Overview
Closeup |
The large capacity switching gear indicated in the figure produces electrodynamic
repulsion force by the current flowing in the contacts during excitation.
Therefore, the contact stress needs to be larger than the electrodynamic
repulsion force produced by the maximum excitation current.
This example presents the use of a magnetic field analysis to obtain the
electrodynamic repulsion force of a switching gear from the Lorentz force
when a short-circuit current of 100 kA is applied. |
Current Density Distribution
| The current density distribution is indicated in Fig. 1, 2 and 3. The current
flowing into the support conductor of the lower electrode branches in the
coil as indicated by (a) and flows to the contacts through the contact
points between the contacts. The current flowing in the contacts concentrates
at the contact points as indicated by (b). The current flowing through
the small contacts tries to expand when flowing into the contacts of the
upper electrode as indicated in Fig. 3. |
Closeup |
Closeup |
Closeup |
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Lorentz Force Density Distribution/Electromagnetic Force
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The Lorentz force density distribution is indicated in Fig. 4. A force
repelling from top to bottom is produced in the contacts by the flowing
current, as indicated in Fig. 3.
A 724 N electrodynamic repulsion force is produced in the contacts. |
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