PTC thermistor
A thermistor is a material whose resistance varies with temperature. The thermistor is broken down into two types, NTC (negative temperature coefficient) thermistor and PTC (positive temperature coefficient) thermistor, in view of its temperature coefficient. The NTC thermistor is a material which has a negative temperature coefficient and whose resistivity decreases with increasing temperature, and is applied in the form of a temperature sensor to temperature compensation elements, etc. A thermistor having a positive temperature coefficient (PTC thermistor) is known as one of the overcurrent protective devices. The PTC thermistor is on the other hand a material which has a positive temperature coefficient and whose resistivity increases sharply at a certain specific temperature. PTC thermistors increase their resistivities within a particular temperature range in the vicinity of their ferroelectric Curie temperature. Exposure to overcurrent in an electric circuit causes the conductive polymer sheet inside a PTC thermistor to heat up and expand. This thermal expansion of the conductive polymer sheet increases the resistance of the PTC thermistor and thus reduces the current to a safer level. PTC thermistors have been used as an overcurrent protection element. When an electric circuit gets overloaded, conductive polymers of a PTC thermistor, which have PTC properties, emit heat and thermally expand to become high resistance, thereby reducing the current in the circuit to a safe small current level. The PTC thermistor includes a conductive polymer in which conductive particles are filled in a crystalline polymer, and a pair of electrodes that are arranged on both surfaces of the conductive polymer. Various PTC thermistors have long been used as protective circuit elements for protecting circuit component parts from the overcurrent. Of these various PTC thermistors, organic PTC thermistors are well known and comprise a thermistor element made from electroconductive particles such as those of carbon black or any other metal, mixed into synthetic resin of a polyolefin system. An organic positive temperature coefficient thermistor can be used as a self-regulated heater, an overcurrent-protecting element, and a temperature sensor.
PTC thermistor product listings
ZMZ31 series of PTC Thermistor are applicable to various types of fluorescent lamp, electronic ballast and electronic energy-saving lamp. ZMZ6 series as a temperature indicator is small in size and little in calorific capacity.
PTC thermistor heating elements are used wherever measurement and regulating equipment as well as heating devices must be housed in tight confines.
Linear PTC thermistor resistance increases with the temperature rises in linearity, displays a virtually linear temperature coefficient over their entire temperature range, suitable in measurement and control system, temperature compensation.
PTC (positive temperature coefficient) thermistor switches at one particular temperature. PTC thermistor protect such equipment and components as motors, transformers, power transistors and thyristors against over-temperature.
This series of ceramic PTC thermistors help provide protection against power cross, power induction surges and lighting surge defined in ITU, Telcordia, UL.
PTC thermistor
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