Differences

This shows you the differences between two versions of the page.

--- reprap:anet:a8:improvements:understanding_my_heatbed [2018/12/30 09:43] – [Investigating other effects] cj_elec_tech
+++ reprap:anet:a8:improvements:understanding_my_heatbed [2018/12/30 10:01] – [Simulating the heat bed] cj_elec_tech
@@ Line 49: / Line 49: @@
 {{ :reprap:anet:a8:improvements:mypicture15.gif |}}.
-==== The power supllied to the heatbed ====
+==== Heat-bed Power ====
-As the curves where very similar I investigated if the controller was ajusting the PWM duty cycle and therefore the curves where a controler effect and not a thermodynamic. The voltage was a flat line on the osziloscope, therefore this theory was discarded.
+As the curves were very similar, I investigated if the effect was caused by the controller rather than being a thermodynamic effect (the controller adjusts the PWM duty cycle - and thus the curve). The voltage was a flat line on the oscilloscope, therefore this theory was discarded.
-Than I measured the current and observed that it drops with increasing temperature.
+Then I measured the current and observed that it drops with increasing temperature.
 {{ :reprap:anet:a8:improvements:mypicture2.gif |}}
-If the resistance is calculated by divinding the voltage through the current this leads to the following resistance{{ :reprap:anet:a8:improvements:mypicture3.gif?direct&400 |}}
+Resistance is calculated by dividing voltage by current - this lead to the following resistance{{ :reprap:anet:a8:improvements:mypicture3.gif?direct&400 |}}
-And this gradinet fits nearly to the gradient expected for cupper with an temperature coefficient of appximatly 0.0039 1/K
+This gradient nearly fits the gradient expected for copper with an temperature coefficient of approximately 0.0039 1/K
-This is probably also the reason why there are values of 1.2 to 1.6 Ohms mentioned in some forums and sites for this heat bed.
+This is probably the reason why there are values of 1.2 to 1.6 Ohms mentioned in some forums and sites for this heat-bed.
 ==== Simulating the heat bed ====
-In  order to undertstand the heat bed behavior in more datail I made a {{ :reprap:anet:a8:improvements:warm_up_2.xlsx |heat bed simulator}} in excel (dispite I don't like to this software for simulations). It fits quite well to the measured data, therefore it seems to be not so bad. But keep in mind that it is a model and not the reality.
+In  order to understand the heat bed behavior in more detail I made a {{ :reprap:anet:a8:improvements:warm_up_2.xlsx |heat bed simulator}} in Excel (despite not liking this software for simulations). It fits quite well to the measured data, therefore it seems to be not so bad - but keep in mind that it is a model and not reality.
 {{ :reprap:anet:a8:improvements:mypicture4.gif |}}
-The cool thing about simulations is that you can evaluate heat fluxes which are difficult to measure and to make a serios of variations which would require months of testing in a few minutes.
+The cool thing about simulations is that you can evaluate heat fluxes which are difficult to measure and to make a series of variations which would require months of testing in a few minutes.
 {{ :reprap:anet:a8:improvements:mypicture7.gif |}}
-When the steady state is nearly reached the initial 110W of electric power are reduced to 0 by the following contributions (for a heat bed without insulation). It can be seen that a large portion of the heat is irradieted by infrared radiation. This should possible to easily reduced by a factor of 8 to 9 by applying a aluminium foil(emissivity 0.11) beneath the heatbed or insulation.
+When the steady state is nearly reached the initial 110W of electric power are reduced to 0 by the following contributions (for a heat bed without insulation). It can be seen that a large portion of the heat is radiated by infrared radiation. This should possible to easily reduced by a factor of 8 to 9 by applying a aluminium foil (emissivity 0.11) beneath the heat-bed or insulation.
 {{ :reprap:anet:a8:improvements:mypicture8.gif |}}