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(14 115)Types of power supplies in industry and electronics
Power supplies are a group of electrical devices that convert the power grid voltage into a direct voltage required to power a given electrical device or circuit. Depending on the way of operation, power supplies are divided into three basic types:
- capacitive supply,
- AC to DC supply,
- switched mode supply.
The first type of power supply usually does not provide any galvanic isolation between the power grid and the power supply output. AC to DC power supplies feature a transformator which reduces voltage, a converter and can also be equipped with a voltage stabilizer. Switched-mode power supply includes a rectifier and a DC/DC switching inverter. Switch-mode power supplies are characterized by high efficiency and small dimensions, even with high current efficiency.
Power supplies can be divided, depending on the target application, into: open (to be placed in the housing), to be built in (on a board or into a device), on a DIN rail (usually for industrial automation devices), for LED (for lighting systems), plug-in (external, placed in a power network socket), desktop (external, in plastic housing), for laptops (for notebook computers), PoE (for powering devices via Ethernet), computer (for computers) and UPS (emergency power supplies).
Power supplies– most important features
Power supplies basic parameters are: output voltage, number of outputs, load current or power of the power supply allowing its estimation, input voltage range. The mechanical parameters of the power supply are extremely important for the target application, i.e. the type of housing, its dimensions and method of assembly, input / output connectors. For many applications, built-in safety features and the operating temperature range will also be important. Modern switched-mode power supplies provide voltage with parameters very similar to linear power supplies. This is why currently the type of power supply (linear or switched-mode) is of little importance. The considerably smaller dimensions and greater efficiency speak in favor of the switched-mode power supply.
The difference in the design of various supplies
Any difference in the power supply design results mainly from their application. Open frame power supplies are intended to be built in your own device. Desktop or laptop power supplies are housed inside a plastic housing that provides insulation and protection for the user. PoE power supplies superimpose the supply voltage on the Ethernet signal, delivering power to remote points of the network using structured cabling.
What is more, uninterruptible power supplies are a special type of power supply. They feature built-in batteries, a charger and an inverter that generates an output voltage (usually 230V AC) in case of input voltage failure when powered by built-in or external batteries.
Power supplies protection
Typically, a power supply has built-in protection against overheating, exceeding the permissible load current and too high output voltage. Overcurrent protection can be either simple (output fuse) or complex electronic, including limiting the output current. Switched-mode power supplies may also have built-in protection against low supply voltage and exceeding the input voltage.
The selection of power supplies
The selection of the correct power supply depends on the target application and the conditions under which it will be used. Sometimes, to be able to use a given power supply, its producer to have the appropriate product certification.
Open power supplies are ideal for incorporating into their own equipment, while DIN-rail power supplies for industrial automation equipment. Desktop and plug-in power supplies will also be useful for devices that are too small to insert the power supply inside. This is also beneficial in terms of electrical safety standards.
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