Padmount - ABB

1 Padmount Small Power Transformers 2500 kVA Through 20,000 kVA. 5 kV Through 46 kV Primary Voltage 120V Through 25 kV Secondary Voltage ABB's Padmounted Transformers provide tamper-resistant protection in a compact package for underground power distribution systems. Padmounted Transformers feature tamper-resistant construction which prevents entry by unauthorized personnel. The bolts, hinges, screws, and fasteners are not accessible in this safe, self-contained unit . Padmounted Transformers utilize a rectangular core and coil design that is a distinguishing characteristic of ABB small power liquid filled transformers. This proven design provides excellent mechanical strength, dependability, and space-saving economy needed for under- ground power distribution. With most ratings, a choice of fluids including mineral oil, silicone, R-Temp , and BIOTEMP is offered. Mineral oil is typically specified for outdoor applications.

2 When flammability is a concern, Silicone or R-Temp are generally used. BIOTEMP is used ABB Padmounted Transformers are completely factory anywhere any insulating fluid spill could assembled and are shipped as one-piece. require expensive clean-up procedures. Quality With Pride Product Scope: 2500 kVA-20,000 kVA. As a single-source supplier, ABB is the largest and most complete Primary Voltages: 5 kV Through 46 kV. manufacturer of power transmission and distribution equipment in Secondary Voltages: 120V Through 25 kV. the world. We make certain that our world renowned quality is Three Phase exemplified by every product that bears our name. An experienced Available Fluids: and dedicated work force ensures the quality of our work and your Mineral Oil Silicone satisfaction with our products. We strive for operational excellence, R-Temp BIOTEMP lowest manufacturing cost, and short cycle times. Padmounted Benefits/Advantages: ABB's mission is to be the leader in delivering quality products and Rectangular core/coil design services for power generation, transmission and distribution, industrial Minimal size: space saving processes, mass transit, and environmental control that meet the needs Minimal weight: energy saving and requirements of our customers and contribute to their success.

3 Captive and recessed tamper-proof hardware in LV compartment door To ensure customer satisfaction ABB will provide value-added, Tamper resistant integrated solutions that are driven by superior technology Insuldur layer insulation system for and performance. thermal upgrade and mechanical strength DuraBIL turn insulation superior adhesion, ABB's employees are committed to leadership standards in applying abrasion resistance, and thermal stability the Company's unique combination of experience and global High efficiency with best combination of resources to meet societal goals for sustainable growth and initial cost and low operating cost. clean energy. The evolution of ABB's rectangular core and coil design The basic configuration of a transformer research and development, the first through successful short circuit tests, core was originally circular, due to the rectangular core and coil was placed as defined by ANSI standards, in natural shape suggested by a coil.

4 As into commercial service. Service addition to thousands of service years space and material considerations records starting then and up through in the field. became more critical, engineers explored today have shown the overall superiority more efficient methods for transformer of the rectangular core and coil design ABB has continued development and design. The greatest incentive for for conserving space and materials. testing of the rectangular core and change came from the excessive cost Just as importantly, the rectangular coil design. Advanced materials of vault space in larger cities. core and coil has an outstanding and state-of-the-art manufacturing record for reliability, strength, and techniques currently allow ABB to offer In 1954, after more than a decade of efficiency. This has been demonstrated ratings through 20,000 kVA and 69 kV. 3 4. 2 5. 9. 6. 1. 8. 10. 1. Tap Leads 2. Tap Changer 3.

5 High Voltage Leads 4. Low Voltage Bus 5. Low Voltage Bushing Connection 6. Flexible Bus 7. Phase Coil 11. 8. High Voltage Lead 9. Core Ground (Removable). 10. Step-Lap Core 11. Side Braces and Support Tie 7. 12. Bottom Support 13. Inner Phase Barrier Insulation 13. 12. 1. The rectangular core and coil process ABB's rectangular design offers excellent The Coil mechanical strength that has been ABB coils feature aluminum or proven through years of service and in copper conductors in both high and special testing. low voltage windings. The low voltage winding is accomplished on a constant The mechanical strength is achieved tension machine and consists of a through the use of a unique six-piece full-width or part-coil sheet conductor supporting structure. This supporting extending the full height of the coil. structure is assembled in a pressure jig around the core and coils and arc The advantage of the low voltage welded to form a rigid structure.

