Variable 100-350VAC output controlled by PLC?

AI Thread Summary
A client requires a system to control the voltage of a burn-off device between 100-350VAC, adjustable via an HMI. The discussion explores options like a motorized variable transformer (Variac) but notes the lack of feedback for voltage monitoring. Suggestions include using digital outputs for motor control and converting voltage to a feedback signal for the PLC, though an off-the-shelf frequency converter with variable output is recommended for ease. An alternative, cost-effective solution is to use a non-motorized Variac with manual adjustment. Ultimately, the feasibility of integrating these solutions with the existing PLC system is emphasized.
Purple_Dan
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Hello, I have a strange request from a client.

He has a "burn-off" which is used to burn bits of labels that are stuck onto his products, that's a bit vague, but it's all the info I have.

The request is that he wants to be able to change the voltage going through the burn-off anywhere between 100-350VAC, presumably to burn things quicker/slower depending on the product and label.

He wants the voltage to be selectable via his HMI, but I'm not quite sure how to go about it.

A variable transformer makes sense, you can even get motorised ones. However, they don't have a feedback from what I can tell. I've found a 0-580VAC motorised Variac.
My idea is that I can use 2 digital outputs for forward and reverse on the motor, then, for feedback I can somehow convert the voltage to 0-10VDC or 4-20mA (the AI card has both). I say "somehow convert" because I know it can be done with simple electrical components, but I dare say my company would prefer an "off the shelf" solution.

Or am I going about it all the wrong way?

Thanks for any help you can provide!
 
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If they are ready to buy it, then 'off the shelf' sell them a frequency converter with variable voltage output.

Ps.: for myself I too would go for the transformer... But for a company it's different. Don't forget to make a big, demonstrative box for that few component in the voltage feedback.
 
Rive said:
If they are ready to buy it, then 'off the shelf' sell them a frequency converter with variable voltage output.

Ps.: for myself I too would go for the transformer... But for a company it's different. Don't forget to make a big, demonstrative box for that few component in the voltage feedback.

I suppose the thing that bumps the cost up is he wants it selectable from the HMI.
So then it needs to go through the PLC and all that jazz.
We could just put a non motorised Variac next to the HMI. Much cheaper, only one component needed and he only needs to twiddle a knob.
 
Nidum said:
You beautiful person!
Well done, that's the hardest part out of the way, helps me immensely!
Thank you!
 
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