Research On Inductive Potential And Loss Of Cables In Trefoil Formation

With the wide application submarine cables in trefoil formation,the calculation of the induced potential and loss of cable metal sheaths in the adjacent state has become an important research topic in the cable industry.It is difficult to obtain the inductive potential distribution of the metal sheath in the adjacent state by considering the cable metal sheath as a simple equivalent circuit established by the indiscriminate whole,and it is impossible to accurately calculate the loss of the metal sheath in the adjacent state.It is assumed that the "wire" of the metal sheath can be used to obtain the induced potential of the metal sheath at different positions.On the basis of this,the equivalent circuit can be used to explain the loss generation principle of the cable metal sheath under different grounding modes.When the cable core adopts a structure such as a split conductor that can suppress the adjacent effect of the core,the adjacent effect loss in the metal sheath is not negligible,and this effect is more apparent as the laying pitch is reduced.The metal sheath loss formula of the equidistant triangular laying cable derived from the simple circuit model has a certain calculation error in the adjacent state.This error gradually decreases with the increase of the laying pitch.Therefore,the loss calculation potential must be determined in the adjacent state.Correction.Using the physics simulation technology to establish two-dimensional and thre×10dimensional models respectively,the general law of the adjacent effect loss and eddy current loss with the installation spacing can be obtained.IEC-60287;2006 provides a correction factor for the increase of sheath loss due to the reinforcing effect of ferromagnetic materials on the thre×10core cable armored or laid in steel pipes.However,the method is still analyzed.There is a certain inapplicability.The residual error of the modified calculation method can be analyzed by the finite element method,and the influence of the armor structure and parameters on the loss of the metal sheath can also be explored.Establish a complete thre×10core cable model,set reasonable environmental factors,use electromagnetic-thermal coupling to calculate the maximum temperature of the insulation layer under a certain core current,and repeatedly calculate the cable to allow the insulation to allow the highest long-term use temperature.Core current,which is the cable current carrying capacity at this condition of use.