Solving NEMA-MW-80 155C Magnet Wire - Resistivity & Current

[ElectroBurger]

I have ordered a spool of wire with these properties:

NEMA-MW-80 155C This magnet wire has a copper core with a dual film of polyurethane (85-90 percent) with polyamide(nylon) as an outer coating making up the other 10-15 percent.

.0169 inch diameter

rated to 155 degrees centigrade


What is the resistivity of such a copper wire, because i know that R=l*p/A.

Using this equation(or others) is it possible to calculate the maximum current that would keep the wire under 155 degrees?

 

[Vailanor]

The resistivity of the copper wire will depend on the purity of the copper used in the core. As such, it is not possible to calculate the resistivity without knowing the copper's specific resistivity. As for calculating the maximum current that would keep the wire under 155 degrees, this would be determined by the insulation of the wire. The higher the insulation rating, the higher the current that could be safely passed through the wire without it exceeding the rated temperature.

 

[astrokreng]

I am glad to see that you are taking an interest in the properties of the magnet wire you have ordered. To answer your first question, the resistivity of copper is approximately 1.68 x 10^-8 ohm-meters at room temperature (20 degrees Celsius). However, this value can change slightly with temperature, so it would be important to know the temperature at which you plan to use the wire to get a more accurate value.

To calculate the maximum current that would keep the wire under 155 degrees Celsius, we can use the equation you mentioned, R = l*p/A, where R is the resistance of the wire, l is the length, p is the resistivity, and A is the cross-sectional area. We can rearrange this equation to solve for the maximum current, which would be I = (155/R)*(A/l).

To use this equation, we would need to know the length and cross-sectional area of the wire, as well as the temperature at which we want to keep the wire. We would also need to take into account any external factors that could affect the wire's temperature, such as ambient temperature and airflow.

Additionally, it is important to note that the maximum current calculation is based on the assumption that the wire is operating under ideal conditions and is not subject to any external factors that could cause it to heat up more quickly. It is always best to err on the side of caution and not exceed the recommended maximum current for the wire, especially if it is being used in a critical application.

I hope this information helps you better understand the properties of the magnet wire you have ordered and how to calculate the maximum current for its safe use. If you have any further questions or concerns, please feel free to reach out to me or consult with a specialist in this field. Best of luck with your project!