An isolated relay can have more than one pole and can have normally closed contacts as well as normally open contacts.
2.
When the normally open contacts of both switches close, electricity is able to flow to the motor which opens the door.
3.
For example, the boolean AND function is realised by connecting normally open relay contacts in series, the OR function by connecting normally open contacts in parallel.
4.
Change-over ( CO ), or double-throw ( DT ), contacts control two circuits : one normally open contact and one normally closed contact with a common terminal.
मोबाइल