PTC resettable fuses are a step-up from one shot fuses. When a short circuit occurs, they heat up and transition from a low resistance state to a high resistance state. Allowing them to cool down (typically by removing the power) resets them to the low resistance state.
Q. How do I choose a PTC fuse?
Choosing the Correct PTC Resettable Fuse
Table of Contents
- Determine your circuit’s parameters.
- Select a PTC resettable fuse.
- Compare ratings.
- Determine time-to-trip.
- Verify your operating temperature range.
- Verify fuse dimensions and mounting style.
Q. When would you use a PTC fuse?
A PTC resettable fuse is a protection device only intended to operate during overcurrent and/or overtemperature events that are not normal operation and are generally undesired conditions. They are not intended to be a switch that operates numerous times in normal operation.
Q. What does PTC Fuse stand for?
Positive Temperature Coefficient
Q. What is holding current in PTC?
Hold-current means a maximum current value which can be flowed in normal operation. And, Trip-current indicates a minimum current value which is necessary for PTC device to move to high-resistance state.
Q. What does a PTC thermistor do?
With PTC thermistors, resistance increases as temperature rises; usually due to increased thermal lattice agitations particularly those of impurities and imperfections. PTC thermistors are commonly installed in series with a circuit, and used to protect against overcurrent conditions, as resettable fuses.
Q. How do I check my PTC thermistor?
Testing a PTC thermistor follows all the same steps as a NTC thermistor. First check, with an ohmmeter, the thermistor without any heat applied. With a PTC thermistor at room temperature or below, the thermistor should measure a very low resistance. Now apply heat, just like before, to the thermistor’s body.
