An electrical connector is a device used to join electrical terminations and create an electrical circuit. The connection may be temporary and might require a tool for assembly and removal, or it can serve as a permanent electrical joint between two wires or devices. Each connector consists of a plug assembly and a receptacle assembly. The two assemblies are coupled by means of a coupling nut. Each consists of an aluminum shell containing an insulating insert that holds the current-carrying contacts. The plug is usually attached to the cable end and is the part of the connector on which the coupling nut is mounted. The receptacle is the half of the connector to which the plug is connected. It is usually mounted on a part of the equipment.
Electrical connectors are identified by their size, insulation between pins, contact resistance, resistance to vibration, resistance to contaminants, pinout and physical construction, resistance to pressure, reliability, lifetime, and ease of connecting and disconnecting. They may have grooves installed to prevent insertion in the wrong orientation, connecting the wrong pins to each other, and have locking mechanisms to ensure that they are fully inserted and cannot work loose or fall out. Some connectors are designed such that certain pins make contact before others when inserted, and break first on disconnection; this protects circuits typically in connectors that apply power and sequence connections properly in hot swapping applications.
It is desirable for a connector to be quick to produce, easy to identify visually, require simple tooling, and be cost friendly. In some cases, an equipment manufacturer might choose a connector specifically because it is not compatible with those from other sources, allowing control of what may be connected.
Aircraft Connectors
Aircraft connectors need to be durable, reliable, and fail-safe due to exposure to thermal humidity, air pressurization cycles, and the like. Civilian aircraft use several different types of connector families. Most of the flight-critical electronics are contained within rugged boxes, connected to each other with cabling. Both the boxes and cables need to be replaceable with minimum effort in the maintenance hangar or on the flight line. The airline industry and airplane manufacturers embrace the idea of a field replaceable unit (FRU) that is easily replaceable for maintenance or upgrades.
Cables need to be routed through complex paths in the airframe, around corners and through holes. To tolerate this, special abrasion resistant cable jackets are used for aircraft cables, and every component on the airplane must be non-flammable. Special dielectrics and flex circuit materials have been chosen for their ability to not contribute to a fire. The connectors for this cabling are quite similar to the cylindrical families used in military applications. For every pound of weight in an aircraft, the plane will burn many gallons of additional fuel over the life of the aircraft. This puts a huge premium on reduced weight for
cable connectors and strain relieving back shells.
Types of Electrical Connectors
Aircraft utilize a variety of different connectors including: 8P8C, audio & visual, power supply connectors, USB, backplane, and many more. 8P8C refers to the array of pins, hence the name eight position, eight contact. In 8P8C connectors, each plug has eight positions that are spaced approximately 1 mm apart. Individual wires are then inserted into these positions. There are a variety of 8P8C connectors out there, with the modern
RJ45 Ethernet connector being the most prevalent.
Audio connectors and video connectors are electrical or optical connectors for carrying audio and video signals. For digital audio and video, this can be thought of as defining the physical layer. For analog audio and video these layers represent signal specification like direct speaker driving signals. Physical characteristics of the electrical or optical equipment includes the types and numbers of wires required, voltages, frequencies, optical intensity, and the physical design of the connectors. Any data link layer details define how application data is encapsulated.
USB connectors are designed to standardize the connection of peripherals like keyboards, pointing devices, digital still and video cameras, printers, portable media players, disk drives and network adapters to personal computers; both to communicate and to supply electric power. The connector has largely replaced interfaces such as serial ports and parallel ports and has become commonplace on a wide range of devices. USB connectors have been increasingly replacing other types for battery chargers of portable devices.
