Carl Emil Krarup

Infobox Scientist
box_width =
name = Carl Emil Krarup


image_size =
caption =
birth_date = 1872
birth_place = Copenhagen, Denmark
death_date = 1909
death_place =
residence = Copenhagen
citizenship =
nationality = Danish
ethnicity =
fields = Engineering
workplaces = Danish Telegraph Administration
alma_mater =
doctoral_advisor =
academic_advisors =
doctoral_students =
notable_students =
known_for = Continuously loaded cable
author_abbrev_bot =
author_abbrev_zoo =
influences =
influenced =
awards =
religion =


footnotes =

Carl Emil Krarup (1872–1909) was a Danish telegraph engineer who is chiefly known for the invention of a kind of loaded cable, eponymously called Krarup cable, which made improvements in the transmission of telephone signals, especially on submarine cables.

Career

Krarup was originally a civil engineer. He was in charge of public works in Copenhagen until 1898 when he joined the Danish Telegraph Administration. In 1901 he conducted research at the University of Würzburg in Germany on loaded lines. Returning to Denmark he continued the theoretical work at the University of Copenhagen and published a paper in 1902.Huurdeman, p 321]

Krarup cable

Krarup cable is a method of loading lines to reduce their distortion. All methods of loading add series inductance to the cable to try to compensate for the shunt capacitance which in most practical cables is too high to meet the Heaviside condition for no signal distortion. Krarup cable consists of iron wires wound tightly around the copper conducting cores and it is the iron that is the source of the additional inductance. However, it still does not have sufficient inductance to fully meet the Heaviside condition. Its construction also makes it expensive compared to the previously existing method of adding discrete loading coils at intervals along the cable. Against this, Krarup cable is lighter and easier to lay. The weight of early submarine cables using loading coils could cause excessive stress in the cable if not handled carefully. Additionaly, Krarup cable has none of the problems of sealing the joins against seawater which was a major problem with loading coils before modern polymers began to be used.

For these reasons, Krarup cable was popular on shorter distances, where the capacitance was not so high that loading coils had to be used, until the advent of permalloy cable superseded it. [Huurdeman, p 314] The first cable to be laid with Krarup cable, indeed the first cable to be laid with any kind of continuous loading, was between Helsingør (Denmark) and Helsingborg (Sweden) in 1902. This cable was engineered by Krarup himself.

Notes

References

*Huurdeman, AA, "The worldwide history of telecommunications", pp 321–322, Wiley-IEEE, 2003