The resettable fuse is a heat-sensitive semiconductor material. The sensitivity itself is not high. If the sensitivity is not considered, it can be used. The main parameter of the fuse is the fusing current. As long as the withstand voltage exceeds the voltage in the actual circuit, it will be fine. For example, we often Glass tube fuses generally have a withstand voltage of 250VAC, but in actual application, whether it is AC or DC, whether 220V or 12V, it is the same. What you need to consider is whether the fusing current is highly sensitive or needs to be broken quickly. The fuse is that the resettable fuse is a slow-blow type fuse. The material of the resettable fuse generates heat after being energized. When the current is too large and the heat reaches a certain level, the material will no longer conduct electricity. This is the same as ordinary fuses, except that Ordinary fuses only blow once. Resettable fuses are composed of specially treated polymer resin (Polymer) and conductive particles (Carbon Black) distributed inside. Under normal operation, the polymer resin tightly binds the conductive particles outside the crystal structure, forming a chain-like conductive path. At this time, the resettable fuse is in a low resistance state (a), and the current flowing through the resettable fuse on the line generates The heat energy is small and will not change the crystal structure. When a line is short-circuited or overloaded, the heat generated by the large current flowing through the resettable fuse melts the polymer resin, and the volume grows rapidly, forming a high-resistance state (b), and the operating current decreases rapidly, thereby limiting and protecting the circuit. When the fault is eliminated, the resettable fuse re-cools and crystallizes, shrinks in volume, and the conductive particles re-form a conductive path. The resettable fuse returns to a low-resistance state, thus completing the protection of the circuit without manual replacement.

　　Huaju Electronics is one of the earliest domestic manufacturers engaged in the R&D and production of resettable fuses for overcurrent protection products. The company mainly engages in the R&D and production of thermistors, varistors, and resettable fuses. Relying on its strong R&D capabilities, the company has recently launched a low-power, low-resistance chip resettable fuse, which is suitable for battery-powered handheld devices and can effectively increase the use time of the device. It is another flagship product of the company. The company's plug-in resettable fuses (PPTC&CPTC), chip resettable fuses, and chip fuses (fast-blow chip fuses/slow-blow chip fuses) are widely used in military, medical, human life, industrial automation, and automobiles. , security and fire protection, home appliances, communications and other fields and occasions that require over-current protection and over-load protection. We are one of the few manufacturers in the world that masters the core technology of polymer over-current protection components and ceramic over-current protection components. Huaju Resettable Fuse Company has always been adhering to the principle of technology-based and application-led to continuously develop self-recovery fuse products that meet current needs. Our R&D team not only has the technical background of the Institute of Metals, Chinese Academy of Sciences, but also has strong technical force. Our self-resettable fuses All indicators of fuse products meet the standards of domestic and foreign authoritative organizations; we have senior engineers from the United States and Taiwan who have many years of experience in the development and application of PPTC resettable fuses and CPTC resettable fuses, and have successively developed low-power resettable fuses for handheld devices. New products such as ceramic substrate chip resettable fuses, PPTC overcurrent protection sheets and high voltage and high holding current resettable fuses are used to replace some products that we could not produce domestically and had to rely on imports. We provide a variety of resettable fuses that can meet the high standards and stringent needs of today's high-tech applications. The quality and performance of Huaju Electronics' resettable fuse products can completely replace imported brand products such as Littelfuse, Juding and Raychem.

　　●Basic principles

　　The full name of polymer PTC is "polymer positive temperature coefficient thermistor". It has excellent overcurrent protection function due to the special properties of its material. Polymer PTC is connected in series in the circuit (as shown in Figure 1). Under normal circumstances, it is in a low resistance state and the working current can pass smoothly; when an abnormally large current occurs in the circuit, its impedance increases rapidly (it is in a high resistance state) ), effectively limiting the passage of large current and protecting the circuit from damage (Figure 2). When the fault current is eliminated, the resistance of the polymer PTC drops rapidly and returns to the low resistance state.

　　●Selection guide

　　Using polymer PTC is safe and convenient, which is a win-win strategy. When selecting, first consider that the working voltage should be less than or equal to the maximum voltage that the polymer PTC can operate; secondly, match the working current. The working current (IH) listed in the specification refers to the current value when the working environment temperature is 25°C. , if the actual working environment temperature is different from it, the temperature and current reduction factors should also be considered. Please refer to Figure 3 for details. Finally, the installation method (such as plug-in, light sheet insertion) must be considered. For other technical indicators, please refer to the specification sheet. If there are special circumstances, please contact our company directly to see if special processing is possible.

 

　　Figure 1 Figure 2

IT decay ratio

Typical current IT time action curve at 25℃

●U30 electrical characteristics and product dimensions

●U30 parameters and dimensions (25℃)