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Thomas Walsh
09-16-2013 06:16 AM

Energy Savings Inverers Servos

Where can I get the best information on energy savings of inverters vs.std. electric motors and energy savings information on servos vs. vs. electric motors. I need this for high pressure 2000- 5000 hydraulic pumps operating presses and machine tools savings at each part of the cycle time in percentage and dollars
09-16-2013 08:21 AM
Top #2
09-16-2013 08:21 AM
Hi Thomas, I'm note making promotion of company, but I worked for ABB and Siemens before and they energy saving tools for pump, so they can calculate you the energy saving you want. According my knowledge this work for std motor and drive, not for servo because due to small power range and product price, I'm not sure that it help, because energy saving as nothing to see with small power, most important thing in servo is the product and application's solution more than the price. Hope it helps !
09-16-2013 01:24 PM
Top #3
Dan Tolstrup
09-16-2013 01:24 PM
Hi Thomas
WEG have a range of IE4 motors from 0.55kw to 400kw.
Contact your local dealer or see technical on
Best regards
Dan Tolstrup
09-16-2013 03:42 PM
Top #4
Jairo Muñiz
09-16-2013 03:42 PM
Hello Thomas
ABB has in my opinion the best investors, since they have a significant energy savings.
The servo consumes much less energy than a conventional electric motor, but is more delicate and requires more maintenance.
If your mechanical press is over 1000 tons Integres advise that an electric motor, is also good to do a calculation of the volume of a hydraulic power unit to be able to model the flow of the pump, RMP, etc.
Best regards from Mexico
09-16-2013 06:07 PM
Top #5
Jeff Butler
09-16-2013 06:07 PM
Are your hydraulic pumps variable torque or constant torque? The real savings when using VFD's is if the load is variable torque.
09-16-2013 08:09 PM
Top #6
Chris Heron
09-16-2013 08:09 PM
As Jeff Butler mentioned above - the best results (in terms of economic cost) occurs when the duty cycle requires variable torque.

But also remember - you need to be looking at ALL the parts in the various alternative systems. The input (energy in) comes from the electric utility line. The output (energy out / work done) is after the actual mechanical pressing action (i.e. you have a finished product).

That means checking losses for transformers, cabling, power electronics (including drives), rotating machines (including external excitation, if required), gearing, mechanical device (driven equipment), and so on ... for EACH operating point in the duty cycle.

Different devices will have - for the most part - different efficiency characteristics as the load varies from zero to full (to potential overload). Try to use information that is as accurate as possible for each device at each point ... that way you have the truest comparision.
09-16-2013 10:16 PM
Top #7
Wayne Vyrostek
09-16-2013 10:16 PM
Usually a positive displacement pump can be considered a Constant Torque type of load, i.e. torque does not vary significantly with rpm, whereas, impeller or centrifugal type pumps can be considered Variable Torque, of course you need the pump curves, flow rates, head pressure range, etc. to really get an accurate assessment. ABB, Rockwell, Siemans, etc. all have software to calculate the energy savings based on percentage of full speed vs slower speed operation.
09-17-2013 01:00 AM
Top #8
Bhushan Soni
09-17-2013 01:00 AM
sir, cantact your local emerson control techniques drive application center, they are having good solution for pump application.
09-17-2013 03:20 AM
Top #9
Michael Linden
09-17-2013 03:20 AM
ABB have a library of information on this subjet. Go to and enter Energy Efficiency in the search box. Follow the inverter and drive links for calculation tools etc.

This is an Aussie site but would be replicated in most countries.
09-17-2013 06:00 AM
Top #10
Hugo Coral
09-17-2013 06:00 AM
If one of this is fixed and the other one is variable you get energy savings.
If both are fixed at nominal values, there is no chance. Take care with constant torque applications in low speed range, you will need to include forced ventilation and wasted power in your ecuation.
09-17-2013 08:42 AM
Top #11
Istvan Butkai
09-17-2013 08:42 AM
I measured same system what Thomas described. The drilling machine started and stopped by 2-3 minutes. It drilled and removed the drilling tool.Using motor speed driver the energy savig appeared, because there was soft starts and no inrush current. In 24 hour this was enormous saving. At the oil pump, which used these machines, the regulation of pressure worked by bypass valves. I think your case is similar. I closed the bypass valve and regulated the oil pressure by motor speed driver too (Altivar 71). I installed a small measuring system, it was Power Logic software and PM810 devices of Schneider Electric. I measured the energy for 2 weeks with speed driver and without speed driver. The result was, the price of installing speed driver come back in less than 1 year. This was a car factory. They installed speed drivers in first step to 20-25 machines. And there was a second step too but this is an another story.
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