The meter detects condition when phase voltage rises above or drops below certain threshold levels. Such conditions are categorized as over-voltage or under-voltage. From samples of phase voltages the meter calculates the average values over a time period. This time period is synchronized with the meter clock. At the end of time period, each value of average phase voltage is compared to the over-limit and under-limit threshold parameters. When specific phase voltage value rises above over-limit threshold, an event for voltage over-limit is generated. Also when certain phase voltage drops below under-limit threshold, an event for voltage under-limit is recorded.
The meter also records end of voltage under/over limit condition (voltage normal event) when phase voltage returns between the two threshold levels. In order to prevent several events when phase voltage is exactly on the level of thresholds, a 2% hysteresis is implemented. This means that in order to detect normal voltage, phase voltage must rise additional 2% above parametrized under-limit threshold, or drop additional 2% below parametrized over-limit threshold.
|Threshold for voltage over-limit||220.127.116.11|
|Time threshold for voltage over-limit||18.104.22.168|
|Threshold for voltage under-limit||22.214.171.124|
|Time threshold for voltage under-limit||126.96.36.199|