IEC 60255-24 pdf download Electrical relays — Part 24: Common format for transient data exchange (COMTRADE) for power systems
1 scope and object
This part of lEC 60255 defines a format for files containing transient waveform and event datacollected from power systems or power system models.This standard applies to files stored onphysical media such as digital hard drives and diskettes. It is not a standard for transferringdata files over communication networks. The format is intended to provide an easilyinterpretable format for use in exchanging data; as such，it does not make use of theeconomies available from data encoding and compression which proprietary formats dependon for competitive advantage.
For the purpose of this part of IEC 60255, the following definitions apply.2.1
data stored in files as a series of binary bits
NOTE Each bit can be either a 1 or a 0.The bits are organized in groups of 8 bits called bytes. When a computerreads the data in a file, it reads the data as a series of bytes.
data organized in the form of bytes
NOTE The 8 bits in a byte can be organized in 256 different combinations.They can be used，therefore，torepresent the numbers from 0 to 255. If larger numbers are needed, several bytes can be used to represent a singlenumber, e.g., 2 bytes (16 bits) can represent the numbers from 0 to 65535.When the bytes are interpreted in thisfashion, they are known as binary data. Several different formats are in common use for storage of numeric data inbinary form.
ASCll(American National Standard Code for Information Interchange) datasymbols that match 127 of the combinations of eight binary bits
NOTE As an alternative to a byte representing the numbers 0 to 255,it can be used to represent 255 differentsymbols.The American National Standard Code for Information Interchange (ASclIl) is a standard that lists symbolsthat match 127 of the combinations of eight binary bits, e.g. the byte 01000001 represents an upper case“A” while01100001 represents a lower case * a” . with 127 different combinations, it is possible to represent all of the keys onthe keyboard plus many other special symbols. The remainder of the 256 combinations avallable from an 8-bitformat are used for drawing and other special application characters. To represent a number in AScll formatrequires one byte for each digit of the number.
critical/non-critical some of the data in the configuration file is not absolutely necessary for the reproduction of the sample data, and some variables provided for in the configuration file may not be relevant to a particular application. Such data may be described as non-critical and may be omitted. An example of such non-critical data is the recording device channel name. However, the position normally occupied by such variables must be maintained in order to maintain the integrity of the file. If data is described as non-critical in any section of the standard, the position may be left empty or filled, using the space character, and the corresponding data separator following the preceding data separator applied with no intervening characters or spaces.
Any data which is necessary for the reproduction of the sample data is termed critical. If such data is missing, the file may be unusable.