Hammond Industrial Control Transformers

Selecting a Control Transformer requires that you have first hand knowledge of the application for the transformer and that you understand some basic terms related to the selection process. By using the following information, you will be sure to select the HPS Control Transformer which best meets your application.
The HPS PT Series machine tool control transformers are specifically designed for high inrush applications requiring reliable output voltage stability. Designed to meet industrial applications where electromagnetic devices such as relays, solenoids, etc. are used, the HPS PT series transformers maximize inrush capability and output voltage regulation when electromagnetic devices are initially energized. To select the proper transformer, three characteristics of the load circuit must first be determined. They are total steady-state (sealed) VA, total inrush VA, and inrush load power factor.
A. The total steady state “sealed” VA is the amount of VA that the transformer must supply to the load circuit for an extended length of time. Simply add the total steady-state VA of all devices in your control circuit. The operating VA data of these components is available from the manufacturers.
B. The total inrush VA is the amount of VA that the transformer must supply for all components in the control circuit which are energized together. Some consideration to the start-up sequence may be required. Inrush VA should be obtained from the device manufacturer.
C. The inrush load power factor is difficult to determine without detailed vector analysis of all the
control circuit components. Such information is not generally available. Therefore, HPS is recommending that a value of 40% power factor be utilized. Although some other control transformer manufacturers still recommend a power factor of only 20%, HPS, through recent tests
conducted on many popular brands of control devices has determined that the 40% power factor value is more accurate. Once the above circuit variables have been determined, transformer
selection is a six (6) step process.
SIX EASY STEPS
1. Determine what your Primary (supply) and Secondary (output) voltage requirements are, as well
as your required frequency (i.e. 60 Hz)
2. Calculate the Total Sealed VA of your circuit. (See Step A)
3. Now calculate the Inrush VA by adding the inrush VA of all components being energized together. Remember to add the sealed VA of all components that do not have inrush VA, (lamps, timers etc.) as they do however present a load to the transformer during maximum inrush. If the inrush for the components in your circuit are not known, assume a 40% Inrush Power Factor.
4. Calculate the Total Inrush VA using one of the two methods:

A. Total Inrush VA =
(VA sealed)2 + (VA inrush)2
OR
B. Total Inrush VA =
VA Sealed + VA Inrush
Note: method B will result in a slightly
larger transformer being selected.

5. If the nominal supply voltage does not fluctuate more than 5%, then reference the 90% secondary voltage column in the Regulation Data Table for the correct VA rating. If the supply voltage varies upwards of 10%, the 95% secondary voltage column should be used to size the transformer. Current standards require electromagnetic devices to operate reliably at a minimum of 85% of their rated voltage. However, contact life may be affected with
continuous start-ups at that voltage level. Therefore, the minimum 85% secondary voltage column should only be used as a reference.
6. Using the regulation data tables below, select the appropriate VA rated transformer:
A) With a continuous VA rating that is equal to or greater than the value in Step 2.
B) With a maximum inrush VA equal to or greater than the value obtained in Step 4.
To determine the correct HPS Transformer and its Catalog Number, just refer to the tables on this page
for the voltage ratings, frequency and corresponding VA required.

“PT” TRANSFORMERS
REGULATION DATA TABLE

Inrush VA @ 40% Power Factor

It is recommended that a Control Transformer be sized at a 40% Power Factor. Some components
in a circuit, such as electromagnetic devices, typically operate at that level due to their inherently lower power factor. Selecting a transformer at 40% Power Factor will more than adequately size the unit for all the various loads in the circuit.

PT SERIES CONTROL TRANSFORMERS

Features:

