Adequate sizing and motor exploitation: Motor energy management

Abstract

Motor energy management includes adequate sizing, control and improvement of electric energy quality, i.e. voltage quality (reducing voltage unbalance and harmonics distortion), and the proper maintenance. The specific motor price per kW is approximately constant for motors rated from 5 kW to 20 kW. By adequate sizing, or by proper replacement of the old motor with the new one, with rated output power reduced by 20% to 50% the smaller motor will be also cheaper by 20% to 50%. When the 22 kW motor is replaced with the new 15 kW that costs 64% of the price of a new 22 kW motor, the efficiency is increased by 3.6% (Example in paper). On the basis of our investigation results, it is confirmed that there are significant possibilities for energy savings by setting voltage values within the ±5% voltage band (Un±5%), since more than 80% induction motors are under loaded (£70%), especially small and medium rated power (1-30 kW) motors.

Keywords

• motor energy management
• energy savings
• adequate sizing
• voltage unbalance
• harmonics distortion
• setting voltage values