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Process Monitoring of Vibrations at Hydro Turbines

Delphin TopMessage System Diagnoses Faults

Delphin Technology recently provided the vibration monitoring solution for Femaris, a Romanian company focusing mainly on providing products and services for measuring and analyzing technical parameters.

Femaris offers complete solutions for the implementation of predictive and proactive machine maintenance, as well as online and offline monitoring of industrial values. This includes static and dynamic balancing of different kinds of rotors, data acquisition systems to record vibrations and noises, and service including training of personnel. CAS DataLoggers, a Delphin distributor, presents this Applications Note showing how Femaris supplied its own customer with a Delphin system to monitor vibrations in hydro turbines.

 

Introduction:

Femaris required a solution for its customer HIDROELECTRICA SA, Romania’s main electrical producer. The company is divided in several branches depending on the geographic area. HIDROELECTRICA has an installed power of 6438 MW and produces approximately 30% of the entire electrical power in Romania. This particular Delphin Vibration Monitoring system was implemented in Hidroelectrica Oradea SA.

 

Application/Problem:

Technicians at Hidroelectrica noticed a suspect sound originating from the generator of a turbine, a sound believed to be caused by vibrations at a hydro turbine within their plant. Because of this situation they required vibration measurement. To discover the source of this sound, their main objective was to install an easily-configurable real-time portable monitoring system to increase the safety conditions and improve fault prediction.

Besides this, the system had to be modular so that it could be extended in the future, for example to make absolute vibration measurements with piezoelectric accelerometers.

The customer decided to install a Delphin TopMessage Data Acquisition and Control system along with Delphin ProfiSignal software to monitor the following parameters:

  • Global vibration – peak-to-peak displacement
  • FFT analysis
  • Smax parameter
  • Orbit
  • Trend analysis etc.

 

Technical Conditions:

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: Radial 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] for the distance between the sensor and shaft

Analysed machine: Hydro turbine Vertical Kaplan, 10 MW power.

Monitored journal bearings:  Turbine bearing – LT

Inferior radial bearing – LRI

Axial radial bearing – Lrax

 

Solution/Hardware:

For this application Femaris recommended the following components:

  • Delphin TopMessage Master device
  • AMDT Module (enables shaft/bearing vibration monitoring & analysis)
  • Voltage divisor
  • Proximity systems – Transducers with conditioner
  • Delphin ProfiSignal Basic software

 

Here the necessary vibration measurements were performed with proximity systems 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° 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 presented electrical or mechanical faults. The figure below shows the system mounted in the electrical panel.

The software used for fault diagnostics are ProfiSignal Basic and ProfiSignal Vibro.

Following the vibration measurements, it was 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 software tracks the relative vibrations at different turbine loads.

 

Proposal/Hardware:

Following this vibration diagnosis, the data recommended that users check the fixation mode of bearing LRI onto the foundation, the state of the bushing, and also the mechanical looseness inside the bearing.

While checking bearing LRI, the repair team found that the nuts which adjusted the looseness in the bushing (Y direction) were all destroyed, as well as the thread on the bolts.

The absolute vibration measurements were taken with accelerometers using a portable analyzer, and the highest vibrations were recorded on the radial axial bearing LRAx, while on the inferior radial bearing the vibrations amplitudes were small.

In conclusion we can say that the machine diagnosis of those machines which have journal bearings in their assembly 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 machine’s bearings. For this purpose the TopMessage system was ideal here and the customer was very satisfied post-installation.

 

Benefit Summary:

The advantages of vibration monitoring using the Delphin TopMessage system and the Profisignal software are as follows:

  • Simultaneous monitoring of vibration amplitudes on all the bearings of the machine
  • The possibility of extending the system for on-line monitoring and other technical parameters needed for machine diagnosis
  • The creation of virtual channels to calculate looseness in the journal bearings
  • The possibility of copying the measured data – amplitude 1x and phase 1x – in a balancing program which allows balancing–in situ, static and dynamic–of the rotors.
  • Precession movement simulation of the shaft within the journal bearings.
  • Data transmission and storage within the TopMessage device and on the hard disk of a computer.
  • The ability to connect vibration transducers with an output of 4-20 mA as an economical solution for vibration monitoring
  • The increase in safety conditions and the prevention of machine damage with the help of the Alarm Management software and the TopMessage system’s analog and digital outputs.