Variable 100-350VAC output controlled by PLC?

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Discussion Overview

The discussion revolves around the challenge of controlling a variable output voltage between 100-350VAC for a "burn-off" application, which is used to burn labels off products. Participants explore various methods to achieve this control, including the use of transformers and frequency converters, while considering integration with a PLC and HMI for user selection.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests using a variable transformer (Variac) to control the voltage, noting the potential for motorized options but expressing concerns about feedback mechanisms.
  • Another participant proposes using an off-the-shelf frequency converter with variable voltage output as a more straightforward solution for the client's needs.
  • There is a suggestion to consider a non-motorized Variac for cost-effectiveness, allowing manual adjustment next to the HMI instead of complex automation.
  • A later reply questions whether the heating element is resistive, suggesting that a basic electric heat controller with thermal feedback could be a viable option.

Areas of Agreement / Disagreement

Participants express differing opinions on the best approach to achieve the desired voltage control, with no consensus on a single solution. Some favor the use of transformers, while others advocate for frequency converters or simpler manual controls.

Contextual Notes

Participants mention the need for feedback mechanisms and integration with PLCs, but there are unresolved details regarding the specific requirements for voltage feedback and the implications of using different control methods.

Who May Find This Useful

This discussion may be useful for engineers and technicians involved in industrial automation, particularly those working with voltage control systems and PLC integration in heating applications.

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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Likes   Reactions: dlgoff
Is this a radiant (resistive) heater element? Then a basic electric heat controller should work, feed back would be some type of a thermal sensor.
 

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