6. Press Enter to view the data.
One or more plots display after the data is collected.
7.
Press F9 Store Data to save the data to a route or a job, or press F8 Start to redo the
measurement.
6.8.14 Rotor Bar Test Motor Current
Rotor Bar Test Motor Current finds rotor bar defects in AC motors. The motor should be at least
50 percent loaded. Sidebands around electrical line frequency, spaced at the number of
poles times the motor’s slip frequency, indicate a rotor bar defect. If the difference
between the sideband amplitudes and the line frequency amplitude is less than 60 dB,
suspect rotor bar problems.
Prerequisites
• Connect a current clamp to the volts input on the analyzer.
• Place the current clamp around one wire of the three-phase power source.
• Enter the correct sensitivity for the clamp, and account for a current transformer
(CT) ratio if you measure on a secondary wire.
Procedure
1. Create a job or open Analyze from a route measurement point.
2. From the Analyze main menu, press F7 More Experts > F6 Rotor Bar Test Motor Current.
3. Press Start or Enter to collect the data.
4. Press Enter to view the data.
One or more plots display after the data is collected.
5. Press F9 Store Data to save the data to a route or a job, or press F8 Start to redo the
measurement.
6.8.15 Order Tracking
Order Tracking normalizes data from equipment that has fluctuating speed. Data from
equipment with variable speed can cause vibration frequencies to look “smeared”
between adjacent frequency lines.
The tachometer input of the analyzer must have a reference pulse. The tachometer pulse is
typically from the shaft turning speed, but it could be from a belt.
The resulting data is related to the reference pulse and is displayed in orders of turning
speed. Frequencies that vary with turning speed do not look smeared in the data.
Frequencies that do not vary with turning speed, like electrical line frequency, may look
smeared. A marked frequency is not used for any special data acquisition.
Procedure
1.
Create a job or open Analyze from a route measurement point.
Analyze and Advanced Analyze
MHM-97432 Rev 7 133
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