A transformer is one electrical an equipment that offers electromagnetic induction to pass an alternate current (AC) signal indigenous one electrical circuit to another, often an altering (or "transforming") the voltage and electric current. Transformers execute not happen direct current (DC), and also can be used to take the DC voltage (the continuous voltage) the end of a signal while keeping the part that changes (the AC voltage). In the electrical grid transformers are vital to an altering the voltages to reduce exactly how much energy is lost in electrical transmission.

Transformers readjust the voltage of the electric signal coming out of the power plant, usually enhancing (also recognized as "stepping up") the voltage. Transformers likewise reduce ("step down") the voltage in substations, and also as distribution transformers.

You are watching: A transformer is a device used to

<2> Transformers are also used as a component of devices, like current transformers.

How transformers work

It regularly seems surprising the a transformer keeps the complete power the same when voltage goes up or down. One need to keep in psychic that when the voltage goes up, the current goes down:

P=I_1 V_1 = I_2 V_2

Transformers use electromagnetic induction to change the voltage and also current. This readjust is called transformer action, and describes exactly how the transformer transforms an AC signal native its primary to its second component (like in the equation above). As soon as an AC signal is used to the primary coil, the an altering current causes a magnetic field to readjust (get larger or smaller). This transforming magnetic field (and associated magnetic flux) will certainly pass v to the an additional coil inducing a voltage throughout the an additional coil, thereby successfully coupling the AC input from the main to an additional component of the transformer. The voltage applied to the major component will also be existing in the second component.

As pointed out before, transformers carry out not enable DC intake to circulation through. This is known as DC isolation.<2> This is because a readjust in present cannot be generated by DC; an interpretation that there is no changing magnetic field to induce a voltage throughout the secondary component.


Figure 1. A straightforward operating transformer.<3> present I_p comes in v a voltage V_p. The existing passes v the N_p windings producing magnetic flux in the steel core. This flux is traveling with N_s loops of wire on the various other circuit. This creates a present I_s and also a voltage difference in the 2nd circuit that V_s. The electric power (V imes I) continues to be the same.

The an essential principle that enables transformers to adjust the voltage of alternating current is the direct relationship between the proportion of loops of wire in the major winding to the secondary winding and the proportion of the primary voltage to the calculation voltage. The ratio between the number of turns (or loops) in the major coil come the variety of turns in the secondary coil is recognized as the turns ratio. The transforms ratio establishes the adhering to relationship v voltage:

fracN_pN_s = fracV_pV_s=fracI_sI_pN_p = variety of turns in the main coilN_s = variety of turns in the an additional coilV_p = Voltage throughout the primaryV_s = Voltage throughout the secondaryI_p = current through the primaryI_s = current through the secondary

From this equation, if the number of turns in the major coil is better than the number of turns in the second coil (N_p gt N_s), then the voltage across the secondary coil will be much less than in the main coil. This is well-known as a "step-down" transformer, since it lowers, or procedures down, the voltage. The table below shows common types of transformers used on the electric grid.

Transformer TypeVoltageTurns ratioCurrentPower
Step downinput (primary) voltage > output (secondary) voltageNp>NsIpIsPp=Ps
Step upinput (primary) voltage NpNsIp>IsPp=Ps
One-to-oneinput (primary) voltage = output (secondary) voltageNp=NsIp=IsPp=Ps

The one to one transformer will have equal worths for everything and also is used largely for the objective of providing DC isolation.

A step down transformer will have a higher primary voltage than an additional voltage, however a lower main current worth than its secondary component.

In the case of the step up transformer, the primary voltage will certainly be lower 보다 the second voltage, an interpretation a greater primary current than the an additional component.


Under ideal conditions the voltage and also current change by the same aspect for any transformer, which describes why the major power value is same to the secondary power value for each situation in the over table. Together one value decreases the other increases to keep at a continuous equilibrium strength level.

See more: Quick Answer: How Many City Blocks Is A Mile ? How Many City Blocks Equal One Mile


Transformers have the right to be very efficient. High-power transformers can reach the 99% note of efficiency, together a result of successes in minimizing transformer losses. However, a transformer will constantly output a slightly reduced power 보다 its input, together losses cannot be got rid of completely. There is part transformer impedance.

To learn more about transformers please view hyperphysics.

For additional Reading

For further information please check out the associated pages below:


Authors and also Editors

Bethel Afework, Gokul Dharan, Jordan Hanania, James Jenden, Kailyn Stenhouse, Jasdeep Toor, Jason DonevLast updated: April 28, 2020Get Citation