Distribution transformer guide
Distribution transformer guide gy steincrmt I ,qeKabpR 03, 2010 96 pagos Distribution Transformer Guide Distribution Transformer Division Athens, Georgia Jefferson City, Missouri June, 1979 Revised March, 2002 ISO 9001 CERTIFIED Foreword The purpose of this guide is to assemble fundamental information concerning common ratings, connections, and applications of distribution transformers. The information presented is a summary of these fundamentals and is intended as a reference for those who deal occasionally with distribution transformer applications.
This guide does nat ur ort to cover all aspects of election and applica r further details are PACE 1 org6 required, contact AB to View nut*ge Index I. General Application — 4 g Physical Description . Protection and Accessories 11 II. Performance A. B. C. D. E. F. G. H. l. J. K. Designation of Winding Voltage Ratings — Polarity — Terminal Designations Short Circuit Ratings . Sound Level Ratings . Tolerance Calculations Efficiency Calculations Example Current—120/240 Volt Systems . 2424 26 27 III. Three-Phase Transformers and Banks A. Application Considerations — B.
Summary of Common Connections . 41 C. Common Three-Phase Banks Using Single-Phase Overloading Impedance Regulation performance Secondary Fault 17 20 21 22 22 23 23 . 34 Transformers IV. Loading Paralleling . Delta-Delta Bank Loading
Open-Delta Banks 71 71 73 73 74 75 VI. Reference Data Solid and Concentric Stranded Aluminum and Copper Conductors . Temperature Correction Factors for Resistance of Aluminum Conductors Logarithm Tables . Nominal direct-Current Resistance, Ohms per 1 000 Feet, at 200C and 250C of Solid and Concentric Stranded Conductors Natural Functions of Angles Isokeraunic Map . Equivalents — 87 88 2 l. General page444611 11 11 13 A. Application . Physical Description Mounted . Typical Selected SI 8081 83 85 86 B. . 1. Pole 1. Pole . 2. pad c. protection and Accessories — General — — 2.
Types of Accessories and Transformer Protection Packages — pole Mounted Protection — Pad Mounted 3. Types of Accessories and A. Application ABB single-phase and three-phase, oil-filled, pole- and padmounted distribution transformers are specifically designed for servicing residential distribution loads; they are also suitable for light commercial loads, and industrial lighting and diversified power applications. The transformers described herein are designed for the application conditions normally encountered on electric utility power distribution systems.
As such they are suitable for use under the «usual service conditions» described in ANSI CS7. 12. 00 General Requirements for Liquid- Immersed Distribution, Power and Regulatlng Transformers. Al other conditions are considered «unusual service» and should be avoided unless specific ABB Division approval is obtained_ B. Physical Description 1 . Pole Mounted • Meets Industry Standard ANSI C57. 12. 20 • 0. 5 – 1000kVA • 650 C temperature rise • Insulation leve Insulation levels: Rated Insulation Voltage Ranges Class 480- 500 1. 2 2160- 2400 5. 4160-4800 8. 7 7200-12470 1 15. 0 13200-14400 18. 0 19920-22900 2 25. 0-34400 34. 5 1 Optional 125 kv BIL 12000 volts available 2 Optional 125 kv BIL 19920 volts available Basic Impulse Level (kW 30 60 75 95 125 150 200 4 Type csp kVA Type S High Low Voltage Voltage pole Mounted (Single-Phase) 0. 5 2400 through 120/240 1. 5 34,400 volts 240/480 3 5 10 15 25 371/2 50 75 100 167 250 333 500 667 750 833 1000 Three-Phase Pole Mounted (Three-Phrase) 15 2400 to 208/120 30 13,800T 240X480T 45 480/277 75 1121/2 150 225 330 500 jumbo JUMBO @ Step-Down Transformer.
