Hydraulic Turbines

ISO 20816-5:2018 This document provides guidelines for evaluating the vibration measurements made at the bearings, bearing pedestals or bearing housings and also for evaluating relative shaft vibration measurements made on machine sets in hydraulic power generating and pump-storage plants when the machine is operating within its normal operating range. The normal operating ranges for each type of turbine covered by this document are defined in Annex A.
This document is applicable to machine sets in hydraulic power generating plants and in pump-storage plants with typical rotational speeds of 60 r/min to 1 000 r/min fitted with shell or pad (shoe) type oil-lubricated bearings.
NOTE The current database includes machine speeds ranging from 60 r/min to 750 r/min (with a very small sample of 1 000 r/min machines).
This document defines different limit values of bearing housing and shaft vibration depending on the type of turbine, the orientation of the shaft (i.e. horizontal or vertical) and for each of the bearing locations.
This document is based on statistical analysis and provides criteria for the most common types of turbines, pump-turbines and pumps. For specific information on which types of units are covered in this document, see Annex A.
Machine sets covered by this document can have the following configurations:
a) generators driven by hydraulic turbines;
b) motor-generators driven by pump-turbines;
c) motor-generators driven by hydraulic turbines and separate pumps;
d) pumps driven by electric motors.
This document is not applicable to the following unit configurations, parameters and operating conditions:
— hydraulic machines with water-lubricated bearings;
— hydraulic machines or machine sets having rolling element bearings (for these machines, see IEC 62006 and/or ISO 10816‑3);
— pumps in thermal power plants or industrial installations (for these machines, see ISO 10816‑7);
— electrical machines operating as motors except for the use of these machines in pump-storage applications;
— hydro generators operating as synchronous condensers (with the water in the turbine depressed by compressed air);
— assessment of absolute bearing housing vibration displacement;
— assessment of axial vibration;
— assessment of transient conditions;
— non-synchronous operation;
— assessment of vibration of the generator stator core or the stator frame level.
Measurements made of the bearing housing vibration and shaft vibration occurring in machine sets in hydraulic power generating and pump-storage plants can be used for the following purposes:
1) Purpose A: to prevent damage arising from excessive vibration magnitudes;
2) Purpose B: to monitor changes in vibrational behaviour in order to allow diagnosis and/or prognosis.
The criteria are applicable for the vibration produced by the machine set itself. Special investigation is needed for vibration transmitted to the machine set from external sources, e.g. transmitted to the machine via the station foundations.

IEC/TS 62882:2020(E) which is a Technical Specification, provides pressure fluctuation transposition methods for Francis turbines and pump-turbines operating as turbines, including:
- description of pressure fluctuations, the phenomena causing them and the related problems;
- characterization of the phenomena covered by this document, including but not limited to inter-blade vortices, draft tube vortices rope and rotor-stator interaction;
- demonstration that both operating conditions and Thoma numbers (cavitation conditions) are primary parameters influencing pressure fluctuations;
- recommendation of ways to measure and analyse pressure fluctuations;
- identification of potential resonances in test rigs and prototypes;
- identification of methods, to transpose the measurement results from model to prototype or provide ways to predict pressure fluctuations in prototypes based on statistics or experience;
- recommendation of a data acquisition system, including the type and mounting position of model and prototype transducers and to define the similitude condition between model and prototype;
- presentation of pressure fluctuation measurements comparing the model turbine and the corresponding prototype;
- discussion of parameters used for the transposition from model to prototype, for example, the peak to peak value at 97 % confidence interval, the RMS value or the standard deviation in the time domain and the relation of main frequency and the rotational frequency in the frequency domain obtained by FFT;
- discussion of the uncertainty of the pressure fluctuation transposition from model to prototype;
- discussion of factors which influence the transposition, including those which cannot be simulated on the model test rig such as waterway system and mechanical system;
- establishment of the transposition methods for different types of pressure fluctuations;
- suggestion of possible methods for mitigating pressure fluctuation;
- definition of the limitations of the specification.
This document is limited to normal operation conditions. Hydraulic stability phenomena related to von Karman vortices, transients, runaway speed and speed no load are excluded from this document.
This document provides means to identify potential resonances in model test rigs and prototype turbines. Scaling-up resonance conditions are not treated in this document. When resonance exists, the transposition methods identified in this document do not apply. Under these conditions, the relationship between model and prototype pressure fluctuations cannot be determined.
This document is concerned neither with the structural details of the machines nor the mechanical properties of their components, so long as these characteristics do not affect model pressure fluctuations or the relationship between model and prototype pressure fluctuations.

The contents of the corrigendum of August 2000 have been included in this copy.