Application and Development of Aluminum Electrolytic Capacitors
During the last couple of decades, there has been a major interest in the use of aluminum electrolytic capacitors and Medium and high voltage aluminum electrolytic capacitor. These capacitors are used in a variety of applications. For instance, they are used for DC-link and AC-line filtering.
Cathode foil
During the manufacturing process of aluminum electrolytic capacitors, the cathode foil of aluminum is etched. This etching operation enlarges the surface of the aluminum foil and increases its surface area. The anode is then oxidized and the resulting oxide layer is an insulating layer.
A high specific capacitance is required for the charge-discharge stability of the capacitor. This capacitance is achieved when the thickness of the foil is reduced to 30 mm. The volume gain is 12% compared to the original 60 mm foil.
The electrolyte acts as the dielectric between the anode and the cathode foil. It contains solutes such as glycerin, ammonia, boric acid, and various additives.
During the development of aluminum electrolytic capacitors, several types of new electrolytes were produced. The use of organic liquids broadened the operating temperature range and decreased the operational leakage current. These new electrolytes are formulated by mixing two solvents.
The quality control department of the manufacturing company supervises the whole development process of the capacitor. All steps of the process are inspected.
The cathode foil of aluminum is produced as a "mother roll". It is then fed into an automatic winder, which makes the wound section. This wound section is then mechanically tightened by curling.
A spacer or separator is then made to protect the anode and cathode foils from mechanical damage. The spacer is usually made of special high purity paper. This ensures the longer lifetime of the capacitor.
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DC-link capacitors
During the past several decades, aluminium electrolytic capacitors have become the standard in power-supply designs. They are used in industrial and switched-mode power supplies, as well as in frequency converters. They are available in several different ripple current ratings with High Temperature Resistance 130℃ Electrolytic Capacitor. They have a high reliability and offer an excellent price/performance ratio.
In addition, they have good decoupling properties in the lower frequency range. However, they are susceptible to failure when applied to an overvoltage. Hence, it is important to select them for individual applications.
The main factors affecting the reliability of DC-link capacitors are voltage proof, current, design defects, and moisture. They can also fail from extrinsic factors, such as mechanical stress. In addition, they may have a short lifetime due to the internal heat generated. Fortunately, modern electrolytic capacitors are more reliable.
In addition to a large capacitance, aluminum electrolytic capacitors offer a low ESR. The ESR value depends on the frequency, temperature, and dielectric layer thickness. They are generally rated at 2000 h / 105 degC, and their life span is usually 15 years. In some cases, they are rated at less than 5000 hours / 105 degC.
In addition, the capacitors have a specific ripple current rating. The ripple current is calculated by the manufacturers' data sheets. The ESR of the capacitor is often a limiting factor in the ripple current rating.
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AC-line filtering applications
Typically used in power supplies, switching mode converters and other electronic equipment, Aluminum electrolytic capacitors have relatively high capacitance values. They also have relatively low impedance values at lower frequencies.
Aluminum electrolytic capacitors with non-solid electrolytes are the most common type of capacitor. They are known to be relatively inexpensive and adaptable to different industrial requirements. These types of capacitors can be charged up to the rated voltage without reaching a peak. They are also relatively insensitive to transient energy or voltages. However, their lifetime is limited by the ESR.
The anode and cathode foils of these capacitors need to be protected from direct contact like in Snap-in Type Standard Aluminum Capacitor 85℃. This can cause short circuits. They are often insulated from each other with an insulating shrink sleeve film. Using a spacer or separator can extend the life of the capacitor.
In addition to its capacitance value, Aluminum electrolytic capacitors are standardized in IEC/EN 60384-1 for their surge voltage. The rated voltage of these devices is up to 315 V. The surge voltage is standardized at 1.15 times the rated voltage.
Most electrolytic capacitors have screw terminals on their bottom plates. In addition, most have solder tabs on their sides. Smaller devices are often mounted with hot glue. Larger devices are normally mounted with special circular mounting hardware.
Customers can acquire aluminum electrolytic capacitors from first-class industry-proven top manufacturers ecomponentshop.com online 24 hours a day.
In many electrical systems, aluminum electrolytic capacitors are used to smooth and buffer rectified DC voltages in power supply and DC-DC converters.
In addition, they are employed in industrial power supplies.
Because of its anodization principle, aluminum electrolytic capacitors are polarized capacitors.
