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[frayedknot]

I am attempting to reduce our facility's power consumption/demand (monthly cost) by 20% this year. On the list of target items are the motors used to power our mechanical power presses manufactured in the 1950's and 1960's. These motors are 3-phase ranging from 5HP to 20HP. From what I can tell, the motors are original and have never been serviced. The technology of course has changed since then with the advent of higher efficiency motors. The question is: what is a good source to determine the cost benefit (payback) of newer, more efficient motors?

With that being said, what is the effect of the large inertia of the fly-wheel on the demand the motor requires?

 

[jbartos]

Comments marked ///\\I am attempting to reduce our facility's power consumption/demand (monthly cost) by 20% this year.
///This sounds very impressive.\\ On the list of target items are the motors used to power our mechanical power presses manufactured in the 1950's and 1960's. These motors are 3-phase ranging from 5HP to 20HP. From what I can tell, the motors are original and have never been serviced.
///What about bearings?\\ The technology of course has changed since then with the advent of higher efficiency motors. The question is: what is a good source to determine the cost benefit (payback) of newer, more efficient motors?
///The motor manufacturers have loaded websites with calculations, since they like to have those high efficiency motors sold like hot cakes.\\With that being said, what is the effect of the large inertia of the fly-wheel on the demand the motor requires?
///When it comes to the flywheel, it is considered "on the purpose." Then, everything else is the lower priority including the effect of the large inertia of the flywheel on the motor demand.\\\

 

[jbartos]

Suggestion: Visit

http://www.fpl.com/savings/energy_advisor/EA/PA_35.html

for:
Calculations
and
For evaluations of more complicated applications, or if hand calculations aren't your cup of tea, consider using a computer program called MotorMaster+. It contains an extensive database of motors, including efficiency and price for each, which allows the user to easily compare the economics of different motor selections.

For information on the MotorMaster+ motor selection software, contact Motor Challenge Information Clearinghouse, P.O. Box 43171, Olympia, WA 98504-3171, tel 800-862-2086, fax 206-586-8303.

 

[ozmosis]

High efficient motors are certainly the way forward and more and more companies are pushing these as 'standard' now. I would not suggest just replacing a working motor with a high efficient motor as this will not bring a return on investment you are looking for. Introduce a policy of replacing the motors as they fail, especially if they are sub-20Hp as this range would not benefit from re-winding generally. However, with such a high target of energy reduction I would be monitoring what you motors are actually doing as a priority and looking at control. This could mean switching off when not needed, as a start, then move on from there to look at better methods of control. Energy saving is a by-product of good control.

 

[jbartos]

Comment on the previous posting: The motor duty is often dictated by some other engineering than electrical one, e.g. HVAC, Mechanical, Process, "Owner Engineering," etc. Therefore, the actual energy savings must come from a proper interdisciplinary energy savings effort that should also include the Owner, if applicable.