DETECTION OF ROUGH LOAD ZONE IN 
FRANCIS TURBINES 
 
 
A.S. Kalansooriya. 
M.Eng 
 
 
 
 
Department of Electrical Engineering 
University of Moratuwa 
Sri Lanka 
 
2004 
 
82484 
 
 
 
 
 
 
 
 
 
 
  
Abstract 
 
Mostly in multi disciplinary hydropower machines runner cavitations occur due to 
the operation in partial loads and running closer or below minimum operating level. 
That is operation in rough zone. In Francis turbines it is visible in the edges of the 
runner and draft tube. The damages to the above makes not only the replacement 
cost, also the down time cost and hence water release to irrigation without producing 
power. 
 
Considerable interests have been shown over years in prevention of runners from 
cavitations through condition monitoring. It has been demonstrated that investment 
in equipment to monitor the state of health of machinery can reduce down time, 
improve efficiency and enhance safety, thus producing great economic as well as 
social benefits. 
 
This study basically discusses the process of vibration-based elimination of rough 
zone using Microlog CMVA 60 portable data collector and PRISM4 data analyzer. 
This data collector is basically developed to analyze general bearing related problems 
in small and medium size rotating machines. 
 
It is expected that the research work followed by the proposed design will result a 
greater benefit in the long run. 
Table of Content 
1 . . . Dec arat1on .... . ... ... .. .. .. .. .................................... .. .. . .. . .. . .. . ... .... u 
Abstract.. ................................. . ... . .. . ... . .. .. .... ... . ................. 111 
Ack.nowledgement.. .. . . .. . . . . . . . .. . . . . . . .. . ... . . . . . . . . . .. . . . .. . . .. . .. . . .. . . . . . . .. 1v 
List of Tables............... . ..................................................... v1 
List of Figures . . .. . .............................................................. . . vu 
1.0 introduction .... . .................................... ······;~······· ............. 01 
1.1 Background ................................................................... 04 
1.2 Motivation .. .. .... . ... . .. . .................................................... 04 
1.3 Goals .......................................................................... 06 
1.4 Achievement ................................................................. 06 
2 Problem Identification .. . .. . .. . .. . .. . ..... . .. . ... . ... .. ......................... 07 
3 Proposed Solution ............................................................... 20 
4 Theoretical development ...................................................... 26 
5 Measurement of Shaft Vibration (Microlog CMV A60 System) .......... 28 
5.1 Design ................................................ . ... .. ... .. .. . ........... 30 
6 Results ....................... . .. . ..... . .. . .. . .. . . ·~· .. .. .. ... . ..................... 35 
7 Conclusion ......... .. ... . .. .... . .. .. ... . .. . ...................................... 40 
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Declaration 
I hereby declare that the work presented in this report is my own and not has 
been submitted earlier or concurrently for any other degree. 
Name: .. h. .  '5. ·. ·tl~·<?. R r:•.!f.' ... · ... ....... .... .... .................. . 
Signature:-:$. ........ cy: ................................... .......... . 
Date: . ..... 1 ~ J•. ~.l ?7?~ .'-f-. ......................... .. .. ... .. .. ............ . 
j 
I certify that this work was supervised by me and that the above declaration 
is true. 
Name: .... J?::: ... ~~.~ .~ ..... '0.dC~-w .:::-.it'-
Signature: .... .. . :-: ... ·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·.·. 
Date: ....... ~!. .. ~~: .. : . ~.~ :1. ................... ... .. ..................... . 
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Acknowledgement 
I would like to express my deep appreciation and gratitude to my supervisor, 
Dr. Lanka Udawatte, Lecturer in Department of Electrical Engineering, 
Faculty of Engineering, University of Moratuwa, Sri Lanka, and the former 
supervisor Dr. J. Peiris, Lecturer in Department of Electrical Engineering, 
Faculty of Engineering, University ofMoratuwa Sri Lanka, for providing me 
valuable advice and guidance at every stage during this study and during this 
thesis writing. 
/ 
I deeply appreciate the assistance and encouragement given by Mr. A.K. 
Samarasinghe Chief Engineer (Electrical and instrumentation), Mahaweli 
Complex, Ceylon Electricity Board. 
I wish to extend my sincere thanks to Mr. P.G.P. Indrasiri, Chief Engineer 
Randenigala power station, and Mr. E.M.U. Ekanayake, Mr. M.G. 
Weerakoon, Mr. R. M. H .K. Karunaratne, and Mr. B.A.J. Kithsiri electrical 
engineers of Randenigala power station and Mr. M. Tissera, Electrical 
superintendant Randenigala power station, without whom I would not have 
been able to successfully complete this study. 
Also I should specially thank Mr. B.A.P.T.K. Perera Electrical 
Superintendent Randenigala power station for designing current driver 
circuit and assisting me in assembling and fixing the equipment and SUW2Qn 
.... 
rendered during taking the measurements and supervising the construction of 
fixing equipment. Finally , I express my appreciation and gratitude to my 
IV 
parents, wife and two daughters for the support given to me throughout this 
period. 
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List of Tables 
Table 1.1 Classification ofTurbines 
Table 2.1 Vortex turbulence level 
VI 
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Page no. 
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02 
18 
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List of Figures 
Page no. 
Figure 1.1: Francis Turbine 03 
Figure 2.1: Runner Cavitations 08 
Figure 2.2: Apparatus set up to measure vibration 09 
Figure 2.3a: Frequency spectrum load at 0 [MW] / 10 
Figure 2.3b: Frequency spectrum load at 2.5 [MW] 10 
Figure 2.3c: Frequency spectrum load at 5 [MW ] 11 
Figure 2.3d: Frequency spectrum load at 7.5 [MW] 11 
Figure 2.3e: Frequency spectrum load at 10 [MW] 12 
Figure 2.3f: Frequency spectrum load at 12.5 [MW] 12 
Figure 2.3g: Frequency spectrum load at 15[ MW] 13 
Figure 2.3h: Frequency spectrum load at 17.5 [MW] 13 
4 • 
Figure 2.3i: Frequency spectrum load at 20 [MW]· 14 
Figure 2.3j: Frequency spectrum load at 22.5 [MW] 14 
Figure 2.3k: Frequency spectrum load at 25[ MW ] 15 
..... 
tC" 15 Figure 2.31: Frequency spectrum load at 27.5 [MW] 
/ 
Figure 2.3m: Frequency spectrum load at 30 [MW] 16 
Figure 2.3n: Frequency spectrum load at 32.5[MW] 16 
Vll 
Figure 2.3o: Frequency spectrum load at 34[MW] 
Figure 2.4:Load Vs. Vortex turbulence Vibration 
Figure 3.1: Vortex Turbulence 
Figure 3.2: Designed circuit with vibration indicator 
Figure 3.3 :Components of designed circuit. 
Figure 5.1.1: High pass RC filter. 
Figure 5.1.2: Active band pass filter 
Figure 5.1.3: Unit gain buffer circuit. 
Figure 5 .1.4: Rectifier circuit. 
Figure 5.1.5: Peak detector circuit 
Figure 5.1.6: Current converter circuit. 
Figure 5.1.7: Total designed circuit. 
Figure 6.1: Fixing of probe 
Figure 6.2:The designed circuit 
Figure 6.3: the display for the operator 
Figure 6.4: Frequency response of the circuit 
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