Hi has anyone got advice as to using a fuse in heated bed circuit ?, also using heat sink on solid state relay?, as ive had a bit of a incident where heated bed overheated …
You mean the mosfet overheated?
Fuses are great, but slow acting. It won’t save you from bad wiring or connectors. Its meant as a protection for a direct short or other large current spike. These beds take 10-15 amps (assuming you are using the old standard 12v). Thats still plenty of current to cause a fire with a properly rated fuse.
Now if you have a 24v supply, thats half the currect. It’s still kind of high, but much less risky and a fuse would add real protection.
If you are switching to 120v or other mains, the current is low enough where a fuse will add optimal protection.
As for heatsink, just get some thermal greese and a heatsink.
@Stephanie_A my heated bed uses relay so that Ramps board is only sending a signal , I was thinking of a fuse in circuit somewhere between power supply , relay, and heated bed so that if there is a failure of heated bed or relay i dont fry more stuff
Wow, ive used plenty of those relays before, never had an issue, it looks like something is drawing more current than what it should, test your heating bed and all other components and see what is drawing more current than it should, other than that, im not sure what 3d printer controller you have, but try to get a good thermocouple, from digikey or even adafruit has a few with good temp range, and monitor the heating bed’s temperature and use your current MCU or an external MCU to throttle the power to the heating bed, in other words, make a PID controller system for your bed heater, this way, you can program it to turn off power if temp gets out of control, for this i’d advise 2 or more thermocouples for monitoring temp for reliability
hi Lone wolf , i was printing from laptop, but computer shut down, seemed like heated bed kept heating, maybe i damaged heated bed and drawing too much current , then hurt SSR ?, do you find these relays get hot under normal operation? also this PID system you talk of sounds like a good idea
www. filafarm. de offers silicone heater pads with built-in overheat protection. AFAIK they are only one on the market to offer such thing.
That Fotek is counterfeit one, but many people that use it said it work fine if you keep it way underload.
I usually wire a thermal fuse in-line with the heater leads, wrap it in a round of kapton tape for electrical isolation, and tape it to the heat spreader with fiberglass/aluminum heat barrier tape for insulation.
With SSRs, you always have to worry about the “fails-on” risk so a thermal fuse between the SSR and bed is smart.