an rms decrease in the ac voltage, at the power frequency, for a duration greater than 1 minute.
A decrease in voltage outside the normal voltage levels (10% or greater) for more than one minute.
Any reduction, interruption or failure of voltage that may cause equipment to stop or cycle incorrectly.
Negative change in amplitude of a voltage.
When used to describe a specific type of long duration variation, refers to a measured voltage having a value at least 10% below the nominal voltage for a period of time greater than one minute. Undervoltages frequently occur during air conditioning season due to peak power demands and may last only minutes or several hours, days or months in duration. See Rolling redout.
An undervoltage is a measured voltage that falls below the nominal voltage for more than one minute.
By definition, it is voltage at 90% or less of the normal level for more than one minute. Sometimes it is called a brownout.