Structurally, vacuum relays can be classified into two major categories:
Exhaust-Type Structure
The defining characteristic of this type is the presence of an exhaust tube, necessitating the use of a vacuum exhaust station to evacuate the air. The armature actuation mechanism is situated *inside* the vacuum system; the electromagnetic force generated by control current flowing through the coil causes a hinged armature-located within the vacuum-to move. This movement drives the movable contact, thereby executing the switching (opening or closing) operation.
Diaphragm-Type Structure
The key feature of this design is that it requires no separate evacuation process, as the vacuum environment is established directly within a vacuum brazing furnace. In this configuration, the armature mechanism is located *outside* the vacuum chamber, and the motion of the armature is transmitted into the interior of the vacuum chamber via a flexible sealing diaphragm.