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The Book of Terms

The Book of TermsThe WJI Book of Wire & Cable Terms: an interactive experience of learning and sharing
This book, written by industry volunteers and containing more than 5,000 entries, is an asset for newcomers to wire and cable.

At the same time, it also represents an opportunity for industry veterans to give back by either updating or adding to the more than 5,000 entries. This is an honor system process. Entries/updates must be non-commercial, and any deemed not to be so will be removed. Share your expertise as part of this legacy project to help those who will follow. Purchase a printed copy here.


 

0-9   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Dielectric Loss Angle

The difference between 90 degrees and the dielectric phase angle. Also called dielectric phase difference.

Dielectric Loss Factor

The product of its dielectric constant and the tangent of its dielectric loss angle. Also called dielectric loss index.

Dielectric Phase Angle

The angular difference in phase between the sinusoidal alternating potential difference applied to a dielectric and the component of the resulting alternating current having the same period as the potential difference. Es­sentially, this means that when an alternating current is applied across an insulating material, the resulting alternating current passing through it (no matter how small) will be at a different phase than the voltage. The dielectric phase angle is the difference in the timing of the peak of the alternating input voltage across the dielectric and the peak of the resulting alternating current through it.

Dielectric Power Factor

The cosine of the dielectric phase angle (or sine of the dielectric loss angle).

Dielectric Strength

The voltage which an insulating material can withstand before breakdown occurs, usually expressed as a voltage gradient (such as volts per mil). Also called electric strength and disruptive gradient.

Dielectric Strength, Breakdown Test Equipment

High potential test equipment is produced in both alternating current and direct current types. Equipment for measuring dielectric breakdown of electrical insulation usually consists of a 60-hertz step-up transformer, a variable primary voltage, a circuit breaker and a means of indicating the voltage applied.

Dielectric Test

A test in which a voltage higher than the rated voltage is applied for a specified time to determine the adequacy of the insulation under normal conditions. Sometimes called a Hi-Pot test (high potential).

Dieletric Constant Rating

All dielectric constants are compared to air or vacuum, which is given a value of 1.0. The higher the constant number, the poorer the dielectric characteristics. A lower-quality PVC insulation may have a dielectric constant of 5.0 to 6.0 or higher. Polyethylene has a much better dielectric constant of approximately 2.0. Foamed polypropylene or polyethylene insulations have constants as low as 1.6.

Difficult-to-Shape Zone

In an extrusion process, a marginal zone in front of the dummy block where material gathers until it finally flows into the core.

Diffraction

Phenomenon that results when light passes by an opaque edge or through an opening, generating weaker secondary wavefronts. These secondary wavefronts interfere with the primary wavefronts as well as with each other to form various patterns.

Diffusion Streaks

Brown colored streaks in copper-bearing clad products resulting from diffusion of core-alloying constituents to the surface of the coating during thermal treatment.

Digital

A data format that uses discrete or separate physical levels to contain information.

Digital Signal

A signal in which the data is represented by a series of discrete steps or pulses.

Dimensional Stability

See Test, Dimensional Stability.

DIN Standards

Specifications equivalent to the BS series issued by the British Standards Institution.

Diode

A two-element electronic device that allows current to flow in only one direction, serving as a rectifier.

Dip Coating

An insulating coating applied to the conductor by passing the conductor through an applicator containing liquid insulating medium. This medium can be used for magnet wire.

Dip Forming

A process for continuous production of copper wire rod in any re­quired length. A shaved copper rod is passed vertically upwards through a cruci­ble of molten copper, emerging as a much thicker rod that passes up a cooling tower before being led to a rolling mill for reduction to the required size as a continuous process.

Dip Process

The process of covering a surface by means of dipping it into or through a molten bath of the coating material. This may be followed by dippings or baths in other solutions and/or materials to produce desired results.

DIR

Designation for double lapping of pure rubber. Also abbreviated to “DPR.”

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