So for a coil that starts at 1.0Ω, every degree ☌ of heating will increase its resistance by 0.006Ω (0.006 *1). This means that for every ☌ hotter a Ni200 wire gets, its resistance rises by (0.006 * )Ω. The TCR of pure Nickel is approximately 0.006. So a 0.10Ω coil heated hundreds of degrees will only increase in resistance by a few 0.1's, whereas a 1.0Ω coil heated the same amount will increase by multiple ohms. The TCR is relative to the starting resistance, meaning that the higher the starting resistance of the coil, the greater rate of increase in resistance with temperature. (For its intended purpose, this is a benefit I think it may even have been engineered specially to achieve this.) Kanthal has an extremely low coefficient - its resistance barely rises at all even with hundreds of degrees of heating. Ni200 was chosen by Evolv as the first TC wire because it has one of the highest coefficients amongst common metals/wires. When it is low, resistance rises a smaller or negligible amount. When the coefficient is high resistance will increase a lot as temperature increases. The Coefficient is a numerical value that indicates how much resistance will rise for a given temperature increase relative to its starting resistance. TC is possible only with wire that has a reasonably high Temperature Coefficient of Resistance (TCR). It works because resistance increases linearly and predictably with temperature, although the amount that it increases varies greatly between wires.
Temperature Control works by monitoring changes of resistance in the coil and using this to estimate temperature changes. How does TC work and what is the Temperature Coefficient of Resistance?
0 kommentar(er)
