Positive temperature coefficient
- Positive temperature coefficient
Positive Temperature Coefficient (PTC) refers to materials that experience an increase in electrical resistance when their temperature is raised. Materials which have useful engineering applications usually show a relatively rapid increase with temperature, i.e. a higher coefficient. The higher the coefficient, the greater an increase in electrical resistance for a given temperature increase.
This effect can be used to create resettable fuses, often as part of a semiconductor. As the temperature rises, nearing danger levels, the resistance increases, so less current flows, thereby protecting the vulnerable equipment that receives the current flow. These products often use electron beam processing in their manufacture.
Commonly used PTC materials include:
*High density polyethylene filled with a carefully controlled amount of graphite, so that the volume increase at the glass transition temperature causes the conducting particles to break contact (also known as Polyswitch fuses)
*Titanate ceramic materials, which work by grain boundary effects
PTC materials are sometimes used to make heating elements, as such elements act as their own thermostats, switching off the current when reaching their maximum temperature.
Wikimedia Foundation.
2010.
Look at other dictionaries:
positive temperature coefficient of resistance — teigiamasis temperatūrinis varžos koeficientas statusas T sritis radioelektronika atitikmenys: angl. positive temperature coefficient of resistance vok. positives Widerstandstemperaturkoeffizient, m rus. положительный температурный коэффициент… … Radioelektronikos terminų žodynas
positive temperature coefficient — (PTC) a thermistor (temperature sensor) whose resistance increases as the temperature increase. The opposite of a negative temperature coefficient (NTC) thermistor … Dictionary of automotive terms
positive temperature coefficient — noun : a larger than 1 ratio of a quantity (as resistance or length) at a higher temperature to the corresponding value of the quantity at a lower temperature … Useful english dictionary
positive temperature coefficient thermistor — (PTC) Electronic thermistor which increases in resistance as temperature increases … Dictionary of automotive terms
Temperature coefficient — The temperature coefficient is the relative change of a physical property when the temperature is changed by 1 K. In the following formula, let R be the physical property to be measured and T be the temperature at which the property is… … Wikipedia
Negative temperature coefficient — A negative temperature coefficient (NTC) occurs when the thermal conductivity of a material rises with increasing temperature, typically in a defined temperature range. For most materials, the thermal conductivity will decrease with increasing… … Wikipedia
Coefficient de température négative — Thermistance Les principaux capteurs de température utilisés en électronique sont basés sur la loi de variation d’une résistance. Ces éléments ne suivent pas la loi d’Ohm : ce sont des résistances non linéaires. Thermo résistances :… … Wikipédia en Français
coefficient positif de température de résistance — teigiamasis temperatūrinis varžos koeficientas statusas T sritis radioelektronika atitikmenys: angl. positive temperature coefficient of resistance vok. positives Widerstandstemperaturkoeffizient, m rus. положительный температурный коэффициент… … Radioelektronikos terminų žodynas
Coefficient of variation — In probability theory and statistics, the coefficient of variation (CV) is a normalized measure of dispersion of a probability distribution. It is also known as unitized risk or the variation coefficient. The absolute value of the CV is sometimes … Wikipedia
coefficient — 1. The expression of the amount or degree of any quality possessed by a substance, or of the degree of physical or chemical change normally occurring in that substance under stated conditions. 2. The ratio or factor that relates a quantity… … Medical dictionary
