Powerflex 753 ignoring analog speed reference

mylespetro

Member
Join Date
Dec 2015
Location
NS
Posts
740
Hey everyone, back with yet another PF753 question,

We have a Powerflex 753 drive with Ain0 and Ain1 (I/O card in Port 04) both accepting 4-20mA (different sources). I have Speed Ref A Sel set to Port 4: Anlg In1 Value, but when we start the drive it just ramps to 60Hz regardless of what we have applied to Ain1. The drive is seeing the input, Anlg In 1 Value reads whatever we're putting into it, but it just ramps to 60Hz anyways.

Do I need to utilize the DI Speed Sel 0-2 to use the analog input as a speed reference? I didn't think so, but I don't know what else to do.

Thanks!
 
I don't use PF drives much so no idea what parameter it would be, but what is your minimum speed set to? If min is at 60hz then the drive will run up to that.
 
You don't have it taking the reference from the HMI do you?
And are you actually using SpdRefSelA?

Another thing, have you gone through the full startup on the drive?
 
Are you using only hardwired reference and commands, or do you also have the drive connected to a network ?

By default a PowerFlex 753 will follow Reference A. With all the Speed Select bits set to zero (discrete and networked), Reference A will be used.

By default, Reference A is Analog Input 1.

To tell which speed reference you are actually using (which is delivering 60 Hz), look at Parameter 930, Speed Reference Source.
 
Because you're using digital inputs on this drive (you mentioned it in a previous post) be sure that you understand the configuration and function of all of them.

Also, if you have disabled any of the discrete inputs, it's possible to get an "orphaned" bit value in the drive memory. Tie the input to zero volts, then re-enable it, then re-disable it to clear any "orphaned" values.
 
I don't mean to be condescending, but I've done this...


Did you double check to see that you told it you are using 4-20mA? The factory default is 0-10VDC, so if it is getting a constant 10VDC or more from your 4-20mA circuit, that would explain it... On a 753, you change it for all AIs by moving Jumper J4 on the main control board. See page 226 of the installation manual, the jumper needs to be across pins 3 and 4 for current inputs.
 
Get the spec sheet on that card. All unused inputs should be grounded according to AB, stupid, the sheet will show config.
Where the heck did you read that??? I've never seen or heard of such a thing. In fact on the 22 Series cards, the closest thing I could find says almost the opposite:
"I/O terminals labeled “(–)” or “Common” are not referenced to earth ground and are designed to greatly reduce common mode interference. Grounding these terminals can cause signal noise."
 
I always connect the unused Discrete Inputs to DC common so that they stay logically FALSE and there's no possibility of them "floating" into the true voltage range.

That's different from connecting the DC Common to the frame or earth ground.

It's a normal thing in control systems of all types and voltages to tie down unused inputs if you can't disable them.
 
Hey guys, sorry for the delay. Figured out the issue. For some reason the Port 0 parameters that were showing up when I was using the HIM module (which were what we wanted) were completely different than what showed up when I opened the 753 Startup Wizard. The wizard showed that the Speed Reference was coming from Anlg In 0 and was configured 0-20. When I changed it to Anlg In 1 and 4-20 the drive worked perfectly. I'm just not sure why there was a discrepancy between the two. The parameters were even set correctly in the parameter list, but the wizard didn't match up.

Thanks again everyone, I've read through the responses anyways to get more info.
 
I don't mean to be condescending, but I've done this...


Did you double check to see that you told it you are using 4-20mA? The factory default is 0-10VDC, so if it is getting a constant 10VDC or more from your 4-20mA circuit, that would explain it... On a 753, you change it for all AIs by moving Jumper J4 on the main control board. See page 226 of the installation manual, the jumper needs to be across pins 3 and 4 for current inputs.

Definitely not condescending, I can see it being overlooked often. But yes I did this lol, those jumpers are a pain in the *** to deal with if you don't have tiny needle nose pliers. Thanks!
 

Similar Topics

How to remove faceplate from power flex 753 and not shutting the system down. What parameters should i change?
Replies
1
Views
74
Hi all, I am having a problem with a powerflex 753 we have on site and keep getting input phase loss. The drive has been running for a long...
Replies
7
Views
1,267
Hello Friends, We have a powerflex that stopped working sometime last week. It doesn't communicate over the network, or use CCW directly from my...
Replies
1
Views
403
Hello all! I am fairly new to the world of PLC's and this forum, so I apologize for my lack of knowledge. I have a Powerflex 753 that keeps...
Replies
6
Views
491
I am bench testing a PF753 (20f11nd096aa0nnnnn). I replaced the IGBT's and IC's in the firing circuit. Upon power up, I get the STS light...
Replies
7
Views
686
Back
Top Bottom