Observation period of one year with fixed steps of 10 seconds.
N = the number of valid 10-second intervals monitored by your meter.
N1= the number of 10-second intervals in which the frequency exceeds ± 1% of nominal.
N2 = the number of 10-second intervals in which the frequency exceeds +4% or -6% of nominal.
Ninvalid = the number of observed intervals or partial intervals that are not included in EN50160:2010 compliance calculations.
Power frequency complies with the standard if N1/N ≤ 0.5% and N2 = 0.
EN50160 data (current observation period): the meter generates the N, N1 and N2 counts described. These counters are reset at the beginning of the next observation period.
EN50160 data (previous observation period): the meter stores the N, N1 and N2 counter values at the end of each observation period before these counters are reset. These registers are also stored in a data recorder for each observation period.