Journal of Vibroengineering, Vol. Received 29 September ; received in revised form 23 November ; accepted 1 December ; published 30 December Machines that generate vibroacoustic processes are tested at every stage of their life cycle. Many years of research, whose results and conclusions are contained in the standards give a good methodological tool to assess the state of machines.
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Vibration assessment aims to ensure reliable and safe operation of a machine, based on evaluation of the machine operating state by means of vibration measurements. Solutions for diagnostic condition monitoring of components such as roller bearings and gear units are described separately below. The scope of this standard includes steam turbines up to 50 MW, electric motors and fans. Because the scope is quite wide, the standard is explained in more detail below. The standard aims to classify the machine state in four different classes by means of vibration data for acceptance measurements and operational monitoring.
Assessment criteria according to the standard are the RMS value of the vibration velocity and the RMS value of the vibration displacement. Usually it is sufficient to measure the vibration velocity. The additional evaluation of the vibration displacement is recommended if low frequency components are encountered. If both vibration parameters are logged and analyzed, the poorer of the two determined classes is applied.
Suitable measuring points are characterized by the fact that they reflect the dynamic forces of the machine as purely as possible. For example, locations where local resonances occur are not suitable. Suitable locations tend to be bearing stands and bearing covers; measurements are usually carried out in two orthogonal directions. The classification also takes into account the machine substructure, subdivided into rigid and elastic substructures.
This evaluation should be carried out separately for each measuring direction two orthogonal directions, see above. The implementation of the described vibration assessment according to ISO is implemented in two examples.
Vibration assessment. A number of standards exist for assessing machine vibrations, including the following:. This standard consists of several parts. The frequency range of the vibrations to be captured depends on the machine speed:.
Machine group. Zone A. The vibrations of recently commissioned machines tend to be in this zone. Zone B. Machines with vibrations in this zone are usually regarded as suitable for continuous operation without restrictions. Zone C. Machines with vibrations in this zone are usually regarded as unsuitable for continuous operation.
The machine may generally be operated in this state for a limited period, until a suitable opportunity for remedial measures arises. Zone D. Vibration values in this zone are usually regarded as dangerous in the sense that damage to the machine may occur. Machine group 1. Large machines with a rated output of kW to 50 MW and electrical machines with a shaft height of more than mm. Machine group 2.
Medium-sized machines with a rated output of 15 kW to kW and electrical machines with a shaft height between mm and mm.
The main target of condition monitoring and machinery protection systems is to ensure the health and continuous operation of the plant machinery. In this regard vibration measurement systems along with vibration transducers are installed for continuous measurement and analysis of machine vibrations. To this end users need a reference to compare machine vibration with it to evaluate the state of each machine. ISO provides a reference like allowable vibrations and alarm or trip conditions for various machinery based on some statistical analysis of historical data gathered by ISO TC
ISO 10816-1:1995/Amd 1:2009