Electric transformers are inductively coupled electro-magnetic devices that transfer electrical energy from one circuit to another. All electronically operated equipment depends on power transformers to convert electrical currents into voltages that fit a specific application, and current transformers are also required in order to store and transport energy through power lines and grids.
Because there are so many contexts in which electronic transformation is necessary, there exists a wide variety of electric transformers to accommodate them. Auto transformers, step-up and step-down transformers, toroidal transformers, zig zag transformers and pulse transformers are just a few examples. By transferring electrical energy through two coil stages, transformers can increase, decrease, isolate, translate and pattern electrical currents to safely power electronic equipment of all voltage requirements. Electric transformer manufacturers configure transformers differently to meet all types of electric transformation applications and range in size from thumb-sized transformers in electric lamps or microphones to the enormous stationary transformers in power facilities. Low voltage transformers convert electrical currents into voltages that fit appliances such as dimmer lights and other small electronic devices, while high voltage transformers are used in the transmission of electricity between power generation facilities and its points of consumption. Most transformers are isolation transformers because they facilitate the transmission of electricity through induction, and many transformers are 3 phase transformers, capable of transforming electricity in 3 phases.
In addition to converting currents to a higher or lower voltage, electric transformers can serve to isolate parts of circuits from others. Auto transformers, however, have no isolation between the source and load circuit; they transmit electricity through conductors that are in contact with each other. An electric transformer can be as large as the fenced-in transformers for whole facilities, or they may be small enough to be tucked away in household appliances such as light fixtures. Electric transformers are necessary when there is a voltage difference between an electronic component or appliance and an electrical power supply. Safety is of the utmost concern in such situations, since using a voltage that is too high or too low to power a device can cause serious problems. Excessive voltage can cause device failure or destruction; in severe cases, over-voltage can cause fires and can expose users to powerful electric shocks. In the case of under-voltage, voltage deficiency can also cause device failure.
Instrument transformers, including current transformers, accurately measure and monitor power voltage as it is transmitted proportionally through the primary and secondary coils. Step down transformers convert higher voltages to lower voltages by having fewer secondary coil windings, while step up transformers' higher number of secondary coil windings allow them to convert lower voltages to higher output voltages. Toroidal transformers are donut-shaped transformers that are highly space efficient and excellent for reducing electromagnetic interference; inductors limit the amount of AC flow to an appliance or transient application while suppressing high frequency noise, similar to toroids. Isolation transformers decouple two circuits, allowing AC power to move from one device to another without the two circuits connecting; this is achieved by having the primary and secondary coils not directly connected. Inverters are capable of converting direct current voltage (DC) to alternating current voltage (AC), while pulse transformers create the electrical surges that are used in telecommunication and detail logic applications such as camera flashes, radar equipment and particle acceleration. In addition, zig zag transformers are special-purpose 3-phase transformers that are intended for use in providing earthing for ungrounded electrical systems as well as filtering and controlling harmonic currents.
Electric transformers are comprised of two sets of coils or windings linked by a magnetic field. The core is iron or a ferrite compound or a laminated core wound with bare copper or enameled coils. The coils are primary and secondary and function as conductors. When the primary coil receives AC voltage, this produces a varying magnetic field of voltage surrounding the conductor; the magnetic field activates the secondary conductor coil. This results in the transformers changing the voltage and transferring electrical energy, ideally with the least amount of energy loss. The number of windings on each coil is important, as this determines the voltage that is conveyed from the primary to the secondary through the magnetic field. The ratio of turns (also called windings) in the primary coil to the number of turns in the secondary coil determines the magnitude of the voltage; for example, a step-down transformer will have fewer turns in its secondary coil than the primary, while a step-up transformer will have more secondary coil windings than primary. Once the voltage conversion is made, the energy is transferred to the load center and the electrical process continues from there. Both the size and expense of electric transformers increases in proportion to the number of primary windings.
Purpose of Transformers
Transformers are regulators. They make sure that enough, but not too much, voltage is supplied for specific use. If too high, a voltage is used on an electronic device then it could destroy the device, cause a fire, and even send out sparks of electricity in arch form. If a device receives too low a voltage, it could cause the device to malfunction. For these reasons, it is important that the voltage level is regulated before it is transferred to the device that is to utilize the electricity.
Power transformers are utilized in every electronically powered device or equipment. They are necessary to convert the current into the proper voltage so that the electricity can be used by the device. Whether it’s a computer, hair clippers, or a remote-control car, there is a transformer in it that is regulating the way and amount of electricity is transferred to where it will be used.
Single Phase Transformer – Lenco Electronics, Inc.
Isolation Transformer – Johnson Electric Coil Company
Three Phase Transformer – Lenco Electronics, Inc.
