Search results
Results from the WOW.Com Content Network
A positive-temperature-coefficient heating element (PTC heating element), or self-regulating heater, is an electrical resistance heater whose resistance increases significantly with temperature. The name self-regulating heater comes from the tendency of such heating elements to maintain a constant temperature when supplied by a given voltage.
Resettable fuses - PolySwitch devices. A resettable fuse or polymeric positive temperature coefficient device (PPTC) is a passive electronic component used to protect against overcurrent faults in electronic circuits.
[1] NTC thermistors are widely used as inrush-current limiters and temperature sensors, while PTC thermistors are used as self-resetting overcurrent protectors and self-regulating heating elements. An operational temperature range of a thermistor is dependent on the probe type and is typically between −100 and 300 °C (−148 and 572 °F).
Another type of thermal switch is a PTC (Positive Temperature Coefficient) thermistor; these thermistors have a "cutting off" temperature at which the resistance suddenly rises rapidly, limiting the current through the circuit. When used in conjunction with a thermistor relay, the PTC will switch off an electrical system at a desired temperature.
NTC thermistors can be used as inrush-current limiting devices in power supply circuits when added in series with the circuit being protected. They present a higher resistance initially, which prevents large currents from flowing at turn-on. As current continues to flow, NTC thermistors heat up, allowing higher current flow during normal operation.
With the PC industry rising from the 1980s in Taiwan, its NTC thermistor is adapted as the inrush current limiter in switched-mode power supply to suppress the inrush current when power supply turns on, and the varistor protects the circuit from damaged by surge current occasionally occurred in the electricity network.
PTC ceramic elements: PTC ceramic materials are named for their positive thermal coefficient of resistance (i.e., resistance increases upon heating). While most ceramics have a negative coefficient, these materials (often barium titanate and lead titanate composites) have a highly nonlinear thermal response, so that above a composition ...
Here α has the dimension of an inverse temperature and can be expressed e.g. in 1/K or K −1. If the temperature coefficient itself does not vary too much with temperature and α Δ T ≪ 1 {\displaystyle \alpha \Delta T\ll 1} , a linear approximation will be useful in estimating the value R of a property at a temperature T , given its value ...