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I bought this cartridge heater for my reflow oven. Since this was rated for 220VAC I connected it to my mains through an SSR which is in turn controlled by the reflow oven firmware. The firmware goes into a 'learning' mode that tests the heaters and then adapts the duty cycles according to the rate of rising temp etc. There is a K-type thermocouple that measures the temp inside the oven.

When I connected it, and starting running tests, the heater became red hot and then literally exploded inside the oven (image attached). Is this normal for this style of heater? Should I bother trying to reach the manufacturer or is it something that I did?

enter image description here

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Cartridge heaters are typically intended to be buried in a deep hole in a piece of metal. You run them at full power in open air- this is a typical result.

The watts per square cm or inch is too high for them to operate in free air. You might be able to operate the heater at a fraction of rated power.

You might do better with an IR or calrod type of heater- like the elements inside a home electric oven. enter image description here Image from this site.

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  • \$\begingroup\$ Got it. How are these guys using it then? It looks like a similar heater. \$\endgroup\$ – electrophile Feb 17 '18 at 4:01
  • \$\begingroup\$ @electrophile Spehro said the following "You might be able to operate the heater at a fraction of rated power.", in case you missed it. \$\endgroup\$ – Harry Svensson Feb 17 '18 at 4:06
  • \$\begingroup\$ @HarrySvensson I got that but the build guide mentioned above does not really talk about how to reduce that power. I'm guessing the software does that but I'm not sure. I simply installed it the way they did and I'm wondering why it would work for them and not for me. This brings me to my original Q which was if I should go back to the manufacturer or the distributor cause it obviously seems to be working for some in the same installation configuration. \$\endgroup\$ – electrophile Feb 17 '18 at 4:12
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    \$\begingroup\$ @electrophile I can ensure you that the problem is not with the manufacturer, it is 100% your fault. The reason for why I can say this is because as Spehro stated: "The watts per square cm or inch is too high for them to operate in free air.", but something else that you should react on is that it is 400 W. Soldering irons comes as low as 30 W. - What did you expect? - You need to turn it off / on / off / on, in a controlled manner. If you have it on for 1 second and off for 9 seconds, and repeat this cycle, then it will be on for 10% of the time and behave like a 40 W heating element. \$\endgroup\$ – Harry Svensson Feb 17 '18 at 4:15
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    \$\begingroup\$ No, you said it got red hot and then exploded. The fact that it got red hot tells you that its power wasn't being correctly controlled. \$\endgroup\$ – Brian Drummond Feb 17 '18 at 14:48

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