AC Motors

Reduce the load on the motor.To reduce the load to the maximum amount, turn it off.

Hey, maybe our first customer for one of these?

_{"how do I reduce current drawn by ac motors"}

Under what circumstances? Lyn's suggestion is a little tongue-in-cheek, but is valid nonetheless. Motor current is generally load dependent.

And by the way, current is relatively meaningless, POWER is what you pay for, there is a difference. AC Motor POWER then can be divided into three main segments: Work, Energization and Losses. If you look at a motor's nameplate or data sheet, they will usually give you the Efficiency rating of the motor. That is the difference between the electrical power in and the mechanical power out, the work the motor is performing. Of the non-work related energy, the Energization is what it takes to make your pile of copper and steel into a motor, as opposed to a boat anchor. Losses are what is wasted in the process due mainly to resistance, wind, and friction, but are a small portion of a small portion.

So for example if a motor says it is 92% efficient, that means if it draws 100kW from the line source, the mechanical work it is doing is 92kW, the rest is Energization and Losses. So right there, no matter what lies someone tells you about "saving 25% (or 40%) of your motor energy", it's a lie. You cannot save 25% when you are converting 92% to useful work. But if you are REALLY interested in saving energy, reduce the amount of work the motor must accomplish. If you can't, then that's just the cost of doing whatever it does.

Of the remaining non-work related energy, only a tiny fraction can be theoretically manipulated to reduce losses, but in 99.9999999999% of applications, it isn't worth pursuing.

If they are dual voltage motors wired for the lower voltage (say 240), then provide a supply at the higher voltage (say 480). That will cut the current draw in half. You can also rip out all the wiring and put in smaller, but that's just an option, not required.

Do you perhaps mean how do you reduce ac motor Starting Current?

If so, try a motor soft starter or a variable speed drive.

http://en.wikipedia.org/wiki/Motor_soft_starter

http://en.wikipedia.org/wiki/Variable_speed_drive

Additionally this topic has been discussed in depth on CR4 before, so you could also try the search function on the right hand side of the screen.

_{Crystal ball polished and ready to go.}

Turn them off when they are not needed.