MaintTech CX20 Manuel de l'utilisateur - Page 2
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FUNCTIONS
Press this key to start the instrument and press again to turn off the
instrument.
The instrument also turns off automatically. The instrument shows
"STOP" after 3 minutes. You have 30 seconds to press any key
(not ON/OFF key). Otherwise the instrument will be turned off.
If the Battery voltage is below 5.5V, the instrument will be shut off.
Press this key to change the measurement between Vibration and
Bearing Energy.
Press this key to stop the measurement.
Press again and the measurement will continue.
When the transducer is mounted with the magnet, the frequency range of the
measurement is reduced to approximately 2000 Hz depending on the flatness of the
measuring surface.
When the measuring tip is used, the frequency range is reduced to approximately
500 Hz.
ISO 10816-3 standard allows some higher limits when a foundation is considered
flexible than when if it is rigid. A conclusion from this is also that a resonant condition
in principle is not allowed or at least should be avoided at operation speeds. In practice
this also includes the double speed as well as any other natural excitation frequency
such as blade passage etc.
Modern machines have high speeds, flexible bearing supports and foundations and can
be considered as flexible even if they are not mounted on rubber or springs.
Group 1: Large machines with
Rated power above 300kW.
Electrical machines with shaft height H>315mm.
Operating speed ranges from 120 to 15000rpm.
Group 2: Medium-sized machines with rated power
above 15kW up to and including 300kW.
Electrical machines with shaft height between
160<H<315mm. Operating speed normally above
600rpm.
Group 3: Pumps with multivane impeller and
with separate driver with rated power above 15kW.
Group 4: Pumps with multivane impeller and with
intergrated driver with rated power above 15kW.
The diagram above is only a guide to interpret the Bearing Energy value.
If vibrations of other causes (flow surge, gear mesh) are within in the frequency
range 3200-20000 Hz, this can give a high bearing condition value without the
bearing being damaged.
A high bearing energy value can also be acquired if the bearing is poorly lubricated
or is overloaded (e.g. by misalignment or belt forces).