From Motors and Drives

AC Motor Types

AC motors can be divided into two major categories-asynchronous and synchronous. The induction motor is probably the most common type of asynchronous motor (meaning speed is dependent on slip). When reviewing induction motors, there are two rating designations-NEMA and IEC.

Another type of asynchronous motor is the wound rotor motor. This type of motor has controllable speed and torque because of the addition of a secondary resistance in the rotor circuit. A third type of popular asynchronous motor is the single-phase motor. The single-phase AC motor will not be covered because of their limited use in industrial applications when connected with variable-frequency drives.

The synchronous motor is inherently a constant-speed motor, when operated directly across the line. This type of motor operates in synchronism with the line frequency. Two types of synchronous motors are non-excited and DC-excited.

The basic principles of AC induction motors have been previously covered. In this section, attention will be given to motor designations, ratings, and designs.

Standard AC Induction Motors (NEMA and IEC)
NEMA frame motors are in widespread use throughout U.S. industry. This motor design was developed before the 1950s and has well served many types of fixed-speed applications. In...

More >>
© 2003 ISA

Products & Services
Bulk Material Loaders and Unloaders
Bulk materials loaders and unloaders are used to fill and remove powders, granular substances and other bulk solids from bags, bins, boxes, carts, drums, hoppers, railcars, trucks, and silos. They often include solids feeders and break down clumps or arches to allow for the more uniform distribution of bulk materials.
Lift Tables
Lift tables are devices used to elevate cumbersome materials or workpieces to an ergonomic and reachable height. Capacity, mobility, and elevation are some of the main factors determining its capabilities.
Lifting and Rigging Attachments
Lifting and rigging attachments are used on a crane or hoist between the hook and the item to be lifted. Items include sling release systems, product specific lifters, clamps and grapples.
Lifting Slings
Lifting slings are material handling accessories for load attachment to lifts, cranes, and hoists.

Topics of Interest

IEC Ratings At this point, it would be helpful to briefly review IEC motor ratings and then compare IEC with NEMA. The motor market today has become more global, with IEC rated motors on equipment...

Bulk material inverters are used to reposition or empty material handling containers. Inverters empty containers (boxes, drums, bins, etc.) by tilting them to allow materials to pour out below.

Sometimes the enormous power and precision of synchronous hydraulic technology is the best option; sometimes standard indoor and outdoor cranes can do the job cost-efficiently; and sometimes lifting...

Frank van Hoorn 52.1 DESCRIPTION 52.1.1 General Heavy-lift transport ships form a particular sector of the dry cargo ships. These specialized ships are capable of transporting heavy and awkward...

Handling Procedure: Load and unload pallets from a machining center. Pallets are brought into the workcell on carts. Operators must lift them off the carts and reach into the machining center to...