The basic performance and working principle of the connector

2021-09-27 10:45

The working principle of the connector

For connectors, you may not know more about them. The so-called connector is two or more containers that communicate with each other below the liquid level. Containers with the same liquid and equal pressure on the liquid surface have equal liquid levels.

(1) The connector contains the same liquid, but the pressure on the liquid surface is different, the pressure difference of the liquid surface is equal to the pressure difference generated by the liquid level difference between the two containers of the connector.

(2) The pressure on the liquid surface of the connector is equal, but there are different liquids that are not mixed with each other on both sides. The height of the two liquid surfaces from the interface is inversely proportional to the liquid density.

The connector principle has a wide range of applications in engineering. Such as all kinds of liquid level gauge (water level gauge, oil level gauge, etc.), mercury vacuum gauge, liquid column type air pressure gauge, differential pressure gauge, etc., are made of the principle of the application connector.

Understanding the definition and working principle of connectors will help us to better understand and develop the connector market.

Basic performance of the connector

The basic performance of connectors can be divided into three categories: mechanical performance, electrical performance and environmental performance. Another important mechanical property is the mechanical life of the connector. Mechanical life is actually a durability (durability) index, which is called mechanical operation in the national standard GB5095. It is based on one insertion and one pull-out as a cycle, and whether the connector can normally complete its connection function (such as contact resistance value) after the specified plug-in cycle is judged.

Connector

1. Mechanical Properties As far as the connection function is concerned, the insertion force is an important mechanical property. Insertion force is divided into insertion force and pull-out force (pull-out force also known as separation force), the requirements of the two are different. There are provisions for maximum insertion force and minimum separation force in the relevant standards, which indicates that from the point of view of use, the insertion force is small (thus having a structure with low insertion force LIF and no insertion force ZIF), and if the separation force is too small, it will affect the reliability of the contact. The insertion force and mechanical life of the connector are related to the coating quality (sliding friction coefficient) of the contact part of the contact structure (positive pressure) and the dimensional accuracy (alignment) of the contact arrangement.

2. Electrical properties The main electrical properties of the connector include contact resistance, insulation resistance and electrical strength.

A high-quality electrical connector should have a low and stable contact resistance. The contact resistance of the connector varies from a few milliohms to tens of milliohms.

② Insulation resistance is an indicator of the insulation performance between the contacts of the electrical connector and between the contacts and the housing, ranging in magnitude from hundreds of megaohms to several gigaohms.

The electrical strength or withstand voltage, dielectric withstand voltage, is the characterization of the connector between the contact or contact and the shell between the rated test voltage tolerance capacity.

④ Other electrical properties.

Electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, and electromagnetic interference leakage attenuation is to evaluate the electromagnetic interference shielding effect of the connector, and is generally tested in the frequency range of 100MHz to 10GHz.

For RF coaxial connectors, there are electrical indicators such as characteristic impedance, insertion loss, reflection coefficient, voltage standing wave ratio (VSWR), etc. Due to the development of digital technology, in order to connect and transmit high-speed digital pulse signals, a new type of connector, namely high-speed signal connectors, has emerged. Correspondingly, in terms of electrical performance, in addition to characteristic impedance, some new electrical indicators have emerged, such as crosstalk (crosstalk), transmission delay (delay), time lag (skew), etc.

3. Environmental performance Common environmental performance includes temperature resistance, humidity resistance, salt spray resistance, vibration and shock resistance.

At present, the maximum working temperature of the connector is 200 ℃ (except for a few high temperature special connectors), and the minimum temperature is -65 ℃. Since the current generates heat at the contact point when the connector is working, resulting in a temperature rise, it is generally believed that the working temperature should be equal to the sum of the ambient temperature and the contact temperature rise. In some specifications, the maximum allowable temperature rise of the connector at the rated operating current is specified. ② The intrusion of moisture and moisture will affect the insulation performance of the connection and rust the metal parts. Constant damp heat test conditions for the relative humidity of 90% ~ 95% (according to product specifications, up to 98%), temperature +40±20 ℃, test time according to product regulations, at least 96 hours. The alternating damp heat test is more severe. ③ When the salt spray resistant connector works in an environment containing moisture and salt, its metal structure and contact surface treatment layer may cause galvanic corrosion, which will affect the physical and electrical properties of the connector. In order to evaluate the ability of the electrical connector to withstand this environment, a salt spray test is prescribed. It is to hang the connector in a temperature-controlled test chamber, and use a specified concentration of sodium chloride solution to spray with compressed air to form a salt spray atmosphere. The exposure time is specified by the product specification and is at least 48 hours. Vibration and shock resistance to vibration and shock is an important performance of electrical connectors, especially in special application environments such as aviation and aerospace, railway and road transportation. It is an important indicator to test the robustness of the mechanical structure of electrical connectors and the reliability of electrical contact. There are clear provisions in the relevant test methods. The peak acceleration, duration and shock pulse waveform, and the time of interruption of electrical continuity shall be specified in the impact test.

⑤ Other environmental properties According to the requirements of use, other environmental properties of the electrical connector include sealing (air leakage, liquid pressure), liquid immersion (resistance to specific liquids), low air pressure, etc.

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