Over speed fault on Power Flex 525.

We have conveyors controlled by Power Flex 525 and they are Ethernet connected via stratix switch with PLC 5000. We have a fault Over Speed on one conveyor and shutting down the whole system. We replaced the Encoder and the Encoder cable and the communication cable from Stratix switch to Power Flex. We still have that fault coming up. I raised the acceleration time from 20 to 30 sec. and I lower the deceleration time to 10 sec and still have fault. the Power Flex doesn't go on fault. Any idea?

Welcome to the PLCTalk forum community !

Overspeed faults usually come when the internal trim features on the drive end up putting the drive over the maximum output frequency.

The most common sort of issue that causes that is high inertia loads that the drive can't slow down without an external braking resistor.

Are the faults occurring while you are trying to stop a load, or while it's running at a controlled speed ?

When you say "the PowerFlex doesn't go on fault", can you explain that in more detail ? Where do you see evidence of the overspeed fault indication ?

What is your maximum frequency (Parameter P044)? What frequency are you commanding it to go?

P044 needs to be higher than the max freq you will command it to go (it needs to have some room for overspeed). If you will command it to go 60hz, I'd set P044 to at least 70Hz.

Every time when that happened the touch screen (GDU) Power view 5000 from PLC show up the fault Over speed, but like I said, power Flex is not faulted.
I will try to set P44 to the higher Hz, maybe 70 and see what will happen.
Thank you guys.

power Flex is not faulted??

so the drive is not faulting? just a fault on the pv?

If the drive itself is not showing any faults it could be a setting for the fault in the PLC or HMI that is set to low. You might want to look into that before changing anything in the drive.

agreed sounds like the plc is looking for drive at speed. and for what ever reason there is a laps in that signal. i would look at the logic rather then the drive.

I took a step back and read my 520-series User Manual, and "Overspeed" is not a fault code that appears for the PowerFlex 525.

My experience with "overspeed" faults is from the PowerFlex 70/700 series, where there's an Overspeed Limit parameter related to the Maximum Speed parameter. That feature does not appear to exist in the PowerFlex 525.

The user program might be declaring its own condition that it considers to be "overspeed", which would also explain why there is no fault on the drive.

Ken Roach said:

I took a step back and read my 520-series User Manual, and "Overspeed" is not a fault code that appears for the PowerFlex 525.

My experience with "overspeed" faults is from the PowerFlex 70/700 series, where there's an Overspeed Limit parameter related to the Maximum Speed parameter. That feature does not appear to exist in the PowerFlex 525.

The user program might be declaring its own condition that it considers to be "overspeed", which would also explain why there is no fault on the drive.

Click to expand...

Beat me to it. There is no "Over Speed" fault in a 525. So it must be in the PLC program, likely something that is not reading correctly, i.e. the encoder scaling is incorrect.

I agree, PF 525 doesn't have a parameter for over speed, I checked that first. Only PF 753, 755 have that.
The problem now is:I don't have my PLC laptop because crushed 2 months ago and I'm still waiting for new one to arrive and in the mean time I tried to fix that fault locally with what I have. I know is hard sometimes without laptop, but I try to make everybody happy! For now, I increase P044 from 60 Hz to 75 Hz to force the drive to stay on the continuous speed of 58.45 Hz comanded speed and if exceeds that, to don't fault on over speed if the P044 is only 60 Hz! Only 1.55 Hz difference! See what will happen next couple of days...I will keep you guys posted!
Thank you for your input, greatly appreciated!!!

I have an issue with an elevator being driven by a 525 where when the second shelf (of 8 tiers) gets loaded on to the conveyor the drive over speeds and then the decel command to reduce speed (commanded by prox on cam switch) seems to have no effect. Monitoring B001 on the drive as the machine is cycling the command freq of 50 hz over speeds to 62+ hz and never seems to get to the slow speed of 10 hz for positioning and overshoots. I’ve advanced the cam timing for the slow, lengthened and shortened the decel time and nothing seems to successfully stop it in the right position.

The only thing that has worked is reducing my speed to 30 hz and I finally get the carriers to stop in the right position when the second shelf is being carried by the chain. 2 concerns remain, I might not be able to make rate Monday morning when we start loading product in to the machine and I am not sure how it will react with 2000 +/- kg of product on the shelf unit (x2) when fully loaded.

Thoughts? Thanks in advance.

geofftheelectrician said:

...Thoughts?...

Click to expand...

Start a new thread?

To back that up so I don't just sound like a smartass...

While you may think this thread has similar issues to yours, it reads to me as though this thread's issue was PLC/HMI overspeed monitoring which was misbehaving and the resultant alarm interlock was shutting down the system i.e. programming issue and nothing directly to do with the drive or load itself. Your issue appears to be directly related to the drive and it's load and a positioning error or overshoot. Considerably different symptoms in my opinion, enough so to warrant a new thread?

Regards,
George

I hadn’t thought of that, good point. Thank you.