Below are definitions relating to dry type transformers, components and accessories. Please feel free to print this page for reference. If you have any questions, please e-mail us.

Condition	KVA	Phase	Voltage	Windings
Taps	Fan Cooling	Accessories	Environment	Enclosure
Temperature Rise	Frequency	E-Mail Us

Condition New All components are new Remanufactured Transformer coils have been rewound; this may include all primary and secondary coils or primary coils only; even if secondary coils are not rewound they will carry the same warranty as the rewound primary coils Reconditioned Transformer has passed all standard tests; if needed, broken or missing parts are replaced As is Transformer will be sold in its present condition without warranty Rental Transformer condition can vary but all rental units will be in good, working condition Return to Dry Type Quotation Request Page

KVA Kilovolt ampere; designates the output which a transformer can deliver at rated voltage and frequency without exceeding a specified temperature rise Return to Dry Type Quotation Request Page

Phase Classification of an alternating current circuit; most common phases are single-phase and three-phase; standard transformers do not have mixed phases; if a transformer has a three-phase input, it will have a three-phase output; the same is true of single-phase transformers; it is common to connect a single-phase transformer to a three-phase system and get a single-phase output Return to Dry Type Quotation Request Page

Voltage Primary Voltage The INPUT voltage of a transformer; this should include a numeric value and a vector designation (see below) Secondary Voltage The OUTPUT voltage of a transformer; this should include a numeric value and a vector designation (see below) Vector DELTA - A standard three-phase connection in which each phase winding is connected in series to form a closed loop; on a Delta connection of a three-phase transformer, the transformer will have three (3) bushings WYE - A standard three-phase connection in which similar ends of each phase winding are connected together at a common point which forms the electrical neutral and is often grounded; on a Wye connection of a three-phase transformer, the transformer will typically have four (4) bushings Single-phase dry type transformers can also have vector designations to indicate how they will be connected to the primary (input) voltage source. Return to Dry Type Quotation Request Page

Windings The primary and secondary windings of the transformer can either be copper or aluminum, or one can be copper and the other aluminum. The industry standard, since the early 1970's, has been aluminum. For more information on copper and alumimum, see our Copper vs. Aluminum article. Return to Dry Type Quotation Request Page

Taps Tap Terminals Used to adjust for low or high incoming voltage; for de-energized operation only; taps are adjusted by moving a jumper wire between the tap terminals Return to Dry Type Quotation Request Page

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Fan Cooling Fans Fans can be optionally installed on many dry type transformers as a means of reducing the transformers operating temperature; generally, fans are not used on transformers below 750 KVA because it is cost-prohibitive; cooling fan packages can include fans, thermocouple well, thermocouple, analog controller, digital controller, or other options Return to Dry Type Quotation Request Page

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Accessories Drive Isolation (for SCR drives) SCR drives generate voltage spikes and transient feedback. Drive isolation transformers are designed to withstand mechanical forces associated with SCR drives and to isolate the line from these destructive electrical conditions. Electrostatic Shield Computer installations, hospital operating rooms, X-ray equipment and instrumentation are typical applications where electrostatically shielded transformers can be used. Electrostatically shielded transformers are designed to protect sensitive equipment from unwanted high-frequency voltages that can occur due to switching and loading on distribution lines by taking these unwanted signals to ground. Surge Arresters Used to protect transformers from switching surges and lightning Dimensions Restrictions When transformers are installed between immovable objects such as a switchgear line-up or a building, certain dimensions can be critical when replacing an existing transformer. Sometimes a core and coil assembly can be replaced inside an existing enclosure which also requires maximum dimensions. These dimensions should always be specified when replacing an existing transformer. Return to Dry Type Quotation Request Page

Environment Certain environments require certain types of transformers or specific materials. Ventilated dry type transformers operate best in an indoor environment with no airborne contaminants such as dust, metal dust, corrosive chemicals, salt water, etc. Dry type transformer enclosures can include weathershielding to protect from typical weather conditions such as rain so they can be placed outdoors. Return to Dry Type Quotation Request Page

Enclosure Dry type transformer enclosures vary, depending upon the environmental conditions listed above. These enclosures are typically specified by a NEMA rating. The most common dry type transformer enclosures are listed in the table below. NEMA RATING ENCLOSURE DESCRIPTION NEMA 1 General Purpose For indoor use wherever oil, dust or water is not a problem NEMA 2 Driptight Used indoors to exclude falling moisture and dirt NEMA 3R Weatherproof Provides protection against rain, sleet and snow NEMA 4 Watertight Needed when subject to great amount of water from any angle, such as areas which are repeatedly hosed down NEMA 4X Watertight Same as NEMA 4, except stainless steel NEMA 12 Industrial Use Used for excluding oil, coolant, flying dust, lint, etc. Return to Dry Type Quotation Request Page

Temperature Rise The temperature increase over the ambient temperature due to loading; lower temperature rises are better because the transformer operates cooler than an equal, higher temperature rise transformer; standard temperature rises for dry type transformers are 150°C, 115°C and 80°C. Return to Dry Type Quotation Request Page

Frequency The number of times an alternating current voltage will alternate from positive to negative and back again within a specified period of time; usually express in cycles per second and identified as Hertz (Hz); the Western Hemisphere primarily operates on 60 Hz systems; some 60 Hz systems exist in the Eastern Hemisphere but it is primarily 50 Hz systems Return to Dry Type Quotation Request Page

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