Electrical Connector Bases and Covers Information
Closure cover. Micro D Shell. Plastic sealing cover
Image Credit: AutomationDirect | Glenair | Multi-Contact USA
Electrical connector bases and covers are designed to provide mechanical protection for electrical connectors. The connector covers discussed in this guide are exclusive for electrical uses. These covers are used for dust or other contamination prevention applications, as well as with new cables, equipment, and other applications where a connector needs protection.
Electrical bases and covers are available in many shapes and sizes to accommodate different types of electrical connections. For example, covers for D-subminiature connectors are shaped like the letter D while covers for Bayonet Neill Concelman (BNC) connectors are round.
Types and Shapes
Bases and covers are used to protect electrical connectors. They are available as a cover or a base.
Cover - A cover fits over the electrical portion of a connector and may also have a strain relief built into it.
Base - A base is a mating surface or locking part of a connector.
The base of the connector can have either a single or double lever locking mechanism to secure the connector to the shaft or fitting.
There are several cross sections available for bases and covers. The shape should be selected based on the intended application and the space in which the device must fit. The most common sections are below.
Rectangular; rectangular; square covers
Image Credit: Allied Elect.; Glenair; Delta Tech Mfg
If the application requires a square or rectangular cover then the width and length must be determined to ensure the cover will be effective. For round connectors, the diameter should be noted.
How the wire enters the base or cover is an important consideration when selecting an electrical connector bases and covers. This should be selected based on the needs of the applications.
Top entry - The electrical connector cover or base has a place for the wire to enter in on the top.
Side entry - The electrical connector cover or base has a place for the wire to enter in on the side.
Electrical Connector Types
Common types of electrical connector bases and covers include devices for D-subminiature socket or pin connectors with 9, 15, 25, 37, or 50 contacts. Covers for 50-pin and 68-pin small computer system interface (SCSI) electrical connectors are also common for heavy-duty rectangular connectors.
Electrical connector bases and covers are made from a variety of metals and plastics.
Aluminum is a common industrial metal with good electrical and thermal conductivity, high reflectivity, and resistance to oxidation.
Stainless steel is chemical and corrosion resistant and can have relatively high pressure ratings.
Ethyl vinyl acetate (EVA) is a transparent thermoplastic elastomer that remains flexible at low temperatures and resists cracking.
Polyethylene (PE) is a semi-crystalline, whitish, semi-opaque thermoplastic that is soft, flexible and tough - even at low temperatures - with outstanding electrical properties but poor temperature resistance.
Polypropylene (PP) exhibits excellent cold flow, bi-axial strength, and yield elongation properties.
Polyetheretherketone (PEEK) is another thermoplastic, provides excellent chemical and fatigue resistance and thermal stability.
Vinyl exhibits good flexibility and chemical resistance, while polyamides provide strong pressure ratings.
Paper covers are frequently used for high-temperature applications that may degrade plastic covers or bases.
Natural rubber and styrene butadiene (SBR) provide good resistance to petroleum hydrocarbons, oils, and fuels.
Silicones are polymers in which organic groups are bonded to silicone atoms in chains of inorganic siloxanes. They provide excellent electrical insulation, water repellency, and heat and cold weather resistance. Silicones maintain their natural lubricity at a wide range of end-use temperatures and are both resilient and resistant to creep.
Some electrical connector covers and bases are designed to dissipate electrostatic charges. Others provide an electrical shield.
Static dissipative- Also called anti-static, static dissipative connectors are designed to dissipate electrostatic charges; these covers provide mechanical and electrical protection.
Electrical shield- These covers are made of a conductive material, such as polyethylene, and provide an electrical shield in addition to dissipating electrostatic charges.