single-phase and three-phase overhead

Document No. 1001-04Revision 3October, 2020

Howard Industries, Inc. P.O. Box 1588

Laurel, MS USA 39441-1588

www.howardtransformers.com

1

Howard Industries, Inc.Certified to ISO 9001:2015

Distribution TransformersSingle-Phase and Three-Phase Overhead

Howard Industries, Inc.

10002179ISO 9001:2015

Document No. 1001-04Revision 3

October, 2020

Howard Industries, Inc. P.O. Box 1588 Laurel, MS USA 39441-1588


2

Life-Cycle Cost Reduction

Howard Industries’ Customer Assistance Team excels at helping customers find ways to reduce cost. Using activity-based cost analysis techniques, our commercial and technical experts help customers analyze costs throughout the transformer supply chain, identifying and eliminating activities which add cost but have little or no value.

Quality and Reliability Built into Every Transformer

Higher quality means lower failure rates, and that translates into lower operating and maintenance costs. Higher quality also means customers can reduce cost by reducing or eliminating incoming receipt inspection and testing.

At Howard Industries our Quality Assurance Program is designed to achieve the high level of quality required by our most demanding customers. Abandoning the traditional manufacturing-only focus, we have created a quality system that links all aspects of the company’s operations, including Marketing, Engineering, Management Information Systems, Manufacturing, Shipping, and Accounting, to make sure that not only our products, but everything we do for our customers is of the highest quality. Howard Industries’ quality management system has earned ISO-9001 certification.

ISO-9001, the most comprehensive standard in the internationally recognized ISO-9000 series, covers design, manufacturing and servicing systems. This achievement demonstrates Howard Industries’ commitment to continuous quality improvement.

Howard Industries excels at delivering exactly what our customers want.

The Product Automated Design System (PADS) ensures that each customer’s unique requirements are satisfied.





3

Automated and robotic welders perform 100% of all oil-compartment seam welds.

Electrostatically applied powder paint provides a durable, corrosion-resistant finish.

Computerized final test stations perform a complete series of electrical tests prior to shipment.

Designs Optimized for Superior Performance and Economy Our design philosophy is to provide our customers exactly what they want. That means transformers that are individually designed in precise accordance with each customer’s specifications. Each transformer design is optimized to satisfy the customer’s needs at the lowest possible cost. Howard’s Product Automated Design System (PADS) is driven directly by each customer’s specifications to ensure that all the necessary requirements are satisfied. PADS synthesizes each transformer design and produces all critical manufacturing documents. PADS, then, links with a sophisticated computer-integrated manufacturing

(CIM) system to automatically carry out fabrication on the factory floor. The PADS and CIM systems eliminate manual processes, with their inherent inefficiency and error, and make it possible to quickly modify and customize transformer designs.

Advanced Manufacturing

Howard transformers are manufactured in the largest, most advanced facility of its kind. The 2.3 million square foot Laurel plant is the result of a multi-year expansion project, which saw the introduction of the latest and most sophisticated robotics and automated process equipment available.

Environmentally-controlled winding facility


October, 2020



4

Single-Phase and Three-Phase Overhead Transformer Features

Howard Industries manufactures a complete line of single-phase and three-phase overhead distribution transformers, including conventional, self-protected and step up/step-down designs. Howard transformers have always been designed with increased margins of safety and reliability, and include the following standard features.

Standard Features

• Meets or exceeds current IEEE, NEMA and RUS standards as applicable

• Shell-type core design for both silicon and amorphous units

• Vertical triplex design for three-phase transformers

• Wet-process porcelain high-voltage bushings (oil-filled at 125 kV BIL and above for reduced radio interference)

• Molded polymer or wet process porcelain low voltage bushings

• Tin-plated bronze terminals suitable for connection to copper or aluminum

• Low-voltage grounding provision (except step-up/ step-down units)

• Lightning arrester mounting provisions

• Low-voltage ground strap (1-bushing units only; not available on step-up/ step-down units)

• Permanently stamped identification on internal secondary leads for ease of paralleling

• Visible cover ground connected to upper mounting bracket or coupling on tank wall

