A Step-down transformer is one whose secondary voltage is less than its
primary voltage. The step down transformer is designed to reduce the
voltage from the primary winding to the secondary winding.
To Order Step-Down Transformers We Recommend
This kind of
transformer "step down" the voltage applied to it. They often range in
voltage sizes from 0.5 kva to 500 kva.
There is many uses for step-down transformer and the
larger devices are used in electric power systems, and
small units in electronic devices. Industrial and
residential power transformers that operate at the line
frequency (60 Hz in the U.S.), may be single phase or
three-phase, are designed to handle high voltages and
currents. Efficient power transmission requires a
step-up transformer at the power-generating station to
raise voltages, with a corresponding decrease in
current. Line power losses are proportional to the
square of the current times the resistance of the power
line, so that very high voltages and low currents are
used for long-distance transmission lines to reduce
losses. At the receiving end, step-down transformers
reduce the voltage, and increase the current, to the
residential or industrial voltage levels, usually 115 to
In electronic equipment, transformers with capacities
in the order of 1 kw are largely used ahead of a
rectifier, which in turn supplies direct current (DC) to
the equipment. Such electronic power transformers
are usually made of stacks of steel alloy sheets, called
laminations, on which copper wire coils are wound.
Transformers in the 1-to100-W power level are used
principally as step-down transformers to couple
electronic circuits to loudspeakers in radios,
television sets, and high-fidelity equipment.
Known as audio transformers, these devices use only a
small fraction of their power rating to deliver program
material in the audible ranges, with minimum distortion.
The transformers are judged on their ability to
reproduce sound-wave frequencies (from 20 Hz to 25 kHz)
with minimal distortion over the full sound power level.
How does a step-down transformer work?
A transformer is a electrical device with one winding of wire placed
close to one or more other windings, used to couple two or more
alternating-current circuits together by employing the induction between
the windings. A transformer in which the secondary voltage is higher
than the primary is call a step-up transformer, if the secondary voltage
is less than the primary, then its a step-down transformer. The product
of current times voltage is constant in each set of windings, so that in
a step-up transformer, the voltage increase in the secondary is
accompanied by a corresponding decrease in the current.
Factors in choosing a step-down transformer:
Transformers must be efficient and should dissipate as little
power as possible in the form of heat during the transformation process.
Efficiencies are normally above 99 percent and are obtained by using
special steel alloys to couple the induced magnetic fields between the
primary and secondary windings. To increase transformer efficiency
and reducing heat one of the most important considerations is choosing
the metal type of the windings. Copper windings is more efficient
than aluminum and other winding metal choices.
Transformers with copper windings cost more initially, but can save on
electrical cost and maintenance over time and more than makes up for the
initial cost. The dissipation of even 0.5 percent on the power
transmitted in a large transformer generates a large amount of heat,
which requires special cooling. Typical power transformers are installed
in sealed containers that have oil or another substance circulating
through the windings to transfer the heat to external radiator-like
surfaces, where it can be discharged to the surroundings.
Information on a typical step-down transformer:
A transformer is a device for stepping-up or stepping-down electric
signal. Without efficient transformers, the transmission and
distribution of ac electric power over long distances would be
There are two circuits; the primary circuit, and the secondary
circuit. There is no direct electrical connection between the two
circuits, but each circuit contains a winding which links it inductively
to the other circuit. In transformers, the two windings are wound onto
the same iron core. The purpose of the iron core is to channel the
magnetic flux generated by the current flowing around the primary
windings, so that as much of it as possible also links the secondary
winding. The common magnetic flux linking the two windings is
conventionally denoted in circuit diagrams by a number of parallel
straight lines drawn between the windings. In other words, the ratio of
the peak voltages and peak currents in the primary and secondary
circuits is determined by a the ratio of the number of turns in the
primary and secondary windings; this latter ratio is usually called the
turns ratio of the transformer. If the secondary winding contains more
turns than the primary winding then the peak voltage in the secondary
circuit exceeds that in the primary circuit. This type of transformer is
called a step-up transformer, because it step us the voltage of an ac
signal. Note that the peak current in the secondary circuit is less than
the peak current in the primary circuit in a step-up transformer
(as must be the case if energy is to be conserved). Thus, a step-up
transformer actually steps down the current. Likewise, if the secondary
winding contains less turns than the primary winding then the peak
voltage in the secondary circuit is less than that in the primary
circuit. This type of transformer is called a step-down transformer.
