IEC 60255-24:2013

Measuring relays and protection equipment - Part 24: Common format for transient data exchange (COMTRADE) for power systems

IEC 60255-24:2013 defines a format for files containing transient waveform and event data collected from power systems or power system models. The format is intended to provide an easily interpretable form for use in exchanging data. The standard is for files stored on currently used physical media such as portable external hard drives, USB drives, flash drives, CD, and DVD. This standard defines a common format for the data files and exchange medium needed for the interchange of various types of fault, test, and simulation data. The main changes with respect to the previous edition are as follows:
- this new edition allows single file format (with extension .CFF) in lieu of four separate files;
- the single file with .CFF extension contains four sections of information corresponding to .CFG, .INF, .HDR, and .DAT. The DAT section is either in ASCII or Binary;
- the following additional data file types are also supported: binary32 and float32.

Relais de mesure et dispositifs de protection - Partie 24: Format commun pour l'échange de données transitoires (COMTRADE) dans les réseaux électriques

La CEI 60255-24:2013 établit un format pour les fichiers contenant des données sur les événements et les formes d'ondes des transitoires obtenus à partir des réseaux électriques ou de leur modélisation. Le format est destiné à fournir une forme facilement interprétable pour une utilisation dans l'échange de données. La norme est destinée aux fichiers stockés sur des supports physiques actuellement utilisés tels que des disques durs externes portables, des clés USB, des disques à mémoire flash, des CD et des DVD. La présente norme établit un format commun pour les fichiers de données et le support d'échange nécessaire pour échanger des données de différents types sur les défauts, les essais et la simulation. Les principales différences par rapport à l'édition précédente sont les suivantes:
- cette nouvelle édition autorise un seul format de fichier (avec extension .CFF) à la place de quatre fichiers séparés;
- l'unique fichier avec extension .CFF contient quatre sections d'information correspondant à .CFG, .INF, .HDR, et .DAT. La section DAT est en codage ASCII ou Binaire;
- les types de fichiers de données complémentaires suivants sont également pris en charge: binary32 et float32.

General Information

• Status: Published
• Publication Date: 29-Apr-2013
• ICS: 29.120.70 - Relays
• ICS: 33.120.30 - RF connectors
• Technical Committee: TC 95 - Measuring relays and protection equipment
• Current Stage: PPUB - Publication issued
• Start Date: 30-Apr-2013
• Completion Date: 15-May-2013

Relations

• Revises: IEC 60255-24:2001 - Electrical relays - Part 24: Common format for transient data exchange (COMTRADE) for power systems
• Effective Date: 05-Sep-2023

Overview

IEC 60255-24:2013, titled "Measuring relays and protection equipment - Part 24: Common format for transient data exchange (COMTRADE) for power systems," is an international standard published by the International Electrotechnical Commission (IEC). It specifies a standardized format for files containing transient waveform and event data related to electrical power systems and their simulations. This standard streamlines the exchange of fault, test, and simulation data by defining a common data file structure compatible with existing physical storage media like external hard drives, USB drives, CDs, and DVDs.

Significant updates in this 2013 edition include the introduction of a single file format (.CFF extension) substituting four separate files (.CFG, .INF, .HDR, and .DAT). The .CFF single file houses all relevant information sections and supports both ASCII and binary data types, including new binary32 and float32 data file types, enhancing data interchange flexibility and accuracy.

Key Topics

COMTRADE File Structure

• Single File Format (.CFF): Combines configuration, header, information, and data sections into one file for improved ease of use and management.
• Data Types: Supports ASCII, binary, binary32, and float32 formats to accommodate varying precision and storage needs.
• File Sections:
  • .CFG (Configuration): Describes channels, sampling rates, and time stamping.
  • .HDR (Header): Contains meta-information about the recording.
  • .DAT (Data): Holds recorded transient waveform or sequence data.
  • .INF (Information): Includes descriptive details like events and file descriptions.

Data Representation and Storage

• Binary and ASCII: Allows data to be stored in binary for compactness or ASCII for interpretability.
• Floating Point Notation: Uses floating-point formats for channel data values to maintain measurement accuracy.
• File Access Methods: Supports both random and sequential access to accommodate various software and hardware environments.

Time Synchronization and Sampling Rates

• Defines methods for precise time stamping, including local and UTC relationships, ensuring data integrity across systems.
• Addresses sampling frequency standards and conversions for consistent data analysis.

Applications

IEC 60255-24:2013 is crucial for industries and organizations involved in power system protection, fault analysis, relay testing, and simulation, including:

• Power Utilities: Facilitates accurate recording and analysis of transient fault data to enhance grid reliability and response.
• Protection Equipment Manufacturers: Enables interoperability between devices by adhering to a standardized data exchange format.
• Test Laboratories: Supports consistent documentation of protection relay and system testing results.
• Research and Development: Provides a common framework for simulating power system events and sharing results globally.
• Energy Management Systems: Integrates transient data into monitoring and control platforms, improving system diagnostics.

