Contacts are divided into communication contacts (voltage ac) and current contacts (voltage dc), which are used in electrical, distribution and electrical settings. In the broad sense, a contact device means a magnetic field in industrial power, which uses the current of wires over currents, which closes the tentacles to the electrical engineering of electrical appliances that control loads, because of the rapid cut-off of communication and direct flow main circuits and the frequent connection and disconnection of large current control (up to 800a) circuits, so that electric motors are frequently used as control objects and can also be used to control electrical loads such as plant equipment, heaters, work carriers and various power units, not only to connect and disconnect electrical circuits, but also to protect against low voltage releases. The high control capacity of the contact point, which applies to frequent operations and remote control, is one of the important components of the automated control system。
In industrial appliances, the exposures are of many types and work currents range from 5a to 1000a and are of considerable use. The method of operation of the contact point is that, when the wire of the contact point is wired, the current of the wire creates a magnetic field, which causes the electro-magnetic insulation of the static core to attract the iron core and drives the point of contact point action of the contact point, the frequent contact point is disconnected and the frequent contact point is closed, and the two are connected. When the wire is out of power, the electromagnetic insulation disappears, the cortex is released as a spring of release, which restores the contact point, which is often disconnected and closed. The work of the straight-flow contacts is somewhat similar to that of the temperature switches。
