I need help to detect an AC burned heater element

[Gevo]

Hello,

Maybe someting with a magnetic (Murata AS-M15TAN-R) sensor ? This give you a 5-volt low/high signal when detect a magenetic field.

Regards,
/ Gevo

[Archangel]

Hello igeorge,
Could you elaborate a bit on the conditions you want to test the device? It seems you want / need to test during the welding operation. Can you install a tiny reed switch along the power wires? Honestly I do not know if a reed will activate on an A/C load wire, a coil like a Tape Head or a guitar pickup will. If you do not need to test during operation, then a simple continuity test should work, neon lights used to work very well for that.

[igeorge]

Thank you Gevo for suggestion. I have to test it first because i do not know the value of magnetic field at 10 amps.
I will update you when i get it

[igeorge]

Hello igeorge,
Could you elaborate a bit on the conditions you want to test the device? It seems you want / need to test during the welding operation. Can you install a tiny reed switch along the power wires? Honestly I do not know if a reed will activate on an A/C load wire, a coil like a Tape Head or a guitar pickup will. If you do not need to test during operation, then a simple continuity test should work, neon lights used to work very well for that.

Thanks Archangel for reading my post and offer to help.
Here are the conditions:
I must check during the weld process, and i have to make sure that the current going through the wire is over 1 amp.
I do not think the other solution is feasible, due to the number of wires involved.
What i have in mind is to have a PCB for 16 heaters and bring the wire heater to it to one terminal, run a trace through some device to get the current, then get out on the next terminal and go to heater.
Current transformers is not a solution, as they are bulky, not to many models PCB mount and i still need to interpret the reading.
My option was for ACS712 , but if you look at the attached graph you will see that the output is + and -
I need somehow to convert it, or do something that i will get only the + portion, but not pulsating, i need it as a continuous line.
Also, i need that any voltage over 2.6 volts to be a logic 1 and any voltage from 0 to 2.6 to be a logic ZERO. In this case, i will have my inputs to PIC set to read 1 for a good heater, and 0 for a bad heater.
Thank you

[Archangel]

Thanks Archangel for reading my post and offer to help.
Here are the conditions:
I must check during the weld process, and i have to make sure that the current going through the wire is over 1 amp.
I do not think the other solution is feasible, due to the number of wires involved.
What i have in mind is to have a PCB for 16 heaters and bring the wire heater to it to one terminal, run a trace through some device to get the current, then get out on the next terminal and go to heater.
Current transformers is not a solution, as they are bulky, not to many models PCB mount and i still need to interpret the reading.
My option was for ACS712 , but if you look at the attached graph you will see that the output is + and -
I need somehow to convert it, or do something that i will get only the + portion, but not pulsating, i need it as a continuous line.
Also, i need that any voltage over 2.6 volts to be a logic 1 and any voltage from 0 to 2.6 to be a logic ZERO. In this case, i will have my inputs to PIC set to read 1 for a good heater, and 0 for a bad heater.
Thank you

Ok so I am thinking, use 2 diodes in parallel with their polarities reversed so there is a path for both phases, then only run the forward phase through the device.
0 amps = 2.5v 1 amp or more, is above 2.7v.
What do you think, will this work?

[Pic_User]

Hi igeorge,

If you just need an un-calibrated “Go - No Go” measurement, a simple “peak detector” could work.
If a silicon diode has too much junction drop, maybe a germanium or Schottky diode would work.
Just a diode to a capacitor circuit on the output of the ACS712.

-Adam-

[igeorge]

Hello Adam,
Thanks for reply but i am afraid, like i mentioned before about the power dissipation on the diodes.
I have to do some tests to see if it will work.
Thanks
Ion

[Pic_User]

Hi Ion,
You are right to be concerned with the several watts per diode dissipation with diodes passing Amperage..
But I am proposing using them in the 5V output circuit of the ACS712.
They would have almost no current. and would give your digital pin a 2.5V to 5V swing.
If the peak Voltage was a little too high for your logic levels then add a “Voltage divider (= two resistors).
-Adam-

[igeorge]

Thanks Archangel,
I do not know if it will works, but i will try it. I am some how concerned about the power dissipation as they are 5 amps going through the diodes, and they will be 32 on one PCB for 16 heaters. I will test and let you know.
Thanks again
Ion