Autotransformer
Transformer with an electrically common winding section for stepping AC voltage up or down or providing adjustable AC voltage.
An autotransformer uses an electrically common winding, so power is transferred between input and output through both conductive and electromagnetic paths.
Unlike a conventional isolation transformer, an autotransformer generally does not provide galvanic separation between input and output circuits.
The device may operate in step-up or step-down mode. Adjustable versions use winding taps or a moving sliding contact and may provide stepped or continuous adjustment.
Motorized and servo-driven models allow remote voltage adjustment, including under load where this application is permitted by the manufacturer.
Selection criteria include adjustment range, power, common and series winding portions, adjustment method, under-load operation, sliding-contact design, and compliance with IEC 61558-2-13.
Step-up, step-down, adjustable, motorized, and servo-driven autotransformers.
Autotransformer
General6
Commercial or technical designation of a manufacturer's product family sharing a common design and compatible characteristics.
Range of tasks and systems for which the manufacturer recommends the component.
Primary function of the device and its intended use as defined by its design and the manufacturer's documentation.
Permissible installation location of the product: indoors, outdoors, in a technical area, or as part of equipment.
Environmental conditions under which installation and operation of the product are permitted.
Permissible spatial orientation of the component during installation and operation.
Dimensions3
External horizontal dimension of the product between its outermost lateral points.
External vertical dimension of the product from its lowest to its highest point.
External distance between the foremost and rearmost surfaces of the product.
Materials and Finish25
Mechanical and magnetic construction form of the transformer core.
Magnetic material used for the transformer core.
Effective or manufacturer-declared magnetic core cross-sectional area.
Manufacturer-declared magnetic flux density at the specified rated operating condition.
Electrical conductor material used for the primary winding.
Electrical conductor material used for the secondary winding.
Physical form of the conductor used to manufacture the primary winding.
Physical form of the conductor used to manufacture the secondary winding.
Electrical insulation materials used directly in or between transformer windings.
Indicates that the transformer windings are impregnated during manufacture.
Manufacturing method used to impregnate transformer windings.
General type of resin, varnish or compound used to impregnate the transformer winding assembly.
Indicates that all or a substantial portion of the transformer assembly is encapsulated or potted in an insulating compound.
Manufacturing method used to encapsulate or pot the transformer assembly.
General material used for transformer encapsulation or potting.
Indicates that the transformer winding is manufactured on a bobbin or coil former.
Material used for the winding bobbin or coil former.
Indicates that a dedicated clamp, strap or bracket is used to mechanically secure the magnetic core.
Material used for the principal mechanical core clamp, strap or bracket.
Principal material of the moving electrical contact or brush used by a variable autotransformer.
Primary visually perceived colour of the product's external surface.
Designation of the product's primary surface colour according to the RAL colour system.
Type of final surface finish of the product determining its appearance and service properties.
Primary material from which the product is manufactured.
Grade, alloy, class, or technical designation of the product's primary material.
Mounting and Installation49
Physical connection interface used for the primary transformer winding.
Physical connection interface used for the secondary transformer winding.
Number of electrically accessible primary-side connection terminals or leads.
Number of electrically accessible secondary-side connection terminals or leads.
Manufacturer-declared free length of primary-side flying leads where present.
Manufacturer-declared free length of secondary-side flying leads where present.
Nominal conductor cross-section of permanently attached primary-side leads.
Nominal conductor cross-section of permanently attached secondary-side leads.
Principal insulation material used on permanently attached transformer lead wires.
Indicates whether a dedicated point or terminal is provided for connection of the PE protective conductor.
Number of PE terminals included in the product's standard equipment or provided for the specific version.
Indicates whether a separate functional earth connection is provided that does not replace the PE protective connection.
Indicates whether the design provides for mounting equipment on a DIN rail.
List of DIN rail profiles with which the product is mechanically compatible.
Spatial orientation of the DIN rail relative to the product in its intended installed position.
Type of surface or supporting base to which the product may be fixed.
Number of holes provided in the product for mechanical fixing.
Diameter of the hole provided for a fixing element used when mounting the product.
Geometric shape of the hole intended for mechanical fixing of the product.
Distance between the centres of mounting holes in the horizontal direction.
Distance between the centres of mounting holes in the vertical direction.
Horizontal dimension of the mounting pattern between the outermost fixing points of the product.
Vertical dimension of the mounting pattern between the outermost fixing points of the product.
