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How to judge whether the PTC thermistor is reliable or damaged

2014-05-03

Do you know how to judge whether the PTC thermistor is reliable or damaged)?

Use a multimeter to measure the Resistance,see if resistance rises when temperature rising, and see if the resistance meets the specification requirements.And also can use test method of  large current shocking to measuring the resistance etc.

There's two main indicators to measure the reliability of PTC thermistor:

A.voltage withstanding ability- in excess of the rated voltage can result in PTC thermistor short circuit breakdown,applying high voltage can eliminate products with low voltage withstanding ability,which can ensure that the PTC thermistor is safe under maximum working voltage (Vmax) ;
B, current withstanding ability-in excess of the rated current or frequency switch can lead to  unrecoverable high impedance staute and failure of PTC thermistor, circle on-off test cannot eliminate all the early failure products.

Under the specified use conditions, thermal resistor shows a high resistance status after failure.Apply voltage on PTC thermistor long term (generally more than 1000 hours) may lead to the tiny range increasing of its normal temperature resistance, PTC heating element with Curie temperature over 200 ℃ is obvious relatively.

In addition to the PTC heating element,the main reason of the PTC thermistor failure is due to stress cracking produced by switching operation in ceramic body center.In the process of PTC thermistor action, the temperature, resistivity,electric field and uneven distribution of power density inside the PTC ceramic heating element can result in big center stress cracking and stratification.

The PTC Heaters produced by DXM have stable performance, you can contact with DXM's sales and markeing for more details accordingly.