Aerospace Glossary Letters D - E

DBS - Acronym meaning Digital Broadcast System.
Decibel (dB) – A unit to express differences of power level. A term that expresses two power levels used to indicate gains or losses in a system.
Derating Factor – A factor used to reduce the current carrying capacity of a wire when used in environments other than that for which the value was established.
Dielectric – The ratio of the capacitance using the material in question as the dielectric, to the capacitance resulting when the material is replaced by air.
Dielectric Constant (e) – The ratio of the capacitance using the material in question as the dielectric, to the capacitance resulting when the material is replaced by air.
Dielectric Strength – The voltage which an insulation can withstand before breakdown occurs. Usually expressed as a voltage gradient (such as volts per mil).
Digital – Representation of data by discrete characters.
Direct Current (DC) – An electric current which flows in one direction.
Drain Wire – In a cable, the uninsulated wire in intimate contact with a shield to provide for easier termination of such a shield to ground.
Duct – An underground or overhead tube for carrying electrical cables.
Duplex Insulated – In the thermocouple industry, a combination of dissimilar metal conductors of a thermocouple or thermocouple extension wire.

E

EIA – Abbreviation for Electronic Industries Association.
Elastomer – A class of long-chain polymers capable of being crosslinked to produce elastic compounds, e.g. polychloroprene and ethylene propylene rubber.
Electromagnetic – Pertaining to the combined electric and magnetic fields associated with movements of electrons through conductors.
Electromotive Force (emf) – Pressure or voltage. The force which causes current to flow in a circuit.
Electrostatic – Pertaining to static electricity or electricity at rest. A constant intensity electric charge.
Elongation – The fractional increase in length of a material stressed in tension.
EMI – Abbreviation for electromagnetic interference.
Epoxy – An adhesive used in the connector termination process.
Ethylene Propylene Rubber (EPR) – An ozone-resistant rubber consisting primarily of ethylene propylene copolymer (EPM) or ethylene propylene diene terpolymer (EDPM).
Expanded Diameter – Diameter of shrink tubing as supplied. When heated, the tubing will shrink to its extruded diameter.
External Interference – The effects of electrical waves or fields which cause spurious signals other than the desired intelligence, e.g. noise.