Aerospace Glossary Letters P - Q


P

Pairing – The union of two insulated single conductors through twisting.
Pick – Distance between two adjacent crossover points of braid filaments. The measurement in picks per inch indicates the degree of coverage.
Pitch – In flat cable, the nominal distance between the index edges of two adjacent conductors.
Plastic Deformation – Change in dimensions under load that is not recovered when the load is removed.
Plasticizer – A chemical agent added to plastics to make them softer and more pliable.
Plenum – The air return path of a central air handling system, either ductwork or open space over a dropped ceiling.
Plenum Cable – Cable listed by Underwriters Laboratories for installation in plenums without the need for conduit.
Polyester – Polyethylene terephthalate, which is used extensively in the production of a high-strength moisture-resistant film used as a cable core wrap.
Polyethylene – A family of insulations derived from the polymerization of ethylene gas and characterized by outstanding electrical properties, including high I.R., low dielectric constant, and low dielectric loss across the frequency spectrum. Mechanically rugged, it resists abrasion and cold flow.
Polymer – A material of high molecular weight formed by the chemical union of monomers.
Polyolefin – A family of thermoplastics based upon the unsaturated hydrocarbons known as olefins. When combined with butylene or styrene polymers, they form compounds such as polyethylene and polypropylene.
Polyurethane – A family of flexible, abrasion resistant jackets used for XTRA GUARD 2 harsh environment cables.
Polyvinylchloride – A general purpose family of insulations whose basic constituent is polyvinylchloride or its copolymer with vinyl acetate. Plasticizers, stabilizers, pigments and fillers are added in lesser quantity to improve mechanical and/or electrical properties of this material.
Porosity – Multiple air voids in an insulation or jacket wall.
Potting – The sealing of a cable termination or other component with a liquid which thermosets into an elastomer.
Power Factor – The ratio of resistance to impedance. The ratio of an actual power of an alternating current to apparent power. Mathematically, the cosine of the angle between the voltage applied and the current resulting.
Primary Insulation – The first layer of nonconductive material applied over a conductor, whose prime function is to act as electrical barrier (sic...insulation).
Propagation – Delay time required for an electrical wave to travel between two points on a transmission line.
Pulling Eye – A device fastened to a cable to which a hook may be attached in order to pull the cable into or from a duct.


Q

Quad – A four conductor cable.