Benstone Fieldpaq, Руководство пользователя

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adversely affect the rotor to operate in a non-linear
region causing the coefficients to be inaccurate. If
the trial weight causes the amplitude to change
more than 200%, it is considered that the trial
weight to be too much and will need to be reduced.
Position : Enter the position where you plan on
adding or cut the trial mass.
If there is no special consideration, it is
recommended to place the trial mass at 0 degree
for convenience.
For your safety: Sometimes the original
imbalance of a rotor is very large, and may cause a hazard if one happens to
place the trial weight on the heavy spot of the rotor- thus increasing the unbalance.
To prevent this from happing, a good estimate of the trial weight may be necessary.
By referencing the phase angle of the original measurement one can reduce this
risk by placing the trial weight not on the high spot, because the phase derived by
Fieldpaq is absolute “high spot” phase.
If the rotation of the machine has a rigid foundation and is rotating at low speeds
(lower than the first critical speed), the location of its heavy spot would be on the
same position of displacement phase. For example, if you measure the
vibration in displacement unit (mil) and got the phase reading
θ
degree, then
you know that the heavy spot of the rotor is in the neighborhood of
θ
degree. So
it is recommended to place the trial weight at (
θ
+180) degree because the trial
weight will reduce the vibration level and maintain a safer operation.
If the vibration is taken in velocity, then the high spot position is at (
θ
-90) degree.
If the vibration is taken in acceleration, then the high spot position is at (
θ
-180)
degree. If you are not sure if your phase guessing is correct or not, you may
need to perform a coast down test with the order tracking program to examine the
phase lag of the machine, or consult a vibration expert to determine.
After : Select Remove or Remain. In general, it is recommended to remove the
trial weight after the trial measurement. In some cases, it is hard to recover the
trial mass, (by drilling a hold or welding a mass to the rotor, etc. ) then you have to