Checkout the Bently Nevada Vibration Probes Setup and Setting Up The Bently Equipment for vibration measurement.
NOTE: For more information look in the top left-hand drawer to find manuals
for the Bently equipment, the Oscilloscope Interface, and the oscilloscopes.
- The shaft should be flush with the right side of the first gap on the coupler (See figure to the right)
- The SCSI cable must be plugged into the computer before it is turned on
- The masses and the tools needed for the labs are in the top right-hand drawer
The rotation direction, X axis, and Y axis are defined as viewed by the driver (motor) to the driven (shaft). The rotation direction can be confirmed by checking the CW/CCW switch on the back of the Speed Control. The system should be set up to rotate in the CCW direction.
The X and Y axis are defined as follows…
- The probes must be staggered in the probe block (see figure to the right)
- The gap between the probe and the shaft can be determined by reading the voltage from the corresponding Prox output on the back of the Proximitor Assembly. The voltage should be -8V, give or take 0.5V
- The Key Phasor and Encoder probes (the two right next to the motor) should have a voltage of -5V, give or take 0.5V when the probe face is centered on the highest spot for each sprocket
- The probe output to the oscilloscope must be zeroed using the Oscilloscope Interface. If the green LED is lit then turn the knob CW and if the red is lit then turn CCW.
- The vertical probe goes to Probe #1 input of the RK4 Proximitor Assembly.
- The horizontal probe goes to Probe #2 input of the RK4 Proximitor Assembly.
- Both channels should be set on AC
- The Time/Div knob needs to be in X-Y mode (These are the values marked in blue)
- Set 0.5 Volts/Div for both channels
- Center the scope by switching both channels to GND and then using the position knobs at the top
NOTE: The scopes will slowly wander so be sure to recenter occasionally
Aligning the Mass
- The system should be set up to rotate CCW when viewed from the motor looking towards the mass.
- Rotate the system in that direction until the leading edge of the keyphasor notch is lined up with the center of the keyphasor probe (see figure to the right)
- Align the 0 degree mark on the mass with the keyphasor probe and tighten both setscrews
IMPORTANT: Before the Rotor Kit can be run through resonance the shaft must be straightened. This can be done by running the Rotor Kit at slow roll and using the ADRE software to determine the deflection, and then physically bending the shaft straight. The slow roll shaft deflection must be in the range of 0.5 to 0.7 mils peak-to-peak (mils pp) BEFORE running through resonance to assure that the shaft bow will not contact the probes.||
NOTE: 1 mils = 1 thousandths of an inch**|
Slow Roll Balancing Technique:***|
1.Power up the computer and Bently equipment|
2.Click on “ADRE for Windows” icon|
3.File -> Open -> Adrewin\database\single -> Ok|
4.Run the Rotor Kit at Slow Roll|
5.Click on Store Enable|
6.Read values for 1X: Amplitude = … Phase Angle = …|
7.Stop Rotor Kit|
NOTE: When the Rotor Kit is stopped the ADRE software will give a “Keyphasor Error”
When you start the Rotor Kit again, click on the “Clear Error” button.|
8.Rotate mass until the phase angle from step #6 lines up with the Keyphasor probe|
9.Push down vertically to straighten the shaft. This will require some practice. If not enough force is applied the shaft will not be fully straightened. If too much force is applied then the shaft will be bent in the opposite direction.|
10.Run the Rotor Kit at Slow Roll and read the new values for 1X:
Amplitude = … Phase Angle = …|
11.If the amplitude increases after bending at approximately the same phase angle, then stop the Rotor Kit and rotate the mass until the phase angle is 180 degrees away from the keyphasor probe and apply force.|
12.Repeat steps 7-11 until the shaft bow is 0.5 -> 0.7 mill pp|
|Now the system (without any balancing weights) should be capable of running through resonance without contacting the probes.|
- Multiply the number on the “Max Speed Setpoint” dial by 10 to get the RPM (ie. knob reads 243 = 2430 RPM)
- Slow Roll speed is 250 RPM
- The acceration rate is valid when ramping up or ramping down, but not when you switch from ramp to Slow Roll