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High frequency line trap

QuickField simulation example

An example of the calculation of the forces and mechanical stresses for the high-frequency line trap at the short circuit current.

Problem Type
Axisymmetric multiphysics problem of AC magnetics coupled to Stress analysis.

Geometry
High frequency line trap Calculation of the forces and mechanical stresses for the high-frequency line trap at the short circuit current. Fiberglass Aluminum wire(20 mm²) 468 mm Ø700 mm

Given
Current (peak value) I = 12 kA, frequency f = 50 Hz.
Aluminum cable cross-section area A = 2 cm², conductivity σ= 37 MS/m;
Young's modulus E = 70 GPa, Poisson's ratio ν = 0.34.

Fiberglass case Young's modulus E = 20 GPa, Poisson's ratio ν = 0.11.

Task
Determine forces and mechanical stresses in the high-frequency line trap body.

Solution
The actual spring-coil is modelled as a set of circular turns embedded in a fiberglass case. That facilitates 2D axisymmetric simulation.
The solution consists of two stages: the calculation of forces in a AC Magnetic problem, and then the calculation of mechanical stresses in a mechanical problem. The transfer of forces from AC Magnetic problem to mechanical one is automated using the coupling mechanism.

Results
Current density distribution in the aluminum cable:
line trap Lorenz force distribution

Mechanical stress in the aluminum cable, wave trap deformed shape (zoomed 1000:1) and Ampere force value acting on the ending turn:
wave trap mechanical stress

*Reference: Line trap in Wikipedia.