VFD provides voltage or the load draws?

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J

Jordan_

Member
Location
Los angeles
Occupation
Contractor
Hello, we have a dust collector that we recently replaced the motor on to a 3 phase 5 hp motor and connected it with a 1 to 3 phase VFD. We programmed the VFD according to the manufacturer but when it's on the parameter are a bit off
Our input is

3.7kw
230v
12 amp
3600 rpm
60 hz

but when the motor is running the VFD shows 60hz but only 1800rpm and when we measure the output voltage we see barely around 200v on two legs and ~195 on the third leg.

We get good suction but I'm afraid the motor is running underpowered

This is the motor

This is the VFD

I'd really appreciate any input on what might be wrong here!

TIA!
 
P

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
usually you have to tell the drive how many poles the motor has when you set the drive up to get the right RPM display.

you cannot use a cheap volt meter to measure the output voltage of a drive, as the output is not a sine wave. the drive usually has a display that you can look at the output voltage.

by the way. VFDs that can run over 900 Hz are banned in the US without a special permit that is very hard to get. I don't recall off hand if it is a felony or not to have one without the permit.
 
Last edited:
J

Jordan_

Member
Location
Los angeles
Occupation
Contractor
tom baker said:
What does the vfd software show for amp draw?
What did you program for service factor? And you used 12 Amps for motor FLA?
Click to expand...
Around 9.5, It used to run around 11 but it seems like it's going down as the dust bin gets full
I didn't program service factor and I don't see an option for that in the manual same as FLA, what I have is "Rated current of motor" where I used 12. I sent the name plate of the motor to the supplier and that's all that was sent back to me

Parameter​
Setting Range​
Instruction​

FP-01​
2​
Factory setting , All parameter reset to factory(First step)​
F1-02​
230​
Rated voltage of motor​
F1-03​
11.8​
Rated current of motor​
F1-05​
3500​
Rated speed of motor【RPM】​
F0-10​
60​
Set maximum out frequency 【60Hz】​
F0-12​
60​
Set upper limit of the running Frequency【60Hz】​
F1-04​
60​
Rated frequency of motor【Hz】​
F0-19​
0​
Set Acceleration/Deceleration time【1S】​
F0-17​
10*​
Set Acceleration time【10S】​
F0.18​
10*​
Set Decelerating time【10S】​


petersonra said:
usually you have to tell the drive how many poles the motor has when you set the drive up to get the right RPM display.

you cannot use a cheap volt meter to measure the output voltage of a drive, as the output is not a sine wave. the drive usually has a display that you can look at the output voltage.

by the way. VFDs that can run over 900 Hz are banned in the US without a special permit that is very hard to get. I don't recall off hand if it is a felony or not to have one without the permit.
Click to expand...
So it runs on 3600 RPM, just displaying 1800 if I didn't set it up?

The VFD actually shows that the voltage fluctuates between roughly 200 to 215 so it makes sense!

I did not know that, thanks for the info!

-------

I appreciate the quick responses
 
tom baker

tom baker

First Chief Moderator
Staff member
Location
Bremerton, Washington
The rated current of the motor may be 12x service factor. AB drives I programmed have entry for sf as it’s not always 1.15. The drive sw won’t let the motor overload
Interesting Amazon sells VFDs
 
G

garbo

Senior Member
Jordan_ said:
Hello, we have a dust collector that we recently replaced the motor on to a 3 phase 5 hp motor and connected it with a 1 to 3 phase VFD. We programmed the VFD according to the manufacturer but when it's on the parameter are a bit off
Our input is

3.7kw
230v
12 amp
3600 rpm
60 hz

but when the motor is running the VFD shows 60hz but only 1800rpm and when we measure the output voltage we see barely around 200v on two legs and ~195 on the third leg.

We get good suction but I'm afraid the motor is running underpowered

This is the motor

This is the VFD

I'd really appreciate any input on what might be wrong here!

