ISO 7919-5:2005. Mechanical vibration, Evaluation of machine vibration by
measurements on rotating shafts. Part 5: Machine sets in hydraulic power
generating ...
Title of Application Note: Process Monitoring of Vibrations at Hydro Turbines
Introduction: The customer is HIDROELECTRICA SA, which is the main electrical producer with the help of hydro turbines. The company is divided in several branches depending on the geographic area. HIDROELECTRICA has the installed power of 6438 MW and it produces approximately 30% of the entire electrical power produced in Romania. The system of Vibration Monitoring was implemented in Hidroelectrica Oradea SA. Application / Problem: For the vibration monitoring at hydro turbines and generators, the customer decided to install a Delphin TopMessage with ProfiSignal to monitor the following parameters: ¾ ¾ ¾ ¾ ¾
Global vibration – peak-to-peak displacement FFT analysis Smax parameter Orbit Trend analysis etc.
The main objective is to install an easy to configure real time portable monitoring system used for increasing the safety conditions and the prediction of faults. Technical condition The measurements were done according with the following standards: ISO 7919-5:2005
Mechanical vibration, Evaluation of machine vibration by measurements on rotating shafts. Part 5: Machine sets in hydraulic power generating and pumping plants ISO 10817 Rotating shaft vibration measuring system Measurement direction: Rafial on two directions X – Y with two proximity transducers mounted at 90 Measured parameters: relative vibration of journal bearing Measuring unit: peak-to-peak displacement of vibration [µm] The distance between the senzor and shaft Analysed machine: Hydro turbine Vertical Kaplan with the power of 10 MW. Monitored journal bearings: Turbine bearing - LT Inferior radial bearing - LRI Axial radial bearing – Lrax 1
Proposal / Solution / Hardware: The customer has observed a suspect sound at the generator of one turbine, sound which is believed to be caused by vibrations at a hydro turbine within the plant. Because of this situation a vibration measurement was done using the TopMessage system. For this application we recommended the following components: ¾ ¾ ¾ ¾ ¾
TopMessage Master device AMDT Module Voltage divisor Proximity systems – Transducers with conditioner ProfiSignal Basic
The scheme for the monitoring system is presented in Annex 1. The vibration measurements were done with proximity systems which were mounted on all three journal bearings of the turbine. Two transducers were mounted on each journal bearing, with a radial direction and at an angle of 90 degrees between them. The TopMessage system was mounted within an portable electric panel. The customer requested that the system must be portable to be mounted on different hydro turbines that present electrical or mechanical faults. Beside this, the system had to be modular so that it could be extended in the future, for example: for making absolute vibration measurements with piezoelectric accelerometers. The figure below shows the system mounted in the electrical panel.
Figure 1 - The TopMessage system as a portable system
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The software used for fault diagnostic is ProfiSignal Basic and ProfiSignal Vibro. Following the vibration measurements it has been established that the operating mark is UNALLOWED according to ISO 7919. The vibration diagnosis indicated a misalignment of the turbine’s shaft, but this offsetting is caused by the instability of the inferior radial bearing LRI, practically an increased mechanical looseness inside this bearing having the Y direction. The figures below present the scheme of the turbine, trend analysis, orbit and FFT in the ProfiSignal software
Figure 2 – The scheme of the Kaplan turbine
Figure 3 – Tracking the relative vibrations at different turbine loads 3
Figure 4 – The shaft orbits within the journal bearings
Figure 5 – FFT analysis recorded on the bearings, X and Y direction The measurement bulletin is presented in Annex 2. 4
Following the vibration diagnosis it was recommended checking the fixation mode of bearing LRI onto the foundation, the bushing state and the mechanical looseness inside the bearing. While checking bearing LRI, the repair team that the nuts that adjust the jocul in the bushing, Y direction, were destroyed, as well as the thread on the bolts. We must point out that absolute vibration measurements were done with accelerometers using a portable analyser and the highest vibrations were recorded on the radial axial bearing LRAx, and on the inferior radial bearing the vibrations amplitudes were small. In conclusion we can say that the machine diagnosis which have in their assembly journal bearings are done more precisely if the vibration measurements are done with proximity transducers and are acquired using the on-line mode, simultaneously on all the bearings of the machine. For this purpose the TopMessage system was one to be appreciated and our customer was pleased. Summary of Benefits: The advantages of vibration monitoring using the TopMessage system and the Profisignal software are as follows: ¾ Simultaneously monitoring of vibration amplitudes on all the bearings of the machine ¾ The possibility of extending the system for on-line monitoring and other technical parameters, except vibrations, needed for machine diagnosis ¾ The creation of virtual channels for the calculation of jocurilor in the journal bearings ¾ The possibility of copying the measured data – amplitude 1x and phase 1x – in a balancing program which allows the balancing, in situ, static and dynamic of the rotors. ¾ The precession movement simulation of the shaft within the journal bearings ¾ The transmission with ease of the remote measured data and the storing of these both within the TopMessage device and on the hard disk of a computer. ¾ The possibility to connect vibration transducers with an output of 4-20 mA as an economical solution for vibration monitoring ¾ The increase in safety conditions and the prevention of machine damage with the help of the Alarm Management software and the analog and digital outputs which the TopMessage system has. For more information please see: DelphinTechnology http://www.delphin.com/
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Annex 1
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Annex 2 MEASURING BULLETIN OF THE GLOBAL VIBRATION LEVEL NO. 1 1. Measurement location: CHE LUGASU – Hidroagregat nr.1 - KVB 9,4-23,2 Machinery characteristics: Power:9,4 MW, Revolution: 214,3 rpm, Nr.of rotor blades: 6, Nr of AD blades: 24, Nr.of axiali segments: 10 Operating regimes: 1. MECHANICALLY EMPTY; 2. EXCITED EMPTY; 3. PARALLEL 25%; 4. PARALLEL 50%; 5. PARALLEL 75%; 6. PARALLEL 100% 2. Measured peak-to-peak values. The measurement parameters is peak-to-peak displacement and Smax Measuring point
X [µm] 290 1750 1210
LRAx LRI LT
Measuremen direction Y [µm] 1204 2153 1330
Smax [µm] 540 960 550
3. Operating mark according ISO 7919-5:2005. Hydro Turbine P > 1 MW peak - peak smax [µm] [µm] < 150 < 83 150 - 250 83 - 140 250 - 500 140 - 270 > 500 > 270
Machine type Measuring untis (peak-peak value, smax) Operating mark
Good Usable Admitted under supervision Unallowed
4. Technical characteristics of the turbine Turbine type KVB
Pnominal [MW] 9,4
n [rpm] 216
Peffective [MW] 5
5. Turbine scheme
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Date
Operating mark
11.04.2011
Unallowed
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