Malywr
Senior Member
- Location
- New Jersey USA
Mistyped B move to C
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Rotron blower problem
- Thread starter Malywr
- Start date
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ptonsparky
Tom
- Occupation
- EC - retired
You just did. The current imbalance is over 7%. 2% is the threshold.
Check the connections at the motor. Do a smell test.
You could try a resistance check on each winding. Winding to winding or winding to motor frame may or may not indicate a problem with that meter.
Check the connections at the motor. Do a smell test.
You could try a resistance check on each winding. Winding to winding or winding to motor frame may or may not indicate a problem with that meter.
kwired
Electron manager
- Location
- NE Nebraska
Hooked up a unit that looked very similar to that one last fall, had some offshore branded motor instead of a Baldor but looked much the same otherwise. Was used as a vacuum pump. Not sure exact design of propeller but seems to act like positive displacement for the most part. It was on a soft starter so ramped up to speed, but first time we energized to check rotation it probably wasn't anymore than 1/3 to 1/2 full speed and blew the cap off the filter housing because it was running wrong direction, about needed to go get clean shorts, definitely not centrifugal fan behavior on that one.
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ptonsparky
Tom
- Occupation
- EC - retired
I read a description for how those operate and it stated the results were close to a positive displacement. I Googled.
Malywr
Senior Member
- Location
- New Jersey USA
I try to measure resistance on that motor but with so little time I am not sure of my reading. I notice leads from motor look dark CU like dirty from high temperature. During day machine is running now at A 34.6A. B 32A. C. 31A. I will try to open outlet and let air out to reduce pressure and at same time bring current down if that don’t effect production I will leave it like that.
I don’t know what to do next ....I think this motor is coming to its end if continues to run over 35A.
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ptonsparky
Tom
- Occupation
- EC - retired
AFAIK, this is still a centrifugal fan and will react like one. Opening the outlet will increase the current of the fan because it will be moving more air.
Get a new motor. Be prepared for a shut down, or not. You choice.
Get a new motor. Be prepared for a shut down, or not. You choice.
Malywr
Senior Member
- Location
- New Jersey USA
I would think that opening outlet should increase current like on our other blowers but this one works opposite when I open outlet current going down
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ptonsparky
Tom
- Occupation
- EC - retired
Are the other blowers set up the same?
oldsparky52
Senior Member
- Location
- Wilmington, NC USA
Did you check the connections at the motor jb? It could be a failing connection there, if not, looks like you found a motor going bad.
Malywr
Senior Member
- Location
- New Jersey USA
Check connections and they are tight CU looks dark like would be exposed to high temperature
“Ptonsparky” this typo of blowers we have 3 in different setups other blowers they are different and much bigger build to move volume of air. Rotron is build to make vacuum or pressure
That how I understand
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kwired
Electron manager
- Location
- NE Nebraska
If it is positive displacement or at least a design that acts more like positive displacement then the more pressure (or vacuum) you have the more it should load the motor. True positive displacement design would be piston type compressor or scroll compressor designs, these must just have some pretty close propeller clearances that allow it to mostly act like positive displacement though there is probably still some centrifugal characteristics to them. Think there may be more than one stage to the blower as well on these
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
This type of blower is a "regenerative blower", also called a "ring compressor", acts like a centrifugal machine; as flow decreases, load decreases. But unless you are measuring POWER (kW), you might be getting fooled by reading current alone because as the load decreases, the power factor decreases. So it might APPEAR as though current is going up because the REACTIVE current is going up, but the WORKING current is actually going down. If you listen to the machine, you will hear that as you choke off the flow, the speed INCREASES, because the load is decreased and the slip is lower. The problem is, all of that is lost on the motor; current is current as far as protection of the motor is concerned.
Do NOT blindly change the OL protection until you RTFM for the motor starter. Some (many) OL relays have ALREADY factored in a 125% or even 140% pick-up point, so if you add it AGAIN, you are actually then making it 156% (125% of 125%) or 196% (140% of 140%) and you will lose the motor if it overloads. If you want to use the SF, you do NOT factor in the 140% yourself, they will give you instructions on how to adjust the selection (or adjustment) of the OL protection according to how they have already factored in the pickup point.
If this motor has been running at 36A for years, it is likely failing because it has been overloaded already, and someone has already set the OL protection incorrectly. Even if run into the Service Factor (which is supposed to be temporary), it should not have been pulling more than 35A for any length of time
Do NOT blindly change the OL protection until you RTFM for the motor starter. Some (many) OL relays have ALREADY factored in a 125% or even 140% pick-up point, so if you add it AGAIN, you are actually then making it 156% (125% of 125%) or 196% (140% of 140%) and you will lose the motor if it overloads. If you want to use the SF, you do NOT factor in the 140% yourself, they will give you instructions on how to adjust the selection (or adjustment) of the OL protection according to how they have already factored in the pickup point.
If this motor has been running at 36A for years, it is likely failing because it has been overloaded already, and someone has already set the OL protection incorrectly. Even if run into the Service Factor (which is supposed to be temporary), it should not have been pulling more than 35A for any length of time
Malywr
Senior Member
- Location
- New Jersey USA
Thank you for your input
Motor drawings uneven cutest ph B and C is in 32A range but ph A draw 35.8-36.6A So protection of 34A was tripping from last 2 months that tells me something is different now than was for the past couple of years. I check connections and everything seems to be good. Also I notice one wire insulation inside motor JB was kind of hard like burned or overheated.
As other people suggested on this forum that motor is going bad. Unless I missed something and if you have other suggestions please advise so I can more troubleshoot.
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- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
No, I think you found the issue. The insulation is likely breaking down inside of the motor. Most motor shops will tell you that unless the motor is very unusual or hard to replace, it's not worth rewinding anything that small.
Malywr
Senior Member
- Location
- New Jersey USA
Yes I did ask and that exactly what they told me
Thank you for your input
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