By adopting IEC 60255-24:2013, stakeholders ensure compatibility and seamless data exchange, reducing time and costs associated with data handling and interpretation.

Related Standards

IEC 60255-24:2013 aligns with and complements other international standards relevant to power system monitoring and protection, including:

• IEC 60255 Series: Covers various aspects of measuring relays and protection equipment including performance and testing.
• IEEE Std C37.111: Harmonized with IEEE's equivalent standard for COMTRADE, facilitating global interoperability.
• IEC 61850: Focuses on communication networks and systems in substations; IEC 60255-24 supports waveform data exchange critical to IEC 61850 protection schemes.
• IEC 61000 Series: Relates to electromagnetic compatibility, important for reliable transient data acquisition.
• IEC 60044 and IEC 61869: Standards for instrument transformers, often involved in data acquisition that uses COMTRADE-format files.

---

Keywords: IEC 60255-24, COMTRADE, transient data exchange, power systems, protection equipment, measuring relays, .CFF file format, electrical fault data, power system simulation, waveform data, IEEE Std C37.111, binary32, float32, power grid reliability, relay testing standard, IEC international standard.

Standards Content (Sample)

IEC 60255-24
Edition 2.0 2013-04
™
IEEE Std C37.111
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Measuring relays and protection equipment –
Part 24: Common format for transient data exchange (COMTRADE) for power
systems
Relais de mesure et dispositifs de protection –
Partie 24: Format commun pour l’échange de données transitoires (COMTRADE)
dans les réseaux électriques
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IEC 60255-24
Edition 2.0 2013-04
IEEE Std C37.111™
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Measuring relays and protection equipment –

Part 24: Common format for transient data exchange (COMTRADE) for power

systems
Relais de mesure et dispositifs de protection –

Partie 24: Format commun pour l’échange de données transitoires (COMTRADE)

dans les réseaux électriques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX XB
ICS 29.120.70 ISBN 978-2-83220-766-6

– 2 – IEC 60255-24:2013
IEEE Std C37.111-2013
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references . 8
3 Terms and definitions . 8
4 File and data storage . 9
4.1 Categories of files . 9
4.1.1 General . 9
4.1.2 Executable files . 10
4.1.3 Text files . 10
4.1.4 Data files . 10
4.2 Critical/non-critical data . 10
4.3 Data representation . 11
4.3.1 General . 11
4.3.2 Binary data . 11
4.3.3 ASCII data . 11
4.4 Data field delimiters and lengths. 11
4.4.1 General . 11
4.4.2 Carriage return/line feed delimiter . 11
4.4.3 Comma delimiter . 12
4.4.4 Field lengths . 12
4.5 Floating point notation for ASCII data . 12
4.6 Methods of accessing data in files . 13
4.6.1 General . 13
4.6.2 Random access files . 13
4.6.3 Sequential files . 13
4.7 Primary to secondary ratios . 14
5 COMTRADE files . 14
5.1 General . 14
5.2 Header file (.HDR) . 14
5.3 Configuration file (.CFG) . 15
5.4 Data file (.DAT) . 15
5.5 Information file (.INF) . 15
6 Header file . 15
6.1 General . 15
6.2 Content . 16
6.3 Filenames . 16
6.4 Format . 16
7 Configuration file . 16
7.1 General . 16
7.2 Content . 16
7.3 Filenames . 17
7.4 Format . 17
7.4.1 General . 17
Published by IEC under license from IEEE. © 2013 IEEE. All rights reserved.

