SIC 3677 Electronic Coils, Transformers, and Other Inductors

Contenidos

• NAICS CODE(S).
• INDUSTRY SNAPSHOT.
• BACKGROUND AND DEVELOPMENT.
• CURRENT CONDITIONS.
• INDUSTRY LEADERS.
• FURTHER READING.

SIC 3677

This industry classification includes establishments primarily engaged in manufacturing electronic coils, transformers, and inductors. Establishments primarily engaged in manufacturing electrical transformers are classified in SIC 3612: Power, Distribution, and Specialty Transformers; those manufacturing transformers and inductors for telephone and telegraph apparatus are classified in SIC 3661: Telephone and Telegraph Apparatus; and those manufacturing semiconductors and related devices are classified in SIC 3674: Semiconductors and Related Devices.

NAICS CODE(S)

334416

Electronic Coil, Transformer, and Other Inductor Manufacturing

INDUSTRY SNAPSHOT

According to the U.S. Census Bureau, shipments of electronic coils, transformers, and other inductors grew slightly from $1.21 billion in 2002 to $1.23 billion in 2003—down from $1.51 billion and $1.70 billion in 2001 and 2000, respectively. By the mid-2000s, the industry was returning to more stable footing, although price pressures, stiff competition, and excess supply were continuing concerns. The cost of materials decreased from $492 million to $467 million over the same time period. Employees in 2003 numbered 11,487, of which 8,680 were production workers earning an average hourly wage of $11.47.

BACKGROUND AND DEVELOPMENT

The pioneering figure in the industry was English chemist and physicist Michael Faraday (1791–1867). Credited with discovering the phenomenon of electromagnetic induction in 1831, he also was the first person to use a magnetic circuit to connect two electric circuits. In his experiments with induction, Faraday developed an early version of the transformer. The earliest patent for a power transformer was granted to C. Zipernowski, O. Blathy, and M. Deri of Budapest in 1885. Deri also received the first patent for a distribution transformer in 1885.

"Inductor" is a generic term for an electronic coil, sometimes referred to as an electronic choke. Inductors either filter or select certain frequencies within AC or pulsating DC circuits. In his book, Basic Electricity and Electronics, Delton T. Horn defined inductors and inductance as follows: "An inductor is a device capable of storing magnetic energy in a circuit. Typically it consists of a coil of wire around some type of core, which may be magnetic or nonmagnetic. Inductance is directly proportional to the square of the number of turns (of wire). An inductor opposes changes in current. It also opposes current, and this opposition increases as the frequency of the signal increases." Coil wire must be coated with an insulating material (usually varnish, lacquer, or enamel) to prevent turns of wire from coming into electrical contact. The greater the ferrous content of the core, the greater the coil's inductance. Coils with nonferrous cores...