OVERHEAT PROTECTION DEVICE AND ELECTRICAL SYSTEM HAVING SAME

摘要

Disclosed is an overheat protection device which is capable of effectively preventing secondary batteries from overheating. An overheat protection device (20) comprises a variable resistor (11) wherein the resistance changes according to the temperatures and a switching device (15) for controlling the current according to the applied voltage. The variable resistor is thermally joined to a certain position of an electrical system (1), and the switching device (15) is arranged so that it controls the current flowing through the electrical system (1). When the certain position of the electrical system (1) is heated to a high temperature, the variable resistor (11) changes the voltage applied to the switching device (15) for cutting off the current flowing through the electrical system (1).