AB 1305 Frequency Drive

alive15 · Jun 26, 2018

Good afternoon,

I have an AB 1305 Frequency Drive with an HIM module on it. Normally, after it runs a part, it says "Stopped +0.00 Hz". What happens, the HIM then says 0.00 ?, almost like it does not know how fast it is moving. This happens when we try to run a cycle and then the spindle does not start. So I recycled power, and the "0.00?" popped up from the get-go. This issue is slowly becoming more and more common on our machine. The frequency drive communicates with a SLC-5/03 via Allen Bradley SCANBus remote I/O module.

Would the issue be with this module or perhaps the cable going from the module to the PLC? I want to troubleshoot this without blindly swapping parts, but unsure how to do this?

Thanks!

thingstodo · Jun 26, 2018

alive15 said:
Good afternoon,

I have an AB 1305 Frequency Drive with an HIM module on it. Normally, after it runs a part, it says "Stopped +0.00 Hz". What happens, the HIM then says 0.00 ?, almost like it does not know how fast it is moving. This happens when we try to run a cycle and then the spindle does not start. So I recycled power, and the "0.00?" popped up from the get-go. This issue is slowly becoming more and more common on our machine. The frequency drive communicates with a SLC-5/03 via Allen Bradley SCANBus remote I/O module.

Would the issue be with this module or perhaps the cable going from the module to the PLC? I want to troubleshoot this without blindly swapping parts, but unsure how to do this?

Thanks!

Do you have encoder feedback on this motor?

I have not dealt with this model specifically. But I have seen something similar when the encoder `sees`rotation and the drive is not turning the motor shaft.

In our case, it turned out to be a brake that was not holding things after the drive stopped it and the load `moved`the motor shaft.

After the brake was replaced, the problem went away.

Ken Roach · Jun 26, 2018

we try to run a cycle and then the spindle does not start.

Can you explain more about this case ? Does the spindle motor appear to stall, or does the drive appear to ignore its Start command ?

What are the values of the Status bits when this happens ?

The question mark might indicate that you're running a custom "Process Display" mode on the HIM instead of the ordinary Status Display. That mode allows you to add a user units text string, but the default value is a question mark.

Check out the User Manual and its description of the Process Display mode.

I can't explain why sometimes the Status Display and sometimes the Process Display are shown. It's possible that somebody has programmed something clever to command that over SCANPort, though a quick scan through the user manual didn't show me a parameter that selects that.

You could diagnose it by changing the Process Parameter text to something other than the question mark.

jraef · Jun 26, 2018

That drive never had an encoder feedback option.

It sounds like something is losing communications between boards and it's not likely fixable. They were last sold new 20 years ago, kept around for a while longer to support legacy installations, but the parts to even keep old ones alive have been unavailable since 2011. It might be time to send this one off to the great scrap yard in the sky... There was a migration guide to upgrade to PowerFlex 40s back in 2009, but now the PF40s are getting old and being replaced with PF520s, but I don't think they have a migration guide for going direct from 1305 to PF523 because there were hardly any 1305s left out there once the parts became unobtanium. But if you go to the Knowledgebase and search for "1305 migration", there is a link to a spreadsheet that at least gives you a comparison of 1305 and PF523 parameters.

alive15 · Jun 27, 2018

The drive is ignoring the start command. I see the enable turn on in the PLC, but we check the speed of the spindle as well, so if it does not go above 0, it triggers a "spindle failed to run" fault. I am using refurbished frequency drives from E-bay.

I will check the values of the status bit when trying to run, I am unsure what these are. These would be found on the HIM itself or the PLC program perhaps?

I am unsure why a custom process display would affect the cycle of the spindle? I noticed when it read "0.00 ?", I just flipped through some of the parameters to see if something was off. Once I went back to the main display, it read the usual message of "Stopped 0.00 Hz" and it cycled the very next part.

Thanks for all the help thus far.

kekrahulik · Jun 27, 2018

If the drive is old (a 1305 would tend to be old), I would wonder if the capacitors are past their age. Sometimes old drives with bad capacitors will stall out - I don't know if they would show "torque limiting" or just stall.

Check in the PLC. When the drive says 0.00, do you get the drive running bit? I'm guessing the drive is running but acting like it is in torque limiting due to old caps. So the drive is running at zero speed.

Ken Roach · Jun 27, 2018

We might have to chase the logic through the network a little.

In general, there's a 16-bit Command word and a 16-bit Status word.

Since these are on Remote I/O, we have to figure out what Adapter the 1794-ASB is addressed as, and figure out exactly where in the 1747-SN (the RIO scanner) data table the data is.

It's usually symmetrical; if your Run command is O:1.12/0, then the Active status bit should be I:1.12/0.

I realize you're chasing some boolean logic issues in another thread, but I'm going to ask you to look carefully in this system as well.

The Start and Stop bits for an A-B drive on a network are separate; Bit 0 is Start, Bit 1 is Stop.

STOP always wins; if you were to set START (a rising edge) while STOP is also true, the drive would get them both and would choose to stay Stopped. That could show up as "the drive failed to start". Even when STOP goes false, START would require another false->true transition to start the drive.

This is uncommon on RIO and SLC-500 based systems because their Output data tables are all processed after the ladder logic programs are run.

But depending on your exact logic, it's not impossible that those two bits are inadvertently being set simultaneously.

alive15 · Jun 28, 2018

Ken Roach said:
We might have to chase the logic through the network a little.

In general, there's a 16-bit Command word and a 16-bit Status word.

Since these are on Remote I/O, we have to figure out what Adapter the 1794-ASB is addressed as, and figure out exactly where in the 1747-SN (the RIO scanner) data table the data is.

It's usually symmetrical; if your Run command is O:1.12/0, then the Active status bit should be I:1.12/0.

I realize you're chasing some boolean logic issues in another thread, but I'm going to ask you to look carefully in this system as well.

The Start and Stop bits for an A-B drive on a network are separate; Bit 0 is Start, Bit 1 is Stop.

STOP always wins; if you were to set START (a rising edge) while STOP is also true, the drive would get them both and would choose to stay Stopped. That could show up as "the drive failed to start". Even when STOP goes false, START would require another false->true transition to start the drive.

This is uncommon on RIO and SLC-500 based systems because their Output data tables are all processed after the ladder logic programs are run.

But depending on your exact logic, it's not impossible that those two bits are inadvertently being set simultaneously.

Ok I will check this out and let you know, thanks for the information. It will be some time before I get back to that machine and begin troubleshooting.

alive15 · Jun 28, 2018

kekrahulik said:
If the drive is old (a 1305 would tend to be old), I would wonder if the capacitors are past their age. Sometimes old drives with bad capacitors will stall out - I don't know if they would show "torque limiting" or just stall.

Check in the PLC. When the drive says 0.00, do you get the drive running bit? I'm guessing the drive is running but acting like it is in torque limiting due to old caps. So the drive is running at zero speed.

This is an interesting theory, yes that could be the issue. Sometimes, we run about 4-5 parts before the issue happens, but other times it can run for one week before the issue crops up again, so this could relate to the capacitor life. I bought the drives from E-bay, maybe I can check with Radwell and see if they have any refurbished and tested ones to order. I want to see what the true problem is with this one before I change any parts though.

However, I don't know how to test a capacitor, and I'm 100% positive I cannot stop production and take out the module for bench testing either. I'm the worst engineer, when I don't figure it out, I end up letting the techs swap parts just to keep production up and running, ha ha. Not sure what else to try?

AB 1305 Frequency Drive

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