How to Reduce Energy Consumption (Motors)

[rayhud]

Hi,


I'm a student, and i have been given a task during my internship, which is a study of the energy consumption of all the motors inside the enterprise, in order to try and come up with a plan to reduce their consumption.

I've done some research, and was able to determine that in order to do so, a speed control of motors so as to adapt it to the load is necessary, as well as the optimization of their efficiency and regular maintenance.

The problem is that i can't figure out a way to start working on this project, so what i need to know is how to be able to give a solution through analyzing the motors' energy consumption ? and what are the points i need to focus on ? or the motors i need to target ? and which strategy is to adopt in order to be able to succeed in this task ?

And if there are more ideas on the solutions to reduce motors' energy consumption, please feel free to enlighten me.

Thank you in advance.

 

[Smart $]

Welcome to the forum... :thumbsup:

While I (we) appreciate your posting here in pursuit of your endeavor, as a student we try to not provide you with an unfair advantage over your classmates, potentially improving your grade surreptitiously, and outright hindering the effort you must put forth in learning. That said, we will attempt to help you as best we can without violating the aforementioned principles.

As I see it, there is already a wealth of information available on the internet about "improving motor efficiency" and "reducing motor energy consumption"... so what we can do is attempt to steer you in the right or better direction.

On that note, speed control may improve a motor's energy consumption. It may not. So the initial question is whether this has already been considered in the design stage. If not or cannot be determined, you need to come up with a way to determine if speed control will improve energy consumption. Elaboration is your exercise...

You mentioned efficiency and maintenance. Yes, they are definitely a factor.

Of the three mentioned thus far, which has greater effect? ...and by how much (if you can actually put an empirical value on it)? This is an area an enterprise will want to know. It amounts to finances outlaid versus return on investment.

There are several other ways to improve energy consumption. Elaboration is your exercise...

 

[just the cowboy]

Size matters

Size matters

Size and risk go hand in hand in this. If you can save more money on a large motor and have a better ROI thats more saving, but if it don't work right that is a bigger loss. Small motor savings may not pay back as fast but may have a smaller risk.
Just installed 4- 5hp invertors on exhaust fans, saved 1/3 on electric cost, ROI was 5 years due to material costs. Was this a good deal? Lots to think about, if current did not drop by 1/3 or fans did not work right would there even be a payback?

Good luck ask as many questions as you can and you might get the right answer.

 

[suemarkp]

Also note that "proving" your saving is a bit involved. Just measuring the amp draw of the motor doesn't necessarily tell you about its actual power consumption. Because of its power factor, the volt and amp waveforms aren't in alignment so power used is not just volts * amps. However, reducing the amp draw by changing the power factor can reduce losses in the wires, so that can count too (and if that wire loss is in a cooled environment, you're paying to eliminate that heat). You could also assume the power factor is one, so the power draw could never be higher than volts * amps (this means that if the amps go down, you've probably reduced its power consumption but not necessarily in proportion to the radio of current reduction; but if it goes up you can't really tell).

You'll need a watt meter to measure what your motor is actually drawing.

Reducing the work the motor does should reduce its power consumption. Can anything be slowed down if it is over sized (we have many air handlers that are waaay over sized because someone though we may need 60 tons of cooling in a space that is now using 10 tons). Our utilization of space does change over time, so who knows maybe the next tenant will need 60 tons, or want a clean room with a huge amount of air flow. Reducing the work can be easy by changing pulley sizes if it is a belt driven device (and you can easily restore the original pulley). A 50HP motor doing 20HP of work will not be as efficient as a 25HP motor doing 20HP of work.