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Add:Yongli Road NO.8, Guodian, Yanguan Town, Haining City, Zhejiang
Tel:+86-573-87681018
Fax:+86-573-87681018
Http://www.hn-yongli.com
Sales and Service:
ptc@hn-yongli.com
Technical Supports:
yl@hn-yongli.com |
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 PTC ThermistorsGeneral Information |
A PTC thermistor is a thermally sensitive semiconductor resistor. Its resistance value rises sharply with increasing temperature after a defined temperature (Curie temperature) has been exceeded. This feature makes them ideal for use in countless applications of modern electrical and electronic engineering, for example as resettable fuses against current overload or as shortcircuit protection in motors. You find special motor starter PTC thermistors in the compressors of refrigerators for instance. Thermal protection of motors and transformers is another example of the versatility of PTC thermistors. The applications extend to measurement and control engineering, to entertainment, household and automotive electronics, plus data systems and telecommunications of course. PTC thermistors are also suitable as self-regulating heating elements, in auxiliary heating, nozzle heating and carburetor preheating in automobiles, as well as in many domestic appliances such as door locks for washing machines, or glue guns and hair curlers.
Figure 1 shows the typical dependence of the zero-power resistance on temperature.
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| RR: |
Rated PTC resistance at room temp. |
| Rmin: |
Minimum resistance |
| TRmin: |
Temperature at Rmin |
| Rref: |
Reference resistance,Rref= 2.Rmin |
| Tref: |
Reference/Curie temperature (resistance value reaches Rref = 2.Rmin) |
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The properties of electrically loaded PTC thermistors (in self-heated mode) are better described by the I/V characteristic than by the R/T curve (see figure 2). It illustrates the relationship between voltage and current in a thermally steady state in still air at 25 °C, unless another temperature is specified.
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| Ir: |
Residual current at applied voltage Vmax(current is balanced) |
| Vmax: |
Maximum operating voltage |
| VR: |
Rated voltage (VRmax) |
| VBD: |
Breakdown voltage (VBD>Vmax) |
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| Fig.2 I/V characteristic of a PTC thermistor |
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