| 摘要 |
A device for protecting against excess current comprises a positive temperature coefficient (PTC) device and a tension spring connected by a solder joint adjacent the PTC device. Electrical current passes in series through the spring and the PTC device. Under normal operating conditions, the PTC device is in thermal equilibrium with its surroundings. If the current rises to a fault condition, the power dissipated in the PTC device increases rapidly and the temperature rises to cause melting of the solder joint. Because of the very rapid temperature rise, substantially immediate isolation is assured through the solder joint. |
