Reversing 3Ph Direction on Powerflex 70

Morning,

We were having some trouble with a air handler over the past week and we found out that the source of our problems was the motor running in reverse. None of the electricians swapped leads and the motor hasn't been changed in years. The enable signal was still going to the FWD terminal. Is there a parameter that can be changed to reverse the motor direction? We're trying to figure out what exactly happened to cause this.

Thanks!

https://literature.rockwellautomation.com/idc/groups/literature/documents/um/20a-um001_-en-p.pdf
I would take a look at the following table on page 87 of the above manual.
Table 11 - Drive Does Not Reverse Motor Direction
This will show you the five things to check.
Regards,

Twinmold said:

The enable signal was still going to the FWD terminal. Is there a parameter that can be changed to reverse the motor direction? We're trying to figure out what exactly happened to cause this.

Click to expand...

To my knowledge there is not a dedicated FWD terminal, so I assume you mean a digital input terminal configured as Run Forward or something similar.

The function of the digital input terminals is controlled by parameters 361-366; changes to those parameters will obviously affect what the drive does when power is applied to the inputs.

Without more information, this thread is, like so many other threads, similar to asking "How long is a piece of string?"

Specifically:

• How is control implemented?
  • 2-wire, 3-wire, uni-polar, bi-polar, etc.?
• What are the logic command and status words?
• As @plvce notes, what are the values of parameters 361-366?
  • What are those values supposed to be?
• What controls, and what are, the signals at each of those inputs?
• What physical jumpers are in place or not?

OP states that the motor hasn't been changed in years, and I am not doubting that, but it is a certainty that something has changed. E.g. is it possible that an unseen break in a wire could cause the motor to run in reverse?

Welcome to the forum.

May i suggest that you change the motor.
it's been a while since motor class.
one of the windings may be opening up causing the magnetic field to change in such a way that will cause the rotation to change. Maybe jaref will post.
regards,
james

Thanks for the suggestions. I went up an took a look at the unit. Per what gclshortt recommended I checked parameter 190 and it was set to unipolar. So I had a hypothesis that I could changed the direction by simply hitting the reverse button on the HIM. I pressed it and sure enough it changed directions. Am I correct in assuming "direction dis" on that same parameter means direction disable, which would lock out use of that HIM button? There is no direction control in the program, the motor spins a squirrel cage blower and is unidirectional (not sure why this option was left unchanged in the first place).

Twinmold said:

Thanks for the suggestions. I went up an took a look at the unit. Per what gclshortt recommended I checked parameter 190 and it was set to unipolar. So I had a hypothesis that I could changed the direction by simply hitting the reverse button on the HIM. I pressed it and sure enough it changed directions. Am I correct in assuming "direction dis" on that same parameter means direction disable, which would lock out use of that HIM button? There is no direction control in the program, the motor spins a squirrel cage blower and is unidirectional (not sure why this option was left unchanged in the first place).

Click to expand...

There is definitely a parameter that disables reverse. From memory I couldn't tell you what it is called, but what you describes is probably it.

If 2 wire control can wire like this maybe its just as simple as moving the control wire from terminal 2 to 1?

For a fan or a pump or any device that can crater if it runs backerdz, you want to disable it in the parameters.

Jim3846 said:

If 2 wire control can wire like this maybe its just as simple as moving the control wire from terminal 2 to 1?

Click to expand...

I thought the electricians said no one had swapped leads?

Either someone is telling porkies or the someone swapped the phases. Motors don't run backwards for no reason.

janner_10 said:

Either someone is telling porkies or the someone swapped the phases. Motors don't run backwards for no reason.

Click to expand...

A powerflex70 or 700 will immediately run reverse in local control if reverse is not disable and you touch the direction button. Not sure if that button can reverse it when running from digital inputs ... it has been a few years since I worked on that series VFD.

At a former job, a tech royally fouled up a machine with a non reversible mechanical drive by accidentally fat fingering that button and then hitting the start button. I was tasked with disabling reverse on all 14 of those machines to avoid the same catastrophe going forward. I don't recall if he started the drive from the keypad or from the normal controls.

Nothing is going to prevent it running backwards if the output phases are swapped, but you do all you can to keep it right.