Wiring SSR and some safety devices

I'm building my delta currently. It uses a 12v power supply for cartridge heater and motors etc. The bed is 500w 110v AC mains powered. Currently for testing I have the printer using two outlets, one to power the bed, the other the main power supply. Are there any merits to this as opposed to jumping off the 110 line powering the DC power supply anyway?

Currently



Alternative
[i.imgur.com]

Note that is a NC thermal switch set to 140C to be mounted on the aluminum heat spreader. Hopefully if the relay breaks on , that switch will cut power to the bed and keep it at 140 tops. I'm interested in more security though! I also have a few thermal fuses, that break contact permanently at various temps, can I just cut a power wire to the bed and quickly solder (so as not to trip the fuse) or otherwise attach it inline right on the wire? my concern is mounting it, it pretty necessarily has to be touching or nearly touching the bed, and also connected to the mains power. I could sheath the whole connection (wire - fuse - wire) in shrink tube and run it between the bed and heat spreader I suppose.

Also, normal fuses, how do they work and what do I want with them? I'm looking to eventually mount a power inlet in the frame with a switch, and I feel like I should have a fuse in there, but admitedly don't know much about it, why I need them, and which one to get, and where to put it in the order of connections in either of the two diagrams above. Additionally the raw power line in goes through a GFCI (https://www.amazon.com/gp/product/B0037NXKY0/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1). Additionally I am big on Z-wave and Zigbee stuff, directly above my printer is a smart smoke alarm, that when triggered sends me a notification, and kills the outlet that powers the whole contraption.

Thoughts?

I have mine wired into the same ac input of the dc power supply, with a ground wire to the al bed. I use a fused IEC socket for the ac power, like this one: [www.amazon.com]. A thermal fuse attached to the bottom of the heater, inline with one of the power leads to the heater. If anything fails on, the thermal fuse will kill the power to the bed heater and the fuse has to be replaced.

Thanks! What size fuse should I use given the electronics mentioned above?

Also how'd you attach the thermal fuse inline? Solder? some kind of clip?

Also, I'm looking for a fused+switch power inlet. The power cord will plug into it, then branch out to the DC power supply and bed. What amperage does that switched fused inlet need to be rated for?

For a 110V mains, a 6.3A slow blow fuse would be about right for your printer. The switched and fused IEC inlets take standard 20mm cartridge fuses.

Be careful with thermal fuses because some of them have the case connected to one of the wires.

You can get NC thermal switches like the one you pictured that do not self-reset.

Edited 1 time(s). Last edit at 12/16/2016 02:25AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks as always DC,

So just to verify my plan:

This fuse Fuse

This thermo-switch switch

This inlet

Should work?

The thermal switch link didn't work for me. The other parts look ok.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

For the sake of thoroughness here it is
http://www.digikey.com/product-detail/en/honeywell-sensing-and-productivity-solutions/2455RM-80980261/480-6535-ND/3526430

But I'm most confident in that pick.

Ground fault protector would be nice. If your frame is grounded and you leak some mains or low voltage there, it will trip. It will give early warning in that case.

SSR has some leakage even it is off and electrocuting with it still hurts. I have ground fault protector, energy meter and SSR in that electric box.

GFP is 16A type but the fuse isn't the main idea. Providing ground fault protection and single switch to make the system safe are.

Image can be found from Finnish forum under the "P3Steel projektia" thread
[forums.reprap.org]

Text warns about leakage current and 230V terminals under the cover.

why you use dc with high risk when you can use pc powersupply 600w which are not really expansive