SIC 3612 Power, Distribution, and Specialty Transformers

Contenidos

• NAICS CODE(S).
• BACKGROUND AND DEVELOPMENT.
• Deregulation.
• CURRENT CONDITIONS.
• INDUSTRY LEADERS.
• WORKFORCE.
• RESEARCH AND TECHNOLOGY.
• FURTHER READING.

SIC 3612

This category covers establishments primarily engaged in manufacturing power, distribution, instrument, and specialty transformers. Radio frequency or voice frequency electronic transformers, coils, and chokes are classified in SIC 3677: Electronic Coils, Transformers, and Other Inductors, and resistance welder transformers are part of SIC 3548: Electric and Gas Welding and Soldering Equipment.

NAICS CODE(S)

335311

Power, Distribution, and Specialty Transformer Manufacturing

A transformer is used to reduce or increase the voltage, or electromotive force, of electricity traveling through a wire. It accomplishes this by transferring electric energy from one coil or winding to another coil through electromagnetic induction. Electric-generating plants use generator transformers to "step-up," or increase, voltage that is transferred through power lines. When the high voltage electricity reaches a community, a "step-down" transformer reduces its power. A distribution transformer makes a final step-down in voltage by diminishing the force of the electricity to a level usable in homes and businesses. Some electrical devices, such as doorbells and small appliances, use additional step-down transformers to decrease voltage.

A typical transformer has two windings, or coils of wire, that are insulated from each other. The two coils are wound on a common magnetic circuit of laminated sheet metal, called the core. Each end of the primary coil is connected to the incoming alternating current (AC) power source. Each end of the secondary coil, which receives the energy, is connected to the outgoing power line. The ratio between the number of windings in each coil determines whether the voltage will be boosted or diminished.

There are two types of transformers: core and shell. In core-type equipment the windings surround the laminated metal core. In shell-type transformers the metal surrounds the windings. Distribution transformers usually are core-type, while more advanced high-voltage devices are often shell-type. Transformers also can be classified according to the type of cooling system they use; smaller transformers usually are cooled by air and larger equipment is liquid-cooled. Finally, transformers are either single-phase or polyphase. Polyphase devices typically have a three-legged core that can produce at least three different voltages.

The majority of apparatus manufactured in this industry are power and distribution transformers purchased by electric utilities. These devices accounted for more than 50 percent of industry shipments in the early and mid-2000s. Because most transformers are simple and rugged, they often last as long as 40 years. Therefore, producers are largely dependent on purchases by utilities that are expanding service. Shipments of distribution transformers, for instance, are closely linked to new housing starts. Demand also is influenced by conversion to more efficient or aesthetically pleasing transformers.

The other half of the transformer market is primarily comprised of step-down equipment integrated into individual electrical devices. Fluorescent lamp ballasts...