PF525 With Reactor acting crazy.

Hey folks.

I'm doing a small conveyor job right now with a series of small motors and 1 H.P. 525 drives.
I have never had an issue using line / load reactors before but something isn't just right here.
I'm using the reactor 1321-3R2-B for line and load on all of my drives. This number I got from the AB catalog, web part number configuration tool. I have 3 different motor amperages. .80 , 1.15 , and 1.4 . This is the part number I got for all of these motor amperages. SEW Motors.... However, I'm not sure the motors are the issue.

The problem presents itself like this. Start the drive, connected to the motor, if its not at least set to 20HZ, the output frequency doesn't match the command frequency and the at reference is false. Lets say I tell the drive to start at 5 or 6 HZ just to bump for rotation.... The drive will be flickering a frequency usually around 12 or 13, its changing really fast.. then it will climb, fall , anything but run steady. If I tell the drive to run at 30 or 60 HZ, anything higher than 20, it runs fine, at reference and all is good. Until, stop is pressed. I notice that if RAMP is set as my stop mode, the drive will ramp down to the flickerey 12 13 HZ and never stop until its faults with a STALL fault. If the stop mode is set to COAST, all is well, the drive stops without a hitch.

So, I was thinking it was a motor problem, until I noticed that the load reactor was blistering hot, line reactor cool as a cucumber. Then I opened the disconnect and told the PLC that it was closed so I could start the drive. Now, no motor, just drive, reactor and VFD cable to the disconnect, about 150'. Same thing. No stall fault but the command and output frequency don't jive.

Next I bypass the load reactor and all is well. As I would expect it to be.
Motor can ramp, at reference is set and not faulting.

I have not auto tuned yet as I was thinking there is a problem with the motors at first. I'm wondering if I need to auto tune with the reactor before I even start the motor?? Usually I get the direction and make sure the motor will run before I do the auto tune as I'm used to being asked to use old motors before new ones. (as is the case here, really bad condition motors!) Often I will find the bad ones once connected to the frequency drives and end up trying a few before one works. Then I auto tune. Unless its a project with new motors, then Ill do it right off the hop.

This is the only thing I can think of that could cause this kind of issue. Ill be trying again today at the site but I wanted to see if any opinion exists on this before hand.

Is there any special parameters you guys set up for use with Line / Load reactors. The parameter settings here are as basic as it gets and I'm not doing anything different than I normally would.

Any insight on this would be great. Hopefully somebody has seen this before


Thanks

I'm not sure about the 525 but I know that with the 750 series drives, if you are using a load reactor, you need to run the drive in volt/Hz mode. PF 525 vfd's come preset to run in sensorless vector mode.

This publication may help - http://literature.rockwellautomation.com/idc/groups/literature/documents/at/pflex-at002_-en-p.pdf

I have set up a PFLex70 with sine wave filter in this manner but never a 525.

I wonder if it has similar requirements.

You must always perform an Autotune before running, with or without the reactor. The default settings for the motor circuit are just a best guess and are rarely correct because all motors are different. If you are going to use the load reactor, do the Autotune with the reactor in the circuit.

jraef said:

You must always perform an Autotune before running, with or without the reactor. The default settings for the motor circuit are just a best guess and are rarely correct because all motors are different. If you are going to use the load reactor, do the Autotune with the reactor in the circuit.

Click to expand...

Ditto 100%. I have put in hundreds of these 525s and they all need an auto tune. Even if we change a motor, it need to be auto tuned to that motor.


Gone are the days of dropping in a PF70 and set a couple parameters and your off and running.

JaxGTO said:

Ditto 100%. I have put in hundreds of these 525s and they all need an auto tune. Even if we change a motor, it need to be auto tuned to that motor.


Gone are the days of dropping in a PF70 and set a couple parameters and your off and running.

Click to expand...

As it was explained to me, the Gen 4 IIGBTs used in the newest drives, like the 520s and 750s for Rockwell, are smaller/cheaper/faster because the transistors have lower switching losses because they turn on a lot faster (steeper rise time). But this then makes it MORE critical that the firing algorithm be tuned to the motor equivalent circuit regardless of how you are controlling the motor, whereas in older generations it wasn't critical unless you were doing Vector Control.

So you're right, the days of dropping in a replacement drive and running it in V/Hz mode without having to do an Autotune are over.

Great.
Thanks for the advice. I’ve installed several of these drives all with reactors and never has issues. I was so caught up with all the failed motors in this pile of crud motors that I was finding that I was starting to dout the reactors themselves. I did wire one reactor back in today and it tuned well and did run the drive properly. I’m hoping to get the rest finished this weekend.
Some people will do anything to save a buck and this project lead decided he wanted to use a mixn match of old motors he found on a trailer. They were wet, full of oil, full of rust. Mouse nest, you name it. Some cruched, some squealing and some just plain open and no go. I never do projects this way and I never have problems. It’s been the simplest job from hell ever. Standing in a little corner holding my laptop in front of the panel in my arms while squished into a cramped little production room. A bake room!! I’m begging for downtime but they want the job done. I can’t even open and close the panel door without asking pardon from an equally stressed out production worker. It’s killing time I don’t have due to already having 8 projects on the go, the plant manager asking me for time on this and time on that. Mechanics asking for help, production engineering students asking for process improvements, and the plant down the road calling for help..... going bald to quickly from it all.

Oh I do love my job! I think!

One thing that may help line reactors and load reactors are designed around a very narrow frequency range at very low frequencies they don't work at all so it's no wonder that you are having trouble at the lower frequencies

I love it how some people seem to think that the meager up-front savings from buying used junk is a better business plan that continuous reliable operation of their equipment...