SKOFF electrical components Germany SKOFF model SKOFF price

SKOFF electrical component is a resistive device with nonlinear voltage-current characteristics, mainly used for voltage clamping when the circuit is subjected to overvoltage, absorbing excess current to protect sensitive devices. The resistive body material of the varistor is a semiconductor, so it is a type of semiconductor resistor. The currently widely used "zinc oxide" varistor has a main body composed of divalent element zinc and hexavalent element oxygen. Therefore, from a material perspective, the zinc oxide varistor is a "II-VI group oxide semiconductor". In Taiwan, China, varistors are called "surge absorbers", sometimes also referred to as "electric shock (surge) suppressors (absorbers)". A varistor is a voltage-limiting protection device. Utilizing the nonlinear characteristics of the varistor, when an overvoltage appears between the two poles of the varistor, the varistor can clamp the voltage to a relatively fixed value, thereby achieving protection for the downstream circuit. The main parameters of a varistor include: varistor voltage, surge current capacity, junction capacitance, response time, etc. The response time of a varistor is in the ns range, faster than a gas discharge tube, but slightly slower than a TVS tube. Generally, its response speed can meet the requirements for overvoltage protection in electronic circuits. The junction capacitance of a varistor is generally in the order of hundreds to thousands of Pf, so in many cases it is not suitable for direct application in the protection of high-frequency signal lines. When applied in AC circuit protection, its larger junction capacitance will increase leakage current, which needs to be fully considered in the design of protection circuits. The surge current capacity of a varistor is large, but smaller than that of a gas discharge tube. The varistor, abbreviated as VDR, is a voltage-sensitive nonlinear overvoltage protection semiconductor component.

SKOFF electrical component applications

Inductors in circuits mainly perform functions such as filtering, oscillation, delay, and notch filtering, as well as signal screening, noise filtering, current stabilization, and suppression of electromagnetic interference. The most common function of an inductor in a circuit is to form an LC filter circuit together with a capacitor. Capacitors have the characteristic of "blocking DC and passing AC", while inductors have the function of "passing DC and blocking AC". If DC power accompanied by many interference signals passes through an LC filter circuit, the AC interference signals will be converted into heat energy by the inductor and consumed; when the relatively pure DC current passes through the inductor, the AC interference signals within it are also converted into magnetic induction and heat energy. Higher frequencies are more easily impeded by the inductor, which can suppress higher frequency interference signals. Inductors have the characteristic of blocking AC while allowing DC to pass smoothly; the higher the frequency, the greater the coil impedance. Therefore, the main functions of an inductor are to isolate and filter AC signals, or to form resonant circuits with capacitors, resistors, etc.

SKOFF electrical component classification

Classification by material: a, wire-wound resistors are made by winding resistance wire. They are manufactured by winding high-resistance alloy wire around an insulating core, coated with a heat-resistant glaze insulation layer or insulating varnish. Wire-wound resistors have a low temperature coefficient, high resistance accuracy, good stability, heat and corrosion resistance, and are mainly used as precision high-power resistors. The disadvantages are poor high-frequency performance and a large time constant. b, carbon composition resistors are formed by pressing carbon and synthetic plastic. c, carbon film resistors are made by depositing a layer of carbon on a ceramic tube, specifically by depositing crystalline carbon onto a ceramic rod core. Carbon film resistors are low-cost, stable in performance, have a wide resistance range, and low temperature and voltage coefficients, making them the most widely used resistors at present. d, metal film resistors are made by depositing a layer of metal on a ceramic tube, using vacuum evaporation to deposit alloy material onto the surface of a ceramic rod core. Metal film resistors have higher accuracy, better stability, lower noise, and a smaller temperature coefficient than carbon film resistors. They are extensively used in instruments and communication equipment. e, metal oxide film resistors are made by depositing a layer of tin oxide on a ceramic tube, forming a layer of metal oxide on an insulating rod. As they are oxides themselves, they are stable at high temperatures, resistant to thermal shock, and have strong load capacity. Classified by application, there are general-purpose, precision, high-frequency, high-voltage, high-resistance, high-power, and resistor networks.

