BS ISO 8528-9-2017 pdf free download.Reciprocating internal combustion engine driven alternating current generating sets Part 9: Measurement and evaluation of mechanical vibrations
5 Regulations and additional requirements
5.1 For a.c. generating sets used on board ships and offshore installations which are required to comply with rules of a classification society, the additional requirements of the classification society shall be observed. The classification society shall be stated by the customer prior to placing the order. For a.c. generating sets in unclassified equipment, such additional requirements are in each case subject to agreement between the manufacturer and customer.
5.2 If special requirements from regulations of any other authority, e.g. inspecting and/or legislative authorities, are required to be met, the authority shall be stated by the customer prior to placing the order. Any further additional requirements shall be subject to agreement between the manufacturer and customer prior to placing the order.
6 Measuring devices
The measuring system shall provide the rms values of displacement and velocity with an accuracy of ± 10 % over the range 10 Hz to 1 000 Hz and an accuracy of −20 %/+10 % over the range 2 Hz to 10 Hz. These values may be obtained from a single sensor whose signal is either integrated or differentiated, depending on the outcome of the measuring device, to derive the quantities not directly measured, provided the accuracy of the measuring system is not adversely affected.
The accuracy of measurement is also affected by the method of connection between the transducer and the object being measured. Both the frequency response and the measured vibration are affected by the method of attaching the transducer. It is especially important to maintain good attachment between the transducer and the point on the generating set being measured when vibration levels are high.
7 Location of measuring points and direction of measurements
Figure 1 shows the recommended points of vibration measurement in generating sets. The specifications apply as appropriate for other types of design. If possible, measurements shall be taken at these points in the three main directions, defined by x, y and z.
Figure 1 shows the approximate positions of the measuring points which have to be located on the solid engine block and on solid areas of the generator main body in order to avoid measuring local structural vibrations.
If experience with similar sets has shown at which points the maximum vibration severity is to be expected, not all the points given in Figure 1 need necessarily be measured.
The vertical in-line engine shown is given as an example only. Measuring points 1 to 4 are applicable as appropriate for other types of engine, e.g. V-engines, horizontal engines.
8 Operating conditions during measurement
The measurements shall be taken with the generating set under steady state conditions at its operating temperature and rated frequency at rated power. If the rated power of the generating set is not
attainable, it should be tested at the maximum power that can be attained.
9 Evaluation of results
The main excitation frequencies of the RIC engine are found in the range 2 Hz to 300 Hz. However,when considering the overall generating set structure and components, a range of 2 Hz to 1 000 Hz is required to evaluate the vibration.
Additional testing may be necessary to ensure that no local structural resonances contribute to the measurement result.
Assessment of the potential effects of vibration are made by reference to Table C.1 which gives rms values of vibration displacement and velocity. These values may be used as guidelines for evaluating the measured vibration levels.
Experience has shown that with a standard design of generating set structure and components, damage would not be expected if vibration levels remain below value 1.
If the vibration levels fall between values 1 and 2, assessment of the generating set structure and components may be required along with an agreement between the generating set manufacturer and the component supplier in order to ensure reliable operation.
In some cases vibration levels can be above value 2 but only if individual special designs of generating set structure and components are applied.
In all cases the generating set manufacturer shall remain responsible for the compatibility between each of the generating set components in accordance with ISO 8528-5:2013.
10 Test report
The indicated measurement results shall include the main data of the generating set and the measuring equipment used. These data can be referenced in Annex D to make a record.BS ISO 8528-9 pdf download.