Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

RE: Leakage current vs Hipot

Title: RE: Leakage current vs Hipot

a verbal discussion would be a lot more efficient, but we need to get more people involved here.

Anyway, I absolutely agree, we need a safety expert involved on the working group for guidance.

I actually worked in medical systems for 10 years, and the Hipot tests there all relate to patient safety,
in addition they relate to equipment and personnel safety.
The leakage current tests are all done with the power on, as you say, since that is generally the worst case.
Some tests are also done with the power off.
For the medical case, the patient must be safe whether or not the power for one piece of equipment is on or off.
The leakage currents involved are much lower than the ones used for normal equipment Hipot tests.

For DTE power, we need to be concerned primarily with equipment and personnel safety.

When you say that the Hipot and leakage tests are two different things, I guess I disagree.
They are the same thing in the sense that they relate to safety: equipment and personnel, plus patient safety for medical equipment

Hipot tests use a high potential to induce leakage or fault currents in order to simulate what happens when the
line voltage has high voltage transients. It is tested with the power off, since it is easier to test this way,
and since the fundamental physical isolation barrier does not change in the transformer when power is applied.

The ethernet Hipot test looks for leakage current on the data port.
My opinion is that this test should pass WHETHER OR NOT the power is applied, since we want equipment safety
whether or not power is applied.
In any non-powered port this is the case since again the physical isolation barrier of the data transformer does not
change when power is applied.
If Hipot passes when the power is off, it should pass when power is on.
I think that this Hipot test should pass under all of the following conditions:
        the system power is off
        the system power is on (but the DTE power off)
        and the DTE power is on

This will help assure safety and freedom from ground loops.

any comments?

- Rick