Pt100 onto a generator bearing

[181273]

hello everybody, I`m electric guy, learning something on bearings, I´d to install a PT100 into a old bearing, I wanna know what`s the distance from the antifriction layer to put the head of my PT100, and what could be the real temperature diference between my reading and the real one.
thanks in advance for everybody

 

[wbd]

Is this a babbitted bearing? Typically, RTD installed is spring loaded and the mounting hole is drilled thru the shell, so the head is resting on the babbitt material.
This gives an accurate reading of the babbitt material. If you don't know the setpoint you want, you can trend the temperature for awhile and see what the hottest temp is. Then set a good number of degrees above. Make sure this temp is below the melting point of the babbitt and also below breakdown or flashpoints of the oil. You could look at the spec sheet of the oil and set the alarm to be below the manufacturer's recommended temp range for the oil.

 

[181273]

thanks very much, yes, it´s a babbitted bearing, exactly a journal bearing... this machine is a Siemens generator from 1939,onto a hydro unit, here on Spain.. I don´t know if in the old times the babbit was the same as today, Could I drill the case and put the head of the RTD onto the babbit surface??
Is it posibility to know more or less the accuracy of the RTD, in example, If i insert the RTD 1 mm into the babbit, what is the difference between put it right in the layer between babbit and support metal? I know there´s too much questions, I hope you or somebody will answer it...

thanks a lot,

 

[wbd]

I have some hydro units of a 1920 vintage where I had the bearing housing drilled, tapped and a RTD inserted. I would not go into the babbitt. My reasoning is that a typical sliding type bearing operates around 140F (60C) and babbitt material melts around 500F (260C). This leaves quite a bit of room to set your alarms or trips at and being 1mm into the babbitt is not going to increase your sensitivity enough to make it worth disturb the babbitt.

 

[181273]

hi, thanks a lot for your answers, this will help me on the work to install the RTD, but now I have a new question for you.. or other guys that know abou old hydro units, What kind of babbit was used on that age, and whats is the mean differences between the old one and new material for babbits
(I´m thinking about temperature ranges)??
thank for your attention and sorry for my bad english