What happens to the arc created when contacts open in a medium-voltage motor starter?

When the contacts of a medium-voltage motor starter open, the arc created is indeed subjected to a magnetic field, which plays a crucial role in the arc's behavior. As the contacts separate, an electrical arc forms due to the ionization of the air between them. This arc generates a magnetic field that can interact with the arc itself.

The electromagnetic forces can influence the arc's path, causing it to be elongated or stretched. This phenomenon enhances the cooling effect on the arc since the movement through the magnetic field can help dissipate the heat more effectively. The arc may also be extinguished more efficiently as it is cooled and pushed away from the contact point.

This understanding of how arcs behave in an electrical context is essential for managing electrical systems safely, especially in medium-voltage applications where the potential for dangerous situations exists. Knowing that the arc is not instantly extinguished and is influenced by magnetic forces helps in implementing effective arc quenching and circuit protection strategies in motor starter designs.