Question

What is the principle of PTC sensor?

Answer 1

A PTC (Positive Temperature Coefficient) sensor works on the principle that the resistance of certain materials increases as their temperature increases.

Here's a simple explanation:

1. Material Choice: PTC sensors are made from materials that have a positive temperature coefficient. This means that as the temperature of the material rises, its electrical resistance increases significantly.
   

1. Behavior of PTC Materials: At low temperatures, the resistance of the material is relatively low, allowing current to pass through easily. But as the temperature increases, the material’s resistance increases sharply. This happens because the atoms in the material vibrate more as they gain heat, making it harder for electrons (which carry current) to pass through.
   

1. Self-regulation: The most interesting feature of PTC sensors is that they can regulate current flow. When the temperature goes up, the resistance increases, which reduces the current. In many cases, this behavior is used to protect circuits from overheating. If the current gets too high (because of an over-temperature situation), the PTC resistance increases, and the current flow drops to a safe level.
   

Applications:

1. Overcurrent protection: In power circuits, when the temperature rises (indicating possible overcurrent), the PTC sensor increases its resistance and limits the current flow, helping to prevent damage.
   

1. Thermal protection: In devices like motors, PTC sensors can prevent overheating by limiting current once a certain temperature threshold is crossed.
   

  
So, in short, a PTC sensor is a type of thermistor that changes resistance in response to temperature changes, and it is often used for safety purposes, like preventing overheating in electrical circuits.