Connecting a SSR between Duet and heated bed
-
Hi,
Well it seems clear that your heater is rated for 230 volts. It will work at a 110/120 but it would then be considered a 225 watt heater (more or less) .
SSRs have a rating for the input signal that controls them, usually a range of voltage such as 5 to 35 volts (DC) - just made those numbers up, not suggesting that is what you must have. But you will need an SSR that can handle 24 volts (DC). A higher rating is fine.
SSRs also have a rating for the load they can control. If you search Amazon you will see that again you likely have a range of voltage and a maximum current.
Consider this unit:
https://www.amazon.com/gp/product/B00DE2RNCE/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
You should be able to see from the printing on the device that the input is rated from 3 to 32 volts (DC as indicated by the straight/dashed lines) so that would be fine with a 24 volts system.
You should also see that the output is rated at 240 volts (the ~ character means AC) and 25 amps.
Given the markings on your heater powering it from 230 volts (AC) would draw appx 2 amps. You can calculate that by dividing the wattage rating by the applied voltage (450 / 250 ).
So the SSR I referenced would be fine for that.
Hope that is enough to get you started.
Frederick
-
It will actually have 100ish W at 110.
-
@sigxcpu said in Connecting a SSR between Duet and heated bed:
It will actually have 100ish W at 110.
Right you are - I should learn to never do math in a hurry.
Frederick
-
-
Hey,
can someone tell me, if this wiring diagram for the SSR is right?
The power supply and the SSR are the one which I'm using.
I found this diagram on google: https://lh4.googleusercontent.com/proxy/aJ_yCfp-3W20019wH7vZYGCzsmyo1LDV_nBlZVrClyLhURl64LqPUWeGi6pOEmMlzQ=w5000-h5000
Please correct me if I'm wrong.
Thank you
-
@woelkchen That's I have mine wired. You might want to add a thermal fuse is the only other comment I'd make.
-
Just want to say that the Crydom SSR which fcwit recommended should be good.
Please stay away from the Fotek ones, they have a poor reputation.
-
Genuine Fotek DC-AC SSRs are probably OK, but there are a lot of fakes around.
-
@woelkchen said in Connecting a SSR between Duet and heated bed:
Hey,
can someone tell me, if this wiring diagram for the SSR is right?
I have a 110V (USA) heater that is 600MM in diameter (24 inches) wired exactly as you show. Draws about 13 or 14 amps, using a 40 amp rated SSR with no heatsink. Hundreds of hours, no problems.
GROUND (EARTH) YOUR FRAME. With high quality connections. Please.
-
A few safetytips in addition to the ones mentioned above:
- Add a fuse with an appropriate rating on 230 V input. I use a separate fuse for the PSU and the bed, but that's not necessary. In my case the bed is at almost 1 kW, and the PSU on 200W and a single fuse would allow quite a lot of extra power to the PSU if the bed isn't active
- As Danal said, connect your frame to protective earth, but also the buildplate if that's conductive.
- Add a temperature switch to your buildplate. I use one rated at 130 deg C, which will protect me in case the SSR fails in shorted mode.
- Use the printer from an outlet protected by a RCD.
-
undefined Stephen6309 referenced this topic
