How Do You Calculate Temperature Rise in Copper Windings?

AI Thread Summary
To calculate the temperature rise in copper windings, the resistance change from 5.8 ohms at 22 degrees Celsius to 6.8 ohms is analyzed using the formula Tii = (1 + a * ti) / (Ri / Rii), where 'a' is the temperature coefficient. The user attempts to apply the formula but questions its correctness and the definitions of the variables involved. The calculated temperature rise is approximately 1.28 degrees Celsius, but the user is uncertain about the accuracy of their solution. Clarification on the formula and its components is sought to ensure proper application in the calculation. Understanding the correct usage of the formula is essential for accurate temperature rise determination in copper windings.
Red_shift
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Homework Statement


The copper windings of a motor have a resistance of 5.8ohms at 22degrees when a motor is idle.After runnning for several hours the resistance rises to 6.8ohms. what is the temperture rise of the windings? assume a constant temperture coefficient of a = 5*10^-3

Have i got the right formula for this problem? or have I missed a step? I quite sure my working is correct but the answer definitely is'nt. Please help

Homework Equations



Tii = (1+a*ti)/(Ri/Rii)

The Attempt at a Solution



Tii = 1+5*10^-3*22/(5.8/6.8)

Tii = 1.088/(5.8/6.8)
Tii = 1.28 degrees (2 d.p.)
 
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Red_shift said:
Have i got the right formula for this problem? or have I missed a step? I quite sure my working is correct but the answer definitely is'nt. Please help

Homework Equations



Tii = (1+a*ti)/(Ri/Rii)

Explain this formula, as it does not look right. What are Tii, ti, Ri, Rii?


ehild
 

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