# VFD F05 fault



## Sparky Mcgregor

We've been having this issue at the site I oversee involving F05 (over voltage) faults randomly occurring at our scale belt before our scan tunnel. It only happens a few time a day at most and I simply reset the VFD and scale and everything runs fine till the next one. I've searched high and low for bad wiring to no avail, set the motor to "coast to stop" and increased the max voltage on the VFD but nothing had worked. We're going to try and swap out the motor but I doubt that's the issue since the scale isn't even a year old and this has been happening from the get go. If I could solve this issue I'd be the envy of all my co-workers but I'm plumb out of ideas. Any thoughts?


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## KennyW

Is dc bus regulation enabled? (set to adjust frequency)? What is the regen power limit set to? Is this belt capable of overhauling? 

Does it have a line reactor?


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## thorax181

What is the vfd? Check incoming voltage is not abnormally high. Monitor the dc bus and see what it's running at. What is the average and min/max you see? You could have some regen going on and the drive can't handle it. Maybe it should have had a braking resistor installed?

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## thorax181

Also is this belt running a constant speed or starting and stopping or changing speeds?

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## oliquir

since it happens with coast to stop. i dont think it is related to motor. maybe very high peaks or harmonics on the incoming voltage


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## Vintage Sounds

How long is the run from the VFD to the motor and what type of wire?


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## Cow

I would put a recording meter on the incoming voltage for a few days to rule that out first.


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## JRaef

Sparky Mcgregor said:


> We've been having this issue at the site I oversee involving F05 (over voltage) faults randomly occurring at our scale belt before our scan tunnel. It only happens a few time a day at most and I simply reset the VFD and scale and everything runs fine till the next one. I've searched high and low for bad wiring to no avail, set the motor to "coast to stop" and increased the max voltage on the VFD but nothing had worked. We're going to try and swap out the motor but I doubt that's the issue since the scale isn't even a year old and this has been happening from the get go. If I could solve this issue I'd be the envy of all my co-workers but I'm plumb out of ideas. Any thoughts?


Do we need to play 20 questions here? Please be more descriptive of the entire situation if you want meaningful help.

What brand and model of drive is it? Sounds like an AB drive fault code, but that could be a number of different models and vintages. 

What voltage and HP?

What is your measured (not ASSumed) line voltage? What size transformer is feeding this drive circuit? Do you have a line reactor ahead of the drive, and if not, why not?

How is the drive being controlled? Because if it is under network control, you setting the Decel to "Coast" at the keypad may be getting overridden by the network control. If it is under hard wired control, any chance the Run command is chattering/bouncing?


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## micromind

Coast to stop isn't necessarily always true coast to stop. I know for a fact that the GE VFDs made by Fuji will go into DC overvoltage when a high inertia load is stopped, even though it's set for coast to stop. 

My solution was to time the stop and set the stop ramp a couple of seconds longer. Haven't had a problem in about 2 years. 

If you need a quicker stop, a braking resistor would be needed.


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## Electrorecycler

As JRaef asked, do you have a line reactor before the drive? My facility has a lot of issues with overvoltage faults, whether it be AB, ABB or any other breed of VFD. In almost every circumstance a line reactor has solved the problem and saved a lot of headaches.


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## John Valdes

Does it happen at a certain time of the day?
Many years ago we were having this issue at around 2:00 pm each day on certain machines. 
We even got the power company involved and guess what? For many years, their power correction caps were not switching and after they fixed the problem is when ours started. The written record proved this.
The caps when switching caused the problem/voltage spike. Had they never been repaired we would have never realized we needed line reactors on these machines.

Add a line reactor to every drive you have in service unless it comes with one on board. 
Baldor used to give you the line reactor for free if you bought the motor and drive from them. They would give you half off if you only bought the drive from them. I think thats how it was done?
They believed that the reactor was the best insurance policy regarding nuisance trips and hours wasted by customers calling tech support for nuisance trips.


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## JRaef

Reactors = Cheap insurance. 
All drives should have line reactors ahead of them if the transformer feeding the circuit is more than 10x the kVA rating of the drive. So if you have a 1,000kVA transformer ahead of a 500HP VFD, you don't absolutely need the reactor, but if the drive is 50HP, you absolutely DO need a reactor.

So why don't mfrs just include them? Because having 6 drives behind ONE line reactor (sized accordingly) provides the same protection as having an individual reactor ahead of each drive, but the installed cost is much lower. I once worked for a small company from New Zealand that did in fact include a line reactor in every drive. They didn't survive, because their drives APPEARED more expensive than other drives, and most people buy on price without thinking through the details. But if you compared their drive to the cost of a cheaper drive PLUS a field installed line reactor, they actually cost LESS. Didn't help them though...


