Overview
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Electromagnetic repulsion is generated in small contact bridges, such as
contact terminals of switches or resistance heating in electrical equipment.
It is advantageous to investigate the size of the electromagnetic repulsion
when designing a device, or to understand the phenomena that is actually
occurring.
This example presents the use of a magnetic field analysis to obtain the
electromagnetic repulsion when a switch is closed creating a contact bridge. |
Current Density Distribution/Lorentz Force Density Distribution/Electromagnetic
Repulsion
The current density distribution and the Lorentz force density distribution
for the cross-section of the contact terminal in the length direction with
a current of 10 kA indicated in Fig. 1 and Fig. 2 and the current characteristics
of the electromagnetic repulsion indicated in Fig. 3 are obtained by analyzing
the analysis target described in Section 2.
As the current flows from the contact bridge to the contact terminal, the
current density in the contact bridge increases because the current flows
from the narrow contact bridge to a wider contact terminal causing the
current to spread radially throughout the entire contact terminal around
the contact bridge. Therefore, a strong Lorentz force is produced repelling
the contact terminals in the length direction. This electromagnetic repulsion
increases as the current increases, as indicated in Fig. 3. |
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