240V Oven Question

[james_s]

That's clever, it hadn't even occurred to me to use a single CT with the wires run through in opposite directions. I suppose that's functionally the same as using a pair of CTs though.

[XOIIO]

Sorry, guess I wasn't super clear, the kiln can fire both sections at the same time, you can independently set them to off through high, so it has one box with the main power feed that has live 1 and neutral connected to those elements, and then the second section has another box that connects with a standard plug, wired for live 2, neutral and ground, so both live connections can be powered at the same time, or I could turn one half off entirely, which is where I got running it off of a standard outlet from.

On high a single section would draw more current than a standard outlet could provide iirc, which is why it uses a stove plug.


Very interesting that you can pass them through in opposite directions, I guess since the phases are 180 degrees apart it's as simple as that, interesting, I'll order one of those meters and give it a shot. I suppose reading 120v instead of 240 would be more correct anyhow since that's how it is all wired up inside instead instead of the elements using 240v. I had wondered if there might be a way to use multiple pickups in parallel or series, but figured that might be iffy in terms of how well it worked.

I had looked at some din rail power meter options, but they seemed out of budget and mounting them would get bulky and a bit difficult to work with it seems and I'm sure even the small cabinets for them are a lot pricier than a plain metal one. If there was a cheap version of those that's panel mount it would be cool, but having a separate receiver, and the ~$200 with shipping for one in Canada makes it a tad steep for my taste.

[james_s]

Another approach is to just use a microcontroller to track the amount of time the SSRs controlling the elements are on. You can easily measure how much power the elements consume and your line voltage is probably going to be fairly constant, so from that you can derive the cumulative power consumption. A kiln is essentially an ideal pure resistive load, the only potential unknown is that the resistance of the coils will vary some as it warms up.

[XOIIO]

Well, the power meter works perfectly running one wire through each direction, and I can power it off live and neutral for 120v on the display or both lives for 240 without a problem.

The label on the side of the kiln says 4400w, but that must be like, an average or something? It draws 45 amps total with both sections on high, or over 10kw from a cold start.  Glad I went with beefy, albeit expensive wiring.

edit: Right, powering the meter from both lives means it's reading high, it's actually 5800w or so powering it from a single 120v connection, I guess that's more accurate for the power use.