Electric Transformer Manufacturers – Johnson Electric Coil Company
Small Isolation Transformers – Johnson Electric Coil Company
Single and Three Phase Transformers – Johnson Electric Coil Company
History of Electric Transformers
In the 1830's, Michael Faraday and Joseph Henry discovered the property of induction through their work with electromagnets. Amazingly enough, these two men were on two separate continents, working totally independent of each other, and they made their discoveries within a year of each other.
The Faraday Law, which would lead to the invention of the first transformer about 45 years later, was born when Michael Faraday conducted an experiment to show how an electromagnetic field could provide power. He wrapped two coils around opposite sides of a ring. One side he connected to a galvanometer, and the other side he hooked to a battery. He saw that when he hooked a coil to the battery that it powered the coil hooked up to the galvanometer, just as he had suspected.
However, when Faraday unhooked the coil from the battery, he noticed that a current still flowed from the coil to the galvanometer, which meant that the battery was still powering the coil even though it was no longer physically connected to the coil or the ring that the coil was wrapped around. This scientific breakthrough laid the groundwork for the creation of the first transformer by Ottó Bláthy, Miksa Déri, and Károly Zipernowsky of the now defunct Austro-Hungarian Empire. Theirs was a toroidal shaped transformer that was used for AC powered incandescent lighting systems.
Even though the first transformer was made in Budapest, Hungary in the mid 1870's, it would be another decade before the first transformers that were considered practical for regular use were introduced. This was done by William Stanley and George Westinghouse. In 1886, it would be the transformer developed by William Stanley that would become the first one used for commercial use to provide power to Great Barrington, Ma. Today transformers are a part of all electronic circuitry. They are on the poles that connect power lines, they are in lamps, and even in flashlights.
How Do Transformers Work
Transformers operate off of the principal of electromagnetic induction. For this to occur, there must be an electromagnetic field. A coil wrapped around a core is charged with an alternate current which is converted into a primary voltage to achieve this. The energy in the coil then permeates an electromagnetic field, also called a magnetomotive force, which will travel through the core to another coil, giving it a secondary voltage.
The input voltage is determined by the power source itself. However, the voltage that the actual transformer will output is determined by the second coil that the electricity passes through. If the second set of windings, or coils, is equal to the first set, then the voltage output will be the same as the input. However, if the secondary coil has fewer windings than the primary coil then the secondary voltage will be less than the primary voltage. This is called a step-down transformer. If the secondary coil has more windings than the primary one then it will increase the voltage; this type of transformer is called a step-up transformer.
There is energy lost in the magnetic field of the transformer. This lost energy resonates in the form of heat. To lessen the loss of energy, often times the coils are in a cooling agent within the transformer. Many manufacturers utilize a concentrical configuration in which both the primary and secondary coils are wrapped together around the coil. This configuration is most popular in three step transformers.
From the transformer, electricity is then transported through power lines and power grids. The transformer does the job of regulating the voltage of the electricity to be transferred. Step-up transformers increase the voltage, and step-down transformers decrease the voltage. This process ensures that the end device that is being powered receives the proper voltage. Too little voltage will not power a device, and may affect its functionality long-term. Too high a voltage could destroy the device that is being powered, and could potentially cause fire and electric shock if it exceeds the peak voltage of a device.
While all transformers work based off of the Faraday Law to some degree, there are many types of transformers for different functions.
Laminated Core Transformers- are among the most commonly used type of transformers. These transformers are commonly used in appliances to convert voltages to low voltages. The laminated core prevents eddy current losses in the core.
Toroidal Transformers- are similar to the one invented in Hungary by Ottó Bláthy, Miksa Déri, and Károly Zipernowsky. It is more expensive to make because the winding process is slow and requires special equipment.
Automatic Transformers- have only one coil, but the voltage is regulated by the frequency of windings in the separate portions. Automatic transformers are one of the more cost-efficient types of transformers, as well.
Polyphase Transformers- Polyphase systems can be connected either to multiple single-phase transformers or just one polyphase transformer. Many polyphase transformers use the zigzag configuration, especially if it is a grounded system.
Three-Phase Transformers- the three primary windings are connected to each other, and the three secondary ones are connected to each other.
When it comes to transformers, it is Faraday's Law that is in operation, and they are perfect for storing and transporting electrical power. Ever since transformers were introduced for commercial use in 1886, when they were used to power Great Barrington, Maine, they have been in constant use in some incarnation. Transformers are the safest way to transport electricity between circuits. Many of them are capable of providing electrical power to whole towns and large sections of big cities.
Transformers can be customized to suit specific needs. There are a wide variety of types of transformers, but in the case that you need something suited specifically to your needs there are manufacturers who can help you. The key is finding the right manufacturer. A good manufacturer and the right manufacturer are by no means the same thing.
There are many good manufacturers, but the right manufacturer can only be determined by you. A good place to start when looking for the right transformer builder is of course pricing, but also understand that you may get the quality that you pay for. Also, the right manufacturer will work cooperatively with you to find the electrical power solutions that best suit your company rather than just trying to push their most expensive transformer.
