Normally open (NO) bimetallic thermal protector working principle Bimetal thermal protection device is normally closed and normally open type,They work the same principle,Just work the way it is the opposite.Bimetal thermal protection device is a double metal sheet as a protective element of the switch,When the heat generated by the electrical transmission to the bimetallic disc,Upon reaching operating temperature, the bimetal rapid action,Contact open or closed;When the temperature drops to the reset temperature setting,Bimetallic sheet quickly returned to its original state,The contact is closed or disconnected,To achieve the purpose of turning on or off the circuit,Thus protecting the electrical work. In the case of normal (no power) in the open state of the contact is called normally open contacts,In the closed state called the normally closed contact, In the contact closure (disconnect) process,Do not produce movement of the contact called static contact. (NO) often open, NO is English normally open abbreviation;When the test body is not detected,Load current is not connected to the output form (NC) normally closed, NO is the English regular close abbreviation;When the test body is not detected,Load current connected to the output form; While the normally open thermal protection,Is the normal work of electrical appliances,Bimetal is in disconnected state,Contact is open,When the temperature reaches the operating temperature,Bimetallic sheet heat quickly action,Connect the contact, turn on the circuit,Thus play a role in controlling the temperature.When the appliance is cooled to the reset temperature,Contact automatically disconnect,Electrical appliances return to normal working condition.Common KSD301, Ksd9700, there are often open and normally closed type.