Application of Military Electrical Connectors (1)

1. Circular Electrical Connector

The MIL-C-38999 standard is an internationally recognized standard with advanced levels. This standard is a general specification for small circular, high density, quick separation, environmental resistance, removable, crimping type electrical connectors.

China has developed and produced this standard product for more than ten years. The main features of GJB599 (equivalent to MIL-C-38999) circular electrical connectors are as follows:

(1) High density
The maximum number of cores is 128. Under the same shell size, the number of signal channels passed by the product is twice that of the series products. Good insulation performance, light weight and small volume. The hole arrangement of MIL-C-38999 is to increase the arrangement of high-density holes on the basis of medium-density product specifications (MIL-C-26482, 83723, etc.). Basically, each shell number has a high-density arrangement. Users can not only use high-density connectors for parts with small volume, but also use medium-density products for power transmission circuits.

(2) Long shell
MIL-C-38999 series I, III, IV are long shells, only series II are short shells. Due to the lengthening of the long shell, the length from the end face of the shell to the end face of the pin increases, which can prevent unplugged plugs and sockets from colliding with foreign objects and damaging the pin during use. It can also prevent blind insertion, wrong insertion or oblique insertion. The connecting ring of the plug touches the bent pin, or it causes a short circuit across the live pin.

Due to the extension of the housing, when the pin plug and the pin socket are mistakenly inserted together, the pin end face of the plug and the pin end face of the socket are at a certain distance, so the pin will not be damaged. In addition, due to the extension of the housing, when military plug connectors and socket are mated, when the pin contacts the end surface of the jack insulator, the plug housing and the socket housing have been engaged for a long length, reducing the inclination of the plug and socket when mated, Improves the alignment accuracy of pin and jack.

The total length of the MIL-C-38999 pin is 27.7% shorter than MIL-C-26482. Because the pins are short, the length of the sealing gasket exposed by the pins is also short, which is beneficial to the ultra-small and fine pins to improve the processing performance, increase the rigidity, and prevent the damage from bending. The jack is a closed-end type, and the sleeve protects the working part of the jack to prevent the jack from damaging the reed and changing the elastic force of the reed during the turnover, packaging or use, which affects its contact performance. The end of the jack sleeve is a trumpet, which can guide the pin into the jack smoothly.

(3) High mix
Various signals and energy transmission lines such as low-frequency, high-frequency, bus, optical fiber and power supply can be mixed in a housing, and the maximum current of a single pin can reach 45 amperes. The transmission signal frequency of MIL-C-38999 series products is one hundred times higher than that of MIL-C-26482 series products.
Therefore, one MIL-C-38999 series plug can replace several MIL-C-26482 series mil spec plug.

(4) High reliability
The locking mechanism of MIL-C-38999 series III products is a three-head threaded quick connection, which can withstand strong vibration and shock, and can automatically lock under strong vibration and shock environments.

MIL-C-38999 product's connection ring and plug housing fixing method have also been improved. The connection ring of MIL-C-26482 series II is fixed to the plug housing by a circlip, which is limited by the circlip snapped into the connection ring groove. Bit.

When the plug seat is inserted, the connecting ring exerts a reaction force on the plug housing through the snap spring, the stop washer, and the corrugated spring. This force always exists as long as it is in working condition. Because the contact surface between the circlip and the circlip groove is limited, the circlip may slip out under stress. If the circlip slides out, it will cause fatal failure of the plug and socket.

MIL-C-38999 series I and II, the connecting ring is limited inward by the corrugated spring and the shoulder of the plug shell, and the outer is limited by the retaining ring stuck on the plug shell.

When the plug and socket are not inserted, the retaining ring acts as a limit. When the plug and socket are inserted, the connecting ring moves inside, there is a gap between the retaining ring and the connecting ring, and the retaining ring does not work. The connecting ring exerts an inward moving force on the plug housing through the corrugated spring to realize plug and socket insertion.

The reaction force of the plug housing on the connecting ring is applied to the connecting ring step through the corrugated spring. Unless the step is damaged, the plug housing will not move out and cause abnormal separation, eliminating potential quality hazards from the design.