The concept certainly predates Lindsay’s 1965 Patent that matches the magnetic
mechanism to the vacuum interrupter. The magnetic actuator is a flux-transfer
system; one embodiment is illustrated in Figure.
It consists of a chamber made from a magnetic material (usually steel), inside which
an armature resides also made of magnetic material.
Two coils are placed inside this housing, one at the top and one at the bottom.
Halfway down the inside surface of the chamber, a high-permeability magnetic
material is placed. The housing and/or the armature may have a laminated
structure.
The upside rest position is shown in Figure a.When a current usually supplied by a
charged capacitor is discharged through the lower coil (Coil 2),Figure b, the
magnetic flux transfers to the lower path shown.
The force on the armature is now such that it begins to move down. Figure c shows
the armature in the lower position. To move the armature back to the upper
position, a current pulse is passed through the upper coil (Coil 1), Figure d,which
transfers the magnetic flux to the upper position.
