Which device would best be used to reduce chatter in a contactor?

The shading coil is the best choice for reducing chatter in a contactor. Chatter occurs when the contactor armature rapidly opens and closes due to insufficient torque or when the magnetic field is not stable. The shading coil is designed to create a phase shift in the magnetic field, helping to smooth out the operation of the contactor. By delaying the magnetic field in the shading coil, it provides more consistent and stable actuation of the armature, which reduces the likelihood of chatter and ensures that the contacts remain engaged longer without rapid cycling.

In contrast, other devices like auxiliary relays, latching relays, and seal-in contacts serve different functions. Auxiliary relays are typically used to extend the control capabilities of the main contractor and do not directly address the issue of chatter. Latching relays maintain their state without continuous power, which is useful for saving energy but does not mitigate chatter effects. Seal-in contacts help maintain relay state after the initiation signal is removed but do not actively reduce the rapid opening and closing phenomenon associated with chatter.