The ABB JUMBO single- phase step-down transformer is especially useful during utility system voltage conversions when it is desirable to convert a portion of a substation or a feeder to a higher voltage and Still be ble to supply the remaining customers at the existing voltage. The JUMBO is also available for industrial and commercial applications or for resale customers. 5 2. Pad Mounted A single-phase, single service, Iow profile distribution padmount tra lable in loop or radial feed. Designed to aestheti d economically provide radial feed on a grounded wye underground distribution system.
The Mini-Pak can be furnished in a complete line of ratings and in a wide range of configurations to fully meet the reliability, safety and operating requirements of any distribution system. Mini-pak, 10-167 kVA The Maxi-Pak is designed specifically for those customers requiring straightup feed (Type I) rather than cross feed (Type II). The additional height ofthe Maxi-Pak allows installation of air load break switching in this Iow-profile design. Maxi-pak, 10-250 kVA 5 ABB single-phase padmounted Distribution Transformers meet the follovwng Industry standards: ANSI C57. 2. 00 – IEEE standard General Requirements for Liquid Immersed… Transformers ANSI C57. 12. 25 – Pad-Mounted… Single-Phase Distribution Transformers with Separable Insulated High-Voltage Connectors… ANSI C57. 12. 8 – Pad-Mounted Equipment – Enclosure Integrity or ANSI C57. 12. 29 – … Pad-Mounted Equipment – Enclosure Integrity for coastal Environments ANSI C57. 12. 70 – … Terminal Markings and connections ANSI C57. 12. 80 – IEEE standard -rerrnnology.. ANSI C57. 12. 90 – IEEE Standard Test Code… NEMA Tr-l – Transformer Standards IEEE 386 – …
Separable Insulated Connectors ABB recommends the use of ANSI c57. g1 – Guide for Loading… for the establishment of proper distribution transformer loading practices. Ratings @650 Rise kVA: SO, 75, 100, 167, 250 1 Hv:4160GW2400 through 34500GW19920V 3 BIL: 60, 75, 5, 125, 150 kV LV: 240/120, 480/240, 277 V, 120/240 3, 240/480 2 1 Maxi only 2 Available 6 OF 75, 95, 125, 150kV v: 240/120, 480/240, 277 v, 120/240 3, 240/480 2 1 Maxi only 2 Available only on micros with cable lead secondary 3 Mini and Maxi only (micros available thru 24940GY/14400) Standard Features: 1 .
Equipped with two universal high voltage bushing Wells for loop feed. (Only one bushing well is provided for radial feed. ) 2. A removable flip-top hood and heavy-duty 3/8 stainless Steel hinge pins provide safe and durable semice. 3. A recessed locking assembly with padlock provisions and a entahead locking bolt is standard for tamper resistant operation. A hex-head locking bolt is available. 4. All tanks are constructed of heavy gauge steel. Tank seams are welded and each unit is pressure tested and inspected for leaks prior to shipment.
In addition, all single phase transformers are supplied with: a. b. c. d. 58 / «-11 stainless Steel lifting bosses Oil level/fill plug Oil drain plug Self-actuating pressure relief device Two ground bosses, 1/2″-13 NC tapped hole 7/16» deep. 5. The front sill latches with the flip-top hood, is attached on the side of the tank, and is removable. 6. The high voltage universal bushing Wells are externally clamped and removable. A parking stand betu. ‘een the bushing wells is provided for attachment of bushing accessories. 7. Externally clamped Iow voltage epoxy bushings. . Tamper-resistant design that exceeds ANSI C57. 12. 28. 9. NEMA safety labels per NEMA publication 260-1982. 7 Minimum/Maximum Design Dimensions 1 Micro-pak A B C D 24 24 30. 25 142424 35. 50 16 260-1982. Minimum/Maximum Design Dimensions 1 Micro-PakA B C D 24 24 30. 25 14 24 24 35. 50 16 Mini-pak ABC D 24 32 30. 25 14 42 44 46. 00 20 Maxi-pakA B C D 32 32 30. 25 14 42 44 46. 00 20 Min. Max. 1 Actual dimensions Will Vary according to voltage, loss evaluation, and accessories. Optional Accessories 1. Overcurrent Protection a.
