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# EN 50522 Calculation of Permissible Touch Voltage

## EN 50522 Calculation of Permissible Touch Voltage

(OP)
thread238-470443: EN 50522 permissible touch voltage - body resistance question

Regarding this thread about the calculation of Permissible Touch Voltage depending on fault time, I've been trying to get close to the values of Table B.4 on the norm 50522_2022 and I've made great progress

I made some breakthroughs that lead me in the right path: did a model to have better "fits" for the body impedance (since the ones on the Table B.2 of the Norm are rounded to 25 V) and managed to get the same results erdep did and showed on the other thread (using the graphical method to solve the non-linearity).

After this, I tried to make a "relationship" between those new values and the I_B values, using Excel. Here is what I did: 1) Calculated the "new" I_B values of Table B.3 based on the "new" Z_T values. 2) Made a log-log graph with I_B on x-axis and Z_T on y-axis to get an expression that could relate the two of them. 3) For each tf and I_B given, I calculated the corresponding Z_T value. 4) Did the multiplication for each situation using the corresponding HF and BF. I though this was the right thing to do, but unfortunately, the results obtained wasn't near the theoretical ones.

Then I saw the last post of the thread I refer to and saw that erdep got different values of Z_T for each of the 4 contact situations (in the example of tf = 0.05 s), so I was wrong on my assumptions. I decided to do a code on Matlab, where I did an iterative process of calculating U_Tp with an initial guess and a tolerance, the cycle also corrected Z_T value at each iteration. I managed to get closer to erdep values, with some slight differences. As for the Table B.4 values, the obtained values are very close. Did any of you manage to get better results?

Replies continue below

### RE: EN 50522 Calculation of Permissible Touch Voltage

(OP)

This is my final graph, with the Norm one on the right side

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