Current-Carrying Capacity (CCC)

and Heating of Electrical Devices


Devel­op­er and design­ing engi­neers of switchgears and equip­ment in the field of low, medi­um and high volt­age tech­non­o­gy are intro­duced into a method, with which they can dimen­sion their equip­ment in terms of mate­r­i­al input, cur­rent car­ry­ing capac­i­ty and heat­ing. It will be shown, how ther­mal weak spots in the design can be eas­i­ly detect­ed and elim­i­nat­ed in the con­struc­tion with­out ahv­ing to car­ry out effort­ful devel­op­ment test­ings. The pos­si­ble cur­rent car­ry­ing capac­i­ty can be cal­cu­lat­ed depend­ing on the envi­ron­men­tal con­di­tions, the per­mis­si­ble tem­per­a­ture of the cur­rent path, the design of the sur­faces of the cur­rent path and the insu­la­tion, the encap­su­la­tion and the load by the pow­er of the sun and sky radi­a­tion at out­door devices. The design­ers and installers of the plants of elec­tri­cal pow­er sys­tems are intro­duced to a method and a pro­gram with which they can opti­mal­ly dimen­sion the cur­rent path of the plants depend­ing on the require­ments of the cus­tomer with regard to envi­ron­men­tal con­di­tions and cur­rent load. This enables the oper­a­tors to mak ere­li­able dsci­sions on the cur­rent load of the plants, which is pos­si­ble at this moment, depend­ing on the envi­ron­men­tal con­di­tions and the pre­load­ing of the plants with­out exceed­ing lim­it tem­per­a­tures. By using the ther­mal net­work method, time-con­sum­ing and cost­ly heat­ing tests can be reduced to a min­i­mum or even saved.


  • intro­duc­tion to the prob­lems of the cur­rent car­ry­ing capac­i­ty and warm­ing of an elec­tri­cal equipment

  • cal­cu­la­tion of the cur­rent car­ry­ing capac­i­ty of a infinete long and homo­ge­neous con­duc­tor with the heat bal­ance equa­tion (e.g. cables, bus­bats, over­head line)

  • cal­cu­la­tion of the rat­ed cur­rent car­ry­ing capacity

  • cal­cu­la­tion of the short cur­rent car­ry­ing capacity

  • cal­cu­la­tion of the cur­ryent car­ry­ing capac­i­ty with the ther­mal net­work method

  • con­struc­tion of ther­mal net­works for dif­fer­ent equipment

  • con­struc­tion of ther­mal net­works for equip­ment in low, medi­um and high volt­age engineering

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