Power Plant Instrumentation and Control Handbook

2. Vibration and Turbovisory Instruments

2.0. Vibration and Turbovisory Instruments

2.0.1. General Idea of Vibration

• Vibration is an oscillatory motion of the object set in a rotating machine because of the imbalance of forces generated and/or acted upon the machine. Vibration transducers provide, in the control room, the condition of the rotating machine, and prevent the machine to be operated in its danger mode to cause damage to it and or surroundings. Vibration frequencies are an integral multiple of shaft speed. The complexity in vibration measurements arises from distribution of the disturbance in a mechanical system.

• If an external (imbalance) force is applied (see Figure V/2.0.1-1a), then it will be set to vibrate, which will decay. If ...