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#1 |
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Location: Belgrade
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Variator with VFD?
Hi to all.
Did anybody had experience with driving motor with variator with VFD? Is there something that I should take care additionally? Best regards, Goran. |
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#2 |
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What is a variator with vfd, I know what a vfd is , I know what a variator is.
My understanding is that they are the same. Please correct me.
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My two cents. |
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#3 |
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It's not all the variables I am most concerned with, it's the undiscovered constants. |
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#4 |
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My understanding is the VFD controls motor speed and Variator is a variable gearbox the motor is driving
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B.Pedersen if you are going to assume, assume you're wrong. |
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#5 | |
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Quote:
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"When nothing is going right, go left." "Even a fish wouldn't get into trouble if it kept its mouth shut." (I should probably look into this) |
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#6 | |
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Quote:
Why you would have both is a mystery to me... but maybe SOMEONE who decided to do this has a reason. Find that person and ask them. |
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#7 |
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Location: Belgrade
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Hi,
Thanks for answers. Under variator I think as variable gearbox, and VFD is inverter. I know that it seems unlogical to put them both, but the thing is that it is old machine in question which used and still uses variator and it is with relay logic, but there is now need to install PLC due to thing that it needs to be synchronized with other equipment. Now it is very inconvenient to change motor. There are variators with servo driven shaft, but there is no space for that. I just need to know can I do some harm to motor with inverter. For me it seems that there are few potential problems like that that current is changed along with gearbox ratio so there is no real protection of motor, and there is question of motor ventilation. Any thoughts? |
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#8 |
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Location: Belgrade
Posts: 264
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Jraef,
I do not have problem with torque and also with efficiency. The purpose why this motor has variator is to obtain certain force between it self and other part of sistem which is driven by second motor by changing the speed of the first motor. The second part of system driven by other motor can change rotational speed due to mechanical properties. Now my job is to automate 40+ years old machine and synchronize it with new equipment with minimal impact... |
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#9 |
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Location: Ontario
Posts: 133
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What is the machine?
Almost sounds like a decanter centrifuge. If so that could have complications depending on the setup as the VFD may need to be setup up to deal with an overhauling load. |
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#10 |
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Location: Belgrade
Posts: 264
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No, it is not decanter centrifuge, it's something similar to flowpack.
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#11 | |
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Quote:
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Knowledge is power, share the knowledge. |
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#12 | |
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Quote:
https://www.motovario.com/eng/produc...uminium-series Best regards, Goran. |
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#13 |
Lifetime Supporting Member
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Ditch the variator.
Analyze the system and see what exactly you want to control, and how. Current generation VFD's can easily control speed and/or torque at the motor shaft, and can follow any other shaft at any ratio you desire if that is what you need.
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------------------------------------ How to ask questions the SMART Way! Look First, Ask Second! |
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#14 |
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That is a variable slip clutch into a planetary gear box. It likely has horrible efficiency, maybe as low as 40%. The planetary gear system is amplifying torque, so you must very carefully asses your torque requirements for the load. But if not necessary and the FLT of that motor is ample for your machine, I would get rid of that mechanical device and just drive the motor with the VFD. If the machine does need the added torque provided by the “variator” you could consider using a bigger motor instead.
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#15 |
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To add a bit to jraef's good comments, choose a new motor with the same hp as original but with more magnetic poles. For example, if original is 1800rpm motor (four poles), choose a 1200rpm motor (6 pole) or even a 900rpm motor (8 poles). If this leaves you a little short of top speed, set the inverter up to go over 60hz to get the top speed back to original. As jraef states, overall efficiency will go up dramatically to the extent that you will probably have surplus hp even staying with the same motor hp rating.
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