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Main >> Applications >> Sample problems >> Shielded busbars

Shielded busbars

QuickField simulation example

A three phase shielded busbar carries alternating current. The busbar conductor consists of 2 halves. This simulation example is prepared by Dr. Ioan Popa as a part of the webinar Analyse d'un système de jeux de barres blindés à l'aide du logiciel QuickField.

Problem Type
Plane-parallel multiphysics problem of AC Magnetics coupled to Heat transfer.

Geometry
Shielded busbars Calculate the dependence of the busbar losses on the alternating current frequency. A B C Shield 400 mm 1250 mm Ø960 mm

Given
Material of the busbar and shields is aluminum. Aluminum electrical resistivity is 0.0265 Ohm*mm²/m, temperature coefficient is α=0.00429 1/°C.
AC current I = 10 kA (r.m.s. value), frequency f = 50 Hz.

Task
Calculate the forces and Joule heat in busbars and shields. Calculate the temperatures.

Solution
As the conductors resistance depends on the temperature we specify the electrical conductivity at the anticipated temperatures: 80° for bars and 50° for shields.
In thermal problem we cannot simulate the motion of the air. We exclude the air from the model and specify convection boundary condition on conductor surfaces.

Results
Current in the shield is 14.3 kA (magnitude), Joule heat loss is 203 W per 1 meter of shield length. Force acting on a busbar half conductor is 14.7 N per 1 meter of conductor length, Joule heat loss is 108 W.
Shielded busbars current density distribution

Reference
Ioan Popa, Marian Ciontu, Alin-Iulian Dolan. QuickField Analysis of a Three-Phase Encapsulated Busbars System. Annals of the University of Craiova, Electrical Engineering series, No. 37, 2013; ISSN 1842-4805.