Please can you help me understand where the values for ZS are being derived from

[RCDGuy]

Please can you help me understand where the values for ZS are being derived from?

I have a sub circuit protected by a Schneider NXS160N with ML2.2 trip set to maximum settings (160A). The maximum permitted Zs value on the test certificate generated by Electrical OM is shown as 0.25R. The tables provided by Schneider for this MCCB suggest a max Zs of 0.12R (@ 0.4s disconnect time).

Why the difference in values? What am I missing?

Schneider table were obtained from https://ckm-content.se.com/ckmContent/sfc/servlet.shepherd/document/download/0691H00000DxLGmQAN

Thanks in advance.

[Mert]

When having adjustable devices the device's settings might affect the maxZs value i.e the time the device will disconnect at the given time (0.4sec, 5sec etc)

To get the same maxZs as per Schnieder's table please set the Isd setting to the max i.e 10.

But careful as this change will affect selectivity study, so it's good to use the actual settings if you are aware of them.

See the attached screenshots.