Rotron blower problem

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Malywr

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New Jersey USA
How much current should take 10HP, 208V, 3PH, 25A motor running rotron blower discharge open to atmosphere
It is using 24-25A if I reconnect discharge to machine is using 36A
This set up is used for last 10 years and now is causing issues
I think that blower when is open to atmosphere should not take 25A
Please tell me your opinion
Do you think that is normal or bearings are going bad so current is higher than supposed to


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powerpete69

powerpete69

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10 HP, 208V three phase motor is listed at 32.2 amps.
Power factors certainly can vary between motors.
So not sure what your question is exactly.
 
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Malywr

Senior Member
Location
New Jersey USA
ptonsparky said:
What is a rotron blower? Typical centrifugal fan, axial flow or positive displacement?

Please insert punctuation in your explanations/questions so we can sort them.
Click to expand...

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mayanees

mayanees

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Westminster, MD
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Electrical Engineer and Master Electrician
Malywr said:
Please tell me your opinion
Do you think that is normal or bearings are going bad so current is higher than supposed to
Click to expand...
Given that this just started happening after being in service for a long time, I'd look for anything that's obstructing air flow. You amperage numbers are logical for no-load versus loaded, and NEC 450.250 gives 30.8 amps for a 10 hP motor, and with a 15% overload that's 35 amps which is close to what you're measuring. You could increase the overloads per Part III of 430 if that's what's tripping, but something has changed. If it has a 1.15 service factor, you could go as high as 125%.
 
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GoldDigger

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One very simple experiment is to take an amp measurement wide open and then with either inlet or outlet partially or completely blocked. If current decreases when blocked you have a centrifugal or axial pump whose highest current consumption will be when running wide open without back pressure. The power consumed by those types of fans or blowers depends only on the shaft speed and the volume of gas (at standard temp and pressure) moved.
A dirty filter would decrease performance but would not increase the motor load.
 
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Malywr

Senior Member
Location
New Jersey USA
mayanees said:
Given that this just started happening after being in service for a long time, I'd look for anything that's obstructing air flow. You amperage numbers are logical for no-load versus loaded, and NEC 450.250 gives 30.8 amps for a 10 hP motor, and with a 15% overload that's 35 amps which is close to what you're measuring. You could increase the overloads per Part III of 430 if that's what's tripping, but something has changed. If it has a 1.15 service factor, you could go as high as 125%.
Click to expand...

It is ok if I change protection bace on 430.250 current and protect to 430.32.A.1. 30.8x125% =38.5A that would be protected higher than I am running now
Now motor is protected to motor NP
25A x 133% = 33A. 430.32.C. What is no more than 140% motor NP FLC
NP says Amps not FLC
5767a7e2a7d99431f78e26fcefe7b5e2.jpg



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M

Malywr

Senior Member
Location
New Jersey USA
GoldDigger said:
One very simple experiment is to take an amp measurement wide open and then with either inlet or outlet partially or completely blocked. If current decreases when blocked you have a centrifugal or axial pump whose highest current consumption will be when running wide open without back pressure. The power consumed by those types of fans or blowers depends only on the shaft speed and the volume of gas (at standard temp and pressure) moved.
A dirty filter would decrease performance but would not increase the motor load.
Click to expand...

When outlet is open by pump (vent valve) motor current is 25-26A when outlet partly closed (vent valve closed 100% inside machine is always open so flow is restricted) current is 35-36A


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Malywr

Senior Member
Location
New Jersey USA
GoldDigger said:
Exactly!
Click to expand...

Just for test I removed filter and run for 2 min current went down less than 1 A
Check current a-gene phase A-32A, B-31A, C-35 to 36A. With thermal camera I notice phase c is hot and knife disconnect On PH. “C” is more hot than the other 2 A or B.
I think poor connection on “C” cause current go up
I will check that on Monday



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M

Malywr

Senior Member
Location
New Jersey USA
Ok before I set I removed filter and current went down less than 1A. So inlet filter should not be critical issue.
I assume disconnect has bad contact on leg “C” because leg “C” has higher current than other legs so to test disconnect I rotate leads on the bottom of starter A move to B, B move to V and C move to A and my high current move to leg A
Conclusion disconnect must be good
I don’t know how to test motor. Now I think motor is going bad.
Please suggest how can I test motor with basic multimeter fluke 336?


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