Note that a step-down transformer actually steps up the current (i.e.,
the peak current in the secondary circuit exceeds that in the primary
The use of step-up and step-down transformers in power
Electricity is generated in power stations at a fairly low peak
voltage (sometime like 440V), and is consumed at a peak voltage of 110V
to 220V for households and businesses in the U.S. AC electricity
is transmitted from the power station to the location where it is
consumed at a very high peak voltage (typically 50,000V). As soon as a
ac signal comes out of the generator in a power station it is fed into a
step-up transformer and fed into a high tension transmission line, and
transports the electricity over many miles, and once the electricity has
reached its point of consumption, it is fed through a series of
step-down transformers until its peak voltage is often reduced down to
If Electricity is both generated and consumed at low peak
voltages, why go to the trouble of stepping up the peak voltage to a
very high value at the power station and then stepping down the voltage
again once the electricity has reached its point of consummation? Why
not generate, transmit, and distribute the electricity at a voltage of
110V? Consider an electric power line which transmits a peak
electric power between a power station and a city. We can think of the number of consumers in the city and the nature of
the electrical devices which they operate, as essentially a fixed
number. Suppose that the peak voltage and peak current of the ac
signal are transmitted along the line. We can think of these numbers as
being variable, since we can change them using a transformer. However,
since, the product of the peak voltage and the peak current must remain
constant. The resistance of the line causes power loses that are greater
at lower voltages over distance. The peak rate at which electrical
energy is lost due to ohmic heating in the line is high.
If the power transmitted down the line is a fixed quantity, as is the
resistance of the line, then the power lost in the line due to ohmic
heating varies like the inverse square of the peak voltage in the line.
It turns out that even at very high voltages, such as 50,000 V, the
ohmic power losses in transmission lines which run over ten kilometers
can amount to up to 20% of the transmitted power. It can readily be
appreciated that if an attempt were made to transmit ac electric power
at a peak voltage of 110V then the ohmic losses would be so severe that
virtually none of the power would reach it destination. It is only
possible to generate electric power at a central location, transmit it
over large distances, and then distribute it at its point of
consumption, if the transmission is performed at a very high peak
voltage (the higher, the better). Transformers play a vital role in this
process because they allow us to step-up and step-down the voltage of a
ac electric signal very efficiently. A well designed transformer
typically has a power loss which is only a few percent of the total
power flowing through it.
allows signal or power to be taken from one device and fed into
another without electrically connecting the two.
are devices that transfer electrical energy from one electric
circuit to another, without changing the frequency, by
are designed to meet certain performance specifications and size
requirement that you require. There is a wide range of custom
Buck Boost Transformers
is a ideal solution for changing line voltage by small amounts.
Often used to buck (lower), or boost (raise) the voltage from 208v
to 240v for lighting applications.
Pole Mounted Transformers
are mounted to poles for overhead electrical lines. Used in various applications.
Are available in single phase or three phase transformers.
Medium Voltage Transformers
are used with a medium range of voltages. They come in a full
range from liquid-filled, convention dry type as well as cast coil.
Pad Mounted Transformers
are a excellent choice for commercial and industrial such as
manufacturing facilities, refineries, office buildings, schools,
hospitals, restaurants, and retail stores. They come in various
sizes and can be used underground as well.
typically these voltage transformers are used in power transmission
applications. High voltage transformers are also used in microwave.
- With Acme Electric being in business
over 80 years, they have always believed in offering there customers superior service, quality and technical expertise in the
AMVECO Transformers -
AMVECO designs and manufactures toroids
transformers, current transformers, and auto transformers. Most
AMVECO products are custom designed utilizing their state-of-art proprietary
CAD programs. The AMVECO engineers can quickly generate designs in a
matter of hours, if needed.
Federal Pacific Transformers -
Federal Pacific is a division of Electro- Mechanical Corporation, a
privately held, American owned company founded in 1958. Federal
pacific offers dry-type transformers from .050 KVA through 10,000
KVA single and three phase, up to 34.5 KV, 150 KV BIL with UL
approval through 15 KV.
Marcus Transformer - Ever since they opened their doors for business a half a century ago,
they have been a leader in innovative transformer design. As a
family-owned company they are proud of the reputation they have
earned for making quality-built transformers that deliver
exceptional performance and savings.
Hammond Transformers - Hammond Manufacturing was founded in 1917 in Guelph, Ontario,
Canada. In the last 3 decades it has expanded to the US and the
international markets offering many types of power transformers.
