Vibration Sensor for 3250KVA Genset

Where on the genset are you planning to mount the sensor??

Normal engine vibration should be 0.5 in/sec or less... I would set full scale at about 2 in/sec as you can probably run ok even up to 1 in/sec.

From what I understand they would be mounted into the bearing housing. Is this correct?

What is the configuration and which bearing (or bearings)?

The actual generator should run lower vibration than the engine, so levels on the coupling side of the engine will run higher than the generator. In addition it also depends on how the set is mounted. If it is on springs or isolators and the set is small it might make sense to mount to the skid.

Also what are you trying to achieve? Automatic shutdown in the event of a major issue? Or monitoring of the machine condition?

The customer is asking to monitor vibration. At this point it has not been decided what will actually be done with the data. From research I was under the impression the sensor should be mounted as clost to the center of the shaft as possible, hence near each bearing (if possible, I have not seen the unit). I know of some that have been bolted to the top of the generator.

the Generator is mounted on the engine skid and coupled to the engine.

What would you suggest?

I know that you are a specialist and this is the reason I put the question. As as I know and as far as I met sensors for dynamic monitoring they were accelerometers and used either to measure in/s² or mm/s². Am I wrong or is it a more modern way to monitor via the casing velocity?

The natural unit of measure for an accelerometer is g's (multiples of gravitational acceleration) or as you say in/s² or mm/s² However, it is very common to integrate the acceleration signal to velocity and as a result typical acceptance criteria (such as ISO or API) are stated in terms of velocity in/s or mm/s.

The advantage of velocity is that it is much less frequency dependant. 0.5 in/s at 5 Hertz is every bit as bad as 0.5 in/s at 1000 Hz. However with acceleration, the higher the frequency the higher the level of acceptable vibration. 50 g's at 10 Hz would be ripping the machine apart, while 50 g's at 10 Khz would likely be no problem.

Thank you for the explanations.

The most complete monitoring approach would be to mount a sensor at each end of the engine, horizontal on the crankcase just below the cylinders, and at each bearing on the generator at 45 degrees off vertical.

Low cost approach would be to use one sensor either on the frame or on the generator coupling end bearing to be used as a emergency shutdown.

Thanks for all the info. This was a great helpo