How Do You Calculate Temperature Rise in Copper Windings?

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SUMMARY

The discussion focuses on calculating the temperature rise in copper windings of a motor, where the resistance changes from 5.8 ohms at 22 degrees Celsius to 6.8 ohms after several hours of operation. The formula used is Tii = (1 + a * ti) / (Ri / Rii), with a temperature coefficient a of 5 * 10^-3. The calculated temperature rise is 1.28 degrees Celsius, but the user expresses uncertainty about the correctness of the formula and the result. Clarification on the variables Tii, ti, Ri, and Rii is requested.

PREREQUISITES
  • Understanding of electrical resistance and its temperature dependence
  • Familiarity with the temperature coefficient of resistance
  • Basic knowledge of algebraic manipulation of equations
  • Concept of thermal dynamics in electrical components
NEXT STEPS
  • Review the derivation of the temperature coefficient of resistance in conductors
  • Learn about the impact of temperature on electrical resistance in copper
  • Study the application of the formula Tii = (1 + a * ti) / (Ri / Rii) in practical scenarios
  • Explore methods for measuring temperature rise in electrical windings
USEFUL FOR

Electrical engineers, motor designers, and students studying thermodynamics and electrical resistance in conductors will benefit from this discussion.

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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