Size designation of the screw, bolt, or other threaded fastener used for mounting the product.
Designation of the thread provided in the product's mounting holes or fixing elements.
Tightening torque recommended or permitted for fasteners during product installation.
Indicates whether the product can be installed using vibration isolators or other anti-vibration elements.
Tightening torque specified by the manufacturer for a screw or bolted terminal connection.
Thread designation of the screw used in the conductor clamping mechanism, for example M2.5, M3, M4, or another manufacturer-declared designation.
Drive geometry of the screw head used to clamp the conductor in the terminal block.
Size or designation of the screwdriver, bit, or other tool required to operate the terminal screw.
Nominal diameter of the bolt or threaded stud used for electrical connection of the cable lug.
Usable or manufacturer-declared length of the bolt or threaded stud used for the electrical connection.
Number of electrical connection bolts or threaded studs provided for one connection point.
Minimum tightening torque of the terminal screw, bolt, or nut declared by the manufacturer where a permissible range is specified.
Maximum tightening torque of the terminal screw, bolt, or nut declared by the manufacturer where a permissible range is specified.
Indicates whether the terminal connection nut is retained by the design to prevent it from falling out when loosened.
Indicates whether normal conductor connection can be performed without using a separate hand tool.
Method used to release and remove a connected conductor from the connection point.
Indicates whether a separate tool is required to release the connected conductor.
Type, size, or designation of the tool declared by the manufacturer for actuating the conductor-release mechanism.
Minimum unobstructed installation clearance required above the product for ventilation or heat dissipation.
Minimum unobstructed installation clearance required below the product for ventilation or heat dissipation.
Minimum unobstructed installation clearance required on the left side for normal cooling.
Minimum unobstructed installation clearance required on the right side for normal cooling.
Minimum unobstructed installation clearance required in front of the product for normal cooling.
Minimum unobstructed installation clearance required behind the product for normal cooling.
Installation arrangement permitted by the product design, such as wall-mounted, flush-mounted, floor-mounted, or another specified mounting type.
Method used to mechanically secure the product to a support, surface, or load-bearing structure.
Electrical Parameters83
Rated electrical voltage of the primary winding or primary side of a transformer or voltage-transforming device under manufacturer-declared conditions.
Rated electrical voltage of the secondary winding or secondary side of a transformer or voltage-transforming device under manufacturer-declared conditions.
Rated electrical current of the primary winding or primary side under manufacturer-declared conditions.
Rated electrical current of the secondary winding or secondary side under manufacturer-declared conditions.
Manufacturer-declared transformation ratio between the relevant primary and secondary electrical quantities.
Continuous rated apparent output power for AC-output power conversion equipment.
AC frequency assigned to the product for normal operating conditions.
Lower limit of the electrical network or signal frequency at which product operation is permitted.
Upper limit of the electrical network or signal frequency at which product operation is permitted.
Manufacturer-declared power conversion efficiency at the specified operating point.
Peak input current occurring during energization or startup of the device.
Manufacturer-declared duration associated with the specified input inrush current.
Input power consumed while the device is energized and operating without an external output load.
Input current drawn by the energized transformer with the secondary unloaded under specified conditions.
No-load input current expressed as a percentage of the relevant rated current.
Secondary voltage measured under the manufacturer-declared no-load condition.
Permissible deviation of output voltage from its declared nominal value under specified operating conditions.
Change in output voltage caused by variation of output load within the manufacturer-declared operating range.
Number of electrically distinguishable primary windings provided by the transformer.
Number of electrically distinguishable secondary windings provided by the transformer or transformer-based device.
Electrical connection arrangement of the primary winding or primary phase windings.
Electrical connection arrangement of the secondary winding or secondary phase windings.
Manufacturer-declared transformer vector group designation, for example Dyn11, Yyn0 or Dd0.
Electrical phase displacement between the relevant primary and secondary voltage systems.
Manufacturer-declared DC resistance of the primary winding under the stated reference conditions.
Manufacturer-declared DC resistance of the secondary winding under the stated reference conditions.
Indicates that multiple primary windings have separately accessible terminals.
Indicates that multiple primary windings are electrically isolated from one another.
Manufacturer-approved methods of interconnecting multiple accessible primary windings.
Indicates that multiple secondary windings have separately accessible terminals.
Indicates that multiple secondary windings are electrically isolated from one another.
