美商实快（Square D）：作为施耐德电气公司的旗舰品牌，为配电和工业控制自动化领域提供符合北美标准的元器件、系统与服务，她的产品及系统销往世界各地。

美商实快（Square D）电力的历史： 

1902年：底特律熔断器制造厂成立，该厂主要生产箱式熔断器及盒式熔断器式开关。在公司导管接线盒上的署名《D》拥有很高的声望，因此，公司决定更名为实快电力（Square D）；

2002年，实快（Square D）电力推出了世界上最小的Masterpact NT断路器和PowerBus 225低敏感度布线系统；
2003年美商实快（Square D）电力品牌举办了公司成立100周年庆典。

这100年同时也是电力和自动化管理技术发展与创新的100年； 美商实快（Square D）电力公司作为世界最优秀的电气产品， 服务于美国各大公司及电力设施，并在世界各地遍布企业和销售网络，凭借近百年生产经验的配电设备品牌，它承诺创新和可靠的产品来迎合客户需要。在输配电及工控及自动化，广泛用于商业，建筑及工业各领域。美商实快（Square D）电力的核心业务是电力与自动化管理。实快（Square D）电力始终处在创新前沿，能够对全球的市场需求做出迅速反应，为配电和工业控制自动化领域提供符合NEMA标准的产品、系统与服务。 美商实快Square D 品牌产品具有5大特点：精巧、创新、优质、可靠、安全。

Square D is an American manufacturer of electrical equipment headquartered in Andover, Massachusetts. Square D is a flagship brand of Schneider Electric, which acquired Square D in 1991.

Square D was listed on the New York Stock Exchange for 55 years prior to its acquisition without reporting financial loss in any calendar quarter, paying out 220 consecutive quarterly dividends to shareholders.

Square D was founded on December 15, 1902 by Bryson Dexter Horton and James B. McCarthy. In 1903 they incorporated as the McBride Manufacturing Company. During the first decade of business, the company expanded into various other electrical products. In 1908, the company was renamed Detroit Fuse and Manufacturing. Horton, an 1895 electrical engineering graduate of the University of Michigan, was credited with the invention of the safety switch, which encased high voltage switches and started the company's main line of business of circuit breakers and encased control panels. Their first enclosed safety switch was introduced in 1909.

Soon after their renaming to Detroit Fuse and Manufacturing, the company adopted their famous logo — a capital "letter D" for Detroit, enclosed in a square. The logo was stamped on all Square D's switches and products. The combination of an easily remembered monogram logo and their great popularity resulted in customers referring their products as "Square D". Consequently, the company trademarked the logo and in 1917 they renamed the company Square D. Horton served as Square D's president until 1928

In the early 1920s Square D sold the majority of their fuse business in order to focus more on their safety switches and other safety products. The company began an aggressive marketing campaign to promote their safety switches. Their advertisements, which became to be known as "Jones is Dead!", directed public attention to the safety hazards of exposed electrical switches in factories. Square D hoped to capitalize on the growing concern of factory safety. One such fully working Square D safety switch from 1922 was donated in November 2003 to the Smithsonian's National Museum of American History.

By 1929, Square D merged with a Milwaukee-based industrial controller company and began producing Westinghouse-licensed circuit breakers. In 1935 Square D began producing its own range of circuit breakers for both commercial and residential uses.

In 1991, the company was acquired and became a subsidiary of Schneider Electric. In 2003, the Square D by Schneider Electric brand celebrated its 100th anniversary.