Any one familiar with ABB Drives in Torque Control and DTC?

Hello All,

This is not a PLC question. I deeply apologize for that but I am looking for help from great members like DickDV and others. I am new to this forum.

I work in a plant where we have winders and un-winders machinery. Each of those are built with ABB ASC800 drive powering 1 HP, RPM motor connected to 60:1 reducer. The drives are set in Torque Control macro and DTC function is activated. We run in torque control mode most of the time but sometimes we run in speed control mode. There is a switch connected between point X22.3 and X22.7 (I am assuming you can get a copy of ASC800 wiring diagram). If the switch, on in run on torque mode and if its off, it will run on speed control mode.

The problem we are having and its only on torque mode: at some points when the load speed gets too low (load speed gets too low when the material diameter gets larger) (load speed will be around 3 RPM at load side of the reducer and around 180 RPM at the motor side) the load will start to jerk. By that I mean it will not run smooth like when it faster. The reel will stop for less than a second and fast up again.

We have plenty of those winders and un-winders but we have the problem only on few of them. All of them were built using same exact mechanical parts and the drives were set the same way. Any advice? I would appreciate any help and reply.

Thank you

For more information, please visit our website.

paul said:

A motor is a motor. The drive does not care what your application is.

If you are looking for more details, kindly visit ABB.

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Technically correct, but in reality, there is a "numbers game" played in the drives industry when it comes to drives for CENTRIFUGAL loads, which are comprised of some types of pumps and fans, and you will find those used predominantly in the HVAC industry.

On a centrifugal load, the power DEMANDED by the load (the pump or fan) from the motor varies at the cube of the speed change. So for example, at 50% speed, the pump/fan will only require 12.5% of the HP from the motor as it would at full speed. Since the motor must be sized for the worst case scenario, full speed, that means the VFD must be sized for that as well.

But in VFD design, there is an overload capacity factor that must be built-in to each VFD, to allow it to accelerate, or more importantly RE-accelerate a load after a singificant change. So a VFD used for something like a conveyor is typically designed to handle 150% of its rated current for up to 60 seconds.

When you use a VFD on a CENTRIFUGAL load such as a pump or fan, another aspect of that load it that the load ITSELF cannot change that fast, plus, if the motor is sized for the maximum flow at full speed, it CANNOT be overloaded anyway. Therefore, the added overload capability of the VFD is in essence wasted. So a long time ago, the VFD mfrs, in conjunction with special rules from testing authorities like UL, allowed the VFD mfrs to rate the output motor size for CENTRIFUGAL loads at a higher value than they would for any other type of load. That means that a VFD sized for a 30HP heavy duty load can be used on a 40HP centrifugal load. That special sizing rule however does away with most of the overload capability, since it is not likely to be needed. So a centrifugal load drive, often referred to as a "Variable Torque" drive, will only be capable of 105-110% overload for 30 seconds. Since those loads are most often found in HVAC applications, they are referred to as HVAC drives.

Then too, such as with ABB, since HVAC applications almost never need some of the more advanced control features found in heavy duty drives, the mfrs take cost out of them by not including those. The HVAC industry is notoriously cheap, so even a dollar in cost can make a difference.

So can this work for a "blower"? Probably, as long as it is not a positive displacement type of blower (the word blower is too vague). If it is an exhaust fan, it's about a 99% chance it is a centrifugal blower and that drive will work fine.

A word of caution on buying used drives from FleaBay; if a VFD has been sitting idle and unpowered for more than a year, you must do a procedure called "capacitor reforming" to avoid having your money wasted when it destroys itself in short order. Google that term, there re plenty of instructions on doing that, but the best practice involves using a variable transformer, something you likely do not have. So let the buyer beware.

Technically correct, but in reality, there is a "numbers game" played in the drives industry when it comes to drives for CENTRIFUGAL loads, which are comprised ofof pumps and fans, and you will find those used predominantly in the HVAC industry.On a centrifugal load, the power DEMANDED by the load (the pump or fan) from the motor varies at the cube of the speed change. So for example, at 50% speed, the pump/fan will only require 12.5% of the HP from the motor as it would at full speed. Since the motor must be sized for the worst case scenario, full speed, that means the VFD must be sized for that as well.But in VFD design, there is an overload capacity factor that must be built-in to each VFD, to allow it to accelerate, or more importantly RE-accelerate a load after a singificant change. So a VFD used for something like a conveyor is typically designed to handle 150% of its rated current for up to 60 seconds.When you use a VFD on a CENTRIFUGAL load such as a pump or fan, another aspect of that load it that the load ITSELF cannot change that fast, plus, if the motor is sized for the maximum flow at full speed, it CANNOT be overloaded anyway. Therefore, the added overload capability of the VFD is in essence wasted. So a long time ago, the VFD mfrs, in conjunction with special rules from testing authorities like UL, allowed the VFD mfrs to rate the output motor size for CENTRIFUGAL loads at a higher value than they would for any other type of load. That means that a VFD sized for a 30HP heavy duty load can be used on a 40HP centrifugal load. That special sizing rule however does away with most of the overload capability, since it is not likely to be needed. So a centrifugal load drive, often referred to as a "Variable Torque" drive, will only be capable of 105-110% overload for 30 seconds. Since those loads are most often found in HVAC applications, they are referred to as HVAC drives.Then too, such as with ABB, since HVAC applications almost never need some of the more advanced control features found in heavy duty drives, the mfrs take cost out of them by not including those. The HVAC industry is notoriously cheap, so even a dollar in cost can make a difference.So can this work for a "blower"? Probably, as long as it is not a positive displacement type of blower (the word blower is too vague). If it is an exhaust fan, it's about a 99% chance it is a centrifugal blower and that drive will work fine.A word of caution on buying used drives from FleaBay; if a VFD has been sitting idle and unpowered for more than a year, you must do a procedure called "capacitor reforming" to avoid having your money wasted when it destroys itself in short order. Google that term, there re plenty of instructions on doing that, but the best practice involves using a variable transformer, something you likely do not have. So let the buyer beware.

If you are looking for more details, kindly visit Abb Machinery Drives.