ITT i-ALERT2, Инструкция по применению

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i-ALERT2 Application Guide 16 of 64
Some general limitations to keep in mind when selecting machinery are:
• The i-ALERT2 monitor is designed to measure casing vibration, so machines with sleeve/fluid-film bearings are
inherently not going to be as good a fit due to attenuation of the shaft vibration via the fluid-film. Now that
does not mean i-ALERT2 cannot be used for sleeve bearing machinery, only that the casing vibration measured
will not reflect the true shaft vibration amplitudes.
• The upper and lower frequency cutoffs for the i-ALERT2 devices are 1000 Hz and 10 Hz respectively. Just as
with any condition monitoring instrumentation, it is recommended that the machinery shaft speed and
primary potential fault frequencies fall within this range. For diagnostic purposes, you want to be able to see
more than just the shaft speed and ITT recommends a minimum frequency range of 10x the shaft speed, AKA
the first order. This translates to an effective upper limit on shaft speeds of 6,000 RPM. It can be applied on
higher speed machinery, but the upper frequency cut off will limit its usefulness in that application.
WHERE TO START?
I. Bad Actors. Start with the “bad-actors” list. All plants track their worst performing assets to one degree or
another. (High maintenance cost and effort, low availability, etc.) The reasons for the poor performance
of these assets can be myriad but chances are that one of the reasons they are on the bad actors list is
because not enough information is currently available to diagnose and correct the problems .
Continuous monitoring of vibration and temperature combined with any available process control data
can go a long way towards helping the proactive reliability engineer eliminate the sources of a bad actors
poor performance.
Equipment Type Good Limited
Centrifugal Pumps
Positive Displacement Pumps
Electric Motors
Fans / Blowers
Paper Machine Bearings
Centrifugal Compressor
Reciprocating Compressors
Low Speed
Limitations
Engines
Steam Turbines
Casing
Temperature
Gearbox / Reducers
Mesh
Frequency
Table 3: Recommended machinery applications for i-ALERT2 (Note: Shaft Speeds
must be greater than 600 RPM)