Motor Torque at low frequency

[reilly8282]

I work at a fruit processing plant and need some information on a conveyor system that we have installed. Currently we have a motor turning a 10' by 4' wide conveyor that handles massive loads at time by dumping of product. Because of grading and so on, the line supervisor adjusts the remote speed pot dial down as far as she can. Which in turn she is operating the frequency drive somewhere around 11-15hertz. We have been having a problem depending on the load of stalling out the motor but not recieving a fault from the drive. When testing and we operate the motor at full 50cycles (european equipment) it is not possible to stall the motor. This motor operates a chain drivin sprocket connected to the conver. My thoughts are re-gearing the motor sprocket so we can raise the frequency and run the motor faster providing more torque. Thanks any input will be appreciated.

Reilly

 

[TheBlacksmith]

If they never need the belt moving a a higher speed then gearing down is a reasonable solution. That's the whole idea of gears/transmissions; let the prime mover and the load both run in their sweet spot.

 

[jraef]

You likely have an older drive that is not capable of what is called "vector control", and/or it is in simple V/Hz control mode. When in that mode, the output of the drive has no way of knowing if the load has changed and the motor needs a torque boost to maintain speed, so it allows the slip to increase until it overloads or stalls. Typically V/Hz drivse have trouble maintaining torque beyond a 3 or 4:1 speed range, which is exactly what you are experiencing. You need a vector drive, or if yours is capable, someone needs to enable that functionality.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[jraef]

If you don't know how to tell, post a make and model, we can let you know.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[reilly8282]

The drive is a T-verter E2-2P5 H1F 208V 3phase 0.4KW .25hp
Im currently looking up information now as well. Thanks for the information.

 

[OperaHouse]

Amazing that runs it at all!

 

[ScusaMe]

TECO Inverter

Two parameters : F5 V/F Pattern

F13 Torque Compensation


The problem you describe would seem to be that you are not developing the excitation in the motor necessary to support the torque load in the lower operating range (below 30% in your case)

What is F 5 setting

What is F13 setting

What is output voltage at 10, 11,12,13,14,15,16 hz

What is current at those points both for unloaded and loaded conditions.

If F5 is set correctly .... you can increase torque support by increasing F13 parameter .... watch the current as you increase this parameter. You do not want to exceed rated Inverter current by more than 5 - 8% under transient conditions... ie. when shock load is applied.

 

[jraef]

Not a vector drive, not even a highly capable V/Hz drive. Teco makes good drives and they make cheap drives. That was a cheap drive.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[ScusaMe]

jraef:

you know the story. OEM's always buy on price. It would seem that this may have been the case and as a consequence, the inverter is not well suited for the application. Then again, it might be adequate but just not properly set-up OR the operation thereof is exceeding the design limits. Not unfamiliar scenarios for you.

[purple]Quality is like Buying Oats:

[tab]If you want nice fresh oats you have to pay a fair price. If you can be satisfied with oats that have already been thru the horse, that comes a little cheaper.[/purple]

 

[reilly8282]

Thanks for all the input. Im not quite sure which route to go, I have a Yaskawa V1000 to replace the drive which is what our local dealer handles. From what I understand it is a very capable drive with the parameters I would need. Thanks for all the input.

 

[electricpete]

Quality is like Buying Oats:

If you want nice fresh oats you have to pay a fair price. If you can be satisfied with oats that have already been thru the horse, that comes a little cheaper.

Good one. You made my day.





=====================================
(2B)+(2B)' ?

 

[jraef]

The V1000 is a vector drive, should work fine.

Love the "oats" reference too by the way ScusaMe.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[LionelHutz]

Can you live with a lower maximum speed? If so, then changing the sprockets and gearing it down further would likely be the simplest fix.

You can change the drive and get more torque from the motor. However, you might also overheat the motor by doing so.