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Multiphysics Simulation: An IEEE Spectrum Insert
Manager’s Guide

How Reclosers Ensure a Steady Supply of Power: It’s All in the Magnet

O. Craciun, and colleagues
Ladenburgh, Germany

When a tree branch touches overhead cables and causes a momentary short circuit, your lights may flicker. A device called a recloser ensures that power to your home is not cut off for a longer period.

ABB AG, a leading manufacturer in power technology, is working towards designing a more reliable recloser. One objective in this design process was to optimize the size of the permanent magnet while ensuring excellent switching properties.

To do this, ABB AG created a 2D simulation using the AC/DC Module and calculated the magnetic flux density. Next, they used the electrical circuit feature to couple the actual power amplifier schematic and component values to the magnetic simulation. Finally, the results were fed into optimization software to select the appropriate size magnet and imported back into COMSOL Multiphysics software using LiveLink™ for MATLAB® to verify the design in a 3D model.

A recloser consists of a single-coil actuator, supplied with current from a power amplifier control circuit, and a permanent magnet. The magnetic field generated by the coil must overcome the force of the permanent magnet in order to switch the circuit from open to closed or closed to open.