6 Sheet is a continuous cross section of conductor that allow the electrical The top and bottom pieces exert a centers of high and low voltage Step-lap mitered core joints are utilized for clamping action on the yokes of the efficiency and noise reduction. windings to easily align themselves, core to hold the laminations firmly in virtually eliminating the vertical place and more importantly, to achieve component of short circuit force. optimum sound attenuation by using a precalculated pressure. Welding holds fills the corresponding shaped The high voltage windings use wire this preload for a permanently quiet core. opening in the coil with a minimum conductors and are wound directly of unused space. The short yoke over the low voltage winding on a Steel end plates are pressed into position between the core legs reduces the constant tension traversing machine. and welded to the top and bottom external path of the flux between The high voltage conductors are pieces to form a permanent framing.

7 Active core leg material, resulting in typically insulated with ABB's exclusive The thickness of the end plate is an increase in efficiency. The DuraBIL turn insulation. calculated for each design. The end rectangular shape of the core allows plate's calculated thickness provides for more uniform and rigid support the beam strength required to minimize which prevents the shift of the tendency of the wide, flat part of laminations and improves sound the outside coils to round out level characteristics. during fault conditions. The Core The rectangular core is a series of laminations made from high-quality, grain-oriented silicon steel. The stacked core provides a superior flux path by utilizing a step-lap mitered DuraBIL turn insulation core joint. The effective way in which the core is supported, as well as the efficient step-lap joint, have resulted in: decreases in exciting current up to Turn Insulation 40%; reductions in sound levels up to Traditional crepe paper or NOMEX.

8 3 db; and reductions in no load loss tape is used in some design up to 10%. considerations. However, DuraBIL, which is a tough, flexible and inert turn The core efficiently fills the similar shape The rectangular-shaped core efficiently opening in the coil to minimize unused space. insulation, is used in most designs. It 2. reduces the most prevalent cause of in kVA capacity. Generous oil ducts The large areas presented by the transformer failure: deterioration of extend the height of the coil to provide layer-type winding result in a low turn insulation. cooling in the winding. The staggered, ground capacitance, which gives a diamond epoxy bonds help assure nearly straight line surge distribution DuraBIL is a single layer of epoxy free oil flow through the winding. throughout the winding. A compact, powder deposited electrostatically high-impulse-strength coil is the and baked on the wire conductor.

9 Coil Construction result. The process is closely controlled and The Insuldur layer insulation is coated monitored to insure a continuous, with a diamond pattern of B-stage Tank Construction uniform coating. The result is a compact epoxy adhesive, which cures during The transformer tank is designed turn insulation with superior processing to form a high-strength to withstand a pressure 25% greater characteristics, including: adhesion; bond. This bond restrains the windings than the maximum operating pressure. flexibility; abrasion resistance; and from shifting during operation or thermal and chemical stability. under short circuit stresses. The The carbon-steel plate used to form high-to-low insulation is placed over the tank is reinforced with external DuraBIL will not degrade and the low voltage winding and the side wall braces, and tank seams are contaminate the transformer fluid wire-wound high voltage is wound continuously welded.

10 With moisture. Beyond the chemical directly over the low voltage, forming attributes, DuraBIL maintains a high-strength coil assembly. Each cooler assembly is individually dimensional stability and the coil's welded and receives a pressurized structural integrity. Accurately-located taps and a large check for leaks prior to assembly on winding cross section keep unbalanced the tank. After the coolers are Insuldur Insulation ampere turns to a minimum. attached to the tank, the completed Insuldur insulation thermally upgraded Unbalanced ampere turns create tank assembly is leak-tested before kraft paper is typically used for layer forces during short circuit that drive shipment. and high to low insulation. the high voltage and low voltage coils apart vertically. By minimizing this The Insuldur system of chemical imbalance, vertical forces are stabilizers thermally upgrades cellulose correspondingly reduced and the design insulating materials to permit a 12% is stronger under short circuit stresses.