Ac Adapter Advantages And Problems-www.xinkebiao.com.cn

Customer Service Advantages: Safety External power adapters can free product designers from worrying about some safety issues. Much equipment uses only voltages low enough not to be a safety hazard internally, although the power supply must out of necessity use dangerous mains voltage. If an external power supply is used (usually via a power connector, often of coaxial type), the equipment need not be designed with concern for hazardous voltages inside the enclosure. This is particularly relevant for equipment with lightweight cases which may break and expose internal electrical parts. Heat reduction Heat reduces reliability and longevity of electronic components, and can cause sensitive circuits to become inaccurate or malfunction. A separate power supply removes a source of heat from the apparatus. Weight and size reduction When most power adapters were simple mains-frequency transformer-based designs, they were quite heavy and large, and added considerably to the weight and bulk of devices designed to be light-weight. Even modern power supplies are relatively heavy compared to other circuitry. Removing power components from equipment powered by rechargeable batteries reduces the weight and size which must be carried. Ease of replacement Power supplies are more prone to failure than much other circuitry due to their exposure to power spikes and their internal generation of waste heat. External power supplies can be replaced quickly by a user without the need to have the powered device repaired. Simplified product inventory, distribution, and certification An electronic product that is sold and used internationally must be powered from a wide range of power sources, and must meet product safety regulations in many jurisdictions, usually requiring expensive certification by national or regional safety agencies such as Underwriters Laboratories or Technischer berwachungsverein. A single version of a device may be used in many markets, with the different power requirements met by different external power supplies, so that only one version of the device need be manufactured, stocked, and tested. If the design of the device is modified over time (a frequent occurrence), the power supply design itself need not be retested (and vice versa) Problems: Size Power supplies which plug into the mains directly without using a plug on a cable (true wall warts) are bulkier than bare plugs; sometimes they are too large to plug into power sockets with restricted space, or into adjacent sockets on power strips. Weight Some AC adapters can be heavy, exerting excess weight on the plug socket (this depends on the socket design of the country in question). Some external power supplies are "power bricks" having a short AC cord so they can lie on the floor, thus relieving strain, at the expense of clutter. Other wall-hanging types are made long and thin, minimizing the leverage of their weight vector that pulls the plug out, at the expense of exacerbating the size problem. The weight for equipment that must be carried (e.g., for travelling) is not a disadvantage of external supplies, as the alternative is an equally heavy internal supply; in many cases a single universal supply can replace several proprietary ones. Compatibility problems there is no standardizations of connectors; the same connector is often used for different voltages, and for both DC supplies and AC-to-AC transformers. This easily leads to using the wrong power supply, which can destroy equipment. A survey of consumers showed widespread dissatisfaction with the cost, inconvenience, and wastefulness of the profusion of power adaptors used by electronic devices. The science fiction author and satirist Douglas Adams once wrote an essay bemoaning the profusion and confusion of power adaptors, and calling for more standardization About the Author: 相关的主题文章:

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