Motors consume more than 75% of industrial load across the globe. Knowingly or unknowingly huge amounts of energy are getting wasted due to the non-optimum operation of these motors. Due to Lack of awareness can also be said as one of the important factors contributing to this non-efficient usage of motors.
When any company is planning for procuring a motor for some application, the technical manager calculates the required power and torque for the said application and decides one rating to procure say 100kW. Then it goes to the section head where he adds some margin to be on the safer side and decides the rating as 120kW. At last, the management and the purchasing department come into the picture wherein a few more margins keeping in mind about future expansions were added making the final rating of a motor to be procured as 140kW. Generally, no motor runs at its full load more than 50% of the time, and keeping in mind overload conditions and all, the technical manager would have already oversized and post that all others get added up making the capacity of a motor almost double.
Now let's see what are the ill effects of oversizing a motor below
- Negative effects of Oversized Motor:- Runs at low Power Factor
- Efficiency drops drastically at less than 50% load
- Results in more power consumption for the same load
So just an oversizing is creating a huge energy wastage there are several other factors that need to be optimized.
Few energy-saving ideas have been listed as below:
- Use of energy-efficient motors greater than IE3 for new and replacements- Properly size the motor for optimum efficiency.
- Use a dial gauge to check whether the alignment is properly set up or not.
- Provide proper ventilation. For every 10 Deg, C rise in temperature above recommended peak will, the motor life is estimated to be halved.
- Avoid overvoltages more than 415 V. For every 10% decrease in voltage on an underloaded motor can have around 4% of energy. The performance of motors varies with applied voltage.
- Provide a balanced supply voltage. Unbalance can cause around 3 - 5% of energy losses.
- Practically limit motor re wounding less than 3 times. More number of rewinding’s and poor job may result in around 8 - 10% losses
- Change motor end terminals from delta to permanent star if loading is observed less than 33% permanently.
- In case if loading is less than 33% for most of the time then use an auto star-delta mechanism that works based on current sensing.
- Use flat belts on the drives that are 3 -5% more efficient than V belts
- Use variable speed drives on major motors having constant torque
- Use motor surface-mounted sensors for continuous monitoring of vibration, temperature, and other maintenance-related parameters of a motor.
Thank You !!!