Power Thermistors

  • Semitec offers both current (Power Thermistor) and voltage surge absorbers (Metal Oxide Varistors). The Power Thermistor is an NTC thermistor device used for suppressing inrush current to an electrical circuit. Applications include; power supplies, lighting, heaters and fan motor speed control. MOV are transient/surge absorbers featuring large surge current handling capability and energy handling capability for absorbing transient overvoltage. The D series achieves this in a compact size. Semitec MOV feature a wide product range for transient/surge protection from AC 100V- AC 480 V with peak current ratings from 600amps to 7000amps.


  • D2 Series Power Thermistor

    The D2 thermistor, also known as Inrush Current Limiters, are among the most common design options used in switching power supplies to prevent damage caused by inrush current surges. A thermistor is a thermally-sensitive resistor with a resistance that changes significantly and predictably as a result of temperature changes. The resistance of a Surge Limiting thermistor decreases as its temperature increases. As the inrush current limiter self-heats, the current begins to flow through it. Its resistance begins to drop and a relatively small current flow charges the capacitors in the power supply. After the capacitors in the power supply become charged, the self-heated inrush current limiter offers little resistance in the circuit. So low, that the voltage drop is an insignificant factor with respect to the total voltage drop of the circuit. Semitec inrush current limiters are available in a wide range of initial resistance levels and current carrying capabilities.