Reliable green electricity with Condition Monitoring

Turbine hall with three salient pole synchronous generators
Figure 1: Turbine hall with three salient pole synchronous generators

Stadtwerke München (SWM), Munich’s municipal utility, operates several hydro-electric power plants on the Isar River and its lateral channels for the renewable power generation. These include the run-of-the-river power plant Isarwerk 1, which was taken into service over a century ago in 1908 as a municipal power station with three double Francis turbine-generator units. Three salient pole synchronous generators convert the kinetic energy into 3x 800 kW of electrical
power and supply around 5500 house holds with renewable energy.

Mechanical changes on the shaft can be recognized without delay

Displacement sensors were installed at the critical location where the drive shaft meets the turbines
Figure 2: Displacement sensors were installed at the critical location where the drive shaft meets the turbines

After undertaking numerous constructional maintenance projects over the last several years, SWM now wanted to ensure that the Isarwerk 1 power plant would continue to economically generate electricity in the future and could operate according to the recognized standards of good practice. For this purpose, SWM decided to retrofit the plant with a shaft vibration monitoring system.

In advance, specialists from PRUFTECHNIK Condition Monitoring GmbH examined the situation on-site to determine how changes in the mechanical condition of the shaft could best be detected as soon as they occur. Their diagnosis revealed that the gradual formation of cracks on the shaft was resulting in a change in the shaft curvature. This change can be monitored by measuring the shaft orbit, which changes its shape as cracking occurs.

PRUFTECHNIK Condition Monitoring was then contracted to install an online Condition Monitoring system for monitoring the three drive shafts.

The switch cabinet components of the VIBGUARD online system
Figure 3: The switch cabinet components of the VIBGUARD online system

These  VIBGUARD features along with a very friendly price-performance ratio and a team of experts with a wealth of experience in the field of vibration, ultimately convinced SWW. Moreover, the utility company was able to verify the reliability of PRUFTECHNIK systems on the basis of existing PRUFTECHNIK online monitoring systems already in operation.

The VIBGUARD real-time monitoring system was selected from the PRUFTECHNIK range of online systems. PRUFTECHNIK developed this equipment to monitor critical systems with highly dynamic motion and frequent load  changes, and for situations in which it is necessary to monitor multiple measurement locations in parallel and continuously.

The monitoring system in detail

  • Orbit measurements at two measurement locations per machine
    • Measurement location 1 at the front compression seal fitting (location with the greatest wear)
    • Measurement location 2 at the compression seal fitting across from it (behind the first turbine)
  • The position of the guide vanes is fed in as a 4–20 mA signal

  • Warning and alarm messages via digital outputs if the thresholds are exceeded

  • Global alarm with emergency switch-off for machine 1

  • Global alarm with emergency switch-off for machine 2

  • Global alarm with emergency switch-off for machine 3

  • Global warning for all three machines

  • Central data archiving, trend evaluation/diagnostic evaluation/reporting on the included PC using the VIBGUARD VIEWER software

 

 

SWM employees at Isarwerk 1 can now track the input shaft condition in real-time and are notified about anomalies without delay.

With its technology and know-how, PRUFTECHNIK has thereby contributed to ensuring the continued operation of Isarwerk 1 for many years to come.

 

 

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