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APPENDIX

For current information see:

www.lappgroup.com

1199

Appendix

Glossary

A certain maximum resistance is assigned to the nominal cross-sec-

tion, within which the conductor structure is specified. The cross-

section is normally specified in mm

. However, for certain types of

cables, which are always made up of single-core conductors (telecom-

munications cables), the conductor diameter is used for marking or

description.

CSA

Abbreviation for “Canadian Standards Association”. Canadian standards

and testing body. Similar to VDE in Germany.

Current

Electrical unit, measured in Amperes. Current = Voltage/Resistance.

D.C.

Abbreviation for direct current.

Dark current

Current at the output of an optical receiver if no radiation is present.

Data bus

A system of associated cables, to which data bits are transferred.

Data transmission cable

Cables whose structure make them suitable for transmitting

electric data processing pulses with minimum errors. Simple (pair)

or more complex (screening) constructions are required depending on

the susceptibility of the data pulses to faults (brand: UNITRONIC

Lapp). Computer cables (Li2YCY-PIMF) or other, at least twisted in

pairs, normally screened and often individually screened cables, e. g.

UNITRONIC

LIYCY (TP), UNITRONIC

BUS; UNITRONIC

LAN, tele-

phone cable, also light waveguide cables. TP = Twisted pair.

Data transmission rate

Unit of measure for the transmission speed of a data transmission.

It is measured in bit/s or byte/s.

Data transmission, data transfer

Optical data transmission is always serial. Before data transmission,

pending parallel data is always prepared for serial transfer and is

post-processed to a parallel form after the transmission. We also refer

to bit serial data transmission, as all of this data is always transferred

as digital signals.

Decibel

A decibel is the logarithmic ratio of two levels (e. g. input level to output

level). The unit of measure has no dimension and is specified in dB.

Degrees of protection

Protection of electrical equipment by housing, covers etc. Protection

of equipment against the ingress of foreign bodies and water.

DEL

Abbreviation for Deutsches Elektrolytkupfer für Leitzwecke (German

electrolyte copper for conduction) DEL is the stock market code for

99.5% pure copper in Euro/100 kg (see T17).

DEMKO

Abbreviation for Danmarks Elektriska Materialkontroll – Danish stand-

ards and testing body, testing and certification body, tasks similar to

VDE/UL.

Density

Ratio of the mass to the volume of a body. If the mass is M and the

volume is V, the radio is the density d = M/V.

Density unit

Result of the density of a body relative to the density of water (= 1).

Corresponds to the specific weight.

Designation label

Fixing elements with which single wires, bundles, cables and cables on

machine parts or walls can be permanently fixed in place. They are

transparent or coloured, usually made from nylon and can display

indelible information about their content.

DESINA

The Verein Deutscher Werkzeugmaschinenfabriken e. V. (VDW) [German

Machine Tool Manufacturing Federation] developed DESINA

(DEcen-

tralised and Standardised INstAllation technology), a comprehensive

overall concept for standardisation of electrical installation of equip-

ment and machinery. Colour codes of cables:

• Servo cable, screened: Sheath colour orange RAL 2003

• Cable for measuring systems, screened: Sheath colour green

RAL 6018

• Power cable, unscreened: Sheath colour black RAL 9005

• 24 Volt control cable, unscreened: Sheath colour grey

RAL 7040 (similar to 7001)

• Field bus hybrid cable, Cu and light waveguide:

Sheath colour violet RAL 4001

• Sensor/actuator cable, unscreened: Sheath colour yellow

RAL 1021

DeviceNet

Simple CAN-based communication system for networking of industrial

automation equipment (limit transmitters, photo sensors, motor start-

ers, frequency controlled drives, control terminals and similar) with

master control equipment. Two screened twisted pairs of conductors

within a cable are used as the transmission medium. One is used for

communication (with transmission rates of 125, 250 or 500 kBit/s for

cable lengths of 500 m, 250 m or 100 m) and the other to supply power

to the connected equipment (max. 8 A for 24 V DC voltage).

Dielectric

Dielectric refers to the characteristic of certain substances to be elec-

trically non-conductive – therefore insulating. Any electrically insulat-

ing material in which an external electrical field (e. g. between the

plates in a capacitor) builds up an opposing field is referred to as die-

lectric. A dielectric causes a static electrical field to be retained even

without a continuous supply of electric charge.

Dielectric constant (DC)

A material constant for a dielectric. The dielectric constant specifies

how many times greater the capacitance of the capacitor will be if the

insulating material is used as the dielectric instead of air. Multiplying

the DC of the empty space by the dielectric constant gives the DC of

the dielectric.

Diffusion

The primary cause of attenuation in a light waveguide. It is the result of

microscopic fluctuations in the density of the glass, which deflect part

of the guided light sufficiently from its course that it actually leaves the

light waveguide. With light wavelengths above 1600 nm, this effect is

very weak, however it increases at short wavelengths by the wave-

length to the power of four (Rayleigh dispersion).