Estimate trial weights


The Estimate Trial Weight option lets you enter physical data describing the rotor, along with selected reference run data, to calculate the trial weight to reduce vibration due to imbalance. The analyzer calculates the heavy and light spots.
Note: This is available only in Advanced Balance mode.
Note: The system lag and sensor lag affect the accuracy of the heavy spot. Rotor weight, radius, and amplification factor affect the accuracy of the trial weight size. This calculation is only an estimate. Your inputs and unaccountable cross-effects in multi-plane solutions affect the accuracy of the estimates. Ensure you enter accurate data.


  1. From the Balance main menu, press F4 Acquire Data.
  2. Select a trial run.
  3. Press ALT > F6 Calculator Mode > F6 Estimate Trial Weights.
  4. Set the following options as necessary.
    Option Description
    F2 Select Meas. Plane Select the measurement plane to use. You may want to select the measurement plane nearest the weight plane that has the readings you want to use. The default is measurement plane 1.
    F3 Select Weight Plane Select the weight plane to use. You may want to select the plane nearest the measurement plane that has the readings you want to use. The default is weight plane 1.
    F4 Enter Rotor Weight Enter the weight of the rotor between 0.00 and 100,000 lbs or 0.00 and 45454.54 kg. The default is 1.
    F5 Enter Tr Wght Radius Enter the radius between 0 and 650 inches where you placed the trial weights on the rotor. The default is 1.
    F6 Enter Sensor Lag Enter the sensor/phase lag in degrees introduced by the sensor. For Emerson supplied accelerometers, sensor lag is normally 0 degrees. The default is 0.
    F9 Select MPT in Plane Enter the measurement points to use. You can average all readings in a specific measurement plane. The default is the first point defined.
    Note: If one measurement point has much higher magnitudes than the others, averaging may give the best results.
    F10 Select Speed Enter the measurement speed with the readings, if more than one speed was defined. The default is speed 1.
    F11 Enter Amp. Factor Enter the effect of the mechanical amplification on the vibration magnitude resulting from an amount of imbalance. Enter a unitless value between 0.0001 and 20.000. The default is 3.
    Note: Amplification factors increase as the rotational frequency moves closer to the critical frequency. Use an amplification factor of 3 if unknown.
    F12 Enter System Lag Enter the system lag in degrees introduced by the equipment being balanced. The default is 45.
    Note: System lag is the difference between the angular location of the heavy spot and the phase of the vibratory high spot. If system lag is unknown, use 45 degrees when below first critical or 135 degrees when between first and second critical. If running close to critical, use a number closer to 90 degrees.
  5. Press F1 Calculate Solution or Enter.
    The calculated solution displays as a continuous or discrete weight positions as defined in Job Setup. The calculated solution, heavy, and light spots display.
  6. Press F9 Trial Weights Units to change the selected units.
  7. Press F12 Insert to Trial Weight to send the calculated solution to the Trial Run Weight entry, or press F7 Estimate Trial Wt. Calc. to exit and return to the calculation screen.