1. Rated zero power resistance PPTC thermistors should be packaged according to zero power resistance levels, and the resistance range should be indicated on the outer packaging. After the withstand voltage and current resistance tests, the change rate of the resistance before each group of samples is extremely poor δ| After Ri - Before Ri - (After Rj - Before Rj)/Before Rj | ≤ 100% 2. PTC effect A material has a PTC (Positive Temperature Coefficient) effect, which means that the resistance of the material increases with increasing temperature. Most metal materials have the PTC effect. In these materials, the PTC effect is manifested as a linear increase in resistance with increasing temperature, which is commonly referred to as the linear PTC effect. 3. Nonlinear PTC effect The material undergoing phase transformation will exhibit a phenomenon where the resistance rapidly increases by several to more than ten orders of magnitude along a narrow temperature range, known as the
1. Determine the following parameters of the circuit: A Maximum working environment temperature b Standard working current c Maximum working voltage (Umax) d Maximum fault current (Imax) 2. Select a self restoring fuse element that can adapt to the maximum ambient temperature and standard operating current of the circuit Use a temperature reduction {ambient temperature (℃) working current (A)} table and select the temperature that best matches the maximum ambient temperature of the circuit. Browse this column to view values that are equal to or greater than the standard operating current of the circuit. 3. Compare the maximum electrical rating of the selected component with the maximum operating voltage and fault current of the circuit Use the electrical characteristic table to verify whether the components you selected in step 2 will use the maximum operating voltage and fault current of the circuit. Check the maximum operating voltage and maximum fault current of the device.
The operating principle of a self-healing fuse is a dynamic balance of energy. The current flowing through the self-healing fuse generates a certain amount of heat due to the thermal effect of the current (self-healing fuses all have resistance values), and the generated heat is completely or partially dissipated into the environment. The heat that is not dissipated will increase the temperature of the self-healing fuse components. The temperature during normal operation is relatively low, and the heat generated and dissipated reaches a balance. The self-healing fuse element is in a low resistance state, and the self-healing fuse does not operate. When the current flowing through the self-healing fuse element increases or the ambient temperature increases, but if the balance between the generated heat and the emitted heat is reached, the self-healing fuse still does not operate. When the current or ambient temperature increases again, the self-healing fuse will reach a higher tempe
Fuses are divided into two categories: high voltage and low voltage. High voltage fuses for 3kV-35kV; Low voltage fuses are used for AC 220V, 380V, and DC 220V, 440V. High voltage fuses are divided into indoor and outdoor types, and the model description is as follows: For example, RN1-3/150-200 is indoor. The rated voltage is 3kV, the rated current is 150A, and the breaking capacity is 200MVA. Indoor models include RN1, RN2, RN3, RN5, RN6, etc., outdoor models include RW3, RW4, RW10, etc., and DC electric vehicles use RNZ, RNZ1, etc. Low voltage fuses are commonly classified into three categories: plug-in, tubular, and spiral. It can also be divided into three types: open type, semi closed type, and closed type. The open type is not used alone and is often combined with a knife switch; One or both ends of the semi enclosed tube are opened, and the molten particles are sprayed out in a certain direction. Please pay attention to safety when using; Closed type commonly includes
1. Select the model of the fuse according to the circuit requirements and installation conditions. For circuits with small capacity, choose semi enclosed or unfilled enclosed; The choice for high short-circuit current is the enclosed type with fillers; Select fast fuses for semiconductor component protection. 2. Select the rated voltage of the fuse according to the line voltage. 3. Select the rated current of the fuse according to the load characteristics. 4. The selection of different levels of melts requires mutual coordination, with the latter level being smaller than the previous level. The current on the main switch and each branch line is different, and the selection of fuses is also different. If a short circuit occurs in the circuit, the 15A and 25A fuses will fuse simultaneously, and the protection characteristics will lose selectivity. Therefore, only by maintaining a 2-3 level difference between the main gate and the branch can such a phenomenon not occur. If the low-
The current of a fuse includes two aspects, one is the rated current of the fuse tube, and the other is the rated current of the melt, which cannot be confused. 1. Melt current for direct starting of a single motor IRNIRN ≥ Iq/K (A)... (l) IRN Melt rated current (A) Iq Motor starting current (A) K-coefficient or IRN=(1.5-2.5) IH (A)... (2) In the formula, IH Motor rated current (A) or 380V (AC) IRN=7PH (A)... (3) 22OV (AC) IRN=12PH (A)... (4) In the formula: PH Motor rated power (kW) 2. Multiple motors in the distribution main line (with several units), with a total fuse IRN=(1.5-2.5) IHmax+I (n-1) (A)... (5) In the formula: IHmax - The rated current of the largest motor or motor group that starts simultaneously I (n-1) - The sum of the rated currents of other motors except for the largest motor group or motor group that starts simultaneously, or IRN=I (n-l)+Iqmax/2.5 (A)... (6) In the formula: Iqmax - The maximum starting current of one motor (A) or IRN=K1 [Iqmax I (n-l)] (A)...
MB:+86 13924633629 Ms.vicky
E-mail: waimao@xcfuse.com
Factory :
XC Electronics(Shenzhen)Corp.,LTD
Add: Jinyuan Industrial zone,Heao, Henggang, Shenzhen 518115,China
Shenzhen branch: Shenzhen Xucheng Electronic Commerce co.Ltd
Add: 8-15 Jinyuan Industrial zone,Heao, Henggang, Shenzhen 518115,China
