From BSI Shop
A fraction of the Horsepower! A look at fractional horsepower motors and some old standards
Roaring Twenties – along with the new household goods, the first FHP standard appears
In 1926, BSI released the specification for Electrical Performance of Fractional Horse-Power Electric Motors – BS 170. It applied to FHP motors (including Fan Motors) of any continuous rating “less than one horse-power per 1000 revs per minute” and covered variable speed and inverse speed motors.
In 1939 the scope was expanded to cover “universal” type FHP motors, and AC DC generators.
In 1962, the standard was again revised, with major changes bringing it into line with current practice, with particular provision made for new classes of insulating materials, and guidance was given on performance characteristics.
Standards covering dimensions in the 1950s
BS 2048 appeared in 1953, establishment dimensions for two frame sizes of FHP motors, necessary so that motors of all different makes would mechanically interchangeable when mounted on the driven machines. The dimensions specified were identical to the American NEMA FHP Motor Standard MG2:1951, so that those complying with the standard would be interchangeable between the two countries.
BS 2048 was revised in 1961 to cover more frame sizes, still identical to the US standard.
Paul