SITE NAVIGATION Transformer Applications Transformers (generally) fall into two categories, dry-type transformers and liquid or oil-filled transformers. Even though the primary components are similar between dry and oil-filled transformers (core, coil, leads, etc.), the insulation can be quite different. Dry-type transformers utilize safety-certified CSA and UL-recognized high-temperature insulation systems, while oil-filled transformers use oil and high dielectric strength wood based insulation materials. The Gund Company manufactures a wide range of insulation components for the various types of transformers. Our application engineering expertise can help our customers understand their insulation material selection and component design options, from large oil-filled transformers to dry-type distribution transformers or low-voltage electronics transformers. Select Your Transformer Type Power Transformer Distribution Transformer Dry Type Transformer Oil-Filled Transformers Oil-filled transformers use dielectric oil to insulate and cool the windings of the transformers. With the dielectric oil’s benefit to cool the transformer winding, relatively low-temperature insulation materials can be used in these designs. Typical insulation materials are cellulose-based products such as pressboard and laminated wood with relative temperature indices range from 80 °C to 105 °C. Oil-filled transformers are most commonly classified as power or distribution, depending on their size and application. The Gund Company supplies a range of insulating materials and components for each type of transformer. Power Transformers Power transformers are large, oil-filled transformers and are commonly divided by their rated power. The small power transformer classification typically starts around 10 MVA with a maximum service voltage of 145 kV. Medium power transformers range from about 30 MVA to about 100 MVA and commonly work as network and generator step-up transformers. The large power transformer classification includes transformers with ratings greater than 100 MVA and voltages greater than 345 kV. The Gund Company supplies a wide variety of insulation components for the full range of power transformer designs and ratings. Core Insulation Kits Step Blocks Core Blocks Fletch Plates Core Filler Rods Lead & Cleat Structure Support & Yoke Beams Insulation Fasteners (Rods & Nuts) Winding Forms Dovetail Strips Key Spacers Clamping Rings Coil Support Blocks Washer Assembly Tap Changer Boards Tap Changer, Filament-Wound Housings Composite Core Cooling Ducts & Spacers Lead Clamps Lead Conduit Tubes Tap Changer Enclosure Gaskets Bushing Gaskets & O-Rings Radiator Gaskets Hand-hole and Man-hole Gaskets Ranprex® laminated densified wood manufactured by Rancan is a widely used material in the Oil Immersed Power & Distribution Transformer Industry. The manufacturing of Ranprex® involves the use of specially selected veneers of red beechwood, impregnated with a patented thermosetting resin and pressed at high pressure/temperature to produce a material that complies with the DIN7707 and IEC61061 norms. Ranprex® is available in the form of plates (sheets) and as finish components to your drawing specifications. Rancan’s materials meet and exceed the properties of the following grades used for oil-filled transformer applications: Parallel construction: P1R / KP20210 / ML22EL P2R / KP20212 / ML20EL P4R / KP20214 / ML15EL Crosswise construction: C1R / KP20220 / ML22E C2R / KP20222 / ML20E C4R / KP20224 / ML15E Tangential construction: T2R / KP20242 / ML20ET T4R / KP20244 / ML15ET For more information on our laminated densified wood material for the Electrical Oil Immersed Power & Distribution Transformer, please click here. Click here to view additional material datasheets. Common Rigid Insulation Materials in Power Transformers Rigid Insulation G-11, EPGC 203 G-10, EPGC 201 Nomex® Pressboard 994 Low Power Factor – HP1 Pressboard Paper Phenolic U205, UPGM 205 Ranprex® Laminated Wood X, XX, XXX, PFCP 201, 202, 204 Common Flexible Insulation Materials in Power Transformers Flexible Insulation Kraft Paper Crepe Paper Nomex® Meta-aramid Paper G-Flex™ Meta-Aramid Paper Vulcanized Fiber (fish paper) Click here to view additional material datasheets. Common Elastomeric Materials in Power Transformers Gasket & O-Ring Materials Buna-N Cork Cork-Nitrile Cork-Rubber Fluorocarbon Fluorosilicone Nitrile Sponge Viton and more… Click here to learn more about transformer gasket & sealing materials. Distribution Transformers Oil-filled distribution transformers are most commonly pole-mounted or pad mounted. Pole