Sign up Calendar Latest Topics Donate
 
 
 


Reply
  Author   Comment  
OLi

Sr. Member
Registered:
Posts: 1,914
Reply with quote  #1 
If I have a couple of hi temp hardline accels called "velometers" on the hi temp brg. on a gasturbine and a couple of "accels" from generator and low temp brg. connected to a Bently rack, what sensitivity do you think I would expect on the front BNC connectors?
__________________
Good Vibrations since early 1950's, first patented vibrometer 1956 in the US.
http://www.vtab.se
fburgos

Sr. Member
Registered:
Posts: 670
Reply with quote  #2 
Same as your accelerometer
OLi

Sr. Member
Registered:
Posts: 1,914
Reply with quote  #3 
Thank's just to check the numbers on the sensors then.
__________________
Good Vibrations since early 1950's, first patented vibrometer 1956 in the US.
http://www.vtab.se
John from PA

Sr. Member
Registered:
Posts: 963
Reply with quote  #4 
Quote:
Originally Posted by fburgos
Same as your accelerometer


What type of rack, 3300, 3500 or something earlier?

Usually, as "fburgos" points out, whatever the transducer native sensitivity is, the same sensitivity applies to the BNC outputs.  There is one exception, and that is the 3300 rack.  It is possible within certain 3300 modules to integrate a 100 mV/g accelerometer and have the BNC output as 500 mV/in/sec.  
MachDiag

Avatar / Picture

Sr. Member / Supporter
Registered:
Posts: 130
Reply with quote  #5 

Not sure how you'll be acquiring data from the Bently BNC output's, but when configuring your measurement points, remember to turn >off< sensor power (bet you already knew that).

fburgos

Sr. Member
Registered:
Posts: 670
Reply with quote  #6 
Quote:
Originally Posted by John from PA


What type of rack, 3300, 3500 or something earlier?

Usually, as "fburgos" points out, whatever the transducer native sensitivity is, the same sensitivity applies to the BNC outputs.  There is one exception, and that is the 3300 rack.  It is possible within certain 3300 modules to integrate a 100 mV/g accelerometer and have the BNC output as 500 mV/in/sec.  


Well that would not be a buffered output, never seen a 3300 I guess this is not standard/pointless nowadays
John from PA

Sr. Member
Registered:
Posts: 963
Reply with quote  #7 
Quote:
Originally Posted by fburgos


Well that would not be a buffered output, never seen a 3300 I guess this is not standard/pointless nowadays

A good product in its day. An Rev A “overview” dated 2003 is at http://www.chinaal.net/p-y-1/3300%20overview.pdf.  [Edit]  The product dates from 1988.

It had one shortcoming (IMO) in that the module programming was done by pulling out the module and changing internal jumper positions. As fas as the outputs, I know that DB was not too happy about the output in some circumstances being the integrated output.

Should you ever encounter a 3300 rack, do not pull a module out to examine the jumpers.  The modules are mounted to rails and have a ribbon cable on the back.  That ribbon cable today is very prone to breaking and spares are essentially non-existent.  

OLi

Sr. Member
Registered:
Posts: 1,914
Reply with quote  #8 
It is a 3500 rack not as old as the machine. Do the tacho output(s) also give the same as the proximitor as it in this case are 3x eddy probes? So it is a negative spike as seen in the normal world?
We are not allowed to touch the rack as tripping the gasturbine will trip the refinery and they don't like that they say........ 

__________________
Good Vibrations since early 1950's, first patented vibrometer 1956 in the US.
http://www.vtab.se
fburgos

Sr. Member
Registered:
Posts: 670
Reply with quote  #9 
Usually its sensing a void in the shaft, something between bias voltage and -24V it's ok, I start testing with -12V.
Even if you forget to turnoff the volt settings in your analyzer you won't trip the machine... In theory 😂😂
OLi

Sr. Member
Registered:
Posts: 1,914
Reply with quote  #10 
We hook up a on-line system and power is confirmed off. They will shortly if they are allowed be connecting and I told them to start with the tacho as they are the least possible to trip anything I think. Thank you for the help!


__________________
Good Vibrations since early 1950's, first patented vibrometer 1956 in the US.
http://www.vtab.se
OLi

Sr. Member
Registered:
Posts: 1,914
Reply with quote  #11 

Yes on one trig was found at apprx -11.6 so that seems ok, the other is like -19DCV and signal is tiny only a few mV so it must be far from the target.

Yep, now it works, -19 and -16.


__________________
Good Vibrations since early 1950's, first patented vibrometer 1956 in the US.
http://www.vtab.se
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.