Powerflex 753 displays "Not enabled." Intermittent problem.

unsaint32

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Oct 2012
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minneapolis
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This problem happens only about once/twice per week.

We have an uncoiler motor that the operator needs to run with the safety gate open. The motor is run by PFLX 753. But sometimes, (only when the gate is open) the motor does not run. When that happens, PFLX753 display shows "Not enabled." Then when we close the gate again, the display goes away and the motor starts working again. Once we run the process then the problem goes away for a while and the next time we open the gate and can run the motor just fine.

Thanks for any help.
 
We could use a little more info on how the system is set up.
But I will take a stab, sounds like the Hardware Enable is tied to the gate closing. I imagine there is a switch that has to be made before the Enable will set. I would look at the switch adjustment, a bad switch, loose connections or pinched wire to start with.

If you can give us more info we may be able to help further.
 
No hardware enabled, I don't think. I see a jumper plugged in a socket labeled "enable" on a circuit board inside the drive. Also, after I posted this email, we were able to run that drive/motor just fine with the gate open. So, there is no designed drive disable connected to the gate.

Since it only happens when the gate is open (although not all the time), I should look more at the safety circuit wiring although I think the jumper is essentially the enable wiring.

Thanks.
 
Could you provide a wiring diagram showing how the drive interacts with the gate switch? There is an enable input on the main board. I assume that the gate switch is tied to this, but is muted somehow.

Do you have any more information on a sequence that might consistently cause this problem. Maybe this only happens if the gate is open during a power cycle for example. It will be difficult to help without a little more information.
 
Could you provide a wiring diagram showing how the drive interacts with the gate switch? There is an enable input on the main board. I assume that the gate switch is tied to this, but is muted somehow.

Do you have any more information on a sequence that might consistently cause this problem. Maybe this only happens if the gate is open during a power cycle for example. It will be difficult to help without a little more information.

I will look at the safety relay for any muting function. Doesn't the red "enable" jumper on the circuit board of pflx753 mean the drive is not using any external enable signal as the enable signal?

thanks.
 
Originally posted by unsaint32:
Doesn't the red "enable" jumper on the circuit board of pflx753 mean the drive is not using any external enable signal as the enable signal?

Are you sure the jumper is truly located across both posts? Did someone remove the jumper and put it on one post to act as a "storage" position?

That jumper physically bypasses the hardware enable function, which is tied to a specific input on the drive. I'm pretty sure you can still map the enable function to any of the inputs. You just don't get the hardware enable capability. Also, if you have a Safe Torque Off board installed, loss of the STO input will display as a Not Enabled on the drive also.

Keith
 
I have seen this before. If you are not using the hardware enable it has to be jumped out by a jumper on the main board but A lot of people jump it on the plug which is on the bottom of the drive.

If you are not using it jump it on the main board and if you are using it check the circuit it's going through for a poor connection.

Also the plug on the bottom of the drive IMHO is a very poor design and a loose fit.

If jumped at the plug or used in a circuit that plug could likely be your issue. Installing a new plug will help as it will fit a little tighter but the first few times it's removed and plugged back on you could have issues again.

This is the same on the 755.I know this as when the drive has any issues Bubba likes to start pulling off connectors and plugging them back it tight.
 
If you remove the jumper labeled 'ENABLE' you will bypass an parameter configuration of DI0 and it will be utilized as a dedicated hardware enable. You can find this on page 214 of the 750 Series Installation Guide at http://literature.rockwellautomation.com/idc/groups/literature/documents/in/750-in001_-en-p.pdf.

The DI0 can still be configured to operate as an enable function utilizing parameter 155. Paramater 155 controls which input or bit controls the enable function of the drive. The 750 Series Programming Manual at http://literature.rockwellautomation.com/idc/groups/literature/documents/pm/750-pm001_-en-p.pdf" indicates on page 67 that the default address for the enable function is DI0.

Simply put, your drive is configured out of the box to look at DI0 for an enable function. Unless the enable function is reconfigured through parameters, you will require a signal on DI0 to enable the drive.

If the drive must be disabled for a safety function at any point I would, AT MINIMUM, remove the enable jumper, but I would recommend adding an STO card.

My guess is that the drive is fine and the problem is elsewhere.
 
Last edited:
Thank you so much for all your great input. The reason I don't reply promtply is because I work four days on and four days off. When I go back to work on Tuesday night, I will check more carefully with all your great ideas in mind.

For now, I don't think the Safe Torque Off board is the cause even if we had it. This anomaly happens intermittently but only when the gate is open. When this happens, gate closing clears the "not enabled" sign and the drive works right away. I don't think the gate makes any difference in the drive torque.

I will check P933 when it happens again next time.

I believe the jumper was on the main board. Certainly not on the bottom of the drive. I will make sure the jumper is not loose or misfit.

I will also scour the pdf for the parameter 155 config.

Thanks.
 
Originally posted by unsaint32:

I don't think the gate makes any difference in the drive torque.

The way you wrote that makes me thing you see STO as some type of safe active torque control (it makes sure torque is what you are asking for). STO is Allen-Bradley's drive resident safety functionality. It is designed to make sure the drive can't produce any torque unless its inputs are active. It has nothing to do with setting torque levels other than making sure the motor can't generate ANY torque.

Keith
 
First of all, I should have explained my level of job/education experience to also show my ability to assess them (or lack of it). I have less than 1 yr as an industrial automation technician.

I studied the manual from Califflash (thanks). And here is what I found..

The hardware enable is bypassed (the jumper is plugged in good), and the safety enable is NOT bypassed (this jumper is removed).

It turns out, we do have the STO card in the drive. I simply didn't know where to look for. The 24V for the STO's SE+ and SP+ comes from a safety relay output (SICK FLEXI Soft XTIO's Q4 terminal).

You may not believe this, but our company bought this machine but nobody has the prints. I do not know what inputs are required for the SICK relay for the output Q4, but I know it's not the gate being opened. When I open the gate, the Q4 ouput is still on.

This safety relays for the machine has no muting function.

P155 has disabled the "DI Enable." No wires terminated on the DI0 terminal.

For now, the PFLX runs without problem when the safety gate is open. When it happens again, I will look at the P933, and I will update this post as I find more.

Thanks again.
 

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