Is there anyone that is very familiar with VFD Drive

[sam_sam_sam]

I have a problem with a VFD Drive with blowing fuses at radom it might work one day or maybe 3 or 4 days then blow two fuses at a time

It call for a 30 amp time delay fuse but if you use time delay fuses in this version of VFD drive it will blow the IGBT module before it ever blows the fuses

I was using 30 amp fast acting fuses then when to 40 amp and now when to 60 amp fast acting fuses ( JJS version fuses ) I do not have any results from the 60 amp fuses I just put them in today

But yesterday it blew all three fuses weird

Now this is even more weird and that is the motor plate say running amp 20 amps @ 480 volts

Ramp up time set at 15 seconds 26 amps from 8 HZ to 35 HZ until it reaches 28 HZ then levels off to about 7 amps

Now if I change the ramp up time to 30 seconds ( this is the maximum setting) the same 8 HZ to 35 HZ then we are looking at about 12 amp until it reaches about 25 HZ then level out at 6.6 to 7.5 amp

One note the ramp down amperage is normal


Now I have done quite a few VFD drives to motor and not have this problem most of the time the amperage is less than what motor plate says

Now this motor does not hum or sound like it single phasing the motor sounds good

One note it is for an overhead crane and it probably about 30 years old

Anyone have any ideas what might be going on

One other note the original VFD ( over 10 years old) took a shit it tripped a 50 amp breaker and VFD drive did not smell very good ( did not try to put power to it again ) that is this one (Over Head Crane Current Sensing Board recap this board ) about five years ago

more than likely it is a shorted IGBT module failure

I have not done an autopsy of this drive yet but when I have some time I will do one and let you know what I find

[budm]

Re: Is there anyone that is very familiar with VFD Drive

So at what point do the fuses blown, during ramp up time? May be due to stalled current due to heavy load?

[sam_sam_sam]

Re: Is there anyone that is very familiar with VFD Drive

So at what point do the fuses blown, during ramp up time? May be due to stalled current due to heavy load?

I thought of this

But the employees that I work with can not seem to tell exactly what it was doing just before it would not moving any more

So I do not have answers to this question ( in order for me to maybe get an answer to this question I would have to ride on the crane until the fuses blew or use a data logger that I do not have )

That is what I am trying to figure out

If I have use a time delay fuses I will probably use 20 amp or 25 amp one

Also the camp on current meter that I am using the sampling rate speed is not very fast it is not showing me inrush current spikes so this is some information that I do not have

But one thing I noticed the other night when I had to go and get the crane going again was that the lights in the shop dim some what ( but was not a complete blackout ) and was not all of them at the same time it did it several times while I was there

( now I could use a phase loss monitor and lock it out while this event is going on but when you do this while you are commanding it to move it makes the drive go into an alarm that the overload condition has happened then you have turn off the power to crane and wait for 30 seconds and turn the power back ON then wait 30 seconds for the VFD to boot up and you are ready to go —> how ever the employees —> [ the Children I work with cry to much about this setup] ) I could set it up so that it would just not move while this event is going on ( but this would require another relay with double contacts one for forward and one for reverse inputs )

This could be some of the problem I ask the night supervisor how often this happens he tell me that some nights it does this quite often

Well if you have unbalance phases it will cause the other phase that are not dipping to pull more current and mind you I was only using one current meter at the time

I might have to do a work around for this problem in that I could set it up so that it would just not move while this event is going on ( but this would require another relay with double contacts one for forward and one for reverse inputs )

The problem with this is that the boss that I have does not want to give me the crane to do this type of work when they need to use the crane ( which means most of the time it is being used )—> which means that I would have to come in Saturday to do these changes which is over time but still

This boss also the one that has said that when ever we have any problems with a crane ( and all of them have ([VFD drive for the bridge and trolleys ] that I need to hop on the crane and watch the display and see what seems to be the problem with it but most of the time it is a intermittent problem so when you power it down and power it back up it is working again ( yes they have an error log but they are just numbers not with an explanation of it )

Now one of our crane has this feature that it tell you the error number and it tells you error message which I like this feature but this VFD is more complex in programming it and most of the time I have to call tech support when I have to do changes to it ( it has more than 60 parameters to set not all of them do you use it just depends on your application setup you have)

One note about this in the summer time it is about 30* F hotter up in the rafters than on the ground so you can not stay up there more than about 20 minuets with out dying from the heat yeah you can take a fan up there with you but you are just blowing hot air and take water up there with you you will be alright I have asked come up on the crane with me “O” no I do not want to yeah right

One note that all our cranes except one have cat walks on them

[redwire]

Re: Is there anyone that is very familiar with VFD Drive

There's obviously problems with the site's power if the lights are dimming from other loads, there are sags. I would see if you can figure out what load is switching on/off and causing that problem because any VFD/crane is going to get upset over that. The drive will take more current with a low bus voltage, and might be why the fuses are blowing.

