Among the potential harmful conditions for turbogroups, torsional vibration is one that is generally overlooked. Because it can lead extremely quickly to dramatic failures, effective protection systems must be able to react within seconds.
TORSO, ENGIE Laborelec’s torsional vibration monitoring system for turbo-groups, tackles this issue effectively and brings peace of mind back to your condition monitoring strategy.
An understated but real enemy
Although the risk of damage due to torsional vibration is generally well assessed at the design stage of a power generation system, later adjustments to the shaft line, or modifications to the external power system, can create the perfect conditions for certain phenomena to develop. These conditions include sub-synchronous resonance or interactions with high voltage DC stations which, in turn, lead to excessive levels of torsional vibration. In most operational environments, this specific type of vibration is not tracked, even though it can abruptly lead to heavy damage such as shaft cracking, blade loss or gearbox failure.
TORSO keeps the installation safe
Using specific sensors, easily mountable on toothed wheels or on shaft ends, TORSO protects the shaft line from the effects of harmful torsional vibration. It rapidly detects when this reaches pre-defined thresholds, and trips the unit before severe damage can occur.
What is torsional vibration?
Torsional vibration is angular vibration of an object—commonly a shaft along its axis of rotation. It is superposed to the static torsion and occurs at the frequency of the torsional excitation. It may coincide with the shaft’s natural frequencies. Torsional vibration is often a concern in power transmission systems using rotating shafts or couplings where it can cause failures if not controlled.
- EASY TO INSTALL. Adjustable and easy to install on the most commonly-encountered types of machines.
- OPTIMISED ALARM STRATEGY. Unique, intelligent strategy for triggering alarms and tripping.
- MONITOR & DIAGNOSE. Historical data available for further analysis and troubleshooting.
- NOT A BLACK BOX. Open system allowing power plant staff to visualise and work with data.
- VERSATILE. Available for both permanent and temporary monitoring.
Mounting of a sensor at the turbine – generator coupling
Typically, between 1 and 3 well-positioned sensors are sufficient for the system to offer full protection. Our experts can advise on the most appropriate sensor locations, since these are machine-specific. In addition, existing speed sensors can be used in most cases.
How it works
Initial modelling of the shaft line
Installation and validation
Diagnosis of specific issues
The need for modelling
Each specific machine is different and vibrates in a slightly dissimilar way. Critical locations where material damage is most likely to occur are precisely calculated due to TORSO’s underlying theoretical shaft line modelling.
Finding the right alarm thresholds
Alarm thresholds set too high will lead to undetected excessive torsional vibration and severe damage. However, excessively low thresholds can generate a large number of unwanted alarms. The model behind TORSO makes it possible to calculate precise thresholds, and determine a safe middle course.