Manufacturer-approved methods of interconnecting multiple accessible secondary windings.
Indicates that the secondary winding provides an accessible electrical centre tap.
Nominal voltage between the secondary centre tap and either corresponding winding end where declared.
Transformer short-circuit impedance expressed as a percentage of rated voltage under manufacturer-declared reference conditions.
Manufacturer-declared secondary output current under the specified short-circuit condition.
Manufacturer-declared load-dependent transformer losses at rated load and specified reference temperature.
Total manufacturer-declared transformer power loss at rated load under specified reference conditions.
Manufacturer-declared magnetizing inductance referred to the specified transformer winding.
Manufacturer-declared transformer leakage inductance referred to the specified winding or measurement condition.
Number of AC phases used by the electrical input of the product.
Number of AC phases provided by the electrical output of the product.
Electrical phase and neutral connection arrangement used at the AC input.
Electrical phase and neutral connection arrangement provided at the AC output.
Indicates that a neutral conductor is required for the manufacturer-declared input connection.
Indicates that the AC output provides an accessible neutral conductor or neutral terminal.
Indicates that galvanic isolation is provided between the relevant electrical input and output circuits of the product.
Indicates that the manufacturer declares safe electrical separation between the relevant input and output circuits.
Voltage with reference to which the product's insulation clearances and dielectric properties are specified.
Peak value of an impulse voltage of specified waveform that the product insulation must withstand without breakdown.
Test voltage applied to verify the dielectric strength of the product insulation.
Minimum permissible insulation resistance between the specified electrically separated parts.
Type of electrical insulation used, considered in terms of its protective function and construction.
Manufacturer-declared thermal class of the electrical insulation system or insulation material.
Indicates that selectable voltage taps are provided on the primary winding.
Number of selectable primary winding voltage tap positions.
Minimum primary tap deviation relative to the nominal primary winding voltage.
Maximum primary tap deviation relative to the nominal primary winding voltage.
Nominal percentage voltage step between adjacent primary tap positions.
Indicates that selectable voltage taps are provided on the secondary winding.
Number of selectable secondary winding voltage tap positions.
Minimum secondary tap deviation relative to nominal secondary winding voltage.
Maximum secondary tap deviation relative to nominal secondary winding voltage.
Nominal percentage voltage step between adjacent secondary tap positions.
Manufacturer-approved method used to select or change transformer winding taps.
Indicates that the product can be configured for more than one nominal input or primary voltage.
Number of discrete nominal input or primary voltage configurations supported by the product.
Method used to select between supported nominal input or primary voltages.
Indicates that the product can provide more than one selectable nominal output or secondary voltage.
Number of discrete nominal output or secondary voltage configurations supported by the product.
Method used to select between supported nominal output or secondary voltages.
Electrical and adjustment configuration of the autotransformer.
Indicates that the autotransformer can provide an output voltage lower than its applicable input voltage.
Indicates that the autotransformer can provide an output voltage higher than its applicable input voltage.
Electrical or electromechanical method used to adjust transformer output voltage.
Mechanical or powered drive methods supported for operating the voltage adjustment mechanism.
Indicates that output voltage can be adjusted continuously rather than only between discrete tap positions.
Indicates that the manufacturer permits normal voltage adjustment while the autotransformer supplies a load.
Number of discrete selectable voltage adjustment positions where the adjustment mechanism is stepped.
Rated voltage applicable to the common electrically shared section of an autotransformer winding.
Rated voltage applicable to the series portion of an autotransformer winding.
Manufacturer-declared portion of apparent power transferred directly through the electrically common winding connection.
Manufacturer-declared portion of apparent power transferred through transformer electromagnetic coupling.
Protection and Safety21
Class of protection against electric shock determined by the product design and protective connection method.
Indicates that the product incorporates protection against excessive internal, component or monitored temperature.
Thermal protection or winding-temperature sensing technologies incorporated in the transformer.
Temperature at which the integrated transformer thermal protection device operates.
Reset behaviour of the integrated transformer thermal protection device after operation.
Manufacturer-declared transformer classification describing behaviour under output short-circuit conditions.
Manufacturer-declared current flowing from the product electrical circuits to protective earth under the specified operating condition.
Manufacturer-declared current that may flow through a person or measuring network when touching accessible conductive parts under the specified condition.
Indicates that connection to protective earth is required for the declared electrical safety or operating conditions.
