DC bus issue (2)The

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ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
Small AB PowerFlex 4, 3 hp IIRC, 480, line reactor, coast to stop, on a conveyor that does not coast. It has ran for 5 years as it is set up with no problems. Last week it shut down when it failed to start after an overvoltage fault. Auto restart is set at 5 times, 1 second apart. We powered it off, reset it and it ran until this morning. Same faults. Then of course no problems the rest of the day

POCO said no voltage problems in the area last week. Larger motors in the facility have PFC capacitors but they do not cycle. Only the 3 hp cycles.

I set the delay between restart attempts to 2 seconds before I left this morning but now I see the manual suggests 0 seconds. ?? Why zero?

Can the VFD be reaching EOL, already? I would not think high buss voltage would be an indicator of that.

Buss voltage was 670 while I was there.
 
I always do at least 30-60 seconds for auto restart delay. I've never done something as short as 1-2 seconds.

We don't buy any smaller than a 5HP PF4 as a guideline in our shop. They are reasonably inexpensive. After the troubleshooting you've done, "coast to stop" has been verified, etc I would either lean towards a power co. or drive issue. It's hard to nail down a power co. issue without installing a logger.

May be simpler to replace the drive if it has any age on it. Drives at that size are reasonably priced compared with the cost of a service call. I'd make it a point to talk to the customer and see if they'd be willing to pony up the money for a drive replacement to help narrow it down.
 
One simple and cheap thing to check is to see if someone has messed with the carrier frequency. People don’t like the whine sound a motor makes when run on a VFD, then they read on line how you can make that go away by increasing the CF, then they learn how to do it and they don’t tell anyone because they know they are not allowed to make changes to the drive programming. But increasing the CF not only increases the losses in the VFD, in also increases the Common Mode Noise created by the high speed transistor switching, and that gets trapped in the DC bus causing “DC bus pump up”. In my experience when a previously fine drive starts doing this and you have eliminated external causes like overhauling loads or line side capacitors etc., it turns out to be someone having tweaked this without telling anyone, usually the guy who has to work near the motor.
 
Jraef said:
One simple and cheap thing to check is to see if someone has messed with the carrier frequency. People don’t like the whine sound a motor makes when run on a VFD, then they read on line how you can make that go away by increasing the CF, then they learn how to do it and they don’t tell anyone because they know they are not allowed to make changes to the drive programming. But increasing the CF not only increases the losses in the VFD, in also increases the Common Mode Noise created by the high speed transistor switching, and that gets trapped in the DC bus causing “DC bus pump up”. In my experience when a previously fine drive starts doing this and you have eliminated external causes like overhauling loads or line side capacitors etc., it turns out to be someone having tweaked this without telling anyone, usually the guy who has to work near the motor.
Click to expand...
It’s so noisy in that place hearing that motor would be a blessing. I don’t see it happening there. I’ll check it once I get the new vs of CCW installed and updated. Only my Garmin updates have taken longer.
 
ptonsparky said:
It’s so noisy in that place hearing that motor would be a blessing. I don’t see it happening there. I’ll check it once I get the new vs of CCW installed and updated. Only my Garmin updates have taken longer.
Click to expand...

The latest version of CCW (version 11) has an interesting feature. They removed the ability to print VFD parameters.
 
petersonra said:
The latest version of CCW (version 11) has an interesting feature. They removed the ability to print VFD parameters.
Click to expand...
Not even to a PDF?

My previous vs was 6.01 or similar. 11 seemed a lot faster and connecting to our small bench drive was quick. I demonstrated it twice to my help, had them do it once and sent them out the door with the laptop. If they have troubles, I told them I retired 5 minutes ago, you’re on your own.
 
ptonsparky said:
Small AB PowerFlex 4, 3 hp IIRC, 480, line reactor, coast to stop, on a conveyor that does not coast. It has ran for 5 years as it is set up with no problems. Last week it shut down when it failed to start after an overvoltage fault. Auto restart is set at 5 times, 1 second apart. We powered it off, reset it and it ran until this morning. Same faults. Then of course no problems the rest of the day

POCO said no voltage problems in the area last week. Larger motors in the facility have PFC capacitors but they do not cycle. Only the 3 hp cycles.

I set the delay between restart attempts to 2 seconds before I left this morning but now I see the manual suggests 0 seconds. ?? Why zero?

Can the VFD be reaching EOL, already? I would not think high buss voltage would be an indicator of that.

Buss voltage was 670 while I was there.
Click to expand...
EOL as in end of life?
I would have expected much longer. We made some big drives in the MW range that have been running for over two decades. One thing does have a finite lifetime are the DC link "bucket" capacitors. Typically 10 years for those we used. Sprague or similar.. It might be worth inspecting those. They can be replaced but, at 3hp, that might not be the most economical way to go.
How much of your time equates to the replacement cost of a 3hp/2.2kW VSD?
 
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