mounted distribution transformers are so named because they are mounted to utility poles in most older urban or rural areas. In suburban areas, built within the last few decades, most distribution lines are buried underground, so transformers are mounted on concrete pads in residential, commercial, or light industrial applications. The Gund Company manufactures and fabricates a variety of insulation material solutions for distribution transformers. Layer Insulation Layer Insulation Tape Core Step Blocks Coil Supports Hardboard Coil Packing & Shims Phase Barriers Ground Barriers Sight Window Barriers Lead Supports, Spacers, & Clamps Fuse Boards Fuse Tubes Tap Changer Boards Enclosure Gaskets Bushing Gaskets O-Rings Click here to view additional material datasheets. Common Rigid Insulation Materials Used in Distribution Transformers Rigid Insulation Angles & Channels Filament Wound Tubes G-10, EPGC 201 G-11, EPGC 203 GPO-1, EPGC 201 GPO-3, EPGC 203 Low Power Factor – HP1 Pressboard Ranprex® Laminated Wood S2S Hardboard Standoff Insulators Threaded Rods & Nuts Common Flexible Insulation Materials in Distribution Transformers Flexible Insulation Kraft Paper Diamon-Coated Kraft Paper LFT Paper Crepe Paper Duct Paper – Stick Paper Vulcanized fibre (fish paper) Click here to view additional material datasheets. Common Elastomeric Materials in Distribution Transformers Gasket & O-Ring Materials Buna-N Nitrile Fluorosilicone Cork Cork-Nitrile Cork-Rubber Click here to learn more about transformer gasket & sealing materials. The Gund Company also offers a wide variety of Transformer Gaskets & Sealing Products for your upcoming project. Dry Type Transformers While oil-filled transformers use dielectric oil to insulate and cool the transformer’s windings, dry-type transformers are most commonly used in applications where the use of dielectric oil in the transformer design is not permitted. Without the cooling presence of dielectric oil, dry-type transformer designs must use higher temperature insulation materials. Most dry-type transformers made in North America are certified to UL and CSA recognized insulation systems. The Gund Company is a vertically integrated manufacturer of these high-temperature insulation materials, including materials rated at 155 °C, 180 °C, and 220 °C that have been specifically tested per UL 1446 for chemical compatibility with a long list of UL recognized insulation systems. The Gund Company offers a variety of insulation components for the following types of dry-type transformers. Layer Wound, Dry-Type Transformers Also known as barrel wound transformers, layer-wound transformers are most commonly used in low-voltage (<600v Class) applications. Layer-wound units are so-called because the coil is made by wrapping a layer of conductor around an insulated winding form and then wrapping a layer of insulation over the conductor. The coil is built by wrapping a layer of conductor and then a layer of insulation in successive layers per the design. This design typically relies on high-temperature spacer sticks called “dogbones” used to create the air-cooling passages. Between the primary and secondary coils, it is common to have a flexible insulation layer such as Nomex® Aramid Paper or even a flexible glass polyester laminate such as Grade N200F or Grade FHT. Standoff Insulators Bus Support Angles & Channels Winding Forms & Filament Wound Core Tubes Layer “Turn” Insulation Layer Insulation Tape Axial Spacer Sticks “Dogbones” Yoke Insulation Coil Support Blocks Wedges, Shims, & Filler Lead Supports, Spacers, & Clamps Fuse Boards Terminal Boards Lead Insulation – Sleeving Phase Barriers Fasteners – Rods & Nuts Enclosure Gaskets Disc-Wound, Dry Type Transformers Disc-wound transformer designs are typically rated for higher voltage applications than a barrel or layer-wound transformers. Disc-wound transformers are so-called because the conductor is wrapped around the coil in such a way as to make the coil appear to be a series of stacked discs, separated by airflow gaps. These units use either radial spacers or winding combs to form the conductor support and winding path around the coil while providing airflow gaps through the coil. These radial spacers and winding combs are typically made with high-temperature (130 °C, 155 °C, 180 °C, or 220 °C) glass polyester insulation material such as NEMA GPO-3, NEMA GPO-1 (Grades: N155, N180, N220, SG-200, or HST-II). Standoff Insulators Bus Support Angles & Channels Winding Forms & Filament Wound Core Tubes Conductor Wrap Winding Combs Axial Radial Spacers Spacer Sticks “Dogbones” Yoke Insulation Coil