Polymer Resettable Fuses
These resettable fuses are polymeric positive temperature coefficient (PPTC) device, which is used to help protect against harmful overcurrent surges and overtemperature faults. Like traditional fuses, these devices limit the flow of dangerously high current during fault conditions. However, the fuse resets after the fault is cleared and power to the circuit is removed.
- The PPTC operates like a resistor.
- During normal operations it has a resistance of only 0.07 Ohm.
- During a fault condition resulting in excessive current its resistance will become very high.
- When the fault has been rectified and the fuse cools down, the resistance returns to its normal level.
- Typical use; protecting Feedback 3-phase transformer training panel (below) from damage due to accidental overload or connection short.