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## John Valdes

JRaef said:


> Reactors = Cheap insurance.
> All drives should have line reactors ahead of them if the transformer feeding the circuit is more than 10x the kVA rating of the drive. So if you have a 1,000kVA transformer ahead of a 500HP VFD, you don't absolutely need the reactor, but if the drive is 50HP, you absolutely DO need a reactor.
> 
> So why don't mfrs just include them? Because having 6 drives behind ONE line reactor (sized accordingly) provides the same protection as having an individual reactor ahead of each drive, but the installed cost is much lower. I once worked for a small company from New Zealand that did in fact include a line reactor in every drive. They didn't survive, because their drives APPEARED more expensive than other drives, and most people buy on price without thinking through the details. But if you compared their drive to the cost of a cheaper drive PLUS a field installed line reactor, they actually cost LESS. Didn't help them though...


 Didn't ABB sell drives with on board line reactors?


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## JRaef

John Valdes said:


> Didn't ABB sell drives with on board line reactors?


No, it's always optional. They, like many other EU and North American designed drives (like AB), have DC bus chokes on some drive product lines. Bus chokes are inductors too and they have a similar effect on harmonics, so people often equate then to reactors. But they don't offer all of the same protective benefits against line transients as reactors. The bus chokes are AFTER the rectifier, so they don't protect the rectifier itself as well.

Side story to this side story:
Back when drives were young, NA and EU drive mfrs found out that as we struggled to compete with lower cost Asian drives, we were buying most of the transistors from people like Toshiba and Mitsubishi, but there wasn't much choice. The later, the same Asian companies also completely dominated the capacitor market, and after transistors and heat sink, the caps are the next most expensive thing in a VFD. So rather than continue "sleeping with the enemy" and buying lots of caps from the same people beating us up on the entire VFD, we wrapped some wire around a hunk of steel and cut the number of caps we needed almost in half.

Turned out later when the whole harmonics dragon reared it's head that this had these other benefits, so that's when people started equating the bus chokes with reactors. Asian drives then started offering bus chokes as options, but shipping those heavy parts across the oceans added to their cost, so they left them as optional.


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## Sparky Mcgregor

Wow thanks for all the responses. It will take me a while to try and look into all of them. It sounds like a line reactor is the most popular suggestion. There's currently no line reactor. The truth is I'm not really sure why no one at my work is interested installing a line reactor. I asked my boss if there wasn't some sort of snubber or surge suppressor ages ago and he even mentioned a line reactor at the time. 
JRAEF: Sorry for lack of details. I tried to get as much as I can for you at work today. I hope it's enough. I didn't include the transformer details since the only transformer is the one on the main panel. I figured that probably wasn't relevant but after researching line reactors a bit it seems like it might be, so I can include that tomorrow if you like. I don't think there's any bouncing although I'm not 100% sure what that means. Is that the same as cross-talk? The scale is hardwired (not network). It always runs at the same speed but stops and starts constantly. I first the scale did seem to fault around the same time everyday but now it happens pretty randomly. Thanks again, I'll keep everyone posted.

VFD: power flex 40
Input 414-660V
3 ph
1 HP motor rating

Motor: 575/330V
1.28/0.73A
0.5HP
300-1800RPM
Sew-Eurodrive
KT47 DRS71S4/RI

Line Voltage: input 625
Output 525


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## thorax181

When it is stopping does it just shut off and let it coast (you said it is set to coast) or are you changing to a lower frequency and then stopping at a certain point? 

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## JRaef

OK, that helps a lot. And yes, it IS the main incoming transformer I was speaking of, if that's the only one. So on a 1/2HP drive and motor, it's guaranteed that your transformer is more than 10x the drive rating, so you absolutely should have a reactor ahead of it.

So now you have to eliminate possibilities. On the PF 40, you likely went to parameter P037 to change the "Stop Mode" to Coast by setting it to a value of 5, right? There are however OTHER settings that might override that. 

Look at the settings for the Digital Inputs, programmed in A051 to A054. If any of those are set to a value of 8, activating that input will OVERRIDE the Stop Mode selected in P037, and ramp to a stop. That might cause regeneration that would trip the drive.
If they are using the "Step Logic" sequencer in any way, this too can override the P037 settings. Step Logic is like a small PLC inside of the drive that sets up a pre-selected set of speeds and times for the drive to run at on command. So for example on a conveyor, someone may have used this to have a specific deceleration profile when some types of situations exist, so that if a selection is made (via digital input), it begins a decel operation that slowly steps the drive speed down in a sequence. So look again at A051 to A054 and if any of them are set to "22" or "23", that is triggering a Step Logic sequence, which again will override P037.
 If none of those are in use, then it must be some external source of higher than normal voltage. The PF40 is not sophisticated enough to record the time of a fault event (it doesn't have a real time clock), so you have to look at that externally. If you want to prove this out, here's a somewhat easy way to do it. 