CORE & COILS
• High quality, high permeability silicon steel laminations.
• All-welded construction.
• Computer designed copper wound coils with optimum turns ratio.
INSULATION
• Mylar, Nomex and other insulating materials are used for phase to phase and layer to layer insulation.
• The “PT” series transformers have the following insulation systems:
• Up to 200 VA ; class A, 55°C rise, 105°C class.
• 250 to 1000 VA ; class B, 80°C rise, 130°C class.
• 1500 VA and up ; class F, 115°C rise, 180°C class.
VACUUM IMPREGNATION
• All Hammond Control Transformers are Vacuum Impregnated with “VT” (vinyl-toluene) Polyester Resin”.
• Oven cured after vacuum impregnating.
MOLDED CONSTRUCTION
• All PT series transformers, up to 1000 VA, are molded in a UL 94 flame retardant polyester compound.
• These units have a thermal plastic, injection molded cover with distinctive cooling fins.
TERMINAL BLOCKS
• Fabricated from molded “high-impact” resin, finished in black.
• Combination Phillips (#2) and Robertson (# 2) Red terminal screws with #9 head, 8-32 UNF threads.
• Terminals are tinned brass and chrome plated, and all connections are soldered.
• Terminals are torque tested with automatic drivers.
NAMEPLATE
• Black letters on white background including terminal markings, schematic and CE mark.
• Polyester, non conductive material.
MOUNTING PLATE
• Offers an unique Universal Mounting Plate made of heavy steel, welded to the core.
FINGER SAFE TERMINAL COVERS
• Finger safe terminal covers for both fused and unfused terminals, in a clear, see through finish, are available for all molded PT series units.
STANDARD SECONDARY FUSE CLIPS
• Each “PT” series transformer, that has a single secondary, comes with a factory installed secondary fuse kit (fuses not included).

Benefits:

CORE & COILS
• Provides optimum performance and reliability.
• Rugged one-piece assembly with low noise.
• Enhanced voltage regulation with excellent thermal characteristics.
INSULATION
• Provides the best insulated control
transformer in the industry.
• Insulation materials are of the highest rating available for the temperature class.
• Assures long life and reliable performance.
VACUUM IMPREGNATION
• Impregnating the entire unit provides a strong mechanical bond and offers protection against
environmental conditions.
• Seals the surface and eliminates moisture.
MOLDED CONSTRUCTION
• Completes the protection process by sealing the core and coils against moisture, dirt and other
airborne contaminants.
• Strong and durable, yet still dissipates heat quickly and efficiently.
TERMINAL BLOCKS
• Easy access to terminals while separation barriers prevent unintentional contact.
• Versatile screw head with optimum torque and retention ability.
• Assures integrity and strength of connections and terminals
• Withstands any manual installation method.
NAMEPLATE
• Ease of readability results in easier installation.
• Safe for other conductors, even in close proximity.
MOUNTING PLATE
• Provides direct interchangeability with many other popular control transformers.
FINGER SAFE TERMINAL COVERS
• This ensures your protection against electric shock or accidental contact of any kind and
complies with IEC and CE requirements.
STANDARD SECONDARY FUSE CLIPS
• Accommodates 13/32” X 1 1/2” Midget Fuse.

SELECTION CHARTS

Group AA
Primary Voltage 240/480, 230/460, 220/440 Secondary Voltage 120, 115, 110- 50/60 Hertz

Group BB
Primary Voltage 575, 460, 230 Secondary Voltage 575, 460, 230 115, 95- 50/60 Hertz

 Group CC
Primary Voltage 240/480 Secondary Voltage 24 -50/60 Hertz

Group DD
Primary Voltage 120/240 Secondary Voltage 24 -50/60 Hertz

Group FF
Primary Voltage 460,230,208 Secondary Voltage 115- 50/60 Hertz

Group II
Primary Voltage 380, 277, 208 Secondary Voltage 120-50/60 Hertz

Group LL
Primary Voltage 240/480 Secondary Voltage 12/24 -50/60 Hertz

Group MM
Primary Voltage 415, 400, 380 Secondary Voltage 110/220-50/60 Hertz

Group JJ (Universal, Open Style Transformer)
Primary Voltage 600, 480, 416, 240 Secondary Voltage 130, 120, 99-50/60 Hertz

Group KK (Universal, Open Style Transformer)
Primary Voltage 480, 380, 277, 240, 208 Secondary Voltage 24 -50/60 Hertz

Group NN Primary Voltage 460, 230, 208, 200 Secondary voltage 24, 115-50/60 Hertz

Group PP
Primary Voltage 415, 400, 240 Secondary Voltage 24, 120-50/60 Hertz

Group QQ
Primary Voltage 480, 415, 400 Secondary Voltage 24, 120-50/60 Hertz

Group RR
Primary Voltage 240/480 Secondary Voltage 120/240-50/60 Hertz

Group SS
Primary Voltage 120/240 Secondary Voltage 120/240-50/60 Hertz

PH Series Control Transformer - Applications

The HPS “PH” series of machine tool transformers are specifically designed for high inrush applications
requiring reliable output voltage stability. Designed to meet industrial applications where electromagnetic devices
such as relays, solenoids, etc. are used, the HPS “PH” series transformers maximize inrush capability and output
voltage regulation when electromagnetic devices are initially energized.