- TEMCo Transformer, a family-owned business which has been
manufacturing and distributing electrical products since
1968. They focus on transformers that significantly
reduce power consumption over 30 percent compared to competitive
GE Transformers - GE has been a key player in the energy industry for
more than a century. Since the installation of
their first steam turbine in 1901. They have become
number one provider of high-technology power generation
and distribution equipment.
Jefferson Electric Transformers - Jefferson Electric has
been a pioneer and innovator of magnetic products since 1915.
Jefferson broad line of dry-type transformers are backed by quality
assurance systems so stringent that each and every unit gets
thoroughly tested before it goes out there door.
Distribution Transformers - Distribution
transformers are generally used in electrical power
distribution and transmission power. This class of transformer has
the highest power, or volt-ampere ratings. and the highest
continuous voltage rating.
Substation Transformers - Substation Transformers are large
devices which usually weigh tens of thousands of pounds. They are
filled with tens of thousands of gallons of heat transfer fluid.
Although they are typically 99.8% efficient in the transforming of
electricity from one voltage to another, processing hundreds of Mega
Volts-Amps of electricity force the liberation of hundreds of BTUs
Medical Grade Isolation Transformer -
Medical Grade Transformers generally refer to the transformers
used in medical devices as well as hospital, biomedical and patient
care equipment. There are a number of strict safety rules,
guidelines and laws governing the design, construction and the test
of these transformers.
Drive Isolation Transformer -
They are used to isolate a drive from a main power line to
prevent the transmission of harmonics that the drives produce back
into the power line. They stop drive harmonics from disrupting
computers and other sensitive equipment.
Toroidal Transformers -
Toroidal Transformers are more efficient than the cheaper laminated EI types of similar power level. Some of the advantages are smaller
size, lower weight, less mechanical hum, (making them superior in
audio amplifier), low-off-load loss.
Step-Up Transformers - A Step-Up Transformer is one whose
secondary voltage is greater than its primary voltage.
This kind of transformer "steps up" the voltage applied
to it. -
- A Step-Down Transformer is designed to reduce voltage from primary to
They can range from sizes from .05 KVA to 500 KVA
Isolation Transformers -
An Isolation Transformer is a device that transfers energy from
the alternating current (AC) supply to an electrical or electronic
load. It isolates the windings to prevent transmitting certain
types of harmonics.
Buck Boost Transformers - Buck Boost
Transformers make small adjustments to the incoming voltage. They
are often used to change voltage from 208v to 240v for lighting
applications. Major advantages of Buck boost transformers
include; low cost, compact size and light weight.
High Voltage Transformer - There are many different types of
voltage transformers. A High Voltage Transformer operates with high
voltages. Typically, these voltage transformers are used in power
transmission applications, where voltages are high enough to present
a safety hazard.
Medium Voltage Transformers -
A Medium Voltage Transformer can be connected directly to a primary
distribution circuit and generally has the most load diversity.
These voltage transformers have installation practices that are
generally in accordance with application recommendations from the
Institute of Electrical and Electronic Engineers (IEEE).
Low Voltage Transformers
- A Low Voltage Transformer is an electrical device that transforms
120 volts (line voltage) into 12 volts or 24 volts (low voltage).
Some uses for low voltage transformer are in landscaping lighting.
Single Phase Transformers - In electrical engineering, single-phase electric power refers to the
distribution of electric power using a system in which all the
voltages of the supply vary in unison. Single-phase distribution is
used when loads are mostly lighting and heating, with few large
Three Phase Transformers - Three
Phase Transformers must have 3 coils or windings connected in
the proper sequence in order to match the incoming power and
therefore transform the power company voltage to the level of
voltage needed while maintaining the proper phasing or polarity.
Custom Transformers -
Custom Transformers are designed for a certain performance
specifications and size requirements. The company works with
your engineering specification.
Industrial Control Transformers -
Industrial Control Transformers are used to convert the
available supply voltage to the required voltage to supply
industrial control circuits and motor control loads.
Pad Mounted Transformers - Pad
Mounted Transformers are usually single phase, or three phase, and
used where safety is a main concern. Typical applications;
restaurant, commercial building, shopping mall, institutional.
Pole Mounted Transformers -
Pole Mounted Transformers are used for distribution in areas
with overhead primary lines. Outside a typical house one can see one
of these devices mounted on the top of an electrical pole.
