Resumo:
This dissertation aims at reducing motors over sizing. To pursue this goal it is necessary at first to know the amount of three-phase induction motors operating in Brazil, taking into account the widest range as possible. Thus, data obtained from the Brazilian Association of Electric-Electronics Industry (ABINEE) and from a major electric motors manufacturer have been of great importance. When not possible, other data were estimated in order to reduce the incidence of possible errors.
Initially, a statistic survey of the amount of electric motors in Brazil has been carried out. Then, equations for calculating three-phase induction motors losses, based exclusively upon manufacturers catalog data, have been obtained. Also, from a detailed study on motor over sizing, a new constant for motor analysis, which has been named ‘necessary over sizing constant’, has been suggested.
Estimations about how many motors as a function of the rated power and of the load are operating in Brazil are presented. Losses caused by the use of over sized motors are calculated and alternative ways of reducing over sizing are also shown.
Efforts have been made in order to reduce motor over sizing in electric drives. Thus, three-phase motor losses would be certainly minimized. In such a way, the narrowness of the distance between rated powers of three-phase motor power range in our country has been suggested as a proposal for optimize standardized motors performance.
Motor rated powers suggested for a probable new standardization, have been then used instead of the current ones according to pre-established conditions. Related losses caused by these substitutions have been also calculated. The conclusion is that procedures suggested in this dissertation lead to a reasonable saving of electric energy, although, and most importantly, electric power quality should not be affected at all.
