Rockwell Automation 441-PEN25 Enpac Ex Data Collector - Manual (Page 60)

Publication GMSI00-UM001A-EN-E - February 2005
54 Setting Up Measurements
Order normalized spectra in the Enpac Ex
• Order normalized spectrum measurements have a frequency axis based
on multiples of the running speed (orders). This quickly identifies the
frequency relationship between each measured vibration amplitude and
the running speed of the machine. It is particularly useful on variable
speed machinery.
• An order normalized spectrum measurement requires a trigger input to
the Enpac Ex.
• Set up a Collection Specification with Window set to "Rectangular."
Select the Maximum frequency in "Orders," and make sure to select
the Order normalization option. The Averaging can be either "linear"
or "time synchronous," but should include at least four averages.
• The Enpac Ex may collect more orders than required. For example, if
you set the Maximum frequency to "10 Orders," the Enpac Ex may
collect more than ten orders. The Enpac Ex always collects at least the
number of orders you request in the Collection Specification.
• The Enpac Ex displays an order normalized spectrum. If the
Collection Specification dialog box has the Also collect phase check
box selected, and if the Maximum frequency is eight orders or less, the
table on the Enpac Ex screen shows the magnitude and phase values at
each order. If the Collection Specification dialog box does not have
the Also collect phase data check box selected, or if the Maximum
frequency is more than eight orders, the table on the Enpac Ex screen
shows magnitude values only. The Enpac Ex displays a maximum of
eight orders in the table.
If the table has eight orders or less, the Enpac Ex arrow keys move the
spectrum cursor. If the table has more than eight orders, the Enpac Ex
arrow keys scroll the table values.
Spectrum alarms in the Enpac Ex
The Enpac Ex supports band alarms with up to ten bands.
• You can have the data collector collect a spectrum measurement if a
magnitude alarm is in alarm. Set the Collect and store condition in the
Edit Storage Specification dialog box to "On Magnitude Alarm" for
the storage specification for the spectrum measurement definition.
WARNING
Do not connect the Enpac Ex to an external trigger unless
the area is known to be nonhazardous.