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On-Site Balancing Study of 160MW Skoda Steam Turbine

Problem Detection:


Trip due to high vibration

  • The customer requested support from the Resonance Institute technical team due to the high vibration problem experienced in the steam turbine.

  • Measurement and on-site balancing were performed on a 160MW Skoda turbine.

  • Constant 3000 RPM, variable load

  • Due to high shaft vibration in the LP rotor bearings, the equipment trips before reaching full cycle.


  • The data collected during the first acceleration phase was examined and it was understood that the shaft sensors in the LP bearings caused the trip condition.​

  • It has been diagnosed that the condition causing the high vibration in the data received with these sensors is the “Unbalance” problem in the LP rotor. High vibration values are achieved as a result of the unbalance driving the 1st critical speed of the LP rotor.

  • It was decided to apply the in-situ balancing procedure (modal balancing at the 1st critical speed).


Trip due to high vibration

Possible counterweight insertion zone



Correction weights are evenly distributed on planes 1 and 2

Plane 1&2

  • Correction weights are evenly distributed on plane #1 and plane #2 (rotor front and rear planes).

  • Correction weights are proportionally distributed to approximately 0°  degree (hole 1) and surrounding holes

  • A total of 2-3kg of correction weight has been added to the two planes.


  • In the acceleration test performed after removing the correction weights, it was observed that the vibration levels decreased from 200 micron Pk-Pk value to ~80 micron Pk-Pk value.

  • Since the vibration levels in the final state are acceptable for the customer, the on-site balancing work has been terminated at this point.

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