Comments on: Putting the electric motor on a diet

Technology that monitors and adjusts an electric motor's energy usage is gaining interest.

[Bob H in NPR]

re: electric motors are power hogs.

As a former electric motor repairman, I read this article with interest. It is amazing how much electrical technology has advanced in the past 30 years.
However there is one factor ommitted in your article. The Power Genius will work only in brush type motors. The overwhelming majority of electric motors cannot run on reduced power, because they are designed to run only at full speed & power. They would simply burn out under reduced power.. This would include most motors in industrial/ manufacturihng/ agricultural applications. The soft start feature would is very useful, saving power and minimizing the large electrical surge needed at startup.
I mention this purely as a caution to those who are not aware of this fact. While the Power Genius
is an engineering wonder, it is not a cureall. Some day, I am sure, the problem I mentioned above will be overcome also.

[Bob H in NPR]

re: electric motors are power hogs.

As a former electric motor repairman, I read this article with great interest. It is amazing how much electrical technology has advanced in the past 30 years.
However there is one factor ommitted in your article. The Power Genius will work only in brush type motors. The overwhelming majority of electric motors cannot run on reduced power, because they are designed to run only at full speed & power. They would simply burn out under reduced power.. This would include most motors in industrial/ manufacturihng/ agricultural applications. The soft start feature would is very useful, saving power and minimizing the large electrical surge needed at startup.
I mention this purely as a caution to those who are not aware of this fact. While the Power Genius
is an engineering wonder, it is not a cureall. Some day, I am sure, the problem I mentioned above will be overcome also.

[johnjhurst]

re: re: electric motors are power hogs.

I find it necessqary to disagree with the statement made by Bob H regarding the Power Genius working only on brush type motors. In actuality, this technology works on any squirrel-cage type AC motor, by far THE most common workhorse motor in all industrial and manufacturing applications.

The technology works by reducing the voltage to the motor terminals, which reduces the magnetic flux and the current. By reducing the power input it reduces the output power at the motor shaft - in effect, matching the motor to the load that it is driving.

The obvious limitation to this technology is that it will only save energy in cases where the motor is oversized for the load it is driving - such as with escalators, where most of the time the motor is running at less than 10% of it's full rated load (how often do you see two people on every step of an escalator?).

Note that this technology (unlike, say, a variable frequency drive) does not change the motor's speed. Far from burning out a motor, running it at reduced power - only the amount of power required to drive the load- actually causes the motor to run cooler, extending it's life.

[Seaspray0]

Not viable for every electric motor application

Electric motors do not draw a constant current reguardless of the load. The laws of physics still apply... power in must equal power out. Electric motors automatically vary their current demand based on the load they are given; the more you tax the motor, the more current it draws. An electric motor that isn't attached to a load only requires the current needed to overcome natural loses such as friction and induction loss. The current needed to drive a motor under no load conditions is an extremely small fraction of the current required to drive it under full load. The technology mentioned in this article will only be economical where you have a motor that runs near no load for extended periods of time. Even then you're only going to save on the induction loss as the friction will be the same. I wish this company luck in their venture. I'm sure there are other applications where the motors are mostly idleing where this could be useful, but overall, don't expect a very large percentage of electric motors to recieve this treatment as most ARE run near enough to their rating.

[Andrew J Glina]

That's what I thought...

...but the fact that this technolgy exists seems to prove me wrong! I will have to look into this.