ptonsparky
Tom
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- EC - retired
That is the question. What happened? Worn parts? Loose locknuts? Out of adjustment? Is this the way it has always worked? IDK. We never worked on it before.
Overvoltage fault.
- Thread starter ptonsparky
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That is the question. What happened? Worn parts? Loose locknuts? Out of adjustment? Is this the way it has always worked? IDK. We never worked on it before.
But you said in an earlier post you replaced the offending switch and yet the issue persisted!
ptonsparky
Tom
- Occupation
- EC - retired
Pay attention.
I made adjustment to original switch. It worked for a few days.
They replaced the switch.
I made adjustments to switch again. Locknuts were loose and setting not even close.
It worked for a day. Maybe.
Parts are worn? Maybe, I never looked at it when it was new.
Put Hold timer on control circuit. 1-180 sec. (what was available in town). Worked on start of SM, but told it sporadically would cause grief at stop of SM. ...WTF?
Put better timer on that had range of .15 to 15 second IIRC. The 1.24 sec delay spans the time of erratic switch operation as it sat yesterday.
Added surge suppressor to motor starter coil just in case that may help the WTF moments above. I never witnessed those moments.
No OV fault yesterday. Max peak at 1 msec capture was 726. Close enough.
Time will tell.
ptonsparky
Tom
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- EC - retired
Coil and control voltage is 120 v. The very simple suppressor is rated 130v. It may help the life of the control circuit contacts. The control is ran in the same conduit as the power to the motor for all of 50' and at may aid in the induction from that.
The DC BUS Voltage peak is 726
The DC BUS Voltage peak is 726
kwired
Electron manager
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What is the actual RMS input voltage? If you have a high input voltage to start with it may be easier to have little glitches that wouldn't cause troubles if input voltage were lower.
If input voltage is over 500, maybe POCO has a voltage regulator problem, straighten that out and maybe your overvoltage fault issue goes away.
ptonsparky
Tom
- Occupation
- EC - retired
Well now that is a thought. Had I been paying closer attention post 41 should've made me think a bit more. Then again I've only been looking at the peak DC.
ptonsparky
Tom
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- EC - retired
A transient
ptonsparky
Tom
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- EC - retired
didnt work.
ptonsparky
Tom
- Occupation
- EC - retired
Reduced shot of a transient recorded L-L. May not be the one that caused OV. There were over 100 of these in the time it took to fault the drive. This time.
View attachment 17030
View attachment 17030
ptonsparky
Tom
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- EC - retired
Installed, see Post 1.
mike_kilroy
Senior Member
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ptonsparky
Tom
- Occupation
- EC - retired
No.
Might be a better "next" than the braking resistor which will be fun to hang and protect. The last Input filter I used sat behind the drive, things could get tight.
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mike_kilroy
Senior Member
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Skokian
Member
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- Skokie, Illinois
VFD Overvoltage Tripping.
VFD Overvoltage Tripping.
Most 480 Vac VFD's will shut down on over-voltage when the capacitors hit 750 Vdc. Note that all VFD's, as far as I know, have to be MANUALLY reset and restarted after an over-voltage shutdown.
Fortunately the Fuji (former G.E./Fuji) VFD's trip at 800 Vdc. This is roughly equivalent to an input of 566 Vac. We used G.E. Fuji for fire pump controllers where the controller is very often Service Entrance equipment and where the line voltage is often higher at nighttime. Some of these units have over 80,000 hours of running time without any problems. Some other brands aren't so "lucky".
Check the instruction manual or call the manufacturer for the over-voltage shutdown parameter value for the the drive in question. Also note that line reactors are mainly used to reduce the harmonic current supplying the drive. Without a line reactor, the input current will be around 1.414 times the rated output current. Conductors should be sized accordingly including the 1.25% of MOTOR FLA rule.
VFD Overvoltage Tripping.
Most 480 Vac VFD's will shut down on over-voltage when the capacitors hit 750 Vdc. Note that all VFD's, as far as I know, have to be MANUALLY reset and restarted after an over-voltage shutdown.
Fortunately the Fuji (former G.E./Fuji) VFD's trip at 800 Vdc. This is roughly equivalent to an input of 566 Vac. We used G.E. Fuji for fire pump controllers where the controller is very often Service Entrance equipment and where the line voltage is often higher at nighttime. Some of these units have over 80,000 hours of running time without any problems. Some other brands aren't so "lucky".
Check the instruction manual or call the manufacturer for the over-voltage shutdown parameter value for the the drive in question. Also note that line reactors are mainly used to reduce the harmonic current supplying the drive. Without a line reactor, the input current will be around 1.414 times the rated output current. Conductors should be sized accordingly including the 1.25% of MOTOR FLA rule.
mike_kilroy
Senior Member
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Agreed.
And per last post, perhaps your brand vfd allows increasing the OV fault level; all our brands do: Refu default is 805v (2500 max), Kollmorgen default is 840v (900 max), hitachi default is 760 (790 max) - might be nice bandade until you put in the input line filter to solve the issue.
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- Electrical Engineer
Very few 480V class drives will actually trip at 750VDC. Schneider drives trip at >800VDC, A-B drives trip at >850VDC, ABB is I think 877VDC, Siemens MM440 is actually 900VDC. 750VDC as the DC OV trip point would be very low. But as I said earlier, the AutomationDestruct drives he is using do not state what the trip level is, however it allows you to set the Dynamic Braking trigger point at up to 900VDC, so for example you would not want it to trip at 750V if you can set the DB transistor to not trigger until it gets to 800V.
Tom,
Per your nice little trace picture earlier:
The little spikes you show in there could, if happening in a rapid fashion, cause a build up of voltage on the DC bus caps if the motor cannot pull that energy off the bus fast enough between them. In other words, if they happen once per minute or so, the caps can hold it until the motor uses it, but if happening in rapid succession, it boosts the DC link voltage to the trip point before the motor can suck it out
Are those spikes taking place at relatively regular intervals or do they appear to be random? If regular or in a burst of activity, I would be looking for something that is switching on and off a lot, as you have been. But if they appear totally random, this might be "grid switching transients" from the utility side that you will have little to no control over. Reactors should help, but I can't remember, did you already try that?
mike_kilroy
Senior Member
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- United States
he has input reactor. time for an input emi filter. spend $300 and solve this now.
ptonsparky
Tom
- Occupation
- EC - retired
We put line reactors on the few we do. POCO switching was a PIA so we just do it.
IIRC that trace was one of over a hundred that happened in a minute or so. I would guess no more than four bags. I was watching the bus Voltage at the distant location and it did not take long to shut things down. My help was standing near the chattering starter and it coincided with that. The VFD runs for hours at a time otherwise with no problems.
IIRC that trace was one of over a hundred that happened in a minute or so. I would guess no more than four bags. I was watching the bus Voltage at the distant location and it did not take long to shut things down. My help was standing near the chattering starter and it coincided with that. The VFD runs for hours at a time otherwise with no problems.
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