Patent ID: 6133819
Filing Date: 2000-10-17
Classification: H01C

Abstract:
A load dependent preventive fuse and monitored device for monitoring a fixed period of time, comprising:a ceramic time dependent resistor body having an electrical resistance that initially has a first high resistance value, the electrical resistance changing from the first high resistance value to a second lower resistance value dependent upon an accumulated period of time during which a DC voltage is applied across the ceramic body, the accumulated period of time depending upon the value of the DC voltage and the temperature of the ceramic body;connection leads coupled to the ceramic body for applying a DC voltage across the ceramic body during said fixed period of time,means for sensing a change in resistance of the ceramic time dependent resistor body to the second lower resistance value,a housing which contains at least said ceramic time dependent resistor body; anda heating element in thermal contact with the ceramic time dependent resistor body whereby the heating element maintains the ceramic body at a constant temperature.