Oil Filled Transformers -
Oil Filled Transformers are transformers that use insulating oil as
insulating materials. The oil helps cool the transformer.
Because it also provides part of the electrical insulation between
internal live parts, transformer oil must remain stable at high
temperatures over an extended period.
Dry Type Transformers - Dry-Type
Transformers are available for voltages up through 34.5 kV
(although the most common upper limit is 15) and KVA ratings up
through 10,000 (with 5000 as the usual limit). Dry-type use air as a
coolant, lowering health and environmentally concerns.
Auto Transformers -
An Autotransformer is an electrical transformer with only one
winding. The winding has at least three electrical connection points
called taps. Autotransformers are frequently used in power
applications to interconnect systems operating at different voltage
classes, for example 138 kV to 66 kV for transmission. Another
application is in industry to adapt machinery built for 480 V
supplies to operate on the local 600 V supply.
Electrical Transformers are devices used to raise or lower the
voltage of alternating current. For instance, power is transported
over long distance in high voltage power lines and then transformers
lower the voltage so that the power can be used by a business or household.
An Isolating Transformer is a transformer, often with
symmetrical windings, which is used to decouple two circuits.
An Isolation transformer allows an AC signal or power to be taken
from one device and fed into another without electrically connecting
the two circuits. Isolation transformers block transmission of DC
signals from one circuit to the other, but allow AC signals to pass.
Power Lines - A Transmission Line is the material medium or structure that forms
all or part of a path from one place to another for directing the
transmission of energy, such as electromagneticor acoustic waves as well as electric power
transmission. Components of transmission lines include wires, coaxialcables, dielectric slabs, option fibers,electric power lines, and waveguides.
Transformer Voltage - The measure of the amount of force on a
unit charge because of the surrounding charge.
Transformer Frequency -
The transformer cannot change the frequency of the supply. If the
supply is 60 hertz, the output will also be 60 hertz.
Transformer K Factor - Some transformers are now being offered
with a k-factor rating. This measure the transformer's ability to
withstand the heating effects of non-sinusoidal harmonic currents
produced by much of today's electronic equipment and certain
Primary Voltage - The coil winding that is directly connected
to the input power.
Harmonic Cancellation -
Harmonic cancellation is performed with harmonic canceling
transformers also known as phase-shifting transformers. A harmonic
canceling transformer is a relatively new power quality product for
mitigating harmonic problems in electrical distribution systems.
This type of transformer has patented built-in electromagnetic
technology designed to remove high neutral current and the most
harmful harmonics from the 3rd through 21st.
Enclosed transformers come with a weatherproof standard set by
Epoxy Encapsulated -
A process in which a transformer or one of its components is
completely sealed with epoxy or a similar material. This process is
normally preferred when a unit might encounter harsh environmental
Voltage Regulators - A
Voltage Regulator is an electrical regulator designed to
automatically maintain a constant voltage level.
It may use an electromechanical mechanism, or passive or active
electronic components. Depending on the design, it may be used to
regulate one or more AC or DC voltages.
AC Line Reactor -
AC Line Reactors is a three phase transformer used in
conjunction with AC variable frequency and DC motor drive.
They are a bi-directional protective filtering device.
Line Power Conditioners -
Power or Line Conditioners regulate, filter, and suppress noise in
AC power for sensitive computer and other solid state equipment.
DC Power Supplies -
Conversion of one form of electrical power to another desired
form and voltage. This typically involves converting 120 or 240 volt
AC supplied by a utility company to a well-regulated
lower voltage DC for electronic devices.
Rotary Phase Converters -
Rotary Phase Converters are commonly used in home or small
commercial or industrial settings. Rotary phase converters convert
single-phase power into three-phase power. This is a very
cost-effective way to power three-phase electric motors and other
three phase equipment.
Frequency Converters -
A Frequency Changer or Frequency Converter is an
electronic device that converts alternating current (AC) of one
frequency to alternating current of another frequency.
Voltage Converters -
A Voltage Converter changes the voltage of an electrical power
source and is usually combined with other components to create a
Magnetic Motor Starters - Magnetic Motor Starters are
essentially heavy duty relays mounted in boxes, often equipped with
heater/thermal overloads matched to the motor they start.
Motor Starting Auto Transformers - An Auto
Transformer starter uses an auto transformer to reduce
the voltage applied to a motor during start. The auto transformer
may have a number of output taps and be set-up to provide a single
stage starter, or a multistage starter.