Optional elements of the thermistor

Thermistors are typically characterized by temperature sensitivity and exhibit different resistance values at different temperatures. The positive temperature coefficient thermistor (PTC) has a higher resistance value at higher temperatures, and the lower the resistance value of the negative temperature coefficient thermistor (NTC) at higher temperatures, they belong to the semiconductor device.

1) The large operating current of the NTC thermistor > the operating current of the actual power circuit.

2) The nominal resistance value of the power type thermistor R≥1.414*E/Im where E is the line voltage Im is the surge current for the conversion power supply, the inverter power supply, the switching power supply, the UPS power supply, Im=100 times work Current for the filament, heater, etc. Im = 30 times the operating current.

3) The larger the B value, the smaller the residual resistance and the smaller the temperature rise during operation.

4) Generally speaking, the larger the product of the time constant and the dissipation coefficient, the greater the heat capacity of the resistor and the stronger the ability of the resistor to suppress the inrush current.

In addition to the optional elements mentioned above, the use of the thermistor is also very important, and the environment also determines the longevity of the resistor. Therefore, as a technician, you should pay more attention to the use and avoid unnecessary trouble.