Technical Assistance and Advice to Save Energy Required

No, not likely to save 15% to 20% energy.

But, by all means, contact several vendors of VFD's. They will be happy to tell you how they can help you.

...particularly on <...please quote for both VFDs ...>, as CR4 doesn't do that.

One Billion Dollars....

Go to this web site:

• Variable Frequency Drives

We just discuss stuff. We don't sell anything on this forum.

VFD's can be used on constant torque loads, if selected and set-up for this type of load. If you are running the slip ring (wound rotor) motors at a reduced speed then you have the losses of energy in the secondary circuit going through the slip rings from the motors. You will have to work closely with the manufacturers and be ready with a lot of data about the typical speeds the motors are running. A qualified engineer is a must for your application, so choose the person carefully with a good look at the references and completed projects done by this person. Call the customers that have been named to verify the adequacy of services.

--JMM

I wasn't implying that VFDs don't work for constant torque loads, they absolutely do. But they don't save ENERGY on constant torque loads, unless maybe you are using them to replace a mechanical speed changing system like a vari-drive that has more losses. The OP was implying they wanted to save a lot of energy vs the slip ring control method, and that is not going to be the case if he leaves the old motors in place.

If I remember correctly, a slip-ring (wound rotor) motor can provide nearly full torque over a substantial speed range. If his application is running the motor at a reduced speed because of some form of resistance being used on the secondary conductors, then a VFD can be used, and will give a reduced speed with the losses being drive losses instead of resistor heat losses (with potential energy savings here). He would have to short the three slip rings together and remove the secondary resistor assembly along with the brushes that had been riding on the slip rings. I am sure you know all this.

Some posts have suggested an alternative method whereby the energy loss currently in the secondary resistor circuit is redirected into power being regenerated onto the incoming line. I have never done this nor have I heard of it before, but it certainly sounds reasonable.

If, however, the heat loss in the motor's secondary resistor circuit is being used somewhere else for process heat, then the savings will probably be small.

Hopefully the Original Poster (OP) can log back in and give us some more information.

Thank you Meuller for your kind response and helpful information.

I will update if we go to do anything and whatever response we get from it.

Thanks & regards,

Salman

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Here is a link that will explain slip recovery methods and the considerations you should study before you purchase and upgrades. In the proper applications,much energy can be saved,but only you or your team can decide the best direction. This link is provided for guidance only: https://www.tmeic.com/sites/default/files/assets/files/library/TMEIC_SEPT_ICR_low_1260284113.pdf

Namaska, Aap kaisi hai. Seimens, ABB, Schnieder. Now showing in a local phone book near you.

Happy to quote you, please forward the contact person details, along with none refundable deposit and PO.