Motor vibrations

Hello,

Sorry for my bad English in advance.

I have six identical fans. The construction is motor coupling and fan.

One of them had huge vibrations on 001V had 38 velocity on 30 Hz frequency and 002V 30 velocity also on 30 Hz the motor speed is around the same frequency so I assume it is motor speed. 

The vibration is only on vertical axis and vibrations are only on 30 Hz frequency, no harmonics. So I assumed it must be imbalance.

We Inspected fan, for broken vanes but only found excessive dirt on vanes. So we removed it and it helped significantly the 001V dropped down to 20 and 002V dropped 15, still it more that we want so we will try to balance it, but the thing bothers me that the balancing will only help for short period of time.  I would like to know the root cause and prevent this thing for the other 5 fans.

Original Post

The vibration values after the cleaning done are still high to my standards.

Root cause analysis is very useful to prevent or delay the occurrence of the same problem. It sounds that you expect the "dirt" to accumulate again.

A good recommendation should be based on facts which are not enough from your post.The root cause can be related to the fan's design, operating the unit, poor maintenance or even from the atmosphere. Because I do not know these fans I'll simply ask more questions.

1. Is this problem new or was encountered in the past?

2. Are there other fans of the same design that perform better?

3. How long do these fans operate before the vibration reaches these high vibration levels?

4. What is the service of these fans (forced draft fans, gas recirculation fans etc)?

5. Is there any sort of filter on the inlet side of the fan?

Regards- Ali M. Al-Shurafa

John from PA posted:

Are you getting run to run a consistent 1X phase angle?  

Where physically are the locations you refer to as 001V and 002V?

 

Hi,

I refer these points on top of the motor, Vertical axis.

I have only skf quick collect tool, with it I can't do phase angle readings. Is there a way to do it with some other equipment? 

Shurafa posted:

The vibration values after the cleaning done are still high to my standards.

Root cause analysis is very useful to prevent or delay the occurrence of the same problem. It sounds that you expect the "dirt" to accumulate again.

A good recommendation should be based on facts which are not enough from your post.The root cause can be related to the fan's design, operating the unit, poor maintenance or even from the atmosphere. Because I do not know these fans I'll simply ask more questions.

1. Is this problem new or was encountered in the past?

2. Are there other fans of the same design that perform better?

3. How long do these fans operate before the vibration reaches these high vibration levels?

4. What is the service of these fans (forced draft fans, gas recirculation fans etc)?

5. Is there any sort of filter on the inlet side of the fan?

Regards- Ali M. Al-Shurafa

Thank you for the reply. I'm new to this job and this organization. As it seems in the past they were working in principle "run to fail". No one know how long they are running like this, they only replace then it breaks, so I want to change the habits.

1. As far as I know yes they encountered these problems, and they found out only then machine stopped operating.

2. All the equipment are the same, one of them has a motor changed. I Attached picture so everyone would understand better that I'm talking about.

3. The equipment is installed maybe 6 years ago, maybe more.

4. Fans are for air suction. 

5. There is a filter and I will check it today.

Attachments

Photos (1)

I'm not familiar with your process but it looks like an HVAC outdoor unit. From the illustration you shared, the air is in a closed loop (for the most part.), right?

Since there are inlet filters, I would make sure they are scheduled for reasonable PM. Also, I would inspect if these filters have any differential pressure measurement devices. Investigate if it is worth to invest in an automatic alarm based on dirty filters.

This case sounds like a very good candidate for RCA. Please keep us posted on your update.

 

Regards- Ali M. Al-Shurafa

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