Electrical aids to greater production; by Perry Allen Mason 1890-

Author:Perry, Allen Mason, 1890- [from old catalog] comp
Language: eng
Format: epub, pdf
Tags: Electrical engineering
Publisher: New York, Electrical world, McGraw-Hill book company, inc., sole selling agents
Published: 1919-03-25T05:00:00+00:00

MOTORS, CONTROL, SPECIFIC APPLICATIONS 171

20 per cent. Steam power had increased from some 40 per cent to 60 per cent, and the remaining 20 per cent was furnished by electric power. It has been estimjated that by 1920 the percentage of electric power will easily have doubled. In the earliest electrical mill drives the steam engines were replaced by fairly large motors employed for group driving. The steady tendency of late years has been more and more toward individual drive, which is easily employed in new mills and gives greater possibilities of power economy than have been afforded by the methods that it supersedes.

Probably the typical mill consists of a combination group and individual drive, the former for certain machinery operated, so to speak, in blocks, each consuming no very great amount of power in the aggregate; the latter for the heavier and more independent work. For mill work the induction motor is chiefly used, since for most classes of work unusual flexibility of speed regulation is not required. At the beginning of the art competition with direct-current machinery caused the building of induction motors with extraordinarily low speed variation, a tendency which has of late given way to more normal design. In a few places in mills motors of special type have to be employed on account of the presence of large amounts of dust and lint in the air, and in some cases because of troublesome vapors that arise.

Experience shows that the electric drive for this work has not only the usual advantages of facilitating a cheap supply of motive power but also leads to a larger and more uniform output on account of the better operating characteristics of subdivided motive power. There is every indication that the use of motor drive in mills is going to increase steadily, bringing the greater water powers into active use in this class of manufacturing and superseding not a few of the steam drives now in use.

Loom-Motor Switches. In weave sheds where hundreds of looms are in service and tended by young girls with no electrical or mechanical training, simplicity of control, combined with entire safety of operation of operation, is of vital importance, particularly where the motors are wound for 220 volts and upward. In one installation the looms are mounted with ends reversed, and the adjacent motors are thus brought within 2 in. or 3 in. (5 cm. or 7.6 cm.) of each other. Near the floor in

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