• Tank grounding provisions• Tank ground connector

(1-bushing units only)• Automatic pressure relief

valve for added safety• Mineral oil with oxidation

inhibitor• Mild steel tank, cover and ring• Continuous-bead welding

on lifting lugs and mounting brackets for increased safety and corrosion resistance

• Recessed tank bottom for scuff protection

• Tough powder-paint finish for improved resistance to abrasion and corrosion

• 10 kV minimum cover insulation

• Corrosion-resistant cover-ring hardware

• KVA marking on tank• Internal oil-level mark• Laser-engraved nameplate

In addition to the standard features and accessories previously listed, self-protected transformers also include the following:

• Low-voltage circuit breaker with external operating handle

• External, tank-mounted lightning arrester

• Internal, high-voltage expulsion fuse





5

Standard kVA and Voltage Ratings

Single-Phase Conventional

KVA Ratings (65°C Rise) 0.5, 1, 1.5, 3, 5, 10, 15, 25, 37.5, 50, 75, 100, 167, 250, 333, 500, 833

High-Voltage Ratings 2400/4160Y or 4160GrdY/2400 through 19920/34500GrdY or 34500GrdY/19920(60 kV through 250 kV BIL)

Low-Voltage Ratings 120, 120/240, 240/480 or 277 (30 kV BIL)

Single-Phase Self-Protected

KVA Ratings (65°C Rise) 5, 10, 15, 25, 37.5, 50, 75, 100

High-Voltage Ratings 4160GrdY/2400 through 34500GrdY/19920(60 kV through 200 kV BIL)

Low-Voltage Ratings 120, 240/240/480 or 277 (30 kV BIL)

Three-PhaseConventional or Self-Protected

KVA Ratings (65°C Rise) 30, 45, 75, 112.5, 150, 225, 300

High-Voltage Ratings 4160GrdY/2400 through 34500GrdY/19920(60 kV through 150 kV BIL)

Low-Voltage Ratings 208Y/120 480Y/277 240 480 240 with 120 mid-tap 480 with 240 mid-tap (30 kV BIL)

Single-Phase Step-Up/Step-Down

KVA Ratings (65°C Rise) 50, 75, 100, 167, 250, 333, 500, 833

High-Voltage Ratings 7200/12470Y or 12470 GrdY/7200 through19920/34500GrdY or 34500GrdY/19920 (95 kV through 150 kV BIL)

Low-Voltage Ratings 2400 (60 kV BIL) through 7970 (95 kV BIL)

(Note: Contact your distributor or factory representative for availability of other kVA sizes, voltage ratings, features, accessories, and design standards not listed.)


October, 2020



6

Optional Features, Accessories and Design Standards

• Stainless steel tank and/or cover and/or cover ring

• Lightning arrester, externally-mounted or internally-mounted under oil (externally-mounted lightning arrester standard on self protected transformers)

• High-voltage tap switch with external operating handle: 4-2.5% taps above normal; or 4- 2.5%taps below normal; or 2- 2.5% taps above and below normal; or taps at 13800/13200/12870/ 12540 for units rated 14400

• Dual high-voltage switch with external operating handle

• Dual low-voltage switch (available only on step-up/step-down transformers)

• Interlaced low-voltage windings (not available on step-up/step-down or three-phase transformers)

• Drain valve with oil sampling device

• Temperature gauge

• Liquid level gauge

• Pressure/vacuum gauge

• Wildlife protection

• Overload warning signal light

• Emergency overload reset handle (available only on self-protected transformers)

• Tank ground connector (standard on 1 bushing transformers)

• Low-voltage winding ground strap (standard on 1 bushing transformers except step-up/step-down units)

• Natural Ester dielectric fluid

• Custom stenciling and labeling

• Laser engraved stainless steel nameplate

• Rural Utilities Service (RUS) design standards

• Canadian Standards Association (CSA) design standards

• Other non-U.S. design standards

• NEMA TP-1 compliant designs

(Note: Contact your distributor or factory representative for availability of other kVA sizes, voltage ratings, features, accessories, and design standards not listed.)

single-phase and three-phase overhead

Documents