There are two opto-outputs, meaning optically isolated solid state relay outputs, on the VFD that are programmable to a number of different things. Assuming that you have Opto-Output #2 available (not used for something else), get a small 24VDC relay and wire the coil to that output so that if the output comes on, the relay energizes, then wire one contact of that relay to seal it in, through a NC push button to reset it.
Then using the other contact of that relay, power a pilot light. I would just use an illuminated PB so that both things are in one device.
Then go to parameter A061 which programs the function of Opto-Output #2 and set it to a value of "8", which means “Above DCVolt” and go to A062 and set it to a value of "1000", which equates to 1000VDC on the DC bus.
So what will happen is that whenever the DC bus voltage goes above 1000VDC, that light will come on, and stay on until someone hits the reset button. 1000VDC is actually below the maximum DC bus voltage that causes the trip; that is actually 1005VDC (on a 600V rated drive), but you want the opto relay to change state, and if the OV trip happens at the same time, the relay will NOT change because the OV fault would take precedence. So you want to set the opto relay threshold slightly BELOW the trip threshold.
If you happen to have a PLC or Smart Relay, or even a counter available, use that instead of the pilot light and don't have tye relay seal-in. That way you can see how OFTEN the voltage exceeds 1000VDC.
Read the instructions for wiring to that Opto Output on page 1-21 of the manual.
 What this is going to do for you is to allow you to observe that the voltage is going too high, and when or how often. If you can only use the light, you will have to be there to see it, but if you can connect it to a PLC or even a Smart Relay that has a clock in it, you can actually find out WHEN it occurs, then see what else is happening at that time.


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## Sparky Mcgregor

Thanks so much. I recorded that process in my journal. Really interesting. Is it still necessary to wire into the opto output to test if I install a line reactor and the problem ceases? I've had the operators log everytime the VFD trips to try and figure out what's going on but so far it hasn't really uncovered anything. Part of the problem is we don't really have anyone monitoring the conveyor so someone is rarely around when it happens. I'll try to get them to be more conscious of what's happening at the time it trips.


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## Sparky Mcgregor

SCH-1605:

Unfortunely I'm rarely there to see it happen and monitoring it would be difficult since it happens sometimes as little as a few times a week now that production has slowed. It's comstantly stopping and staring and kind of like a metering belt. When it does stop it looks fairly instantaneous despite being said to coast to stop. This might be partly due to the fact that the freight isn't very heavy most of the time.


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## Sparky Mcgregor

JRaef: 

Disregard my question about wiring into the opto output is the line reactor works. I responded a bit too quick and realized what you were driving at shortly after posting my response. No need to continue trouble shooting if the line reactor works. You were simply giving all the information required to problem shoot the issue from different angles. 

FYI I checked the kVA rating for the transformer and the VFD. The transformer is 30kVA and the drive has a kVA input rating of 2.1 (less than the 10x rating). My employer was always bothered by the fact that the other two drives at the facility weren't tripping, but those ones are rated at 14kVA well within the the 10x rating! Did I mention that you guy's are awesome?


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## John Valdes

Just order the reactor. They are not expensive and if you have no room in your enclosure you can mount one in a enclosure or buy one already in an enclosure.
Such little expense and time it would seem you would have already ordered one by now?

Transcoil is a very good source and they know what they are doing.


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## Sparky Mcgregor

Thanks John, I was wondering what the best way to mount it will be. I'll look into that.


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## JRaef

John Valdes said:


> Just order the reactor. They are not expensive and if you have no room in your enclosure you can mount one in a enclosure or buy one already in an enclosure.
> Such little expense and time it would seem you would have already ordered one by now?
> 
> Transcoil is a very good source and they know what they are doing.


+1 on the Trans Coil (TCI).


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## Sparky Mcgregor

I just wanted to give you an update on the F05 fault for those who are interested. I installed a line reactor as planned. Unfortunately it didn't work but the customer is still happy I tried since it was clearly the best shot at fixing it. My boss want's to try installing a break resistor since the overvoltage seems to be related to the DC bus. If that doesn't work, we'll probably try changing those parameters. Thanks again for all the input. I'll keep you posted.


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## John Valdes

Sparky Mcgregor said:


> I just wanted to give you an update on the F05 fault for those who are interested. I installed a line reactor as planned. Unfortunately it didn't work but the customer is still happy I tried since it was clearly the best shot at fixing it. My boss want's to try installing a break resistor since the overvoltage seems to be related to the DC bus. If that doesn't work, we'll probably try changing those parameters. Thanks again for all the input. I'll keep you posted.


If my memory serves me, high bus voltage gives a "high bus voltage" fault?

Just so I don't have to read the complete thread again.
Does this trip on ramp down or stop?

Some smaller drives have some braking built in. Remind us again when the fault occurs.
High bus voltage comes from two sources. High input voltage and regen power. This should be pretty easy to determine.

If it does happen on ramp down, increase this value and see if it clears up the issue. If it does install the resistor bank with braking transistor.
Does the drive have terminals for the braking transistor?


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## Sparky Mcgregor

It's currently set to coast to stop although it doesn't really seem to coast. It's a tiny belt though so it's hard to tell. We haven't been able to pinpoint when the F05 fault occurs because it happen fairly infrequently and at random times. As little as a few times a week. We've discussed changing the voltage parameter for the DC bus but the break resistor was the plan we were going to go with first. I'm not fimiliar with the transistor you referring to. I look it it up though.


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## Sparky Mcgregor

Oh and I'll check to see if the drive has terminals for the breaking transistor too. I'm still learning my trade and VFD's I'm not too fimiliar with yet. I just purchased an online course for learning VFD's so hopefully down the road I'll be better able to communicate on the subject. Thanks for your suggestions. I'll look into to them and keep you posted.


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