weco electrical components German weco models weco prices

weco electrical components are resettable fuses, known in Japan as permanent fuses. The fuse element automatically restores to its original state immediately after interrupting an overload or short-circuit current. The housing is made of austenitic stainless steel, with a beryllium oxide ceramic core embedded in the center. Glass filler between the stainless steel and the ceramic core provides sealing and reinforces the ceramic core. Metallic sodium is injected into the fine pores of the ceramic core as the fuse element, and the void behind the piston is filled with argon gas to compress the metallic sodium. Under normal operating conditions, current enters from lead terminal A, passes through the metallic sodium in the ceramic core pores, conducts to the stainless steel housing, and exits via output terminal B. When a short-circuit current passes through the fuse, it rapidly heats the metallic sodium in the ceramic core pores, converting it from solid to high-temperature, high-pressure plasma vapor. This causes a rapid increase in resistivity, strongly limiting the short-circuit current and interrupting it instantly. At the end of the interruption, the sodium vapor immediately returns to liquid and solid states, while the argon gas pushes the piston again to compress the sodium, re-establishing the circuit connection.

weco electrical component structure

Some gas discharge tubes use glass as the encapsulation housing, while others use ceramic. The discharge tube is filled with inert gases with stable electrical properties (such as argon and neon). Common discharge tubes have two or three electrodes, separated by inert gas. Based on the number of electrodes, discharge tubes are classified into two-electrode and three-electrode types. Ceramic two-electrode discharge tubes consist mainly of pure iron electrodes, nickel-chromium-cobalt alloy caps, silver-copper welding caps, and ceramic tube bodies. The discharge electrodes inside the tube are coated with radioactive oxides, and the inner wall of the tube body is also coated with radioactive elements to improve discharge characteristics. Discharge electrodes mainly come in rod and cup structures. In discharge tubes with rod-shaped electrodes, a cylindrical heat shield is installed between the electrode and the tube wall. This heat shield ensures uniform heating of the ceramic tube body, preventing local overheating and tube fracture. The heat shield is also coated with radioactive oxides to further reduce discharge dispersion. In discharge tubes with cup-shaped electrodes, a molybdenum mesh is installed at the cup opening, and cesium is placed inside the cup, also serving to reduce discharge dispersion. Three-electrode discharge tubes are also composed of pure iron electrodes, nickel-chromium-cobalt alloy caps, silver-copper welding caps, and ceramic tube bodies. Unlike two-electrode tubes, three-electrode tubes include a nickel-chromium-cobalt alloy cylinder as the third electrode, i.e., the ground electrode.

weco electrical component features

Mercury switches operate by moving mercury sealed within a glass or metal housing to make or break the circuit. Therefore, compared to mechanical switches, mercury switches have many features: (1) Can be used in harsh environmental conditions. Since the mercury switch is sealed, the internal mercury is isolated from the outside, allowing it to be used in environments with oil, steam, dust, and corrosive gases. (2) Requires minimal external force for switching. Mercury is the only metal that remains liquid at room temperature; it has high surface tension and specific gravity. Slight tilting of the mercury switch causes the mercury to move, making or breaking the circuit. (3) Mercury has good conductivity, and the contact resistance between mercury switch electrodes is generally very low. (4) The current carrying capacity of a mercury switch depends on the electrode material. (5) Since the switching action is determined by the gravity of the mercury, it can operate reliably over long periods. (6) The electrode contacts are liquid, producing no noise. (7) Since mercury is fluid, the mercury switch can make or break the circuit whenever acceleration exceeds a set value, allowing it to be used as a vibration-sensitive element. (8) Small size, diverse forms, and fully sealed construction. (9) Simple structure and low cost. (10) High quality and excellent products, suitable for beginners.

weco electrical component applications

The collector-emitter current can be viewed as controlled by the base-emitter current, treating the bipolar transistor as a "current-controlled" device. Alternatively, it can be viewed as controlled by the emitter-base junction voltage, treating it as a "voltage-controlled" device. In fact, these two perspectives are linked by the current-voltage relationship across the base-emitter junction, which can be represented by the current-voltage curve of the PN junction. In analog circuit design, the current-controlled perspective is sometimes adopted because bipolar transistors exhibit approximately linear characteristics within a certain range. In this range (referred to below as the "active region"), the collector current is approximately equal to a multiple of the base current, which greatly facilitates problem analysis and circuit function control. When designing some basic circuits, it is assumed that the emitter-base voltage is approximately constant; in this case, the collector current is approximately a multiple of the base current, and the transistor acts as a current amplifier. However, in reality, bipolar transistors are complex nonlinear devices, and improper bias voltage distribution can cause output signal distortion. Furthermore, even when operating within a specific range, the current amplification factor is affected by factors including temperature. To design precise and reliable bipolar transistor circuits, the voltage-controlled perspective must be adopted. The voltage-controlled model introduces an exponential function to describe the voltage-current relationship. Within a certain range, this relationship is approximately linear, allowing the transistor to be treated as a conductance element. Thus, the design of circuits such as differential amplifiers is simplified to a linear problem, so the approximate voltage-controlled perspective is often chosen. For translinear circuits, studying their current-voltage curves is crucial for analyzing device operation, so they are typically treated as voltage-controlled models where transconductance is proportional to collector current. Transistor-level circuit design primarily uses SPICE or other similar analog circuit simulators, so model complexity does not pose a significant problem for designers. However, when manually analyzing analog circuits, it is not always possible to use exact calculation methods as in classical circuit analysis, making approximate methods necessary.

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