Powerflex 40 Quickie Question

[robertmee]

Does the Powerflex 40 At Reference status bit fluctuate or is it a solid at a given speed reference once the ramp completes (assuming no mechanical binding...more on that in a minute)? I'm waffling on using the Active bit + Delay Timer as a permissive on conveyor to conveyor or the At Reference bit. If the At Bit stays high and remains high it would be better to use it as it would also potentially account for mechanical issues preventing the drive from reaching speed. Better than simply Active + Timer.

 

[MartB]

It should stay high once reference is reached.
And I use the same method and find it a reliable method(i.e. at reference), however I often also alarm if the active + timer to make sure the drive isn't stalling out, and I'll also alarm if the at reference isn't reached within a certain time period (active + at reference + timer). It's overkill but my customers like it.

 

[robertmee]

Thanks...Yeah, I always have the various not running faults too. I just wanted to be sure the At Reference bit didn't fluctuate on/off because the drive is running at 59.99hz on a 60.0hz reference.

 

[MartB]

In my experience you will probably want to build in an 'overlook' or 'debounce' timer to ignore those instances if they occur.

 

[OkiePC]

In my experiences with the "At Speed", or "At Reference" status bits with A/B drives in V/Hz mode:

You may see an occasional drop out of the bit when there's a severe load change, but under normal circumstances, they stay on within a second or two after the acceleration profile is finished.

I agree with MartB, that a fault debounce timer may be useful at least as insurance, and you can trim it down or remove it once you see the machine in action.

I don't know what the tolerances are for the status bit, but it must be at least a couple of hertz according to what I have seen.

With a vector mode drive, that status bit may behave differently.

Paul