What is the function of ultra-small electrolytic capacitors?
Release time:
2022-06-13
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The ultra-small electrolytic capacitor is the industry’s generic term for fixed capacitors used to suppress electromagnetic interference in power supplies. These capacitors are called “ultra-small electrolytic safety capacitors” because they comply with safety regulations and have passed the required safety standard tests and certifications. Moreover, their casings are imprinted with safety certification logos or marks from multiple countries. In practical applications, these safety capacitors adhere to the following safety guidelines: Even if the capacitor fails, it will not cause electric shock and will not pose a threat to personal safety. Additionally, these capacitors are made of flame-retardant materials that, in the event of failure, will only rupture (but will not ignite) and release gas, after which they will short-circuit without causing a fire. Ultra-small electrolytic capacitor
Ultra-small electrolytic capacitor It is the industry-standard generic term for fixed capacitors used to suppress electromagnetic interference from power supplies. Because these capacitors comply with safety regulations and have passed the required safety standard tests/certifications, and their housings are imprinted with safety certification logos or marks from multiple countries, they are referred to as ultra-small electrolytic capacitors—also known as safety capacitors. In practical applications, these capacitors adhere to the following “safety requirements”: Even if the capacitor fails, it will not cause electric shock nor pose a threat to personal safety. Moreover, these capacitors are made of flame-retardant materials and, in the event of failure, will only rupture (but will not ignite; only gas will be produced), after which they will short-circuit without causing a fire. Typically, an ultra-small electrolytic capacitor consists of five main components: the dielectric, the electrodes, the housing, the encapsulation, and the leads. The dielectric is usually made of polypropylene film; the electrodes are composed of metal vacuum-deposited layers; the housing is generally made of flame-retardant PBT plastic (UL94V-0); the encapsulation typically uses flame-retardant epoxy resin (UL94V-0); and the leads are made of tin-plated copper-clad steel wire.
Ultra-small electrolytic capacitor
Filtering in anti-interference circuits. These filters are used in power supply filters to remove both common-mode and differential-mode interference from the power supply. At lower ambient temperatures and at the rated ambient temperature, the maximum root-mean-square (RMS) value of DC voltage that can be continuously applied to a capacitor is typically indicated directly on the capacitor’s casing. If the operating voltage exceeds the capacitor’s withstand voltage, the capacitor will break down, resulting in permanent and irreparable damage.
When ultra-small electrolytic capacitors are used in high-voltage applications, attention must be paid to the effects of corona discharge. Corona discharge is caused by gaps between the dielectric and electrode layers. In addition to generating parasitic signals that may damage the device, it can also lead to dielectric breakdown of the capacitor. Corona discharge is particularly likely to occur under AC or pulsating conditions. For all capacitors, the sum of the DC voltage and the peak AC voltage during operation should not exceed the rated DC voltage. The energy consumed per unit time by a capacitor due to heating under the influence of an electric field is referred to as power loss. Each type of capacitor specifies an allowable power-loss value within a certain frequency range. The power loss of a capacitor is primarily caused by dielectric losses, conductive losses, and resistive losses associated with all metallic parts of the capacitor. Under a DC electric field, the power loss of a capacitor takes the form of leakage current loss, which is generally relatively small. Under an alternating electric field, however, the power loss of a capacitor is not only related to leakage current but also involves the process of periodic polarization establishment.
Simple Ultra-small electrolytic capacitor It consists of two electrode plates at the ends and an insulating dielectric material in the middle. When current is applied, the electrode plates become charged, creating a voltage. However, since there is an insulating material in the middle, the entire capacitor remains non-conductive—provided that the applied voltage does not exceed the capacitor’s critical voltage (also known as the breakdown voltage). In fact, all materials are inherently somewhat insulating. When the voltage across a material reaches a certain threshold, the material can become conductive. We refer to this voltage as the breakdown voltage. Capacitors are no exception. Once a capacitor is subjected to a voltage exceeding its breakdown voltage, it ceases to be an insulator. In practical applications, capacitors are not purely capacitive; they also contain an equivalent series resistance internally. Here, C represents the actual capacitance of the capacitor, Rs is the equivalent series resistance of the capacitor, Rp is the insulation resistance of the dielectric material, and Ro is the absorption-equivalent resistance of the dielectric. For electronic devices, it is desirable to minimize Rs—that is, to keep power losses low—and to ensure that the phase angle δ between the voltage and current through the capacitor remains small.
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Ultra-small electrolytic capacitor
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