Unavailable seconds start accruing when ten consecutive severely errored seconds occur.
Undercurrent Relay - Relay which operates when the current being monitored falls below a specified value. Undervoltage Alarm - Alarm given when the monitored voltage falls below a specified level. Undervoltage Relay - Relay which operates when voltage being monitored falls below a specified value. Unicasting - The transmit operation of a single PDU by a source interface where the PDU reaches a single destination. UPC is responsible for policing or enforcement.