Fuse Resistors serve a dual purpose, as a resistor and also a fuse. They are designed so that they will open with a large surge of current without any flame or other untoward incident.Fusible film resistors are generally used for lower power requirements and applications where the overload and surge handling requirements are not too severe. Many power supply and control circuits need a more robust resistor and safety fusible wire wound resistors fulfill that need of being able to withstand higher power, higher short-term pulses and higher temperatures.Further using Wire Wound technology over Film technology, one can design a safety fusible resistor which fuses instantaneously in fault condition of the circuit and the same technology can be used to tailor the fusing performance characteristics to match the design requirements of many different end products.
Fusible resistors made by utilizing the Film technology are basically constructed by depositing a film either Thick Film or Thin Film resistive film, onto a ceramic core. Various resistance values are obtained by cutting the film in a spiral pattern using either mechanical cutting wheel or laser.
Fusible Wire Wound Resistors are made by winding a precisely selected resistive wire around the ceramic cor. By varying the diameter, length, alloy of the wire and the winding pitch the properties of the fusible wire wound resistor can be precisely tailored for a particular application.
Looking to the very nature of the two different technology constructions, it is evident that in the case of the film technology when the film fusible resistor reaches its fusing voltage/current the resistive film fractures which results in a different resistive path mostly the resistance value increases greatly and this is considered a fused film resistor as due to the greatly increased resistance value, the current that can pass is negligible.
Contrary to the above the fusible resistor made using wire wound technology has the distinct advantage that since the resistive element is a resistance wire, once the wire fuses there is no chance of any voltage/current being able to pass. Hence a wire wound resistor which is fused acts as a more reliable safety device as once it is fused no current or voltage can pass which could damage other expensive and critical components on the PCB, this is not the case in fusible film resistors.
Typical applications of Fusible Wire Wound Resistors include electric power tools, utility meters, communications equipments, kitchen appliances among others.
HTR, ( an ISO/TS 16949 : 2009 company) offers Fusible Wire Wound resistors which are UL 1412 recognized and serve as a reliable dual purpose component, of being a resistor in normal working condition of the circuit and in being a fuse in fault conditions.
To this end we offer the following series.
The FRS series is suitable for those countries where the mains voltage is 2
20/240V and the HFW series is suitable for those countries where the mains voltage is 110/120V.