Question About Changing Gearboxes

Check price for a variable frequency drive to operate your AC motor at slower or faster speeds. There's not really enough information (numbers) in your question to make a concise reply. You need to know what actual loads (torque) is needed and what type of machine you are operating. I've successfully utilized numerous VFDs where speed control on AC motors were required.

Hi !!

You may try using Planatory Gear Box which has better efficiancy than worm gear boxes If for your 4 pole motor Out put RPM is 1440 and RPM required on your machine is 400 reduction ratio is only 3.6 :1 for which planatory gear box with hifgher efficiancy would enable you to reduce Motor hp compared to your exisiting Gera boc if that is worm reduction gear box.

You need to furnish more specific details about your requirement to give you appropriate solution.

Udayan

You have assumed 50 Hz, why?

Sounds pointless to me.

The motor speed is fixed by the electricity frequency; the current varies according to motor load. so at half load you will be getting 40HP using half the electricity. Unless the new motor is more efficient than what you have you will not have any change in electricity usage as it is directly proportional to load. you could rewire the motor or change the motor to one that runs at 400 rpm then dump the gearbox saving the mechanical losses here. However you will need to control the startup surge and consequent highcurrent startup.

I suggest you have alook at late 19th and early 20th century electrical engineering texts. These have some pretty clever ways of reducing electricity consumption (or making it look like you are using less than you are) which have dissappeared since electricity became common and cheap after WW1.

Hope this helps

It's not clear. If you need to keep load speed at 400 rpm and change the motor to lower hp, you need just to keep the same synchronous speed of a new motor as is in the old one. No need for change of gear box.

Of course, in this case you may exchange also for the gear box smaller (lower power).

I would check catalogue for motor+speed reducer set, but generally investing time and money probably will not be economical solution as ROI usually is long - over 5 years. Rule of thumb says: wait to the first big malfunction to rebuild the drive.

Think about the maintenance aspect too.

If you want to reduce energy costs and are prepared to spend some capital, then check out the ABB site specifically Permanent Magnet Synchronous Motors. Direct drive with no gearbox at 400 RPM is in the range. Your description of what you want to do with gearing is not really clear but sounds like the wrong way to go. Never step down and up again or vice versa, every speed change via gears costs money for energy.

If a 80 HP motor has been used in the original setup it must be because that much power is needed. You cannot use a gear box to reduce power. Gears just trade speed for torque. So you need to first get some expert to see if the plant can be modified to consume less energy.