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Associate

Join Date: Feb 2010
Posts: 40

Bently Nevada 7200 System Response

05/14/2010 3:48 AM

We have installed Bently Nevada 7200 at our one of the high speed pumps (16000 RPM). Now i want to inquire

1-What is the response time of this system, i.e. if an event happens just in a 3.5 millisec can this event be logged by the system?

2-In how much time signal travels from the proximity probe to the panel?
Moreover also tell me the same for 3300 and 3500, as we can up-rate the system if they have shorter response time.

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Commentator

Join Date: Dec 2007
Location: texas
Posts: 92
Good Answers: 8
#1

Re: Bently Nevada 7200 System Response

05/14/2010 9:11 PM

Hi,

I don't know the answers to your questions.Are you looking for a system with less than 3.5 milliseconds response? and why? I am just curios

Thank you

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Anonymous Poster
#2

Re: Bently Nevada 7200 System Response

05/15/2010 12:08 AM

Although OEM is the right agency to comment on your question but why is such response time demanded. Mechanical failure does not occur all over a sudden. It develops and first alarm comes where it may sound the operator for shut down the machine and examine for likely failures.

The MCMS works on detailed frequency analysis after collection of sample of data. The analysis takes time to publish results. I think it may not be the order of 3.5mSec. But I am not very sure.

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Associate

Join Date: Feb 2010
Posts: 40
#3

Re: Bently Nevada 7200 System Response

05/15/2010 2:11 AM

There are some cases when there are abrupt changes in the system which can cause damage of the normal running machine having close clearances, without any prior indications.

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Anonymous Poster
#4

Re: Bently Nevada 7200 System Response

05/15/2010 11:10 AM

1. 3.5 millisec is a long time in the electrical world, what you need is a SOE, Sequence of Events Recorder, these things timestamp in microseconds and are used for "first out" identification.

2 Electricity (in this case meaning electron flow translated to one in one out) travels near or at the speed of light, 186000 miles per second or 300,000 kilometers per second, do the math

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Anonymous Poster
#5

Re: Bentley Nevada 7200 System Response

05/17/2010 12:44 AM

For 16000 RPM 3.75 milliseconds is one revolution of the pump shaft.

As I recall there was a Bentley Nevada on a high-speed compressor/expander that had a 10 millisecond delay before tripping, and needed to trip within 100 milliseconds from the beginning of acceleration.

The panel should be close enough that the signal gets to the panel in microseconds (even at one third the speed of light), else there is too much noise picked up to be a dependable trip signal. The input amplifier should be slower than the signal propagation, again so that noise does not add trips or delay necessary trips.

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Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
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#6

Re: Bently Nevada 7200 System Response

05/18/2010 5:07 AM

In the process plant control engineering world, "if it happens in less than a second, it isn't real" - Simon McCandlish

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