Below are definitions relating to pad mounted 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
Terminations	Gauges	Fusing	Loadbreak Switch	Taps
Cooling Fluid	Accessories	Surge Arresters	Temperature Rise	Frequency

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; may also include new oil 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; Alfa Transformer rarely sells transformers in this condition and it is usually at the request of the customer Rental Transformer condition can vary but all rental units will be in good, working condition  Return to Pad Mount 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 Pad Mount 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 Pad Mount 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 pad mount transformers can also have vector designations to indicate how they will be connected to the primary (input) voltage source. Return to Pad Mount 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 Pad Mount Quotation Request Page

Terminations Live Front Porcelain bushings with eyebolt or spade type terminals; most common primary termination type for industrial pad mount transformers; Dead Front Molded rubber components that insulate "live" parts; transformers are typically supplied with bushing wells only; to connect to incoming cables, inserts and elbows are required (see descriptions below); inserts and elbows can be included with transformer Radial Feed Incoming cables are terminated at the primary bushings; there are no outgoing cables from the primary Loop Feed Incoming cables are terminated at the primary bushings; however, a means is provided to connect outgoing cables to the primary for feeding to another transformer; this can be through an additional set of bushings (live front or dead front) or by using a multi-hole spade connector (live front only) Inserts Cone-shaped connector that screws into the bushing well on one end and accepts elbow terminator on the other end Elbows L-shaped device that plugs into insert on one end and accepts incoming cable on the other end; when requesting elbows, cable size and insulation thickness must be specified Return to Pad Mount Quotation Request Page

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Gauges Liquid Level Indicates the level of cooling fluid in the transformer Oil Temperature Indicates the temperature of the cooling fluid; may include a manually-resettable maximum temperature indicator as shown in the photograph Pressure/ Vacuum Indicated the pressure or vacuum of the transformer tank With Contacts When auxiliary equipment is used, such as visible or audible alarms, or other similar equipment, gauges may include contacts Return to Pad Mount Quotation Request Page

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Fusing Bay-O-Net Bay-O-Net fusing is used to protect transformers and distribution systems. It is designed for use in oil filled pad mounted or substation transformers. They typically consist of a Bay-O-Net fuse assembly and a fuse link. Bay-O-Net With ELSP The ELSP fuse is used in transformers to protect and isolate faulted equipment. When connected in series with Bay-O-Net fusing, the ELSP fuse becomes an element of a two-part protection system that gives a full range of fault protection. Drywell Current Limiting Fuse Return to Pad Mount Quotation Request Page

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Loadbreak Switch 2-Position Simple, gang-operated "on-off" switch; primary used on radial feed transformer but is occasionally used on loop feed transformers when sectionalizing is not required 4-Position Sectionalizing switch; the four positions include: (1) Off; (2) A; (3) B; (4) A & B; this type of switch is typically used on a loop feed transformer. Return to Pad Mount Quotation Request Page

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Taps Tap Changer Used to adjust for low or high incoming voltage; for de-energized operation only; tap changers have a variety of appearances but all work similarly Return to Pad Mount Quotation Request Page

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Cooling Fluid Mineral Oil Common dielectric fluid used in transformers, circuit breakers, oil-filled switches and X-ray equipment RTEmp® A fire-resistant dielectric coolant; non-toxic and biodegradable; typically costs about 3X to 5X more than mineral oil Silicone A fire-resistant fluid; a good choice where potential fire hazards exist; typically costs about 3X more than RTEmp® Envirotemp® FR3™ A unique dielectric coolant made from seed oils; exceptionally high fire point; non-toxic, non-bioaccumulating and readily biodegradable Return to Pad Mount Quotation Request Page

Accessories Pressure Relief Valve A self-actuating, self-resetting pressure relief valve Drain Valve with Sampler Standard on 750 KVA pad mounted transformers and above; available on pad mounted transformers below 750 KVA; provides a means of draining oil from the transformer and for sampling oil for testing purposes Return to Pad Mount Quotation Request Page

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Surge Arresters Live Front Arresters Used in live front transformer applications; direct connect Dead Front Arresters Used in dead front transformer applications; plug into loadbreak inserts or feed-thru inserts

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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 oil filled transformers are 65°C and 55°C Return to Pad Mount 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 Pad Mount Quotation Request Page

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