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Major types of power supply

EBR Staff Writer Published 31 March 2018

Many new sources of power generation have emerged in the past few decades, due to a surge in demand for electricity to power industries and households across the world. Coal, nuclear, hydro, solar, wind, geothermal, solar thermal and tidal are currently the major sources of power generation.

According to World Coal Association, coal-fired power plants currently account for 41% of global electricity. Nuclear power is also regarded as one of the prominent sources of energy with a huge potential. Hydroelectricity is produced by harnessing the gravitational force of flowing water. Solar energy is one of the cleanest and most abundant renewable energy sources. Wind energy is also one of the major renewable energy sources with a huge potential.

Power supply involves delivery of electric power to electrical load. The main function in power supply is the conversion of electric current from a source to exact voltage and frequency to power the load. Other functions in power supply include restricting supplies to load to safety levels, halting the current flow in case of electrical fault and power conditioning to avoid spikes in voltages. Power supplies are the devices that supply electricity to loads.  Direct current (DC) power supply and alternating current (AC) power supply are the two main types of power supply.

Here are the types of power supply:

DC power supply: It supplies a constant DC voltage to an electrical load. In DC power supply, the direction of electric current is constant. Although the process involved in the generation of DC power is same as AC power, the DC power supply is delivered by a transformer. The main function of a transformer is to regulate the signal to produce desired level of DC supply for a particular point. Based on the mechanism used to transfer the input power to an output, DC power supplies are divided into various categories.  

AC power supply: Compared to DC power supply that moves only in one direction, AC is the electric current that periodically changes direction. In case of an AC power supply, voltage is taken from a main supply and delivered to an output at desired levels using a transformer. It is the power supply that is delivered to business and residential purposes. AC is the form of electrical energy that is used by kitchen appliances, televisions, fans and electric lamps when they are switched on.















Image: Transformer at the Limestone Generating Station in Manitoba, Canada. Photo courtesy of Jasonbook99/Wikipedia.

Linear power supply: The power supply that regulates the output voltage from a source is called as linear power supply. A linear voltage regulator supplies exact amount of voltage needed at the output. The regulator delivers a constant DC voltage, as it is needed in many power supply applications. A linear voltage regulator is used when an unregulated DC power supply is the source. Some of the major advantages of linear power supplies include simplicity and reliability. Due to simple design, few components are needed for this type of power supply.

Switched-mode power supply (SMPS):  In this type of power supply, a transfer of electricity takes place from a DC or AC source to DC loads, with the conversion of voltage and current characteristics. In SMPS, a DC voltage is attained by direct rectification of the AC mains input. By using electronic switching circuitry, the obtained DC voltage is switched on and off at a high frequency to generate an AC current. To convert electrical power efficiently, SMPS will include a switching regulator.
















Image:  Two programmable power supplies by Hameg. Photo courtesy of Theoprakt/Wikipedia.org.

Programmable power supply: Remote controlling of a power supply using a  analog input or digital interface is known as programmable power supply. Voltage and current are the properties that are controlled in this type of power supply. In case of AC power supply, remote controlling is done for frequency. Automated equipment testing, semiconductor fabrication, and x-ray generators are some of the applications in which programmable power supply is used.

Uninterruptible power supply (UPS): In this type of power supply, a battery is used to provide uninterrupted supply when there is outage in the electricity supply. An UPS takes power directly from the AC mains. It can take power from two or more sources simultaneously. This power supply allows computer operators to shut down the devices in an orderly manner.