruising, molded case flash, rupture, contact a rough machining, the deformation causes such as the appearance of the poor, due to the positioning lock tight fit size out-of-tolerance, consistency processing quality is poor, total separation force is too large to causes such as reversal, is also a common disease, frequently-occurring disease. These faults are generally can timely find out in the process of inspection and use.