There should be a low DC bus voltage trip voltage setting and instead of the drive compensating for low input voltage by taking more current (and blowing fuses) maybe it's better to just have it trip and let the shop reset that.

VFD's are supposed to trip on high current if there is a motor problem, so what is that limit set to? It should be less than the fuse ratings.

I always make a spreadsheet with all the VFD's programming and settings. You need this anyway if a drive gets replaced. Just takes a few minutes in the menus.

Sometimes a bunch of settings are fudged to keep things running. It can endanger the drive or motor by no longer protecting them.
I would also check the VFD is setup properly for the motor.
A (smart) vector drive has an autotune sequence where the drive measures and learns the stator and rotor resistance, inductance etc. But sometimes you have to disconnect the (crane) load for it to work. You can compare settings with other cranes if they use the same motor/drive.

[sam_sam_sam]

Re: Is there anyone that is very familiar with VFD Drive

I thought of this

But the employees that I work with can not seem to tell exactly what it was doing just before it would not moving any more

So I do not have answers to this question ( in order for me to maybe get an answer to this question I would have to ride on the crane until the fuses blew or use a data logger that I do not have )

That is what I am trying to figure out

If I have use a time delay fuses I will probably use 20 amp or 25 amp one

Also the camp on current meter that I am using the sampling rate speed is not very fast it is not showing me inrush current spikes so this is some information that I do not have

But one thing I noticed the other night when I had to go and get the crane going again was that the lights in the shop dim some what ( but was not a complete blackout ) and was not all of them at the same time it did it several times while I was there

( now I could use a phase loss monitor and lock it out while this event is going on but when you do this while you are commanding it to move it makes the drive go into an alarm that the overload condition has happened then you have turn off the power to crane and wait for 30 seconds and turn the power back ON then wait 30 seconds for the VFD to boot up and you are ready to go —> how ever the employees —> [ the Children I work with cry to much about this setup] ) I could set it up so that it would just not move while this event is going on ( but this would require another relay with double contacts one for forward and one for reverse inputs )

This could be some of the problem I ask the night supervisor how often this happens he tell me that some nights it does this quite often

Well if you have unbalance phases it will cause the other phase that are not dipping to pull more current and mind you I was only using one current meter at the time

I might have to do a work around for this problem in that I could set it up so that it would just not move while this event is going on ( but this would require another relay with double contacts one for forward and one for reverse inputs )

The problem with this is that the boss that I have does not want to give me the crane to do this type of work when they need to use the crane ( which means most of the time it is being used )—> which means that I would have to come in Saturday to do these changes which is over time but still

This boss also the one that has said that when ever we have any problems with a crane ( and all of them have ([VFD drive for the bridge and trolleys ] that I need to hop on the crane and watch the display and see what seems to be the problem with it but most of the time it is a intermittent problem so when you power it down and power it back up it is working again ( yes they have an error log but they are just numbers not with an explanation of it )

Now one of our crane has this feature that it tell you the error number and it tells you error message which I like this feature but this VFD is more complex in programming it and most of the time I have to call tech support when I have to do changes to it ( it has more than 60 parameters to set not all of them do you use it just depends on your application setup you have)

One note about this in the summer time it is about 30* F hotter up in the rafters than on the ground so you can not stay up there more than about 20 minuets with out dying from the heat yeah you can take a fan up there with you but you are just blowing hot air and take water up there with you and you will be alright I have asked come up on the crane with me “O” no I do not want to yeah right

One note that all our cranes except one have cat walks on them

[sam_sam_sam]

Re: Is there anyone that is very familiar with VFD Drive

There's obviously problems with the site's power if the lights are dimming from other loads, there are sags. I would see if you can figure out what load is switching on/off and causing that problem because any VFD/crane is going to get upset over that. The drive will take more current with a low bus voltage, and might be why the fuses are blowing.

There should be a low DC bus voltage trip voltage setting and instead of the drive compensating for low input voltage by taking more current (and blowing fuses) maybe it's better to just have it trip and let the shop reset that.