It is important to know what it is you need in a transformer, and even if you aren't 100% sure what is best for your particular powering needs, capable manufacturers can provide you with the best options for your unique situation. Mechanical and electrical systems can be tough fields to navigate, but the good news is that you don't have to go it alone.
Electric Transformer Types
- 3 phase transformers are tools used to change the voltage of 3 phase electrical transmission systems.
- Auto transformers are electrical transformers with one winding that is common between both circuits and does not have any isolation between the two circuits.
- have a primary winding
linked in with the circuit to make the current measurable; they are used to change electrical currents.
- are rated between 3 and 500 KVA with 601 volts or more.
- do not use liquid to cool or insulate.
- have high leakage-to-reactance to limit
the output current to a designated value in the event of a fault.
designed to handle electrical energy in high voltage levels.
- Instrument transformers accurately measure and monitor power voltage as it is transmitted proportionally through the primary and secondary coils.
- convert between AC and DC power.
Transformers are transformers that insulate
the primary circuit from the secondary circuit.
- convert into lower voltages.
- are devices that convert voltage to lower levels.
- Pulse transformers are wide-band devices that are mainly intended for waveform transmission. They transmit rectangular electrical pulses, meaning that the pulses have fast rise and fall times with a fairly constant amplitude.
- Step down transformers have the power to convert higher voltages to lower voltages by means of transferring electrical energy through two coil stages, the second coil stage having fewer coil windings.
- are transformers that have a high voltage winding
connected to the output load and a low voltage winding connected
to the power source.
- have copper wire around a cylindrical core
so the magnetic flux is contained.
- are a static piece of apparatus
that transfers electrical energy from one circuit to another circuit
induction, often with altered values of voltage and current.
- Zig Zag Transformers are special-purpose three-phase transformers that are intended for use in providing earthing for ungrounded electrical systems as well as filtering and controlling harmonic currents.
Electric Transformer Terms
A transformer that uses air to cool by use of fans or normal ventilation.
– A transformer with one winding per phase.
multiple single phase transformers connected together to provide power
to a three phase load.
central part or inductor that enhances the power of the magnetic field.
– A condition that results from a transformer or
inductor reaching highest magnetic strength.
a three phase connection the windings all connect to form a loop.
of time for a transformer to provide full rated power to the load. This
measurement greatly affects the actual size of the transformer.
– A component that sits between windings – typically
the primary and secondary – to supply the most isolation; more
of these can be placed between secondary windings as needed. It is normal
to connect the shielding to the core.
Encapsulated – A dry transformer
with an enclosed core and coil assembly.
amount of current a transformer draws at nominal voltage input in an
– Resonance results from the saturation of a ferrous
core of an inductive component, which increases the inductive reactance
relative to the capacitance reactance.
– A complex system within the transformer that consists
of capacitors, inductors and a resistor; it provides a relative small
opposition to specific frequencies or direct current, as it blocks or
attenuates other frequencies.
– A conductor that can handle thermal expansion and contraction
as well as reduce noise.
the forces that resist the flow of current in AC circuits like resistance
or inductive or capacitive reactance.
– The capability of a coil for storing energy and resisting
changes in the flow of current; it is a function of the core material,
amount of turns of the coil and the cross section.
– This is when the transformer has a short
current surge through it from residual flux, occurring at the moment
energy is applied to the transformer.
– This transformer has physical separation
from the primary and secondary windings in order to allow magnetic coupling
between isolated circuits and minimize electrostatic coupling.
Ampere rating that is a measurement of the output of a transformer without
exceeding a certain temperature.
– The quantity of
electric power supplied or necessitated at any particular spot in the
system. Also a requirement of the KVA or
VA from the transformer; light bulbs are loads.
– This conductive material attenuates stray
magnetic fields by its positioning around a transformer’s coils.
The direction of the current between two leads. If the directions are
the same, the leads have the same polarity. In electric transformers
the polarity is classified as either additive or subtractive.
divided by volt amps, KW divided by KVA - the leading and lagging
of voltage versus current caused by inductive or capacitive
loads. Harmonic power factor relates to nonlinear current.
– The total of the Volts and Amps derived from all
the secondary windings.
– The opposition to variations of alternating
current; capacitive reactance relates to capacitors, and inductive
reactance is the opposition to change from an inductor or coils.
– A condition of an AC circuit in which capacitive and
inductive reactances interact, resulting in a maximum or minimum circuit
– On the load or output side, the connected transformer winding.
– Pressure switch device that detaches the transformer from the
The measurement of the amount of force on a unit charge because of the
– The change, in percentages, of the output voltage from no load
to full load.
connections to a winding that permit varying voltages from the same winding;
typically utilized on the primary winding to permit the transformer to
be used in different countries with varying line voltages.