Calculation of Cable Diameter

Our customer required a cable system to connect several electrical subsystems. Their supplier had given them a quote based on the specification. This was too expensive due to requirements “from above”.

The standard approach for reducing cable costs is to reduce the diameter and therefore the mass of copper. Technically this is only possible if:

  • The maximum temperature is increased
  • The safety factors are reduced
  • The external cooling is improved
  • By considering the maximum period of current loading, it was shown that the temperature peak was not reached.

The standard “IEC 60287-3 Electric cables” only gives very imprecise specifications on this.

Wenger Engineering GmbH was asked to carry out simulations of the load profile and the heat transferred due to the real installation situation. It was still important to reliably adhere to the specifications in IEC 60287-3.

We implemented all the properties and boundary conditions in COMSOL Multiphysics, coupled the current-time series to the partial differential equation system and calculated the cases through.

The result was that, under these special conditions, the ampacity of the cable could be increased by almost 20% with regard to IEC 60287-3. To put it another way: Thanks to focused consideration and calculation, the specific costs could be reduced by almost 20% – calculated across the whole project this resulted in a saving of millions of euros.

 

2012-09-04_EP_dreiadrig_Temp