SKF Microlog GX Series - Measurement Overview

Idler Sound Monitor Module
Overview
Measurement Overview
Using advanced condition monitoring measurement methods, the Idler Sound Monitor
“listens” to each roller’s sound and simultaneously applies four acoustic measurements
that are preset to best detect idler faults for typical conveyor conditions. These
measurements are set up to only monitor the types of sound emitted by conveyor idler
rollers; they filter out other unwanted sounds.
The four Idler Sound Monitor measurements are overviewed in the chart below:
Measurement Detects Type of Idler fault
Acoustic Enveloping (PaE)
true peak overall
Impact type vibration Damaged bearing
Lack of lubrication
Contamination
Acoustic Enveloping (PaE)
Root Sum Square (RSS)
Overall
Overall magnitude of
impact vibration
Damaged bearing
Damaged idler can / shell
Kurtosis Whether acoustic signal
is a hiss, crackle,
rumbling
Rubbing metal-on-metal
Seized bearing
Seal failure
Idler can / shell rubbing on
shaft
Belt abrasion (rumbling)
Harmonic Activity Indicator
(HAI)
SKF patented technology
Bearing harmonic
activity. Provides
earliest indicator of
impact type faults.
The greater the harmonic
activity, the more severe
the bearing damage.
Each of these four measurements is preset with a single alarm threshold that is set at a
level to indicate faulty idler condition for typical conveyor situations.
• If any one (and only one) of the four measurements results in alarm, the Idler
Sound Monitor’s indicator turns yellow to indicate a “suspect” idler. In this case, the
idler is marked as suspect and typically double-checked on the next conveyor
survey.
• If two or more of the measurements result in alarm, the indicator turns red to
indicate a “bad” idler. In this case, the idler roller is typically marked for
replacement.
If an idler roller is indicated as suspect (yellow) or bad (red), in addition to the device’s
traffic light indicator display, an audible alarm tone is sent to the headphones, allowing
the operator to hear as well as see the indication of problem idler rollers.
When such an indication occurs, the operator can choose to appropriately mark the idler
frame with a piece of chalk, etc., or press the Idler Sound Monitor’s Notes function
button to pause data collection while he enters a short note referencing the suspect/bad
rollers’ numeric identifier.
SKF Microlog - GX Series 11 - 3
User Manual