IEEE Std C37.237-2018 pdf download – IEEE Standard for Requirements for Time Tags Created by Intelligent Electronic Devices—COMTAG.
event record: A compilation of data, man or machine readable, which includes information describing one or more events and/or analog quantities. Event records include a time tag and data for a period of time. event time: That time when an event occurred or when a reported quantity was measured on the actual power system. intelligent electronic device (IED): Any device incorporating one or more processors with the capability to receive or send data/control from, or to, an external source (e.g., electronic multifunction meters, digital relays, controllers). intended use: Use of a product in accordance with specifications, instructions, and information provided by the supplier. local offset: Difference, in hours and sometimes fractions of hours, between universal coordinated time (UTC) and a local time zone. Example: Pacific Standard Time (PST) is UTC-0800. Central European Time (CET) is UTC+0100. local time: Time expressed in the custom of the local time zone. Local times are based on UTC and include a local offset, which may depend on the season. See also: summer time; time zone. locked: Tracking a reference signal within acceptable limits. on-time mark: A signal that indicates the beginning of a second, minute, hour etc. The most common on-time mark is 1 pulse per second (PPS).
sampled value(s): One of a sequence of digitized values, representing an analog quantity, not necessarily complying with, nor used with the same meaning as IEC 61850 [B1]. 2 summer time: Local time, which is advanced in summer, generally by one hour, compared to local time during the rest of the year. For example, Pacific Daylight Time (PDT) is (UTC)-07h; Central European Summer Time (CEST) is UTC+02h. Not all parts of a time zone may adopt summer time uniformly, which can cause problems when comparing event records from different locations. The specific day and hour when time is advanced during summer, and set back again during fall, is determined by local law and subject to change for political convenience. See also: daylight saving time; local time; time zone. time quality: A statement of the estimated uncertainty of the internal clock in an IED used to generate time tags. Time quality includes the effects of inherent performance limits of the time distribution system, holdover when “master” sync is lost, and degradations caused by IEDs or other devices used to process or transmit the time signal. NOTE—Time tags compliant with this standard are required to have a time quality field. 3 time scale: A well-known universal system of time, used by a community of persons. NOTE—Examples: UTC, TAI, Central European Time. time tag: A collection of data that uniquely identifies a specific instant in time associated with a single measured or derived value.