A voltage converter is an

electric power converter In electrical engineering, power conversion is the process of converting electric energy from one form to another. A power converter is an electrical device for converting electrical energy between alternating current (AC) and direct current (D ...

which changes the

voltage Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...

of an electrical power source. It may be combined with other components to create a

power supply A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, electric current, current, and frequency to power ...

AC and DC

AC voltage conversion uses a

transformer In electrical engineering, a transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple Electrical network, circuits. A varying current in any coil of the transformer produces ...

. Conversion from one DC voltage to another requires

electronic circuit An electronic circuit is composed of individual electronic components, such as resistors, transistors, capacitors, inductors and diodes, connected by conductive wires or Conductive trace, traces through which electric current can flow. It is a t ...

ry (

electromechanical Electromechanics combine processes and procedures drawn from electrical engineering and mechanical engineering. Electromechanics focus on the interaction of electrical and mechanical systems as a whole and how the two systems interact with each ...

equipment was required before the development of

semiconductor electronics A semiconductor device is an electronic component that relies on the electronic properties of a semiconductor material (primarily silicon, germanium, and gallium arsenide, as well as organic semiconductors) for its function. Its conductivity l ...

), like a DC-DC converter.

Mains power Mains electricity, utility power, grid power, domestic power, wall power, household current, or, in some parts of Canada, hydro, is a general-purpose alternating-current (AC) electric power supply. It is the form of electrical power that is de ...

(called household current in the US) is universally AC.

Practical voltage converters

Mains converters

A common use of the voltage converter is for a device that allows appliances made for the mains voltage of one geographical region to operate in an area with different voltage. Such a device may be called a ''voltage converter'', ''power converter'', ''travel adapter'', etc. Most

single phase In electrical engineering, single-phase electric power (abbreviated 1φ) is the distribution of alternating current electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when load ...

alternating-current electrical outlets in the world supply power at 210–240 V or at 100–120 V. A transformer or

autotransformer In electrical engineering, an autotransformer is an electrical transformer with only one winding. The " auto" (Greek for "self") prefix refers to the single coil acting alone. In an autotransformer, portions of the same winding act as both the p ...

can be used; (auto)transformers are inherently reversible, so the same transformer can be used to step the voltage up, or step it down by the same ratio. Lighter and smaller devices can be made using electronic circuitry; reducing the voltage electronically is simpler and cheaper than increasing it. Small, inexpensive, ''travel adapters'' suitable for low-power devices such as

electric shaver An electric shaver (also known as the dry razor, electric razor, or simply shaver) is a razor with an electrically powered rotating or oscillating blade. The electric shaver usually does not require the use of shaving cream, soap, or water, kno ...

s, but not, say, hairdryers, are available; travel adapters usually include plug-end adapters for the different standards used in different countries. A transformer would be used for higher power. Transformers do not change the

frequency Frequency is the number of occurrences of a repeating event per unit of time. Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio ...

of electricity; in many regions with 100–120 V, electricity is supplied at 60 Hz, and 210–240 V regions tend to use 50 Hz. This may affect operation of devices which depend on mains frequency (some audio turntables and mains-only electric clocks, etc., although modern equipment is less likely to depend upon mains frequency). Equipment with high-powered motors or internal transformers designed to operate at 60 Hz may overheat at 50 Hz even if the voltage supplied is correct. Most mains-powered electrical equipment, though it may specify a single nominal voltage, actually has a range of tolerance above and below that point. Thus, devices usually can be used on either any voltage from approx. 100 to 120 V, or any voltage from approx. 210 to 240 V. In such cases, voltage converters need only be specified to convert any voltage within one range, to a voltage within the other, rather than separate converters being needed for all possible pairs of nominal voltages (110–220, 117–220, 110–230, etc.)

Converters for devices

Mains converters

Another requirement is to provide low-voltage electricity to a device from mains electricity; this would be done by what is usually called a ''power supply''. Most modern electronic devices require between 1.5 and 24 volts DC; lower-powered devices at these voltages can often work either from batteries or mains. Some devices incorporate a power supply and are simply plugged into the mains. Others use an external power supply comprising either a transformer and rectifier, or electronic circuitry. Switched-mode power supplies have become widespread in the early twenty-first century; they are smaller and lighter than the once-universal transformer converters, and are often designed to work from AC mains at any voltage between 100 and 250 V. Additionally, because they are typically rectified to operate at a DC voltage, they are minimally affected by the frequency of the mains (50 vs 60 Hz). Details on operation are given in the article on

power supplies A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a r ...

Mobile converters

Voltage converters can be used in vehicles with 12 V DC outlets. A simple voltage dropper can be used to reduce the voltage for low-power devices; if more than 12V is required, or for high-powered devices, a switched-mode power supply is used. The output will usually be DC in the range 1.5–24 V. Power supplies that output either 100–120 V AC or 210–240 V AC are available; they are called inverters, due to the conversion from DC to AC rather than the voltage change. The output frequency and waveform of an inverter may not accurately replicate that supplied by mains electricity, although this is not usually a problem.

References

{{DEFAULTSORT:Voltage Converter Electric power systems components

AC and DC

Practical voltage converters

Mains converters

Converters for devices

Mains converters

Mobile converters

See also

References