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ISO 14839-4-2012 pdf free download

ISO 14839-4-2012 pdf free download.Mechanical vibration Vibration of rotating machinery equipped with active magnetic bearings Part 4:Technical guidelines
vibrations mécaniques — Vibrations de machines rotatives équipées de paliers magnétiques actifs — Partie 4: Lignes directrices techniques.
6 System condition monitoring
6.1 General
Since an AMB relies on transducers for control, the position signals can be applicable for monitoring the working condition. For this reason, it is possible to perform condition monitoring of the rotor more delicately. and the function of a failure diagnosis can be easily given. Since rotation of a rotor without levitation is harmful. a rotation request, e.g. of the motor inverter, is denied by the AMB system as long as the rotor is not levitated.
For AMB-equipped machines, it is common practice to establish operational condition limits. These limits take the form of ALARMS and TRIPS. An ALARM is set to provide a warning that a defined value of condition has been reached or that a significant change has occurred, at which remedial action may be necessary. In general, if an ALARM situation occurs, operation can continue for a period while investigations are carried out to identify the reason for the change and to define any remedial action. A TRIP is set to specify the value of condition beyond which further operation of the machine can cause damage. If the TRIP limit is exceeded, immediate action should be taken to reduce the change or the machine should be shut down.
Other commonly used names for ALARM are WARNING and ALARM1. Other commonly used names for TRIP are ALARM2, FAULT, EMERGENCY STOP and EMERGENCY SHUTDOWN (ESD) (this ESD should not be confused with PLANT ESD for petrochemical applications).
What can be considered as TRIP or ALARM items which detect abnormalities in the diagnostic equipment during operation is explained in 6.2 to 6.10,
6.2 Excess rotor shaft displacement (radial x, v, and axial z)
In ISO 14839-2, typical evaluation zones are defined to permit a qualitative assessment of the shaft displacement.
ALARM limits may vary considerably for individual machines. The values chosen are normally set relative to a baseline value determined from experience for the measurement position or direction for that particular machine. It is recommended that the ALARM limit be set higher than the baseline by an amount equal to 25 % of the zone boundary B/C. If the baseline is low, the ALARM may be below zone C. Where there Is no established baseline (e.g. with a new machine) the initial ALARM setting should be based either on experience with other similar machines or relative to agreed acceptance values. After a period of time, the steady-state baseline value is established and the ALARM setting should be adjusted accordingly. If the steady-state baseline changes, e.g. after machine overhaul, the ALARM setting should be revised accordingly.
The TRIP limits generally relate to the mechanical integrity of the machine and are dependent on any specific design features which have been introduced to enable the machine to withstand abnormal dynamic forces. The values used are therefore generally the same for all machines of similar design and are not normally related to the steady-state baseline value used for setting ALARMS, There can, however, be differences for machines of different design and it is not possible to give more precise guidelines for absolute TRIP limits. In general, the TRIP limit is within zone C or zone 0.ISO 14839-4-2012 pdf free download.

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