Degree of pollution of the surrounding microenvironment considered when selecting insulation distances and product characteristics.
Environmental corrosivity category for which resistance of the product material or protective coating is declared.
Duration of salt-spray testing withstood by the product or coating under the declared conditions.
Indicates whether the product may be operated in an atmosphere with elevated salt content.
Indicates whether the product material is classified as halogen-free according to the characteristics declared by the manufacturer.
Degree of enclosure protection against access to hazardous parts and ingress of solid objects and water, designated by the IP code.
Class of enclosure resistance to external mechanical impacts designated by the IK code.
Method or level of protection of the user against direct contact with hazardous live parts.
Indicates whether the design prevents finger access to hazardous live parts in the intended condition.
Indicates whether the design provides protection against accidental contact with hazardous live parts.
Classification of a material according to its ability to ignite, sustain combustion, and cease burning under a specified test.
Temperature of the heated wire used when testing the material or product against an ignition source.
Environmental Conditions56
Manufacturer-declared winding temperature rise above the specified ambient temperature at the stated operating condition.
Primary cooling method used by the product during normal operation.
Maximum manufacturer-declared acoustic noise level under the specified operating and measurement conditions.
Minimum ambient temperature at which the manufacturer permits installation of the product.
Maximum ambient temperature at which the manufacturer permits installation of the product.
Indicates whether the product's resistance to repeated temperature cycling has been verified.
Lower cycle temperature used during temperature-cycling testing.
Upper cycle temperature used during temperature-cycling testing.
Number of temperature cycles performed or required in the relevant test.
Indicates whether the product's resistance to rapid temperature changes between specified levels has been verified.
Temperature difference between exposure levels during thermal-shock testing of the product.
Temperature at which the corresponding relative humidity value is specified or standardized.
Nature of the humidity conditions for which product operation or resistance is declared.
Indicates whether the product is intended for operation where condensation may occur under the declared conditions.
Condensation or non-condensation conditions permitted during product operation.
Indicates whether the product's resistance to cyclic humidity changes has been verified.
Duration of product testing under cyclic humidity conditions.
Types of climatic environment for which the manufacturer intends the product to be operated.
Lower limit of vibration frequency applied or permitted in the relevant test.
Upper limit of vibration frequency applied or permitted in the relevant test.
Amplitude or test-method-specified acceleration of vibration applied during product testing.
Amplitude of mechanical displacement under low-frequency vibration.
Duration of vibration exposure during the specified product test.
Spatial axes along which vibration testing of the product is performed.
Maximum acceleration generated during mechanical shock testing of the product.
Duration of an individual mechanical shock pulse during product testing.
Number of shock impacts applied along each test axis.
Spatial axes along which mechanical shock testing of the product is performed.
Manufacturer-declared or calculated mean time between failures under specified reference conditions.
Ambient or component reference temperature associated with the declared MTBF value.
Standard, handbook or manufacturer methodology used to calculate or predict MTBF.
Predicted or declared failure rate expressed in failures per billion operating hours.
Manufacturer-declared design or expected operating service life under specified reference conditions.
Indicates that scheduled preventive maintenance is not required during normal manufacturer-declared service life.
Recommended operating interval between scheduled preventive maintenance activities.
Manufacturer-declared climatic environmental classification according to the applicable IEC 60721 series.
Manufacturer-declared chemically active substance classification according to the applicable IEC 60721 series.
Manufacturer-declared mechanical environmental classification according to the applicable IEC 60721 series.
Minimum ambient temperature at which normal operation of the product is permitted.
Maximum ambient temperature at which normal operation of the product is permitted.
Maximum permissible average ambient temperature over a consecutive 24-hour period.
Minimum ambient temperature permitted during storage of the product while not in operation.
Maximum ambient temperature permitted during storage of the product while not in operation.
Minimum ambient temperature permitted during transportation of the product.
Maximum ambient temperature permitted during transportation of the product.
Indicates whether permissible electrical or thermal loading must be reduced as temperature changes.
Temperature above which the permissible product load must be reduced.
Indicates whether the manufacturer has published the relationship between permissible product load and temperature.
Minimum relative air humidity permitted for the declared operating or test condition.
Maximum relative air humidity permitted for the declared operating or test condition.
Indicates whether the permissible humidity value applies only to non-condensing conditions.
Maximum altitude above sea level at which the product may be installed without exceeding the declared conditions.
Indicates whether the permissible product load must be reduced as installation altitude increases.
