evis electrical components Germany evis model evis price

evis electrical components are current-limiting components. After connecting a resistor in a circuit, the resistance value is fixed, typically with two pins, and it can limit the current magnitude through the connected branch. Resistors with unchangeable resistance values are called fixed resistors. Those with variable resistance values are called potentiometers or variable resistors. An ideal resistor is linear, meaning the instantaneous current through the resistor is proportional to the applied instantaneous voltage. Variable resistors used for voltage division. One or two movable metal contacts are pressed tightly against the exposed resistive body. The contact position determines the resistance value between either end of the resistive body and the contact. A two-terminal device where terminal voltage and current have a definite functional relationship, reflecting the ability to convert electrical energy into other forms, is represented by the letter R, with the unit Ohm Ω. Actual devices such as light bulbs, heating wires, and resistors can all be represented as resistor components. The resistance value of a resistive element is generally related to temperature, material, length, and cross-sectional area. The physical quantity measuring the extent to which resistance is affected by temperature is the temperature coefficient, defined as the percentage change in resistance value when the temperature rises by 1 ℃. The main physical characteristic of resistance is the conversion of electrical energy into thermal energy; it can also be described as a dissipative component, generating internal energy as current passes through it. Resistors typically serve voltage division and current shunting functions in circuits. For signals, both AC and DC signals can pass through resistors.

evis electrical component classification

Fuses can be divided into high-voltage fuses and low-voltage fuses based on operating voltage. Based on the protected object, they can be classified as fuses for protecting transformers and general electrical equipment, fuses for protecting voltage transformers, fuses for protecting power capacitors, fuses for protecting semiconductor components, fuses for protecting motors, and fuses for protecting household appliances, etc. Based on structure, they can be divided into open-type, semi-enclosed, tube-type, and expulsion fuses. Open-type fuses have a simple structure, with the fusible element completely exposed to the air, supported by porcelain pillars without a base, suitable for low-voltage outdoor use. Significant acoustic and optical effects are produced in the atmosphere during current interruption. Semi-enclosed fuses have the fusible element mounted on a porcelain frame, inserted into a porcelain box with metal sockets at both ends, suitable for low-voltage indoor use. The acoustic and optical effects produced during current interruption are blocked by the porcelain box. In tube-type fuses, the fusible element is installed inside the fuse body. It is then inserted into a base or directly connected into the circuit for use. The fuse link is a fully sealed insulating tube with metal caps on both ends or equipped with contact blades. If the insulating tube of this type of fuse is filled with quartz sand, it has a current-limiting effect during current interruption, greatly improving breaking capacity, hence it is also called a high-breaking-capacity fuse. If the tube is evacuated, it is called a vacuum fuse. If the tube is filled with SF6 gas, it is called an SF6 fuse, aimed at improving arc extinguishing performance. Since quartz sand, vacuum, and SF16 gas all have good insulation properties, this type of fuse is suitable for both low voltage and high voltage applications. Expulsion fuses have the fusible element installed in an insulating tube made of solid gas-generating material. Solid gas-generating materials can include electrical anti-white cardboard or organic glass materials. When short-circuit current passes through the fusible element, it melts immediately, producing an electric arc. The high-temperature arc causes the solid gas-generating material to rapidly decompose, producing a large amount of high-pressure gas, which ejects the ionized gas and electric arc from both ends of the tube, emitting intense sound and light, and extinguishing the arc when the AC current crosses zero, thereby interrupting the current. The insulating tube is usually mounted on an insulating support to form the complete fuse assembly. Sometimes the upper end of the insulating tube is designed to be movable, detaching and dropping immediately after current interruption. This type of expulsion fuse is commonly known as a drop-out fuse.

evis electrical component functions

① Sensor functions are often compared to the 5 major sensory organs of humans: photosensitive sensors - vision, acoustic sensors - hearing, gas-sensitive sensors - smell, chemical sensors - taste, pressure-sensitive, temperature-sensitive, and fluid sensors - touch. ② Classification of sensitive elements: Physical category, based on physical effects such as force, heat, light, electricity, magnetism, and sound. Chemical category, based on the principles of chemical reactions. Biological category, based on molecular recognition functions such as enzymes, antibodies, and hormones. Typically, based on their basic sensing functions, they can be divided into ten major categories: thermosensitive elements, photosensitive elements, gas-sensitive elements, force-sensitive elements, magneto-sensitive elements, humidity-sensitive elements, acoustic-sensitive elements, radiation-sensitive elements, color-sensitive elements, and taste-sensitive elements (some have also classified sensitive elements into 57 categories).

evis electrical component parameters

1. Nominal varistor voltage: refers to the voltage value across the varistor when a pulse current of specified duration passes through. 2. Voltage ratio: refers to the ratio of the voltage value generated by the current in the varistor to the voltage value generated by the current in the varistor. 3. Maximum limiting voltage: the peak voltage across the varistor under the maximum pulse peak current Ip that the varistor can withstand and under a specified waveform. 4. Residual voltage ratio: when the current passing through the varistor is a certain value, the voltage generated across it is called the residual voltage for that current value. The residual voltage ratio is the ratio of residual voltage to nominal voltage. 5. Current handling capacity: Current handling capacity, also known as current flow capacity, refers to the maximum pulse current value allowed to pass through the varistor under specified conditions. 6. Leakage current: Leakage current, also known as standby current, refers to the current flowing through the varistor at a specified temperature and maximum DC voltage. 7. Voltage temperature coefficient: refers to the rate of change of the nominal voltage of the varistor within a specified temperature range, i.e., the relative change in voltage across the varistor when the temperature changes while the current passing through the varistor remains constant. 8. Current temperature coefficient: refers to the relative change in current flowing through the varistor when the temperature changes while the voltage across the varistor remains constant. 9. Voltage nonlinearity coefficient: refers to the ratio of the static resistance value to the dynamic resistance value of the varistor under a given applied voltage. 10. Insulation resistance: refers to the resistance value between the lead wires of the varistor and the insulated surface of the resistive body. 11. Static capacitance: refers to the inherent capacitive capacity of the varistor itself. 12. Rated power: the maximum power that causes a change in varistor voltage when operating at a specific ambient temperature. 15. Maximum surge current: the maximum surge current that causes a change in varistor voltage when impacting the varistor once or twice with a specific pulse current.

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