Detecting Overvoltage in 3-Phase AC Signal

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SUMMARY

This discussion focuses on detecting overvoltage in a 3-phase AC signal, specifically addressing the challenges of referencing outputs after full-wave rectification. The user, Hemant, considers using a full bridge rectifier for each phase but is uncertain about the output reference point due to the grounded neutral. Participants suggest that while a single diode can capture peak waveforms, full-wave rectification is necessary to detect overvoltage accurately. Additionally, they recommend using split power supplies for measuring circuitry.

PREREQUISITES
  • Understanding of 3-phase AC signal characteristics
  • Knowledge of full-wave rectification techniques
  • Familiarity with PCB grounding practices
  • Experience with differential voltage measurement
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  • Research full-wave rectification methods for 3-phase systems
  • Learn about differential voltage measurement techniques
  • Explore PCB design considerations for grounded neutral systems
  • Investigate the use of split power supplies in measurement circuits
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Electrical engineers, PCB designers, and technicians involved in power electronics and overvoltage detection in 3-phase AC systems.

hemant03
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Hi,
I have to detect overvoltage on each of the 3 phases (individually) of a 3 phase AC signal. The 3 phase AC source has a neutral that is grounded and I have to use the same ground plane for my PCB.
I was thinking of using a full bridge rectifier for each of the 3 phase but the problem is what do I reference the output to? Is there any other way or would I need a transformer?
I have attached the schematic as an attachment.

Thanks
 

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hemant03 said:
Hi,
I have to detect overvoltage on each of the 3 phases (individually) of a 3 phase AC signal. The 3 phase AC source has a neutral that is grounded and I have to use the same ground plane for my PCB.
I was thinking of using a full bridge rectifier for each of the 3 phase but the problem is what do I reference the output to? Is there any other way or would I need a transformer?
I have attached the schematic as an attachment.

Thanks

The bridge seems like a reasonable approach. If you use a single diode and Neutral ground your PCB, you can see the peak of every other half waveform. Is that sufficient?

BTW, using Neutral for your PCB ground means that your circuit is not going to be SELV. Is the whole circuit isolated from other SELV circuitry nearby?
 
No, the need is full wave rectification as overvtg can occur on any of the cycle.

For the second section, the neutral of the 3 phase is tied to the chassis/system gnd and pcb gnd is also tied to the same so , i guess the answer would be no.
So, what are other options available to me?
 
hemant03 said:
No, the need is full wave rectification as overvtg can occur on any of the cycle.

For the second section, the neutral of the 3 phase is tied to the chassis/system gnd and pcb gnd is also tied to the same so , i guess the answer would be no.
So, what are other options available to me?

What is your power source for your circuitry? You can still do the full-wave rectification, attenuate the voltage, and measure it differentially. You will need split power supplies (like +/-12V) to power the measuring circuitry.
 
115vac 10amps. 3 phase. Can you send me the circuit. I am not sure of what to use as reference after full wave rectification.
 
hemant03 said:
115vac 10amps. 3 phase. Can you send me the circuit. I am not sure of what to use as reference after full wave rectification.

What is the context of your question? Why are you being asked to design this circuit if you do not know how to do it?
 
Hi,
Oh! I guess there was a misunderstanding. What I meant was how do i attenuate. I believe I have figured that out. Thanks for the idea though.

Thanks,
- Hemant
 

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