The basic performance of the terminal blocks

Date:2017-09-15

  The basic performance of the terminal blocks can be divided into three categories: mechanical property, electrical property and environmental performance. Another important mechanical properties are the mechanical life of the terminal blocks. Mechanical life is actually a durability indicators, the national standard GB5095 called mechanical operation. It is based on an insert and once pulled out of a cycle, normal mating cycles specified wiring terminal blocks complete connectivity (such as contact resistance value) basis as a judge.

       1. Mechanical properties in terms of connectivity, the insertion force is important to the mechanical properties. Insertion force is divided into the insertion and extraction force (pullout force also known as a separation force), the requirements are different. In the relevant standards, the maximum insertion force and the predetermined minimum separation force from the usage point of view, the insertion force to be small (and thus with low insertion force, the structure of LIF and no insertion force ZIF), which indicates that, while the separation force is too small, will affect the reliability of the contact. Terminal blocks insertion force structure and mechanical life contacts the (positive pressure size) contact site coating quality (coefficient of sliding friction) of contacts arranged dimensional accuracy (alignment degrees).

       2. The main electrical properties of the electrical performance of terminal blocks including the contact resistance, insulation resistance and dielectric strength. 
      ① contact resistance of high-quality electrical connection terminal blocks should have a low and stable contact resistance. The contact resistance of the terminal blocks Europe ranging from a few milliohms to tens of milliohms. 
      ② insulation resistance to measure the electrical connection between the terminal contact piece and the contact member between the shell and insulating performance indicators, the order of hundreds of megohms to thousands of megohms. 
      ③ dielectric strength or the voltage resistance, dielectric withstand voltage, is a characterization of the terminal blocks between the contact member or the contact member between the shell and the ability to withstand nominal test voltage. 
      ④ other electrical performance. 
      EMI leakage attenuation of electromagnetic interference shielding effect of the evaluation terminal EMI leakage attenuation is the electromagnetic interference shielding effect of the evaluation of terminal blocks, generally in the frequency range of 100MHz ~ 10GHz test. 
RF coaxial terminal blocks, as well as the characteristic impedance, insertion loss, reflection coefficient, voltage standing wave ratio (VSWR) electrical specifications. Due to the development of digital technology, in order to connect and transfer high-speed digital pulse signal, a new class of terminal blocks that high-speed signal terminal blocks, electrical performance, in addition to the characteristic impedance, but also there has been some new electrical indicators such as crosstalk (crosstalk), propagation delay (delay), time delay (skew).

      3. Common environmental performance of environmental performance, including temperature, humidity, salt spray, vibration and shock. 
      ① temperature is the maximum operating temperature of the terminal blocks 200 ℃ (a few special high-temperature terminal blocks are excluded), the lowest temperature of -65 ° C. Terminal blocks work at the contact point, the current generates heat, causing the temperature rise, it is generally believed that the operating temperature should be equal and of the ambient temperature and the contact temperature rise. In some specifications defined terminal blocks rated operating current maximum allowable temperature rise. ② moisture intrusion of moisture will affect the connection insulation properties, and corrosion of metal parts. Damp heat test conditions for the relative humidity of 90% to 95% (depending on the product specification, up to 98%), the temperature of +40 ± 20 ° C, test time required by product, at least 96 hours. Damp heat test is more stringent. ③ resistance to salt spray terminal blocks in environments containing moisture and salt content, its metal structure, contacts the surface treatment layer may produce physical and electrical properties of galvanic corrosion, affecting the terminal blocks. Ability to withstand this environment in order to evaluate the electrical connection terminal blocks, provides for the salt spray test. It is the terminal block is suspended in a temperature controlled test chamber, with a predetermined concentration of sodium chloride solution was sprayed with compressed air, to form a salt spray atmosphere, its exposure time is required by the product specifications, at least 48 hours. ④ vibration and shock resistance to vibration and shock is an important performance of electrical terminal blocks, special application environment, such as aviation and aerospace, rail and road transport is particularly important to test the robustness and electrical contact of the the electrical terminal blocks mechanical structure and reliable an important indicator. Are clearly defined in the test method. The impact test shall be provided that the peak acceleration, duration and impact pulse waveform, and the electrical discontinuity of time. According to the requirements, the electrical terminal blocks environmental performance as well as sealing (air leak, the liquid pressure), liquid immersion vices (specific liquid resistant capabilities), low pressure ⑤ other environmental performance.

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