The physical construction and pinout are what characterize the properties of electrical connectors. However, other factors are considered, including contact resistance, size, resistance to vibration, ruggedness, insulation between the pins, resistance to pressure, lifetime or number of operations before failing, reliability, resistance to contaminants such as entry of water, and the ease for connecting and disconnecting.
To prevent electrical connectors from being connected to the wrong pins or inserted incorrectly, many are keyed. These connectors may also have a locking-type mechanism, which is commonly seen in the form of certain pins that make contact before others upon insertion, or by breaking first on disconnection. As such, the circuits within the connectors that apply power are protected.
In most cases, customers want electrical connectors that are easily identified upon visual inspection. However, customers also prefer connectors that can be assembled quickly, those made for assembly with standard tools, and connectors that are affordably priced. Keep in mind that electrical connectors have different properties, meaning no one connector offers all of the ideal properties that a person a might want.
The Keying Process
As mentioned, it is common to find keyed electrical connectors—those with some type of mechanical component that prevents connection except with a connector that matches correctly. As such, interactions are not damaged. This also prevents damage when connectors are jammed together at the wrong angle, or when using imperfectly fitted plugs.
As a prime example, to ensure proper orientation, XLR electrical connectors have a notch whereas Mini-DIN plugs are designed with a plastic projection that fits into the socket’s corresponding hole. This projection stops people from trying to push the two together.
As for the locking mechanism found on electrical connectors, these help prevent poor environmental sealing, as well as inadvertent disconnection. The locking mechanism is designed to lock levers of different kinds, as well as toggles and screw locking. Based on the requirements for the application, many manufacturing companies test the housings with locking mechanisms under harsh and varied environmental conditions. In this case, things like water spray, shock, dust, and vibration, among others, are the primary focus.
To ensure complete safety, it is imperative to purchase high-quality electrical connectors—those designed and manufactured by a reputable company.