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Can we measure floating voltage (of power supply) with reference to chassis ground?

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Ume_sizz

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Hi,
Sorry if this been repeated. I am new to the forum and your reply is highly appreciated.

Is it possible to measure the floating voltage of power supply with reference to chassis ground, for example if the voltage between +ve and -ve of the power supply is 20V, then, what is the voltage across earth ground/ chassis ground to +ve and -ve to earth ground/chassis. In another words, how can we measure common mode voltage on +ve and -ve of supply with reference to earth ground.

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KlausST

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Hi,

read below "similar threads"

In my eyes measuring this voltage makes no sense, because it is "floating". The voltage ins inpredictable an may change any time. (Caused by airflow, humidity, touching, connections of other floating devices...) Additionally the measurement device usually has a finite input impedance, so the measurement itself affects this voltage. This means the voltage during measurement may be different as when mesurement devise is disonnected.
Another problem is that this voltage usually is a mixture of DC, low frequencies and high frequencies. How do want you handle this?

--> Maybe it is more interesting to ground one point and measure the GROUND current.
--> Instead of "undefined floating" you could pull it defined to GND. Maybe with 1MOhms for DC and 1nF for AC.

Klaus
 

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