Energy conservation in industrial A.C drives

ABSTRACT

The induction motors can be considered the larger users of electrical energy. They are used both
in industrial and commercial sectors in a wide range of applications, such as: fans, compressors, pumps,
conveyor, winders, mills, transports, elevators, home appliances and office equipments. In India, the
electric motors used in the industrial field consume typically the 60 to 70% of the total adsorbed
electrical energy. In the commercial sector, this percentage is up to 35%.
With reference to industrial sector, a general purpose electrical motor consumes about an annual
quantity of electrical energy equal to 5 times its purchase costs and the motor live can he evaluated
around 10 to 12 years. On the base of these considerations, it is possible to obtain consistent energy
saving if higher efficiency motors are used in the final applications.
World-wide, there exist several standards for testing electric machinery. For induction motors, the four
most important are:
IEEE Standard 112-1996
IEC 34-2 and IEC 34-2A
JEC 37
IS 325
Several national standards are harmonized with regard to one of the three general standards above. The
NEMA MG-1- 1993 standard and the Canadian standard C390 correspond to the IEEE standard, while
in most of the European countries; the standards are harmonized to IEC 34-2. JEC stands for the
Japanese standard. The efficiency value obtained from the considered testing standards can differ by
several percent, as will be shown in the measurement results. Moreover, one standard can contain
different methods that do not necessarily lead to one firmly determined value.
In this project, international standards are used to evaluate the efficiency of 3.7 KW, 4 pole three-phase
induction motor and a logic based energy optimizer is developed using the numerical values obtained
from the above standards.