Power supplies are compact devices that are used to supply power to various other devices such as domestic appliances, computers and office equipment etc. These devices are designed to produce both AC and DC power. The term power supplies should not be confused with large-scale electricity grids or electric power stations. Power supplies are also known as power supply units (PSU).
The complete family or range of power supplies is very large, and many people consider it to consist of all types of energy conversion from one form into another. However, the term is generally used to refer to electrical or mechanical energy supplies. There are many important factors you need to know about a power supply such as the amount of power they can supply, how long they can supply power for without having to be refueled or recharged, how stable their output voltage or current is under different load conditions, and whether or not they provide continuous power or pulses.
While selecting the power supply unit, there are various other things you need to consider. These include: the number of output channels on the device such as the DC output voltage. Power supplies are available with a range of DC outputs like +0.75 V, +1 V, +1.5 V, -5V, etc. The DC output power, AC output voltage, AC output frequency and the apparent power (which is the root mean square, or RMS, current multiplied by the RMS voltage) are also important factors to consider.
Depending on the requirement, there are many types of power supplies that you can use. These include: batteries, fuel cells, generators and alternators in automobiles, solar products, rectifiers, inverters, AC to DC converters, DC to AC converters, step-down transformers, UPS and AC/DC wall adapters, etc.
Power supplies can also have various types of output electrical displays such as analog, digital, graphic and video, etc. It is essential to specify the application or purpose for which the power supply will be used. This could include electrical devices such as: computers, electrical instruments, medical devices, high frequencies/currents/voltages, telecommunications, etc. A power supply can also have additional features such as having a heat sink or being fan cooled, having short circuit and over voltage protection, having adjustable frequency/voltage/current or other power factor correction, etc.