An internal primary protective link to remove the transformer from the system in the event of an internal fault. b. A secondary breaker provides protection against secondary overloads and short circuits. c. An oil-immersed bayonet-type fuse link to remove the transformer from the system in case of an internal fault (fault sensing) or secondary short overload (overload sensing). This fuse is a drawout design and is supplied in series vvlth an isolation link. A dnp plate is provided to prevent oil from dripping onto the bushing or elbow. d.
A current limiting fuse mounted in a dry well loadbreak canister_2 • The high interrupting rating of the CL fuse permits its use on systems where the available fault current exceeds the rating of normal expulsion fuses. e. A partial range current limiting fuse mounted under oil within the transformer tank. 2 • An expulsion fuse is supplied in senes with the partial range CL fuse. • Available at 95, 125, and 1 50 kV BIL. 2. Switching a. Externally operated tap changer. b. Externally operated dual voltage switch. c. Externally operated loadbreak oil rotary (LBOR) switch. d. EFD CL fused air loadbreak switch available for either radial or loop feed. 3 switch. 2 d. EFD CL fused air loadbreak switch available for either radial or loop feed. 3 2 Not available on Micro 3 Maxi only Dimensions are in Inches CABLE OPENING 5. 0 «B»+6 5. 0 Recommended Pad Dimensions 8 3. Primary Connection a. Universal bushing Wells (standard) and loadbreak inserts. b. Integral (one piece) loadbreak bushings. 4 Secondary Connections a. Copper studs with rotatable spade type bushings. • Four-hole, NEMA type, tinplated capper alloy pade. ?? Four-hole, in line, tin-plated copper alloy spade. b. Cable lead secondary. 4 5. Corrosion Resistance a. ANSI C57. 12. 29 Full 400 Senes Stainless Steel b. partial Stainless Steel • Mini-SkirtW and Sill • Sill Only • Sill and Hood • Mini-Skirtn•, Sill, and Hood 6. Miscellaneous a. Cleats for anchoring sill to pad. b. Polypad mounting base. 4 4 Micro only The ABB MTR is an oil-fllled, three phase, commercial padmounted distribution transformer speclfically deslgned for servicing such underground distribution loads as shopping centers, schools, institutions and industrial plants.
It is available both live front and dead front construction, for radial or loop feed applications, or without ta tandards ABB three-phase MTR units meet the followl tandards: Pad-Mounted… Three-Phase Distribution Transformers with High Voltage Bushings ANSI C57. 12. 26 – Pad-Mounted… ThreePhase Distribution Transformers… With Separable Insulated High- Voltage Connectors ANSI C57. 12. 28 – … pad-Mounted Equipment Enclosure Integrity or ANSI C57. 12. 29 – … pad-Mounted Equipment • Enclosure Integrity for Coastal Environments ANSI C57. 12. 0 – Terminal Markings and connections… ANSI C57. 12. 80 – IEEE standard Terminology… ANSI C57. 12. 90 – IEEE Standard Test Codea.. NEMA Tr-l – Transformer Standards IEEE 386 – Separable Insulated Connectors ABB Recommends the use of ANSI C57. 91 – IEEE Guide for Loading… for the establishment of proper distribution transformer loading practices. Ratings • 45 through 2500 kVA • 650C average winding rise over 300C average ambient. • Low voltages: 1 208W120, 21 6W125, 460Y/265, 480Y/277, 480d, 240d and 240d with 120 volt mid-tap in one phase. ?? High voltages: 4160 Grd W2400 through 34,500 Grd WI 9,920 for Grounded vvye ystems; 2400 through 34,500 for Delta systems; various dual high voltages. • Taps: All voltages are available with or without taps. • Insulation classes: 35 kV (200 kV BIL) and below. 1 208Y/ 120, 21 25, 240d not avalable above 1 500kVA. 10 C. Protection and Accessories 1. General The distribution transformer functions as an integral part of the distribution system and consideration must be given to proper protection of the transformer from system disturbances. In addition, it is normal practice to apply overcurrent protection on the primary side of the tra