Requirements for electrical parameters of electrical connectors


The connector is an electromechanical component that connects electrical circuits. Therefore, the electrical parameters of the connector itself is the first thing to consider when choosing a connector.

1, the rated voltage

Rated voltage is also known as the working voltage, it mainly depends on the insulation material used by the connecting machine, the size of the spacing between the contact pairs. Some components or devices in lower than its rated voltage, may not be able to complete its proper function. Connector voltage rating should in fact be understood as the maximum working voltage recommended by the manufacturer. In principle, the connector can work properly at voltages lower than the rated voltage. I tend to be based on the connector's voltage (electrical strength) indicators, in accordance with the use of the environment, safety level requirements to reasonably choose the rated voltage. In other words, the same voltage indicators, according to different use environments and safety requirements, can be used to different maximum operating voltage. This is also more in line with the objective use of the situation.

2、Rated current

Rated current is also known as the working current. The same as the rated voltage, in the case of lower than the rated current, the connector can generally work properly. In the connector design process, is through the thermal design of the connector to meet the rated current requirements, because the contact pair has current flow, due to the existence of conductor resistance and contact resistance, the contact pair will be hot. When its heat generation exceeds a certain limit, it will destroy the insulation of the connector and form a softening of the surface coating of the contact pair, causing a failure. Therefore, to limit the rated current, in fact, to limit the temperature rise inside the connector does not exceed the value specified in the design. The issue to be noted in the selection is: for multi-conductor connectors, the rated current must be used in derating. This should pay more attention to the occasion of high current, such as φ3.5mm contact pair, the general provisions of its rated current of 50A, but in 5 cores to derate 33% of the use, that is, the rated current of each core is only 38A, the more cores, the greater the derating range.

3、Contact resistance

Contact resistance refers to two contact conductors in the contact part of the resistance. In the selection of two issues should be noted, first, the connector contact resistance indicator is in fact the contact to resistance, which includes contact resistance and contact to conductor resistance. Usually the conductor resistance is small, so the contact-to-conductor resistance is referred to as the contact resistance in many technical specifications. Secondly, in circuits connected to small signals, it is important to note the conditions under which the contact resistance indicator is tested, because the contact surface can have an oxide layer, oil or other contaminants attached to it, and the surface of the two contacts can produce a film layer of resistance. When the thickness of the film increases, the resistance increases rapidly and the film becomes a poor conductor. However, mechanical breakdown of the film can occur at high contact pressures or electrical breakdown at high voltages and currents. For some small volume connector design contact pressure is quite small, the use of only mA and mV level, the film layer resistance is not easy to be broken, may affect the transmission of electrical signals. In GB5095, "basic test procedures and measurement methods for electromechanical components used in electrical equipment," one of the contact resistance test method "contact resistance - millivolt method" provides that, in order to prevent the contact on the insulating film is broken, the test circuit of the open-circuit electric potential In fact, this is a low-level contact resistance test method, therefore, the choice of this requirement, due to the use of low-level contact resistance indicators of the connector.


In modern electrical and electronic equipment, the density of components and the increasing number of related functions between them, the electromagnetic interference put forward a strict limit. So the connector is often closed with a metal shell to stop the internal electromagnetic energy radiation or interference by external electromagnetic fields. At low frequencies, only magnetic materials can play a significant shielding effect on the magnetic field. At this point, there are certain regulations on the electrical continuity of the metal shell, which is the shell contact resistance.

Safety parameters

5、Insulation resistance

Insulation resistance is the voltage applied to the insulating part of the connector, so that the insulating part of the surface within or on the surface of the leakage current and presents the resistance value. It is mainly affected by the insulation material, temperature, humidity, dirt and other factors. Connector sample insulation resistance values are generally provided in the standard atmospheric conditions of the indicator value, in some environmental conditions, the insulation resistance value will not have to decline. In addition, we should pay attention to the insulation resistance of the test voltage value. According to the insulation resistance (MΩ) = the voltage applied to the insulator (V) / leakage current (μA) applied to different voltages, there will be no results. In the connector test, the applied voltage is generally 10V, 100V, 500V three grades.

6、Voltage resistance

Withstand voltage is the contact pair between the mutually insulated parts or insulated parts and grounding, in the specified time can withstand higher than the rated voltage without producing breakdown phenomenon of the critical voltage. It is mainly affected by the contact pair spacing and creepage distance and geometry, insulator material and ambient temperature and humidity, atmospheric pressure.


Any connector in the work can not be separated from the current, which is the risk of fire. Therefore, the connector is not only required to prevent ignition, but also required in the event of ignition and fire, can be self-extinguishing in a short period of time. In the selection of the choice to pay attention to the use of flame-retardant, self-extinguishing insulation materials for electrical connectors.

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