TIA!
Click to expand...
I have PM'ed & troubleshoot a lot of drives most being 480 volts. For somebody not similar with drives would strongly recommend that you purchase one from a local dealer that has great tech support. The local company that serviced my companies drives were an authorised service center for Danfoss and maybe a few other brands. Anyway for around $200 they would do the start up & program motor specs then extend the free parts & labor warranty out to three years. The highest that I ever saw a drive output frequency was on a pumping station that was set for 70 Hertz output. Think this amazing Amazon drive has the incorrect frequency of 3,000. A two pole motor would only run a few seconds at 3,000 Hertz before bearings & or stator blow apart due to speed attempting to run at 180,000 RPM. Since VFD'S went with IGBT'S over 40 years ago read the switching frequency can be as high as 5,000 and maybe that is what Amazon meant. I have found Amazon to be lacking in not only providing country of origin but a lot of specs. Recently did an Amazon search for a shallow TR duplex receptacle from two separate companies. Both only gave the height & width but not the depth. I have found the display voltage readings to be very accurate. On old drives we had to measure the DC buss voltage for PM'S and when I used my Fluke meter to compare readings were always within 1 volt of one another ( fluke meter verses display voltage). Same with AC output voltages ( as long as drive was running on a steady speed) . Don't think that little of a voltage differences would hurt anything. To eliminate any motor problems causing slight output voltage differences remove the motor leads at drive and run drive on hand and take output voltage readings from 20 to 60 Hertz. ( 10 Hertz intervals ). Most drives at 50% speed will produce around 30 Hertz and halve the rated output voltage ( 120 volts for a 240 volt rated input volts ). I was always more concerned with ampere being fairly close between output phases when troubleshooting. Had bad drives where the output current was close up to 30 to 35% full speed then one phase way too low as I increased speed. ( with motor disconnected ) . With the motor running what was the single phase input voltage. If that's low the DC buss voltage produced to feed IGBT'S will be low causing a reduced output voltage. Believe the DC Buss voltage for a VFD rated for 240 volt three phase output should be around 330 to 329 volts DC so you should see if you can read this off the screen.
 
Jraef

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
tom baker said:
Interesting Amazon sells VFDs
Click to expand...
Technically, they don't, they "facilitate" a direct transaction between the buyer and seller. You are not buying that from Amazon, you are buying it from some Chinese outfit through Amazon. If something goes wrong and someone gets hurt, there is zero recourse, because the Chinese government does not allow liability lawsuits against their companies and somewhere along the line when you made that Amazon purchase, they informed you that they were not doing the actual "selling", sop they bear no responsibility either. That's why these Chinese companies can get away with selling crap electrical products that have no NRTL listings.

My best guess on the problem here, because I have WITNESSED this with these Chinese crap suppliers, is a lack of communication and understanding. They do NOT provide a manual on-line, so you can't mead the DETAILS that they likely state in there ahead of time. Yes, the VFD is capable of single phase input and 5HP output, but not AT THE SAME TIME, pick one! The drive is rated 16A, output AND INPUT. When you connect it to single phase, you must DE-RATE the drive by anywhere from 50-65%, which means a drive rated for 16A output can actually only handle 5.6 to 8A in connected load roughly 2HP. So in all likelihood the VFD is current limiting to protect itself, hence the low output voltage. When you put a 5HP load on it, that will likely result in a stall.
 
P

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Jraef said:
Technically, they don't, they "facilitate" a direct transaction between the buyer and seller. You are not buying that from Amazon, you are buying it from some Chinese outfit through Amazon. If something goes wrong and someone gets hurt, there is zero recourse, because the Chinese government does not allow liability lawsuits against their companies and somewhere along the line when you made that Amazon purchase, they informed you that they were not doing the actual "selling", sop they bear no responsibility either. That's why these Chinese companies can get away with selling crap electrical products that have no NRTL listings.
Click to expand...
Same as ebay, ali baba, and various other sites.

The reason they are able to sell products of a dubious nature is because people want to buy them. They would not sell if there were no buyers.
 
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