Overspeed Trip Data Acquisition System 1

[mluimes]

Hi,

I currently work for a industrial service company. One of the services we perform is testing refurbished turbine overspeed trip shafts prior to returning to service. Yet proven over the years, the current, 30+ year method of testing the units is losing confidence with our client’s young engineers.

Before I dive into this I was wondering if anyone was aware of an off the shelf systems, or a data acquisition module that is able to both chart and record shaft tact and trip points.

Thanks,

 

[pwrengrds]

I like the DATAQ electronic chart recording equipment for high speed information gathering.

http://www.dataq.com/

 

[byrdj]

what type of testing are you doing?
the most I have seen performed in service and in shop is to measure speed with a prox probe/tooth wheel digital tach (confirm its readout near tripping speed with calibrated strobe) and then slowly bring the speed up to trip. the trip in the shop is EASILY determined by sound, since the shaft goes out of balance at trip. two people observing the digital tach and remembering the readout they each saw when trip should be good enough. I found this to well accurate to +/- 1 rpm. I guess for improved "documentation" an event recorder that captures the trip speed, but then some type of triggering swtich would be needed.

The inservice testing is nearly the same, but instead of hearing the unbalance of the shaft, you hear the valves trip closed.

the testing I have not seen performed, would be the determination of acceleration induced drift. that is to compare the "test trip" speed from above with the trip speed if the accceleration is similar to what would occur in service, ie from rated at 10%/sec. For this test a high speed data logger and trip sensing switch.

The BIG problem I've found with shop testing verses inservice testing is the deviation in trip values due to the envorimental diffeances. I was recently caught in the middle where the turbine owner expected the shop value to be exactly the same as the inservice test value. The shop was real awary such devations occur and tried to compensated by heating and spraying with oil. However I observed that a method to negated would invlove the owner providing a series of prevous actual trip speeds before the shaft is sent to the shop. the shop then record their as found trip speed and this enviromental influence devation be used to set the as left shop value