VFD's are supposed to trip on high current if there is a motor problem, so what is that limit set to? It should be less than the fuse ratings.

I always make a spreadsheet with all the VFD's programming and settings. You need this anyway if a drive gets replaced. Just takes a few minutes in the menus.

Sometimes a bunch of settings are fudged to keep things running. It can endanger the drive or motor by no longer protecting them.
I would also check the VFD is setup properly for the motor.
A (smart) vector drive has an autotune sequence where the drive measures and learns the stator and rotor resistance, inductance etc. But sometimes you have to disconnect the (crane) load for it to work. You can compare settings with other cranes if they use the same motor/drive.

The problem with these VFD drive is that this version does not have auto tune
These drive are very easy to program in that you have ramp up and down setting you have HZ setting for low speed and high speed and few other settings and that pretty much it for setting up the drive and most of the time this works

[sam_sam_sam]

Re: Is there anyone that is very familiar with VFD Drive

There's obviously problems with the site's power if the lights are dimming from other loads, there are sags. I would see if you can figure out what load is switching on/off

The problem is with the power company because the only thing that was being used was the light in the shop and one crane and at the time the crane was not in use

The other thing you mentioned I am aware of

The one thing that I do not like about these drives is that they do have have a phase loss monitor build into them and the ones that do cost a lot more than just adding a phase loss monitor and and one control relay

The ones that I have seen that have phase loss monitor build in did not have a way to adjust the percentage of out of balance which to me does not work

[redwire]

Re: Is there anyone that is very familiar with VFD Drive

OK (wild guess) I think the root problem is the site's mains power is sagging. The drive's filter capacitors might not be able to hold up through a dip. I would (carefully) test them, it is hot in the rafters? They could be low in value. High ripple might also explain the amperage readings being off.

I rent a line disturbance/power quality analyzer and get proof of the problem. Something like a Dranetz.

Otherwise, buy a case of fuses and keep changing them. Bigger or slow-blow fuses will eventually take out the rectifer or IGBT's as the high currents are hard on a drive. This VFD sounds pretty basic and does not cutout and trip if the DC bus voltage sags, and instead just cranks up the current too high.

[R_J]

Re: Is there anyone that is very familiar with VFD Drive

It may also be worth checking the wiring in the panel itself, I have seen connections get loose over time and being in a panel they sometimes get overlooked. If it's an older building it can be even worse.

[sam_sam_sam]

Re: Is there anyone that is very familiar with VFD Drive

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[redwire]

Re: Is there anyone that is very familiar with VFD Drive

It's an energy meter, which is slower with longer averaging and I don't think it would catch disturbances.
Say you have a dip from 480VAC to 350V for a 1/4 second, a power analyzer will record that but an energy meter just shows a little drop because it averages over long like 10-60 second intervals.

A good multimeter on min/max can show a drop on at least the one phase you are monitoring. You can get a salesman to demo a power analyzer for free, for a few days and not buy it.

[stj]

Re: Is there anyone that is very familiar with VFD Drive

if you have a digital scope, you could get some inductive probes and record it over usb/ethernet with LXI software.

[sam_sam_sam]

Re: Is there anyone that is very familiar with VFD Drive

I have an update

I have put in JJS-60 fast acting fuses on this VFD drive and set the ramp up to 30 seconds and the ramp down to 18 seconds this seems to work it been almost a week and so far it has not blown any fuses

So it looks like the fuses and the VFD drive are getting along with each other let see just how long this last

A couple days ago we had another VFD failure on another crane this was a little weird in that the fuses for the VFD drive did not blow but the drive would not power ON

I am also going to do an autopsy of this drive but when I have some time I will do one and let you know what I find this one might the first one

This drive had been doing some weird things for a quite a few months now that sometimes it just all of sudden just stop in it tracks and sometimes it just shake the bridge

When you turn it off and back ON again it would run fine for a month or two and do the same-thing again or sometime it might do this couple times in one day and go long time before it do this again

One note this drive did not have any bad smell to it ? Mark to what happened my guess is that the switching regulator ic might have taken a shit if it has one
__________________

[sam_sam_sam]

Re: Is there anyone that is very familiar with VFD Drive

Here are some pictures of the drive that just took a crap the one that would not power ON

One note

The switching power supply regulator has some kind of epoxy resin on it so you can not read the IC chip number

Also there is a 30 amp fuse in it that is not blown