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Well....... after all the questions and great info from this forum I added "change kiln relays" to my to-do list, then failed to do so. And as you would expect, I had a relay stick closed this week.........

It was on my refurb Olympic GF314ETLC, the one with an unknown # of firings. I work at home so when the kilns are running during the day I check the temps to monitor where they are in the schedule. The power here is sometimes flaky so if we have a brown out or some sort of event I will have an idea where to begin recovery. On Tuesday afternoon I was half way through an anneal at 900 F, when I went back to check an hour later the temp read 1045. Hmmmm..... then I noticed through the quartz window that the elements were burning bright, fully on. The controller was also throwing an E-4 code. Yep, that code refers you to another code that says "relay latched closed".

At this point I tried to turn it off with the power switch, but the elements were still burning brightly. So I unplugged it, called Olympic and ordered 3 relays, they arrived today and will be installed tonight. Fortunately the kiln did not have anything complex or thick in it, just a 7"x13" platter and 5-6 small test pieces, all 2 layer. So I just let everything sit and cool to room temp. The platter will be slumped next so if it survives the front end of the schedule (which will be 150 F slower rate) I assume it'll end up properly annealed.

Inspecting the controller it doesn't really seem designed for easy access to replace something that is likely to be replaced by the owner. But I suspect that a price point is in play and it doesn't appear to be too tough if you go slow, take pics/notes and label wires before disconnecting. Here we go.......

I'll tell you one of the best things I've found for marking wires. Nail polish.
Just a dot on the wire connector and a dot on the terminal it plugs onto and you're all set.

And it comes in all the colors of the electrical color code...



Take it slow. You'll do fine.

Great idea, but plunged forward with tape and a fine sharpie to label the wires. Not too bad, took about 2 hours, could probably do it in half that next time. It's kinda tight in the box which is filled with wires of course. So you have to be careful not to accidentally disconnect or damage anything while digging around in there.

One recommendation, label and disconnect the element leads from the relays first. Particularly for the middle elements with connections/wiring through the kiln body where the box is mounted. On my kiln this wiring to those elements made everything very tight and hard to move the box away from the body of the kiln. Disconnecting them first gave me more room to work and space to see what I was doing. Thermocouple lead on mine was plenty long and not in the way so I left it connected, otherwise I would have disconnected it too. Ran it up and down to 1250 F a couple of times at different rates, holding at 900 F for 1 hour, all appears normal now. I'll fire a low risk piece today and monitor.

Seeing how this is built and laid out I see why some folks build their own kilns, lots of ideas for improvement popped into my head as I was working on mine. Wait...... I already have 2 kilns, good work space & shop layout, must resist......

Next project will be to build a separate box for a heat sink and solid state relays to mount away from the kiln on a wall. Anyone have plans, pictures or diagrams of their solution for this?

I assume that all 18 wires to the relays (6 wires each) would run from the wall box back to the original controller box where one or more terminal blocks (rated for the right amp load) would then distribute to the original wiring in the controller box? The wiring would need to be of the appropriate gauge and type for moderate heat, the external wire bundle run inside a length of flexible metal conduit. Am I missing something?

Thanks

Bump to solicit feedback:

Next project will be to build a separate box for a heat sink and solid state relays to mount away from the kiln on a wall. Anyone have plans, pictures or diagrams of their solution for this?

I assume that all 18 wires to the relays (6 wires each) would run from the wall box back to the original controller box where one or more terminal blocks (rated for the right amp load) would then distribute to the original wiring in the controller box? The wiring would need to be of the appropriate gauge and type for moderate heat, the external wire bundle run inside a length of flexible metal conduit. Am I missing something?

Thanks

lbailey wrote:Bump to solicit feedback:

Next project will be to build a separate box for a heat sink and solid state relays to mount away from the kiln on a wall. Anyone have plans, pictures or diagrams of their solution for this?

I assume that all 18 wires to the relays (6 wires each) would run from the wall box back to the original controller box where one or more terminal blocks (rated for the right amp load) would then distribute to the original wiring in the controller box? The wiring would need to be of the appropriate gauge and type for moderate heat, the external wire bundle run inside a length of flexible metal conduit. Am I missing something?

