... Time Constant (τ) and Thermal Dissipation Constant (d) .The WMF21 series NTC thermistors has so wide application area, which is mainly used ... , CFL, Ballast, Circuitry of Power Supply, etc.WMF21 series NTC thermistors are used for limiting the Inrush Current in the ... Constant (τ) and Thermal Dissipation Constant (d) .The WMF21 series NTC thermistors has so wide application area, which is mainly used ...