Electrical connectors are electromechanical components that connect electrical circuits. There are many different classification methods. Therefore, the electrical parameters of the electrical connector itself are the first consideration when choosing an electrical connector.
1. Rated current of electrical connector
Rated current is also called working current. Like the rated voltage, the electrical connector generally works normally when the current is lower than the rated current.
In the electrical connector
design process, the thermal design of the electrical connector is used to meet the rated current requirements, because when current flows through the contact pair, the contact pair will generate heat due to the presence of conductor resistance and contact resistance. When its heat exceeds a certain limit, it will destroy the insulation of the connector and form a contact to soften the surface coating, causing failure. Therefore, to limit the rated current, in fact, the temperature rise inside the connector must not exceed the specified value of the design.
The question to pay attention to when choosing is: For multi-core connectors, the rated current must be derated. This should be paid more attention to in large current occasions.
2. Rated voltage of electrical connector
The rated voltage is also called the working voltage, which mainly depends on the insulating material used in the electrical connector and the distance between the contact pairs. Some components or devices may not perform their proper functions when the voltage is lower than their rated voltage.
The rated voltage should in fact be understood as the highest working voltage recommended by the connector manufacturer
. In principle, the electrical connector can work normally at a voltage lower than the rated voltage. With the same withstand voltage index, different maximum working voltages can be used according to different use environments and safety requirements. This is also more in line with objective usage.
3. Shielding of electrical connectors
In modern electrical and electronic equipment, the density of components and their related functions is increasing day by day, which puts forward strict limits on electromagnetic interference. Therefore, the connector is often enclosed with a metal shell to prevent internal electromagnetic energy radiation or interference from external electromagnetic fields.
At low frequencies, only magnetic materials can significantly shield the magnetic field. At this time, there are certain regulations on the electrical continuity of the metal shell, that is, the shell contact resistance.
4. Electrical connector contact resistance
Contact resistance refers to the resistance generated by two contact conductors at the contact portion.
Two problems should be noted when choosing:
(1) The contact resistance index of the connector is actually the contact-to-resistance, which includes contact resistance and contact-to-conductor resistance. Usually conductor resistance is small, so contact resistance is called contact resistance in many technical specifications.
(2) In the circuit connecting small signals, pay attention to the conditions under which the given contact resistance index is tested, because the contact surface will adhere to oxide layer, oil stains or other pollutants, and film resistance will occur on the surface of the two contacts. When the film thickness increases, the resistance increases rapidly, and the film becomes a poor conductor. However, the film will undergo mechanical breakdown under high contact pressure, or electrical breakdown will occur under high voltage and large current. For some small-volume connectors, the contact pressure is quite small, and the use occasions are only mA and mV levels. The film resistance is not easy to be broken down, which may affect the transmission of electrical signals. Therefore, those who have this requirement choose connectors with low-level contact resistance indicators.