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--- reprap:anet:a8:improvements:understanding_my_heatbed [2018/12/30 09:42] – [Investigating other effects] cj_elec_tech
+++ reprap:anet:a8:improvements:understanding_my_heatbed [2018/12/30 09:58] – [Heat-bed Power] cj_elec_tech
@@ Line 46: / Line 46: @@
 ==== Investigating other effects ====
 A good hint from a Facebook group member was to check the cables. There is a significant voltage drop from the power supply to the heat-bed. Note that the power dissipated at the heat bed is proportional to the square of the heat-bed voltage.
-Replacing the power supply to heat-bed wires with thicker, shorter wires meant I could increase the power a little bit - doing that does not affect the heat-bed loss or contribute any insulating effect though. I also investigated if the problem was caused by forced convection due of the extruder fans. I could achieve slight improvements, but nothing spectacular. Independently, Dan Rogers posted results for his heat-bed (only 2 points) - the results suggested my bed was operating similarly.
+Replacing the power supply to heat-bed wires with thicker, shorter wires meant I could increase the power a little bit - doing that does not affect the heat-bed loss or contribute any insulating effect though. I also investigated if the loss was caused by forced convection from the extruder fans. I could achieve slight improvements, but nothing spectacular. Independently, Dan Rogers posted results for his heat-bed (only 2 points) - the results suggested my bed was operating similarly.
 {{ :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.