Motor Winding Temperature Measurement 1

[JustSavvy123]

Hello all.

I am currently working on measuring motor winding tempertaure using the change in resistance method. I have been going based off of formula R2 = R1*(234.5+T2)/(234.5+T1)for copper winding to calculate.

Does anyone have any advice on plotting it on linear line chart in excel?

 

[FacEngrPE]

You can create a from in excel and not bother with the table.
Rearrange the formula so that the solution is T2.
T1 and R1 are your reference temperatures, set them to your initial conditions.
Input the measured R2 and calculate T2

 

[JustSavvy123]

Are you saying to create a form?

So I used the formula to find R2. Now you’re saying to rearrange formula to find T2? Apologies for questions, just trying to understand in detail.

 

[Gr8blu]

JustSavvy The assumption is that you know initial conditions (R1 AND T1) going into the calculation. That usually means you know one of the two possible outputs (R2 OR T2) and want to find the other one. Set up your form as a two-part calculation. In one version, ask for initial conditions and R2, then output T2 (i.e. calculate behind the scenes). In the other version, ask for initial conditions and T2, and the output will be R2.

If you REALLY want a plot of R vs T, build a table with one set of known initial conditions (R1, T1). Set up one column or row by manually (or semi-automatically) inputting whichever output variable you'd like (R2 OR T2). THen set up an adjacent column or row with the other (calculated) output variable. Then plot one output variable against the other.

Converting energy to motion for more than half a century

 

[electricpete]

There are lots of ways to present the data.

Here's one way assuming you want to find T2 in general.

R2 = R1 (234.5+T2)/(234.5+T1)

Switch roles of 1 and 2 (it just makes the algebra easier)
R1 = R2 (234.5+T1)/(234.5+T2)

Multiply by (234.5+T2)/R1
(234.5+T2) = R2/R1 (234.5+T1)

Subtract 234.5
T2 = (R2/R1) (234.5+T1) -234.5 [EQ1]

Plot a family of curves T2 vs T1 where (R2/R1) is the parameter that changes for each curve of the family.
(now that i think about it, they're not really curves, just lines with slope R2/R1)
When given R1, R2, and T1, you can compute R1/R2 yourself and read straight up from the T1 value to the line that matches your R1/R2 and then read straight left to the vertical axis to find T2.
That will work even with a graph that you print out.
If you're letting yourself do each case in excel, then of course excel can find R1/R2 for you... but in that case I have to ask why you need a chart (you just need a formula EQ1 with 3 inputs and one output).

Now that I ask myself that question, it makes me wonder if we've misunderstood the question. Maybe you want to estimate the winding temperature when running by recording the resistance over time after the motor is shutdown? In that case the horizontal axis is time and you're plotting points vs time after shutdown and extrpolating backwards to t=0 time of shutdown. IIRC there is a shortcut where you can use a a straight line to extrapolate backwards if you're using a log scale. If you clarify your request then I'm sure someone will illuminate that procedure.

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(2B)+(2B)' ?