Cable terminal connectors must be carefully selected through an assessment process that considers all applicable electrical, mechanical, and environmental stresses as well as the design’s requirement for size function, reliability, and at a reasonable price.
Electrical connectors usually consist of a mating pair (plug and receptacle) each with electrically conductive male (pins) or female (sockets) contacts, and one of the connector halves, or inserts/contacts must always be floating.
The contacts are often beryllium copper or phosphor bronze-plated with gold or some other non-corrosive, highly conductive metal. The contacts are contained by an insulator (insert) of adequate dielectric material, and when necessary, housed in an enclosure (shell), often die-cast or sheet aluminum, plated or anodized for corrosion protection. The contacts may be captive or removable with a special tool. The electrical connection into the system at the contact terminal is either a crimp or solder connection. The seal between the shell and insert may be moisture resistant or hermetic.
The inserts in each connector half must be oriented for correct mating, and the shell or insert usually contains a keying feature to prevent mis-mating, which could damage the connector and/or result in a electrical problem. Cable clamps and mounting hardware may be provided and used as required. The mated halves are usually secured by a locking mechanism to prevent untimely disengagements.
Connectors are precision mechanical devices whose interfaces are critical and subject to mechanical wear, more so than most other electrical components. They may be required to make-and-break contact frequently, are often subjected to vibration or repeated physical affect, which contribute to fatigue, abrasion or galling of the contact materials. These life stresses cause degradation of electrical conductivity, and can result in opens or high contact resistance. In some installations, these stresses can also adversely affect the integrity of the securing apparatus. Another concern is chemical activity from the environment, for instance, oxidation and sulfide formation that adversely affect conductivity. These concerns, when applicable to the intended usage, need to be addressed in the connector assessment and test program.
When choosing a connector, provide for additional future circuits and circuit changes by selecting a style that has a few extra contacts. Consider using standard styles that are more likely to remain viable in the market place. Consider carefully the cost of the style in comparison to its expected use.
Cable lugs of various sizes, shapes, materials and configuration are used in the industry. In the wiring, automation, control panel and instrumentation industry, insulated lugs with pin terminal, blade terminal, hook terminal, fork terminal and ring terminal are used. For multiple connection purposes copper ring type lugs are commonly used. Many of the devices such as cable accessories and switchgear are connected with cables using copper cable lugs.
Another type of lug is butt and parallel connector. This is mostly used for connecting and terminating 2 cables. Some of the widely used butt and parallel connectors are PVC insulated, butt type, heat shrinkable and closed end type. Copper cable lugs are used as butt and parallel connector depending on the type of cable used to connect a device with the other.