A DC motor is usually used when variable speed operation is required. A definite purpose motor is any motor design, listed and offered in standard ratings with standard operating characteristics with special mechanical features for use under service conditions other than usual or for use on a particular type of application. A Normal High High Low Mach. The integral AC motor NEMA sizes run from 143T- 445T, and the center of the shaft height in inches can be figured by taking the first two digits of the frame number and dividing it by 4. An open motor in which the ventilating openings are so constructed that drops of liquid or solid particles falling on it, at any angle not greater than 15 degrees from the vertical, cannot enter either directly or by striking and running along a horizontal or inwardly inclined surface.
Some motors can operate on two different voltages, depending upon how it is built and connected.
The voltages are either multiples of two or the 3 of one another. The relationship between the operating and rest times or repeatable operation at different loads. A device which loads the motor to measure output torque and speed accurately by providing a calibrated dynamic load. Helpful in testing motors for nameplate information and an effective device in measuring efficiency.