Supply voltage unbalance
Observation period of one week with fixed steps of 10 minutes.
N = the number of valid 10-minute intervals monitored by your meter.
N1 = number of 10-minute periods in which the supply voltage unbalance exceeds 2%.
Ninvalid = the number of observed intervals or partial intervals that are not included in EN50160:2010 compliance calculations.
Supply voltage unbalance complies with the standard if N1/N <= 5% during the observation period (1 week by default). Voltage unbalance is calculated as follows, using the 10-minute sequence magnitude components from the Symmetrical Components module:
EN50160 data (current observation period): the meter generates the N and N1 counts described. These counters are reset at the beginning of the next observation period.
EN50160 data (previous observation period): the meter stores the N and N1 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.
Events: the meter creates an entry in its onboard event log every time the N1 counter increases.