Bed connector burnt - DUET 0.6
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Hi,
I am building Core XY 300x300x300. I am using DUET 0.6 from RepRap Ltd.
I am using 24V, 20A power supply. All the components are 24V. I bought 24V 300W Silicon heater from Aliexpress. Today I set the temperature to 100deg. It took 20mins to reach only 90deg. After that when I checked the DUET board, the bed connector is burnt.
Please find the image here: http://imgur.com/a/q5RpE (Unable to attach any file here).
As per the DUET 0.6 recommended current, it should be 10A. But I hope I have given more than that. 300W/24V=12.5A. After burnt only, I cross checked the DUET recommended bed current. Now I can changed the connector.
But, as per DUET 0.6 wiki, 'The board is comfortable with 10A bed heater current, but not much more. The weak link is the PCB trace on the top side of the board that connects the Power In V+ and Bed Heater V+ terminals. If you want to use a bed heater that draws more than 10A, solder a thick wire between those terminals on the back of the board.'
This means that I can connect a 1.5sq.mm thick wire (stranded wires) between those terminals directly? Will it withstand that much current?
Or any other way to reduce the current to the bed, so that it runs safetly for a long time?
I am planning to cool down the Electronics by 24V 60x20 cooling fan. Any other precautions to be done?
The Electronics and wiring will be enclosed below the printer.
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I believe you'd want to check out an SSR for such a heat bed (then you don't have to worry about the Duet amp limits):
https://miscsolutions.wordpress.com/2015/06/01/building-a-large-delta-printer/
You could perhaps add a fuse on the heat bed (is 15A the correct fuse for 20% more than 12.5A requirements)?
Also, SeeMeCNC sells thermal fuses (you can get higher rated ones from other sources), you can place those in your heat bed wiring and they will blow if the heat bed gets too hot.
Also, a good crimp on the wiring being placed into the terminal can help - you want as much contact between the wiring and the terminal as possible.
Bootlace Ferrules as referenced here (https://duet3d.com/wiki/Power_wiring) are good for making the wiring clean between the terminal and heat bed power.
