Term DescriptionLAN Local Area NetworkLCD Liquid Crystal Display: The front-panel text display on the relay.LD Level Detector: An element responding to a current or voltage below its set threshold.LDOV Level Detector for OvervoltageLDUV Level Detector for UndervoltageLED Light Emitting Diode: Red or green indicator on the front-panel.LLDB Live-Line Dead-Bus : In system synchronism check, indication that the line is energized whilst thebus is de-energized.Ln Natural logarithmLN Logical NodeLoL A Loss of Load scheme, providing a fast distance trip without needing a signaling channel.LPDU Link Protocol Data UnitLPHD Logical Physical DeviceMC MultiCastMCB Miniature Circuit BreakerMCL MiCOM Configuration LanguageMICS Model Implementation Conformance StatementMMF Magneto-Motive ForceMMS Manufacturing Message SpecificationMRP Media Redundancy ProtocolMU Merging UnitMV Measured ValueN NeutralN/A Not ApplicableN/C A Normally Closed or "break" contact: Often called a "form B" contact.N/O A Normally Open or "make" contact: Often called a "form A" contact.NERC North American Reliability CorporationNIST National Institute of Standards and TechnologyNPS Negative Phase SequenceNVD Neutral voltage displacement: Equivalent to residual overvoltage protection.NXT Abbreviation of "Next": In connection with hotkey menu navigation.O/C OvercurrentO/P OutputOpto A generic term for a digital input.OSI Open Systems InterconnectionPCB Printed Circuit BoardPCT Protective Conductor Terminal (Ground)PDC Phasor Data ConcentratorPh Phase - used in distance settings to identify settings that relate to phase-phase faults.PICS Protocol Implementation Conformance StatementPMU Phasor Measurement UnitPNG Portable Network Graphics – a file format for a computer graphicPol Polarize - typically the polarizing voltage used in making directional decisions.POR Permissive Over ReachMiCOM P747 Appendix A - Symbols and GlossaryP747-TM-EN-1 411
