Models of a cable bunch formed by twisted three-phase cables

We investigate the magnetic field of a bunch of twisted three-phase cables of finite length which are statistically ordered with respect to their installation angles. After deriving integral expressions for the magnetic induction of a single three-phase cable a specific model is proposed which requires no integration. As results of statistical investigations we show that the field of a cable bunch consisting of a sufficient number of cables can be expressed with adequate accuracy by the reduced field of a single cable which leads the overall current of the bunch.