×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Vibration

Vibration

Vibration

(OP)
Can one of you kind gents help me out here. We have specification from a client stating "" that the vibration of the motor shall not exceed 0.5 mil double amplitude in any direction at full or no load "". The motor in question is a IEC 400 frame with sleeve bearings. The motor spec states vibration according to IEC60034-14.and is expressed in vibration velocity as 2.3mm/s rms. So how do you convert 2.3mm/s to  mil double amplitude value.

RE: Vibration

At what RPM?

RE: Vibration

(OP)
It is a 4 pole motor 50 hz 1500 rpm

RE: Vibration

The general relation is that speed v = ds/dt = (A/2)*d(sin(wt))/dt = A/2*w*cos(wt).

Where A is double amplitude, v is velocity and w is angular speed in rad/second.

Since cos(wt) cannot be more than 1, you get:

v = A/2*w
so,  v = A/2*6.28*RPM/60

This is true for SI units, but if you express amplitude and speed in mils and mils/s, you can use it without any further unit conversions.

Convert mm/s to mils/s:

    2.3 mm/s = 2.3*1000/25.4 = 91 mils/s

Which results in
 
    v = A/2*6.28*RPM/60

or, in your case:

     2.3*91 = A/2*6.28*RPM/60

     A= 2*60*2.3*91/(6.28*RPM)

If your machine does 1500 PRM, you get

     A = 2.7 mils double amplitude

And, at 3600 RPM, 1.1 mils double amplitude.


Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: Vibration

Sorry, I see now that your velocity is rms. Multiply by sqrt(2) to get your values.

As your machine is 1500 RPM, the double amplitude is 3.8 mils.

Either I am wrong - or the spec calls for a specially balanced machine.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources