EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: AndyChriss123 on April 23, 2022, 05:35:57 pm
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Hello everyone and thank you for joining!
I need some help if you are willing to spare a couple of minutes.. How would you go about measuring the voltage of a synchronous generator?
It is rated for 800 V and that is all I know as it is missing the plate on it, oops china...
I built a simple sensor that I'm going to test soon. I use a transformer 800-24 followed by a full bridge rectifier with a cap and a voltage divider to get the 0-10VDC that I need for the PLC Analog Input but I have doubts about how well this is going to work.. I never had to measure voltages with greatly varying frequencies before so I expect a huge dead-zone as it will mostly operate in the 400(v) zone. The transformer is rated for 50-60 (Hz) but in this case the sensor will have to operate mostly in the 20-40 (Hz) range.
I don't really care about resolution or complexity (throw whatever at me, easy or hard), i just need the solution to be somewhat reliable a.i. not to have a lot of deadzone or blow up too often.
Soo... How would you go about this?
Transformerless ADC or a Voltage to Frequency converter or some other transformerless solution?
Thank you very much for the time and experience!
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Use some resistors to divide the voltage, assuming 400-800V RMS @ 20-40Hz, and a multimeter on AC range? Or is there more to what you want to do?
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The multimeter part I don't really get it as I'm interested in continuous measurements using a PLC instead of visual readout of the multimeter's screen.
And a simple voltage divider without the transformer as I understand you are suggesting was the first solution I thought of but eliminating any kind of insulation (transformer, optocoupler etc) from the design wouldn't be a serious hazard?
Thank you for taking the time to post a suggestion!
To be honest there are many things that would work in my case as I don't really care about resolution. I'm mostly curious about what is the most efficient/smartest way to do this
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Well if you want the PLC to do something with it and counting the frequency of pulses is accurate enough, a voltage to frequency converter just requires a single optocoupler for signal isolation, as well as its own isolated supply. Use a resistive divider to get the voltage down to reasonable levels, be careful not to exceed the resistor breakdown voltage, use multiple in series if need be, then feed the divided voltage into a precision rectifier which you then filter before feeding it into your VtoF converter and out through a suitable optocoupler.