Motor Efficiencies

It depend on the size u are looking at. Normally U can load it on Dynamometer up to 1000kW 6Pole. Beyond that either loading through a generator /other methods like mixed frequency tests are resorted to .These are normally possible in manufacturer's works. In case of audit u have to see how efficiently the motor is performing. U can measure Input power,Pf .See power consumed and check with type test certificate and curves given by the manufacturer to see the eff. at that load.Normally motors are underloaded between 10 and 15% apart from other factors such as limiting temp rise,Service factor etc and make it more inefficient.

Contact General Electric and find out how they do it.

Also, motor spec sheets give you the efficiency. Unless you are a manufacturer of the motor, just call up and ask for the numbers. Usually available on the spec sheet.

The input power is straight-forward, measure the voltage, current and power factor to calculate input power.

Motor output power is, of course, the difficult part. A calorimetric approach would be to have the motor run a "paddle wheel" or a friction brake in an insulated water bath. Measure the temperature rise over a period of time and you can get the power output.

Hi, contact the company AVL - List in Graz in Austria. These people are experts in testing motors of all kind.

You might find something here:

http://www.peci.org/ftguide/

if these are for energy audits that measures will be paid incentives from utilities, the utilities usually require a standard baseline. This is usually the current NEMA statndards. At least that's the way it is in California.

I perform energy audits and rarely test for actual efficiency of a motor. Typically, i use the rated efficiency.

I did energy aduit 4years before but never thought of deriving actual efficiency as it is test bench method and even there are lots of variable in field like voltage unbalance, voltage variation, harmonic vicinity, frequency variation, cyclic loading, ventilating method and ambient temperature etc.

During energy audit, one should focus more on overall system efficiency by measuring input power( V, I, pf at input frequency) and at the same time measuring mechnical output of motor. If it is pump, we used to meausre flow and pressure and to derive output power. This can give you overall pump-motor efficiency. Depending on pump curve, one can figure out what exactly is pump efficiency and which can help to derive motor output. This is very expertise business as many cases are with parallel operation and it is not easy to derive system curve.

If you don't want to go on mechanical side, there is simple method to measure power and find out % loading on motor. Depending make and model of motor, you should ask motor manufacurer to submit efficiency curve. Again keep in mind that there are many variable in field like voltage unbalance, voltage variation, harmonic vicinity, frequency variation, cyclic loading, ventilating method and ambient temperature etc. The curves to indicate loss of efficiency with regards to these variables are also available.

I think this is enough for your question

Almost every good sized electric motor repair shop will have a dynamometer test stand that can give you an efficiency report. If they want it certified you will need to find one with a PE on staff. they are out there.

Baker Instrument Company has developed an electrical test device that derives motor efficiency from the voltage and current signatures. They say that it is very accurate when compared to dyno testing.

http://www.bakerinst.com/BakerWeb/PDF_Files/Explorer_Series_II.pdf

Regards,
DNorman

Thanks for all the help and answers. Can anyone provide some testing companies or firms that do this sort of testing in the USA?

Thanks

jbadski

What part of the USA? It's a big place!

Facilities in eight different states for now...Indiana, Kentucky, Illinois, Iowa...to name a few....but could grow to even more facilities and more states.

Try to contact EASA (Electrical Apparatus Service Association) 1331 Baur Blvd, st. Louis Missiouri 63132 USA 314-993-2220, fax. 314-993-1269 or www.easa.com

I'm not american, not interest to verify in a map or google-earth, too. Is this place close to you? Disney Land is only place I'd like to watch through google-earth...ha..ha..ha.