Three-phase asynchronous motors - coordination of protective devices - by ABB

Three-phase asynchronous motors can be considered among the most reliable electrical machines - they carry out their function for many years with reduced maintenance and adapt themselves to different performances according to the requirements of both production as well as service applications.

These motors find their application in the most varied industrial sectors, such as food, chemical, metallurgical industries, paper factories or water treatment and extractive systems. The applications concern the equipment with machine components running at fixed or variable speed such as, for example, lifting systems as lifts or goods hoists, transporting systems as conveyors, ventilation and air conditioning installations, plus with pumps and compressors.

From the above, it is easy to see how three-phase asynchronous motors can be considered the most widespread electric machine for industrial applications (the power consumption of electrical motors is about 75% of the total consumption in the industrial field). Considering this, it is also easy to see how a reduction in power consumption can be important for both the business management (the cost of a motor in its whole life is due to power consumption (98%) and to purchase and maintenance costs for the remaining 2%), as well as for the improvement of the power efficiency in general. For example, such reduction can be obtained by using variable-speed drives with inverters, or by implementing power factor correction suitable for avoiding fines or, even more directly, by using high-efficiency motors, which allow a reduced energy consumption of up to 20%.

This Technical Paper (the seventh volume of the series of Technical Papers issued by ABB SACE) can be divided into five parts - after a survey of the motor structure, the main prescriptions of the Standards about coordination are considered. Then, general information about the main starting typologies is offered, giving an overview of products manufactured by ABB for motor starting, with an example of ABB official coordination tables. The last part comprises some of the most important motor ratings.

To see the full and extensive PDF document, which is highly detailed and very comprehensive, please click on the download button below (1.31MB file size)