Usually open contact is also called dynamic contact, refers to the initial condition, the electrical equipment is not subjected to external force, fixed contact and movable contact can also be in a separate situation under the contact.
Normally closed contact is also called dynamic breaking contact, refers to the electrical equipment in the initial situation will not be affected by external force of the fixed contact and movable contact in a closed case.
Usually open the metal button switch, in the case of no press, the contact is broken, when the thick contact will be closed and connected, after loosening the metal button switch will be reset and broken under the action of the reset spring. In the control circuit, metal Push Button Switches are also used to start motors, and are therefore also called start buttons.
Normally closed metal button switch is exactly the opposite of the long open switch, without pressing the condition, the contact remains closed, when pressed will be reset and closed under the action of the reset spring. Normally closed button is often used to control motor shutdown, so it is also called reset button.
Finally, there is the compound Metal Push Button Switch, which is a combination of normally open and normally closed metal push button switches, with normally closed contact and normally open contact. When not pressed down, normally closed contact is closed, and normally open contact is broken. When the button is pressed, the normally closed contact will automatically break, and the normally open contact will close. We can feel that this is a self-locking button. When the button is released, the metal Push Button Switch breaks off the normally open contact and closes the normally closed contact under the action of the reset spring. This metal pushbutton switch is often used in interlocking control circuits.