Features

CORE & COILS
• High quality, high permeability silicon steel laminations.
• All-welded construction.
• Computer designed copper wound coils with optimum turns ratio.
INSULATION
• Mylar, Nomex and other insulating materials are used for phase-to-phase and layer-to-layer insulation.
• The “PH” series transformers have the following insulation systems:
• Up to 200 VA ; class A, 55°C rise, 105°C class.
• 250 to 1500 VA ; class B, 80°C rise, 130°C class.
• 2000 VA and up ; class F, 115°C rise, 180°C class.
VACUUM IMPREGNATION
• All HPS Control Transformers are Vacuum Impregnated with “VT” (vinyl-toluene) Polyester Resin”.
• Oven cured after vacuum impregnating.
MOLDED CONSTRUCTION
• All PH series transformers, up to 1000 VA are molded in a UL 94 flame retardant polyester compound.
• These units have a thermal plastic, injection molded cover with distinctive cooling fins.
TERMINAL BLOCKS
• Fabricated from molded “high-impact” resin, finished in black.
• Combination Phillips (#2) and Robertson (#2) Red terminal screws with #9 head, 8-32 UNF threads.
• Terminals are tinned brass, chrome plated and all connections are soldered.
• Terminals are torque tested with automatic drivers.
NAMEPLATE
• Black letters on white background including terminal markings, schematic and CSA and UL logos.
• Polyester, nonconductive material.
MOUNTING PLATE
• Offers the traditional HPS Mounting plate made of heavy steel, and welded to the core.
FINGER SAFE TERMINAL COVERS
• Finger safe terminal covers for both fused and unfused terminals, in a clear, see through finish, are available for all molded PH series units.
STANDARD SECONDARY FUSE CLIPS
• Each “PH” series transformer, that has a single secondary, comes with a factory installed secondary

Benefits

CORE & COILS
• Provides optimum performance and reliability.
• Rugged one-piece assembly with low noise.
• Enhanced voltage regulation with excellent thermal characteristics.
INSULATION
• Provides the best insulated control transformer in the industry.
• Insulation materials are of the highest rating available for the temperature class.
• Assures long life and reliable performance.
VACUUM IMPREGNATION
• Impregnating the entire unit provides a strong mechanical bond and offers protection against environmental conditions.
• Seals the surface and eliminates moisture.
MOLDED CONSTRUCTION
• Completes the protection process by sealing the core and coils against moisture, dirt and other airborne contaminants.
• Strong and durable, yet still dissipates heat quickly and efficiently.
TERMINAL BLOCKS
• Easy access to terminals while separation barriers prevent unintentional contact.
• Versatile screw head with optimum torque and retention ability.
• Assures integrity and strength of connections and terminals.
• Withstands any manual installation method.
NAMEPLATE
• Ease of readability results in easier installation.
• Safe for other conductors, even in close proximity.
MOUNTING PLATE
• Provides direct interchangeability with many other popular control transformers.
FINGER SAFE TERMINAL COVERS
• This ensures your protection against electric shock or accidental contact of any kind.
STANDARD SECONDARY FUSE CLIPS
• Accommodates 13/32” X 1 1/2” Midget Fuse.