Altitude above sea level above which the permissible product load must be reduced.
Indicates whether the product's resistance to vibration has been verified under the declared conditions.
Indicates whether the product's resistance to short-duration mechanical shocks has been verified.
Included Equipment6
Indicates whether vibration isolators or anti-vibration mounts are included in the standard supply.
Indicates whether terminal markers are included in the product's standard equipment.
Number of terminal markers included in the product's standard equipment or provided for the specific version.
Indicates whether documentation is included in the product's standard supply.
Indicates whether an installation manual is included with the product.
Indicates whether a terminal diagram is included with the product.
Special Features14
Indicates that the manufacturer permits the applicable input or output voltage configuration to be changed while the product remains energized and loaded.
Indicates that winding connections can be reconfigured in the field according to manufacturer instructions.
Manufacturer-declared operating duty for which the transformer is rated.
Maximum continuous energized operating duration associated with a declared short-time duty rating.
Percentage of the operating cycle during which the transformer may remain energized or loaded under the declared intermittent duty.
Total cycle period associated with the declared intermittent transformer duty.
Indicates that an electrostatic screen is provided between transformer windings or between a winding and other conductive parts.
Manufacturer-declared connection arrangement for the transformer electrostatic screen.
Indicates that the output-voltage adjustment mechanism can be operated remotely.
Indicates that a servo-controlled mechanism is used or supported for automatic voltage adjustment.
Indicates that the moving electrical contact or brush used for variable-voltage adjustment is replaceable.
Mechanical angular travel associated with the full usable voltage adjustment range.
Indicates that the product provides a scale, pointer, dial or other indication of the voltage adjustment position.
Indicates that mechanical end stops limit travel of the voltage adjustment mechanism.
Standards and Compliance28
Compliance with applicable IEC 61558-1 general safety requirements for transformers, reactors, power supply units and combinations thereof.
Compliance with the applicable European adoption of IEC 61558-1.
Compliance with UL 5085-1 general requirements applicable to low-voltage transformers.
Compliance with UL 5085-2 requirements applicable to general-purpose low-voltage transformers and autotransformers.
Compliance with UL 5085-3 requirements applicable to Class 2 and Class 3 low-voltage transformers.
Compliance with IEC 61558-2-13 requirements applicable to autotransformers and power supply units incorporating autotransformers.
Compliance with the applicable European adoption of IEC 61558-2-13.
Regions or markets for which the manufacturer declares regulatory or certification compliance of the product.
Certification, market-approval, or conformity marks applicable to the product.
Primary normative document or standard according to which the manufacturer classifies or assesses the product.
Additional normative documents and standards declared by the manufacturer as applicable to the product.
Indicates whether an official declaration of conformity is available for the product.
Indicates whether a certificate relating to the declared certification or conformity of the product is available.
Identification number of the certificate relating to the product or its certified version.
Name of the organization that issued the certificate or performed the relevant conformity assessment.
Indicates whether the product was tested by an organization independent of the manufacturer.
Indicates whether the CE marking is applied to the product where applicable.
Indicates whether the UKCA marking is applied to the product where applicable.
Indicates whether the EAC marking is applied to the product where applicable.
Indicates whether the product has a declared UL Listed certification or recognition status.
Indicates whether the product has a declared UL Recognized certification or recognition status.
Indicates whether the cULus mark is applied to the product where applicable.
Indicates whether the product has a declared CSA certification or recognition status.
Indicates whether the product has a declared TÜV certification or recognition status.
Indicates whether the product has a declared VDE certification or recognition status.
Indicates whether product compliance with applicable RoHS restrictions on hazardous substances has been declared.
Indicates whether the manufacturer declares compliance of the product with applicable REACH Regulation requirements.
Indicates whether the product falls within the scope of WEEE requirements for waste electrical and electronic equipment.
Logistics10
Mass of the product itself, excluding transport packaging, additional accessories, and external equipment.
Mass of the product together with its individual packaging and the accessories included in it.
External horizontal dimension of the product's individual package.
External vertical dimension of the product's individual package.
External depth dimension of the product's individual package.
Design type of the product's individual or transport packaging.
Number of individual products contained in one packaging unit at the specified level.
Country of origin of the goods declared for customs or commercial purposes.
Commodity code under the international Harmonized Commodity Description and Coding System.
Commodity code under the Combined Nomenclature of the European Union.