Fusibili resettabili PTC

When a fuse burns out, it has to be replaced before the protected equipment can be restored into operation. Unfortunately, this isn’t always possible.
Technology advancement has provided us with an alternative—a resettable fuse, or more appropriately, an automatically resetting fuse. The polymer PTC fuse tolerates the normal rated current graciously, but when the current starts increasing beyond ‘tolerable’ levels (trip current), it heats up and fights back furiously. The increased heat very quickly raises its resistance, not manifold, but by many orders of magnitude. This reduces the current to a very small level. Depending on the circuit design, this may take milliseconds to many seconds. The fuse cools down and comes back to its initial mood of tolerance, or reset, automatically. Provided the current overload has been removed, this restores equipment operation.
The PTC resettable fuse is not meant for high power. Current ratings of up to a few tens of amperes and voltage ratings of up to few tens of volts are feasible.
The ceramic PTC thermistor has similar behavior, but the resistance variation is not as fast. Continua a leggere Meno informazioni