Satec Expertmeter EM720 Operation Manual page 212

Appendix E EN50160 Evaluation and Recording
212
Target Values
The voltage levels given by the EN50160 in Figure 1 of
Clause 2.13 are taken from the so-called "Meister-curve"
which defines the maximum permissible ripple control
voltages in LV networks.
Compliance with the EN50160 requires that the 3-second
mean of signal voltages shall be less or equal to the
specified limits for 99% of a day.
EM720 Power Quality and Revenue Meter