Less suction pressure on Blower after Star-delta starter replaced by VFD

[kArTmAN]

Yes. of course. Otherwise pressure would n't have been developed.

 

[kArTmAN]

Another question... What are you measuring the VFD output with? or are you looking at its display for output voltage?

A run of the mill multi-meter can't deal with a VFD output.

And another... did you measure the actual shaft speed of the motor? At "50 Hz", is it running nameplate speed? You might be going into a current limit situation on the drive, reducing the actual output.

Both multimeter and display is showing 360V.

"If VFD output is pure sinusoidal/or close to u can measure its voltage by Multimeter"

I didnot check the shaft speed; Drive is showing 50Hz, Definitely 50Hz Power is going to motor. Now motor is supposed to rotate at its speed at 50Hz whatever maybe its voltage. If it runs at 50Hz,then why the hell i am not getting desired pressure!!!!!

 

[just the cowboy]

Yes it can

Yes. of course. Otherwise pressure would n't have been developed.

Depending on what type of blower, wrong rotation will still produce suction or pressure but not as well. I use centrifical blowers that do it.

Also you have been asked other questions, some answers to them would help, not just come back with the above quote. The experts here spent their time to answer them.

 

[just the cowboy]

Only showing the command

Both multimeter and display is showing 360V.

"If VFD output is pure sinusoidal/or close to u can measure its voltage by Multimeter"

I didnot check the shaft speed; Drive is showing 50Hz, Definitely 50Hz Power is going to motor. Now motor is supposed to rotate at its speed at 50Hz whatever maybe its voltage. If it runs at 50Hz,then why the hell i am not getting desired pressure!!!!!

The drive is probaly just showing the command for freq as most do. What is the current saying

 

[kArTmAN]

Probably a dumb question, but is the motor still rotating the correct direction?

Of course it is.

 

[kArTmAN]

the drive is probaly just showing the command for freq as most do. What is the current saying

34-36a

 

[kArTmAN]

Depending on what type of blower, wrong rotation will still produce suction or pressure but not as well. I use centrifical blowers that do it.

Also you have been asked other questions, some answers to them would help, not just come back with the above quote. The experts here spent their time to answer them.

Sorry for my quote if it is too offending.

Mine also Centrifugal blower. But pressure is not that less that i could come to a decision that it is rotating in reverse direction. And also i had to change the phase during commissioning as at first it started rotating reverse.

Here to mention, I am experiencing same for 2 systems.

Help needed!!!!

 

[robertmee]

Sorry for my quote if it is too offending.

Mine also Centrifugal blower. But pressure is not that less that i could come to a decision that it is rotating in reverse direction. And also i had to change the phase during commissioning as at first it started rotating reverse.

Here to mention, I am experiencing same for 2 systems.

Help needed!!!!

You can scream for help, but until you help us, it's futile.....

You've been asked, but not provided:

What is the FLA rating on the motor
What is the Current Limit setting in the drive
What is the accel rate of the drive set to
What was the type and size of the previous OL protection you used on the fixed starter? This could give us some clue as to what kind of current was being allowed.

When someone asks you what the current is, don't respond 34-36a. That's too ambiguous. Is that what the drive is reporting? A standard 415V 18KW motor has an FLA of 36a. If you're pulling 36a then you are in current limit potentially depending on the drive set up.

Unless you're measuring rotational speed with a hand held tach at the motor shaft/fan, how do you know it's running 50HZ? Don't rely on what a dumb drive is telling you....measure it! You say the drive says 50Hz, but that is commanded frequency....what about speed feedback...what does the drive say?

 

[osmanjdt]

1.) what the distance between motor and VFD?
2.) damper broken?

 

[KB1GNI]

Of course it is.

The only dumb question is one that goes unasked.

I was going to ask that one myself, but someone else beat me to it.

 

[kArTmAN]

You can scream for help, but until you help us, it's futile.....

You've been asked, but not provided:

What is the FLA rating on the motor
What is the Current Limit setting in the drive
What is the accel rate of the drive set to
What was the type and size of the previous OL protection you used on the fixed starter? This could give us some clue as to what kind of current was being allowed.

When someone asks you what the current is, don't respond 34-36a. That's too ambiguous. Is that what the drive is reporting? A standard 415V 18KW motor has an FLA of 36a. If you're pulling 36a then you are in current limit potentially depending on the drive set up.

Unless you're measuring rotational speed with a hand held tach at the motor shaft/fan, how do you know it's running 50HZ? Don't rely on what a dumb drive is telling you....measure it! You say the drive says 50Hz, but that is commanded frequency....what about speed feedback...what does the drive say?

FLA = 36A
Overload Trip Level FU1-67 =120%
Acceleration Time = 20s
Previously used = Thermal Overload set at 22A( as star delta config.)

Soon i will let you know shaft rpm. Currently out of site.

Should i try increasing frequency? But i think that will increase the current.

Also could you please tell me how current limiting decrease the output frequency?

Thanks

 

[kArTmAN]

1.) what the distance between motor and VFD?
2.) damper broken?

1. Distance = 10m max
2. No.

 

[redbarron55]

Make certain the motor is running in the correct direction.
A centrifugal blower will move air when running in either direction.
Just a good bit more when going the right way around.
A lobe type blower would pump backwards if reversed.

If you have a tachometer check the motor speed.
Direct coupled or belt?

Also check the drive parameters for slip compensation if applicable.
If necessary you could lie to the drive and ask for higher rpm from the motor.

 

[Brian123]

Sorry for my quote if it is too offending.

Mine also Centrifugal blower. But pressure is not that less that i could come to a decision that it is rotating in reverse direction. And also i had to change the phase during commissioning as at first it started rotating reverse.

Here to mention, I am experiencing same for 2 systems.

Help needed!!!!

Next possibly dumb question: did you change the phase on the input of the drive or the output of the drive? Changing phase on the input of the drive will not change the motor direction. I ask because I have done this myself...

 

[just the cowboy]

Current limit

FLA = 36A
Overload Trip Level FU1-67 =120%
Acceleration Time = 20s
Previously used = Thermal Overload set at 22A( as star delta config.)

Soon i will let you know shaft rpm. Currently out of site.

Should i try increasing frequency? But i think that will increase the current.

Also could you please tell me how current limiting decrease the output frequency?

Thanks

Current limit overides the speed command. To maintain the proper current the drive will reduce the voltage AND the frequancy. .

Now for the bigger problem. You say that the overloads for the original setup was 22 amps, The drive should be running close to that not 36 amps if that was your loaded amps before.

Is there a torque setting on the drive?? This is important when setting up a pump/blower. It sounds like you are not getting the right torque to break the load free.