Powerflex 40 - 3 different ramp speeds

Hi,

I've quite frequently used this site for gaining information but am having a bit of trouble trying to find details on this, so thought I would sign up to this brilliant resource!

I'm testing out some equipment and need to set up a Powerflex 40 to use 3 different ramp times. I would like to know if I can use 3 separate outputs from the PLC to the VFD Din to control 3 seperate parameter groups?

Any help or direction would be greatly appreciated!

Thanks

Two different ramp times are possible via digital input selection, but not 3. But why are ramp times so important? Is it the time specifically, or are you looking for something more related to how soft it starts? Because you might be able to play with current limit to create a third level of softness to an acceleration profile.

Otherwise, the only way to do it would be to use communications to write a value to the ramp time parameter.

Oh that's not ideal, maybe I could settle with 2 different times then. The reason for the three ramp up times is i'm testing out some conveyor systems for R&D which need to be stressed/pushed to the limit, the conveyor needs to go through these three ramp up cycles one after the other give a true test over the 24 hours of testing

Here is the Sequence -

Ramp up of 1,3 or 5 secs (Alternating)
Run for 5 seconds
Ramp down for 5 secs
Stop for 3 seconds and then restart the programme

So if you want 3, use Ramp 1 for 1 second by selecting it with Input 4, Ramp 2 for 3 seconds by selecting it with Input 5, and for Ramp 3, use Ramp 2 plus a Current Limit. Then observe the current peak during Ramp 2 operation, and set the current limit to a value slightly LESS than that value, then tie the enabling of Current Limit to input #6. So for Ramp 3, you select Input 5 plus Input 6. Adjust the CL to make that combo take 5 seconds. How a VFD performs Current Limit is to artificially extend the ramp time, like an override if you will. You are going to take advantage of that to sort of attain your 3rd ramp profile. If load changes, it will not be repeatable, so keep that in mind.

You could also use an analog output on the PLC to ramp up the speed. This would allow you infinite variations in the ramp time, adjustable from the HMI.

it's possible to get different ramp time in PF40 VFD via DI/DO (or? except Modbus / Ethernet?)

Tom has the right idea, use analog controls. Set the VFD ramp time for 0.2 seconds or less, and let it just be a signal follower, have the PLC ramp the signal.

The drive has only 2 each accel and decel times that can be selected via DI.

Yea the analog control seems like the best idea, will have to get an Analog output card now because I have no spare A I/O on the PLC.

Thanks guys, Any idea if the ABB 355's are able to use more than 2 inputs or is it much the same?