Group A
Primary Voltage 600 Secondary Voltage 120-60 Hertz

Group B
Primary Voltage 480 Secondary Voltage 120-60 Hertz

Group C Primary Voltage 240 Secondary Voltage 120-60 Hertz

Group D Primary Voltage 208 Secondary Voltage 120-60 Hertz

Group E Primary Voltage 600 Secondary Voltage 120/240-60 Hertz

Group F Primary Voltage 240/480 Secondary Voltage 120/240-60 Hertz

Group G Primary Voltage 120/240 Secondary Voltage 120/240-60 Hertz

Group H Primary Voltage 208/416 Secondary Voltage 120/240-60 Hertz

Group I Primary Voltage 347 Secondary Voltage 120/240-60 Hertz

Group J Primary Voltage 600 Secondary Voltage 240-60 Hertz

Group K Primary Voltage 600 Secondary Voltage 24-60 Hertz

Group L Primary Voltage 480 Secondary Voltage 24-60 Hertz

Group M Primary Voltage 480 Secondary Voltage 24-60 Hertz

Group N Primary Voltage 120 Secondary Voltage 24-60 Hertz

Group O Primary Voltage 120 Secondary Voltage 12-60 Hertz
 

Group P Primary Voltage 120/240 Secondary Voltage 12/24-60 Hertz

Group Q Primary Voltage 120 Secondary Voltage 12O-60 Hertz

Group R Primary Voltage 347 Secondary Voltage 24-60 Hertz

Group S Primary Voltage 208 Secondary Voltage 24-60 Hertz

Group X Primary Voltage 600 Secondary Voltage 12/24-60 Hertz

SL Series Control Transformers

Applications

The HPS line of specialty control transformers are ideally suited for general purpose, industrial, light duty loads. Designed for applications where high inrush or machine tool duty are not necessary, the SL control transformer offers an efficient and economical solution. These units are well suited for HVAC applications, signal and alarm systems, small motors, lighting and circuit isolation. The SL control transformer is an open style unit with molded terminal blocks, but available with a full array of features including 10 fusing options, multiple primary and secondary voltages and optional clear plastic ‘finger safe’ terminal covers. For an economical approach for control transformers, the SL is the transformer of choice.

Features

• CSA Certified, UL Listed
• Meets NEMA and ANSI standards.
• Molded terminal blocks for primary and secondary connections up to 1000 VA. Open terminals over 1000 VA.
• 60 Hz Operation.
• Welded core construction.
• Coils with high dielectric strength insulation.
• All SL Series Transformers are Vacuum Impregnated with “VT” (vinyl-toluene) Polyester Resin and oven cured.
• Mylar®, Nomex® and other insulating materials are used. The SL series transformers have the following
insulation systems: Up to 150 VA: 55°C rise, 105°C temperature class (A) 200 VA to 1500 VA: 80°C rise, 130°C temperature class (B) 2000 VA to 5000 VA: 115°C rise, 180°C temperature class (F).
 

o     HAMMOND INDUSTRIAL CONTROL TRANSFORMERS

o     HAMMOND  BUCK BOOST TRANSFORMERS

o     HAMMOND   LINE REACTOR TRANSFORMERS

o     HAMMOND DRIVE ISOLATION TRANSFORMERS

o     HAMMOND MOTOR STARTING AUTO TRANSFORMERS

o     HAMMOND LOW VOLTAGE LIGHTING TRANSFORMERS

o     HAMMOND GENERAL PURPOSE DISTRIBUTION TRANSFORMERS

o     HAMMOND K-FACTOR TRANSFORMERS

o     HAMMOND ENCAPSULATED TRANSFORMERS

o     HAMMOND  AUTOTRANSFORMERS

o     HAMMOND GENERAL PURPOSE MEDIUM VOLTAGE TRANSFORMERS

 Power Transformer Information:

 Power Transformer Manufacturer

• ACME Transformers - 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 transformer market.
• 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 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 makes.
• 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.
• More power transformer brands - Check out more companies by clinking this link.

 Power Transformer Types

• 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 per second.
• 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.

 Power Transformer Types

• 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. -
• Step-Down Transformers - A Step-Down Transformer is  designed to reduce voltage from primary to secondary.  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 electric motors.
• 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.
• More power transformer types - Read further about additional transformer types and their uses.

 Power Transformer Term Definitions

• Electrical Transformers - 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.
• Isolating Transformers - 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. 
• Transmission 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 electromagnetic or acoustic waves as well as electric power transmission. Components of transmission lines include wires, coaxial cables,  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 Phase - Most transformer are either single phase or three phase.
• 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 electrical equipment.
• Primary Voltage - The coil winding that is directly connected to the input power.
• Secondary Voltage - The coil winding  supplying the output voltage.
• 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.
• Weatherproof - Enclosed transformers come with a weatherproof standard set by NEMA.
• 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 conditions.
• More power transformer terms - Such as inductor, ground fault, core saturation, current transformer, faraday shield, etc.

Related Transformer Products

• 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 power supply.
• 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.

For an additional resource the Best of Industry Web Directory : Electrical Power Transformer Directory section is quite useful.