SKOFF electrical component performance

(1) Electromotive force: Electromotive force is the difference between the equilibrium electrode potentials of the two electrodes. (2) Rated capacity: The theoretical capacity of a battery can be precisely calculated based on the amount of active electrode material in the battery reaction equation and the electrochemical equivalent of the active material calculated according to Faraday's law. Due to possible side reactions in the battery and special design needs, the actual capacity of the battery is often lower than the theoretical capacity. (3) Rated voltage: The typical operating voltage of a battery at room temperature, also known as nominal voltage. It serves as a reference when selecting different types of batteries. The actual operating voltage of a battery equals the difference between the equilibrium electrode potentials of the positive and negative electrodes under different usage conditions. It is only related to the type of electrode active material, not the quantity. Battery voltage is essentially DC voltage, but under certain special conditions, phase changes in metal crystals or certain phase films caused by electrode reactions can cause slight voltage fluctuations, a phenomenon known as noise. The amplitude of the fluctuation is very small but the frequency range is very wide, distinguishing it from self-excited noise in circuits. (4) Open-circuit voltage: The terminal voltage of a battery in an open-circuit state is called the open-circuit voltage. The open-circuit voltage of a battery equals the difference between the positive electrode potential and the negative electrode potential when the battery is in an open circuit (i.e., no current flows through the two poles). The open-circuit voltage of a battery is denoted by V open, and is generally less than its electromotive force. This is because the electrode potentials established by the two poles in the electrolyte solution are usually not equilibrium electrode potentials, but stable electrode potentials. It can generally be approximated that the open-circuit voltage of a battery is its electromotive force. (5) Internal resistance: The internal resistance of a battery refers to the resistance encountered when current passes through the interior of the battery. It includes ohmic internal resistance and polarization internal resistance; polarization internal resistance further includes electrochemical polarization internal resistance and concentration polarization internal resistance. Due to the existence of internal resistance, the working voltage of a battery is always less than its electromotive force or open-circuit voltage. The internal resistance of a battery is not constant; it changes continuously (gradually increasing) during charging and discharging processes because the composition of active materials, electrolyte concentration, and temperature are constantly changing. Ohmic internal resistance obeys Ohm's law, while polarization internal resistance increases with current density, but not linearly. It generally increases with increasing current density. Internal resistance is an important indicator determining battery performance, directly affecting the battery's working voltage, working current, output energy, and power. For a battery, the smaller the internal resistance, the better. (6) Impedance: A battery has a large electrode-electrolyte interface area, so it can be equivalent to a series circuit of a large capacitor with a small resistor and inductor. However, the actual situation is much more complex, especially since the battery's impedance changes with time and DC level, so the measured impedance is only valid for the specific measurement state. (7) Charge/discharge rate: There are two representation methods: hour rate and C-rate. The hour rate represents the charge/discharge rate by charge/discharge time, numerically equal to the battery's rated capacity (Ampere-hours) divided by the specified charge/discharge current (Amperes) to obtain the number of hours. C-rate is another representation of charge/discharge rate, numerically the reciprocal of the hour rate. The discharge rate of a primary battery is represented by the time taken to discharge through a fixed resistor to the cutoff voltage. Discharge rate has a significant impact on battery performance. (8) Service life: Storage life refers to the maximum allowable storage time from battery manufacture to the start of use, measured in years. The total period including the storage period and usage period is called the battery's validity period. The storage life of batteries is divided into dry storage life and wet storage life. Cycle life is the maximum number of charge/discharge cycles a rechargeable battery can achieve under specified conditions. When specifying cycle life, the charge/discharge cycle test regime must also be specified, including charge/discharge rate, depth of discharge, and ambient temperature range. (9) Self-discharge rate: The rate at which a battery loses capacity on its own during storage. It is expressed as the percentage of capacity lost due to self-discharge per unit of storage time relative to the capacity before storage.

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