Support Blocks Wedges, Shims, Filler Lead Supports, Spacers, & Clamps Fuse Boards Terminal Boards Lead Insulation – Sleeving Phase Barriers Fasteners – Rods & Nuts Cast Coil Transformers Cast coil transformers have coils that have been manufactured using a vacuum molding process that fully impregnates and insulates the conductors with a polyester or epoxy resin system in most designs. The cast coil design allows for higher short circuit strength and overload capacity. Due to significantly different coil designs, cast coil units require different insulating components than other types of dry-type transformers. Common cast coil insulation components supplied by The Gund Company include saturated DMD, NMN, and glass epoxy B-stage layer insulations, as well as “dogbone” spacer sticks. Standoff Insulators Bus Support Angles & Channels Layer “Turn” Insulation Layer Insulation Tape Axial Spacer Sticks “Dogbones” Coil Support Blocks Lead Supports, Spacers, & Clamps Lead Insulation – Sleeving Fasteners – Rods & Nuts Electronic Transformers Using the term “electronic transformers,” we intend to capture a wide range of low-voltage transformers commonly used in electronic equipment applications. These units are typically rated at less than 600 volts. They are used in various applications, from current transformers to instrument transformers, to lighting ballasts. Other specialty magnetics fall into this category as well, such as shunts and chokes. The range of electronic transformer types and applications is nearly unlimited. Common insulation material applications in electronic transformers include: Fabricated Winding Bobbins Core Insulation Layer Insulation Layer Insulation Tape Lead Insulation – Sleeving Terminal Boards Fuse Boards Reactors Reactors have either iron core or air core construction. They are used to help control quality by limiting load faults and surges or high power lines. Reactors are typically used in substation construction, close to a load that may cause significant power quality swings. Reactors are often used in conjunction with capacitor banks to help control power quality. All air-core reactors have conducting windings that are wound much like a disc-wound, dry type transformer coil. Click here to view additional material datasheets. Common Rigid Insulation Materials in Dry-Type Transformers Rigid Insulation GPO-3, UPGM 203 Class F GPO-1 (N155) Class H GPO-1 (N180) Class R GPO-1 (N220) Convolute Wound Tubing Filament Wound Tubing Flexible, High-Temp GPO NEMA GPO-1, UPGM 201 GPO-3 Angles & Chanels NEMA G-10, EPGC 201 NEMA G-11, EPGC 203 SG-200 & HST-II Standoff Insulators Threaded Rods & Nuts UPGM 205, U205 and more… Common Flexible Insulation Materials in Dry-Type Transformers Flexible Insulation Nomex® Meta-Aramid Paper G-Flex™ Meta-Aramid Paper 3M Cequin® 3M Tufquin® 3M Thermavolt® Kapton® Polyimide Film DMD PET Polyester Film NMN Click here to view additional material datasheets. The Gund Company also offers a wide variety of Transformer Gaskets & Sealing Products for your upcoming project. The Gund Company uses a “Dry Type Transformer Checklist” to help our customers review material and component specifications. The checklist is also helpful for setting up kitting programs and vendor-managed inventory programs by transformer design. Contact one of our transformer application material specialists today to learn more. The Gund Company is a vertically integrated manufacturer and fabricator of engineered material solutions. Since 1951, we have listened to our customers and learned about their industries’ demanding operating environments. We are AS9100D Certified and ITAR Compliant. Our custom fabricated parts are manufactured according to ISO 9001:2015 certified quality systems. We understand the challenges of material selection and the demanding operating environment of your application. Our Application Engineering Team takes a consultative approach to understand your requirements. By relying on our material specialists, our customers gain valuable insight into improving component designs to increase efficiency and functionality while reducing cost. In addition to helping with material selection, we challenge ourselves to optimize production for material yield or fabrication efficiency. As a lean enterprise, we focus on continuous improvement and finding the most cost-effective, efficient solutions for our customers. Please contact us today if we can help answer material property questions or provide an application-specific quote. Thank you for the opportunity to earn your business. 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