Problem with tachometer fluctuations
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We have a turboexpander here, and the tachometer on it shows speeds ranging from 0 to 30,000 revolutions per minute. Once the speed exceeds 20,000 revolutions per minute, there are fluctuations, and these fluctuations are quite significant – they can range from 20,000 to around 25,000 revolutions per minute. Could everyone please help analyze this situation?
It depends on what speed measurement method you’re using; could it be that data is being lost? This speed is high enough.
I think, first of all, the speed range of this expander is too small. If its normal rated speed is 20,000, then its range should be 0–50,000. Additionally, the speed signal is a pulse signal, and strict requirements are placed on shielding
Well, the shielding issue you mentioned is quite possible indeed; thank you.
There are various factors contributing to the large fluctuations in the speed of the expander: 1. Malfunctions in the speed detection system, 2. Oscillations in the expander’s return valve, 3. Oscillations in the expander’s nozzle control valve. The fault needs to be checked part by part.