Variable Frequency Drives Start On The Fly

I am in the sugar industry and our factories tend to be very close to nowhere. We have large energy demands which we meet with a renewable fuel but we do have "brown outs" and short duration "blackouts" aside from the total "blackout" situation. If this is not what you require, stop reading now.

We have recently started introducing "ride through" to many of our critical applications. If the factory is stopped it is very difficult to get going again and the losses are high. The most critical plant are the boiler as from this we generator steam for our process but also our electricity. Keeping the boilers going is critical. The most difficult machine is the ID fan where it can take greater than 10 minutes to stop before we can restart it. During this period we have "lost" the boiler. {Silly statement as it is very difficult to lose something that is that big!}. If we keep the ID fan going or recover it very quickly, we can generally "save" the factory. {No this does not involve a swim recovery, and mouth to mouth. Must be the silly season. Sorry}

We now use variable frequency drives instead of dampers on our air fuel ratio control and with all modern variable frequency drives, we can get "ride through" and "start on the fly". It uses the energy stored in the fan (fly wheel) to keep the DC bus alive and when the power is restored it takes off again. Starting the pumps and smaller fans is not an issue and we can run for about 3 minutes on the steam as the pressure falls so with the modifications we hope to have a better season next year. We have run trials of >3 minutes but will not exceed 30 seconds due to safety concerns. We used a WEG SFW11 on a 500kW, 4 pole 400v induction motor, but Siemens and ABB do offer this as well.

Africa and South Africa are experiencing huge electrical energy supply problems as the growth of the economies has not been matched with installation of new power plants.

Buying a VFD on GoHz, 1hp VFD, 2hp VFD, 5hp VFD...

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