Parameter Requirements for Aviation Plugs

Parameter requirements for aviation plugs
Aviation plugs are electromechanical components that connect electrical lines. Therefore, the electrical parameters of the aviation plug itself are the first considerations when choosing an aviation plug.

1: The rated voltage of the aviation plug
The rated voltage, also known as the working voltage, mainly depends on the insulating material used in the aviation plug and the spacing between the contact pairs. Some components or devices may not be able to perform their intended functions below their rated voltage. In fact, the rated voltage of the aviation plug should be understood as the highest working voltage recommended by the manufacturer. In principle, aviation plugs can work normally below the rated voltage. The rated voltage tends to be reasonably selected according to the withstand voltage (dielectric strength) index of the aviation plug, according to the use environment and safety level requirements. That is to say, the same withstand voltage index can use different maximum working voltages according to different use environments and safety requirements. This is also more in line with objective usage.

m16 aviation plug

male aviation plug

pcb aviation plug

2: Rated current of aviation plug
The rated current is also called the working current. Like the rated voltage, the aviation plug can generally work normally when the current is lower than the rated current. In the design process of the aviation plug, the rated current requirement is met through the thermal design of the aviation plug. Because when a current flows through the terminal contact pair, due to the existence of conductor resistance and contact resistance, the terminal contact pair will heat up. When its heat exceeds a certain limit, it will destroy the insulation of the aviation plug and form a contact to soften the surface coating, resulting in failure. Therefore, to limit the rated current, in fact, it is necessary to limit the temperature rise inside the aviation plug not to exceed the specified value of the design. The problem to be paid attention to when choosing is: for multi-core aviation plugs, the rated current must be derated. This should be paid more attention to in the case of high current. For example, for φ3.5mm terminal contact pairs, the rated current is generally specified as 50A, but it should be derated by 33% for 5 cores. That is, the rated current of each core is only 38A, and the more cores, the greater the derating range.

3: Contact resistance of aviation plug
Contact resistance refers to the resistance generated by two terminals contacting conductors at the contact part. There are two issues to be aware of when choosing. First, the contact resistance index of the aviation plug is actually the resistance of the contact terminal, which includes the contact resistance and the resistance of the contact terminal to the conductor. Usually the conductor resistance is small, so the contact pair resistance is called contact resistance in many technical specifications. Second, in a circuit connected to a small signal, attention should be paid to the conditions under which the given contact resistance index is tested. Because the contact surface will be supplemented by oxide layer, oil or other pollutants, a resistive film will be formed on the surface of the two contact parts. When the thickness of the film layer increases, the resistance increases rapidly, and it becomes a poor conductor film layer. However, the film layer will undergo mechanical breakdown under high contact pressure, or electrical breakdown under high voltage and high current. The contact pressure designed for some small-sized connectors is quite small, and the application occasions are only at mA and mV levels. The film resistance is not easy to be broken down, which may affect the transmission of electrical signals. One of the contact resistance test methods in GB5095 “Basic Test Procedures and Measurement Methods for Electromechanical Components Used in Electrical Equipment” is “Contact Resistance—Millivolt Method”. In order to prevent the insulating film on the contact from being broken down, the DC or AC peak value of the open circuit electromotive force of the test circuit should not exceed 20mV, and the DC or AC test current should not exceed 100mA. In fact, this is a test method for low-level contact resistance. Therefore, selectors with this requirement should choose aviation plugs with low-level contact resistance indicators.

4: Shielding of aviation plugs
In modern electrical and electronic equipment, the density of components and their related functions are increasing, which puts strict limits on electromagnetic interference. Therefore, aviation plugs are often enclosed with metal shells to prevent internal electromagnetic energy from radiating or being interfered by 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 contact resistance of the shell