Rockwell Automation 1441-PEN25-Z Enpac 2500 Data Collector - Manual (Page 75)

Rockwell Automation Publication GMSI10-UM002D-EN-E - August 2012 75
Setting Up Measurements Chapter 2
Order Normalization for Orders Track Spectrum
There are two requirements for implementing Orders Track measurements. The
Fmax value must fall within the range of 10…5000 Hz, and the machine speed
may not vary by more than 10% during the measurement collection. For example,
if you set up a machine that runs at 3500 RPM for an Fmax of 100 Orders, the
measurement will not work because the required Fmax is 15,000 Hz.
To Set Up Orders Track FFT Collection
The Enpac supports the specification and collection of a spectrum with an Fmax
defined in terms of number of orders for a varying machine speed. For Orders
Track data collection, you are required to use a trigger to continually determine
machine speed.
With orders tracking, the sampling rate is not fixed during the collection period.
Instead, the time spacing between the samples may be constantly varying so that a
fixed number of samples per shaft revolution is collected. The x-axis of the time
waveform is no longer measured in seconds, but instead it is measured in degrees
or shaft position. From this, the corresponding spectral information is no longer
measured in Hz or CPM, but instead it is measured in orders. Orders tracking
removes all non-synchronous frequencies from the spectrum.
To set up route points using Orders Track collection, follow these steps.
1. Create a collection specification in Emonitor that uses Orders for the
maximum frequency (Fmax). Also, check the Order Normalization
checkbox to signify Orders Track to the Enpac.
2. Create a Spectrum measurement definition that uses the Orders Based
collection specification.
3. Tag that measurement and load it to the Enpac with a list.
Orders Track