The Transient Interruption Detection of Connectors

 1. Dynamic contact resistance

Since the motion is absolute, actual dynamic application environments such as vibration, impact and collision will affect the contact pressure of the contact position, and the contact resistance will change with the change of contact pressure value, direction and time. At this time, the contact resistance is called dynamic contact resistance. As this change occurs in a very short period of time under the influence of the external dynamic environment, the contact resistance of the electrical connector may reduce caused by the squeezing, or may increase resulted from the pulling, and even cause serious consequences due to the linkage interrupt.

How to detect the transient interruption phenomenon under dynamic stress environments? The detection is usually carried out in the dynamic stress environment simulation tests such as vibration, impact and collision by applying the specified frequency and acceleration on the detected electric connector and its components (wire bundles) in the specified time and the specified direction, then check whether there is the transient interruption phenomenon that is beyond the regulation using transient interruption monitor as the monitoring equipment. For example, in GJB681 General Specification for Radio Frequency Coaxial Connectors, the electrical continuity shall be monitored by a detector that is capable to detect 1μS and better than 1μS interruption interval or the specified interruption intervals at 100mA current when connectors with cables are undergoing high-frequency vibration tests.

2. Influencing factors of dynamic contact resistance detection

(1) There are many reasons for the change of dynamic contact resistance of electrical connectors caused by too small contact pressure. Firstly, the influence of human factors should be excluded. For example, unreliable connection caused by insufficient soldering or non-standard operation in virtual pressure assembly when operators adopt welding, crimping and other terminating technologies, especially the too much or too less force in the connection of RF connectors, or even a tiny bit of eccentricity or air clearance will cause great attenuation or reflection of the transmission signal, resulting in signal distortion. Therefore, the sense of responsibility of operators is particularly important, and a constant torque wrench should be used in the connection as far as possible.

(2) External factors should also be eliminated in the resonance of the installation fixture. The factors mainly refer to the installation of fixtures, testing and detection equipment, etc. When conducting dynamic stress environmental tests such as vibration, impact and collision, the generation of resonance should be prevented as far as possible in the design of structural stiffness, material selection, dimensional processing, installation and debugging of the installation fixture, because the resonance of the installation fixture has great influence on the test result.

3. Transient interruption monitor

Two types of instruments are available; One is the instrument with high sensitivity (minimum perception time) especially designed for transient interruption detection. For example, Nac NM-10A and NM-11A transient interruption detectors have a sensitivity (minimum perception time) of up to 0.1μs. NM-11A can set the monitoring transient interruption time(0.1-99.9μs) and conduct 10 loop parallel detection according to the technical standard of the detected interconnect device. The other is a compatible instrument with relatively low detection sensitivity (minimum perception time). For example, the Nac NMC60 on-off detector has the function of transient interruption detection. The sensitivity of transient interruption detection(minimum perception time) of this instrument is 60ms. 30X series multifunctional automatic testing instruments can be inserted in one time to continuously complete the detection of conduction, insulation, withstand voltage and transient interruption. The sensitivity of transient interruption detection (minimum perception time) is 167ns, which is relatively high.