infrared ceramic heaters with PID controller

[dac68]

I'm looking for confirmation or otherwise, that the following bits of kit will go together to create a temperature controlled heat source for a curing application via a standard 13a plug fitting.
- 2 x 400W ceramic elements in reflectors (1 fitted with Thermocouple)
- PID temp controller, 1 relay output, 100-240V AC
- Solid State Relay, 10A, zero crossing, Triac, 280V max load on heatsink
- all connected with 2.5mm single core control cable
Thanks.

 

[Darkwood]

It would make a very crude version of a control set-up but it is unlikely to satisfy the machine code standards if that is the full list assuming fitted within a suitable 'not mentioned' enclosure, if this is a private project for yourself then not a problem but if this is a paid job then there is far more to designing a control set-up than simply been functional.
-How are you protecting the SSR?
Positioning of the thermocouple is crucial here for ease of setting up the PID Temp' controller, are you saying it is strapped to the element or is it positioned to monitor the ambient temperature within the proving oven?

As you have posted in the DIY section are we to assume you have no formal qualifications here, if so this limits the advice we can give you as this kind of work has strict regulations surrounding it and isn't usually for the DIY sector, if you can satisfy our concerns with some background info' about your electrical knowledge and experience we may be able to offer more help.

 

[dac68]

Thanks for the reply.
It is for a personal project. The controller and relay will be enclosed and the thermocouple is fitted as part of the ceramic heating element.
In theory, the ratings of everything seem ok though?

 

[Chris12345678]

There are thermocouples in both heating elements? If so, how are you connecting both to the PID, or are you just connecting just the one?

Be aware that solid state relays can still give out 230 volts even when 'off'. Ensure correct wiring of the SSR acording to markings as well. Best to use a good brand such as Crydon, although they still fail often, especially if they have suffered a short on the heating element. They also really need to be bolted to a heatsink.

 

[Darkwood]

If this is for personal then you are not required to adhere to the many regulations that cover this project although I must be clear that the regulations are there for very good reasons and many cases are to ensure the safety of the system and or users.
That aside I will point out that I would be protecting the SSR with semi conductor fusing, and and also having the thermocouple on the element itself may not reflect the true ambient temp' and you may have to compensate through programming the PID control or manually by altering the temp' to allow for any offset.

I would make sure you power these controls via a 30mA RCD device to afford you at least some personal protection here, and I realise you have expressed this is a personal project but I must express that you and only you should ever use it, make sure no one is able to use or operate this, you would be facing the full might of the law if anyone other than yourself was injured or killed through the use of this oven.
My words of wisdom I can give here is it is not what ones knows that is a danger in this trade, it is what one doesn't know, a small well of knowledge can give one a false sense of confidence which is a dangerous path and one may learn a lesson the hard way.

 

[dac68]

Thank you for all this. I will read and re-read then probably call an electrician!

 

[Darkwood]

To be fair this will be a little out of your average Electricians field, you need to source someone familiar with machine code standards and building control equipment, few sparkies do this field in my experience.

 

[Marvo]

I've seen ceramic IR heaters temperature controlled by thermocouples in an industrial drying oven application but I've never seen a PID control used. The PID will certainly complicate the setup but I'm not sure if it will improve the temperature accuracy...