Thanks

Well, technically you can probably get away with running only 12 wires...

Each relay has 6 terminals.
2 of those will be switched power back to the elements. You'll need to run all of those. (6 total for 3 relays)

2 terminals will be the 240V power to the relays. You can run just 2 wires for this and split them into 6 at your new relay box, but the wires will need to be sized to handle the current for all the elements. So you can save 4 wires there at the expense of running larger wire.

2 terminals will be to the relay coil. One wire will be the "common" and connects to each of the relays so you can just run one wire for that and save 2. The current is very low so there's no special sizing requirements for the wire.
The other terminal on each relay is the "control" wire from the controller. If all of the elements turn on and off at once then you just need one wire and split it into 3 at the box like with the common. If the controller has separate control over each relay or if there's one or more switches on the front panel that allow the user to select which elements are on then you will need to run all 3.

Use a decent sized heatsink and don't forget to spread a THIN layer of thermal transfer compound (heatsink grease) between the SSR and the sink.

I think if I was building a separate box to house SSR's, one of the things I would add is 3 small indicator lights, one wired across the output of each relay (in parallel with the elements) so that there was some indication of when a relay was on. It would make a good troubleshooting indicator because you can see at a glance when each element is allegedly on. If the lights are on but the kiln isn't heating properly (lights on, nobody home) it would indicate a problem with the element(s) or wiring.

You can create a panel with solid state relays, one for each zone, a controller (many controllers will operate up to 3 zones with the same profile), and if you want a female plug outlet sized for your kiln (or hard wires) You will need to extend the thermocouple wires from the controller over to the kiln.

I have done this several times using the Bartlett RTC 1000 controller. Bartlett supplies the board for this controller. You add the power supply, and a box for it. They have the specs for it. The power supply is one of those black boxes you plug in to stuff. It has to have the right spec though.

Solid state relays are not expensive. I like to put a fuse on these circuits, but the fuse actually costs more than the relay itself. The only difference is that replacing the fuse is really easy, and replacing the relay requires switching 2 wire connections. Given that, it makes more sense to have an extra relay or 2 in your stash.

Got it guys, these are the details I was looking for, indicator lights are a great idea and I'll definitely keep spare SSRs.

Thanks!

Ordered a new kiln (Paragon Fusion 7) for my wife's b-day, since she was getting tired of me "kiln blocking" her with MY stuff. Paid for the mercury relay upgrade - they "forgot". But they remembered the custom paint color. CLick & clack.

From Paragon . . "A mercury relay is not interchangeable with a mechanical relay, because the mercury relay also requires a mechanical relay to drive it. The power from the controller is too low to drive a mercury relay directly. So, the controller turns on a mechanical relay, which turns on the mercury relay."
From the text it sounds kind of pointless. If they really forgot the mercury relay I am just going to ask for a refund on the upgrade and I'll do an SSR upgrade myself, starting with the other, older Fusion 7 I bought used.

Bert Weiss wrote:You can create a panel with solid state relays, one for each zone, a controller (many controllers will operate up to 3 zones with the same profile), and if you want a female plug outlet sized for your kiln (or hard wires) You will need to extend the thermocouple wires from the controller over to the kiln.

Why move the controller? You only need to run the coil wires from the controller and the load wires to the SSR, then bring the load wires back? As the thermocouple is connected to the controller, not the relay. Just my $0.02

The idea behind moving the entire controller is to get the power handling components away from the kiln heat and retain the enclosure. If you didn't do that, you would need to have a separate enclosure for the SSRs.

Tony

Tony Smith wrote:The idea behind moving the entire controller is to get the power handling components away from the kiln heat and retain the enclosure. If you didn't do that, you would need to have a separate enclosure for the SSRs.

Tony

I totally agree that moving the whole thing would be optimal. However, then you also have to do something to cover the element terminals and thermocouple block. I was thinking having the SSRs in a seperate box could keep it a little simpler add-on. Guess I'll find out sometime soon, I have plans of switching our smallest kiln over to SSR as soon as I get our room back together, after moving in a new kiln and some more shelving.