IEEE Std C37.111-2013
7.4.2 Station name, identification and revision year . 17
7.4.3 Number and type of channels . 18
7.4.4 Analog channel information . 18
7.4.5 Status (digital) channel information . 20
7.4.6 Line frequency . 20
7.4.7 Sampling rate information . 20
7.4.8 Date/time stamps . 21
7.4.9 Data file type . 22
7.4.10 Time stamp multiplication factor . 22
7.4.11 Time information and relationship between local time and UTC . 22
7.4.12 Time quality of samples . 23
7.5 Missing data in configuration files . 24
7.6 Configuration file layout . 24
8 Data file . 24
8.1 General . 24
8.2 Content . 24
8.3 Data filenames . 24
8.4 ASCII data file format . 25
8.5 Example ASCII data sample . 26
8.6 Binary data files . 26
8.7 Example of binary data sample . 28
9 Information file . 28
9.1 General . 28
9.2 Content . 28
9.3 Information file filenames . 28
9.4 Information file structure . 28
9.4.1 General . 28
9.4.2 Public sections . 29
9.4.3 Private sections . 29
9.5 File characteristics . 29
9.6 Section headings . 30
9.6.1 Public and private section header name formatting rules . 30
9.6.2 Public section header naming examples . 30
9.6.3 Private section header naming examples . 30
9.7 Entry line . 30
9.7.1 General . 30
9.7.2 Comment lines. 31
9.7.3 Value string . 32
9.8 Adding, modifying, and deleting information . 32
9.8.1 General . 32
9.8.2 Deleting information . 32
9.8.3 Adding information. 32
9.9 Public section header and entry line definitions . 32
9.10 Public record information section . 32
9.10.1 General . 32
9.10.2 Section header definition . 33
9.10.3 Public record information entry line definition . 33
9.11 Public event information definition . 34
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– 4 – IEC 60255-24:2013
IEEE Std C37.111-2013
9.11.1 General . 34
9.11.2 Section heading definition: [Public Event_Information_#n] . 34
9.11.3 Public event information entry line definition . 34
9.12 Public file description section . 35
9.12.1 General . 35
9.12.2 Section heading definition: [Public File_Description] . 35
9.12.3 Public file description entry line definition . 35
9.13 Public analog channel section . 36
9.13.1 General . 36
9.13.2 Section heading definition: [Public Analog_Channel_#n] . 36
9.13.3 Public analog channel entry line definition . 36
9.14 Public status channel section . 36
9.14.1 General . 36
9.14.2 Section heading definition: [Public Status_Channel_#n] . 36
9.14.3 Public status channel entry line definition . 36
9.15 Sample .INF file . 37
10 Single File Format COMTRADE (with CFF extension) . 38
Annex A (informative) Sources and exchange media for time sequence data . 40
Annex B (informative) Data exchange sampling rates . 43
Annex C (informative) Sample file . 47
Annex D (informative) Sample program for sampling frequency conversion. 53
Annex E (informative) Example application of conversion factors . 56
Annex F (informative) Sample COMTRADE file with CFF extension (with ASCII data) . 58
Annex G (informative) Sample COMTRADE file with CFF extension (with binary data) . 60
Annex H (informative) Schema for phasor data using the COMTRADE file standard . 61
Bibliography . 69

Figure 1 – Example of data sample in ASCII format . 26
Figure 2 – Example of data sample in binary format . 28
Figure B.1 – Typical signal processing . 43
Figure B.2 – DSP solution . 44
Figure B.3 – Example of sample rate conversion. 44

Table B.1 – Frequencies corresponding to (ƒ = 384 × ƒ ) samples/cycle . 45
LCM base
Table B.2 – Frequencies corresponding to (ƒ = 3200 × ƒ ) samples/cycle . 45
LCM base
Published by IEC under license from IEEE. © 2013 IEEE. All rights reserved.

IEEE Std C37.111-2013
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 24: Common format for transient data exchange (COMTRADE)
for power systems
FOREWORD
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– 6 – IEC 60255-24:2013
IEEE Std C37.111-2013
International Standard IEC 60255-24/IEEE Std C37.111 has been jointly revised by the Power
System Relaying Committee of the IEEE Power and Energy Society in cooperation with IEC
Technical Committee 95: Measuring relays and protection equipment, under the IEC/IEEE
Dual Logo Agreement.
This second edition cancels and replaces the first edition published in 2001 and constitutes a
technical revision. The main changes with respect to the previous edition are as follows:
a) The new edition allows single file format (with extension .CFF) in lieu of four separate
files.
b) The single file with .CFF extension contains four sections of information corresponding
to .CFG, .INF, .HDR, and .DAT. The DAT section is either in ASCII or Binary.
c) The following additional data file types are also supported: binary32 (using 4 bytes to
represent integer numbers) and float32 (using 4 bytes to represent real numbers).
d) The configuration (.CFG) file/section has been modified. Four new fields have been added
at the end of the .CFG file/section in two separate lines. Two fields represent the time
information and the time difference between local and UTC time, and these two fields
comprise one line. Another two fields represent the time quality of samples and comprise
the last line of the file/section.
e) Some of the fields in the Configuration (.CFG) file/section have been designated critical
instead of non-critical.
f) The use of Unicode UTF-8 characters has been added. However and because of the
extensive use of the terms ASCII and Text throughout this document, any occurrence of
these terms also inherently implies Unicode UTF-8.
The text of this standard is based on the following IEC documents:
FDIS Report on voting
95/308/FDIS 95/311/RVD
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Published by IEC under license from IEEE. © 2013 IEEE. All rights reserved.

IEEE Std C37.111-2013
INTRODUCTION
The increasing use of digital technology in devices such as protection, oscillograph,
measurement, and control apparatus in electric power substations has created the potential
for accumulating large numbers of digital records of power system transient events. In
addition to these sources of digital data, analog and digital power-system simulators may be
used to generate digital records. The users of these records are faced with the problem of
having to cope with different formats used by each system to generate, store, and transmit
records.
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– 8 – IEC 60255-24:2013
IEEE Std C37.111-2013
MEASURING RELAYS AND PROTECTION EQUIPMENT –

Part 24: Common format for transient data exchange (COMTRADE)
for power systems
1 Scope
This International Standard defines a format for files containing transient waveform and event
data collected from power systems or power system models. The format is intended to provide
an easily interpretable form for use in exchanging data. The standard is for files stored on
currently used physical media such as portable external hard drives, USB drives, flash drives,
CD, and DVD. It is not a standard for transferring data files over communication networks.
This standard defines a common format for the data files and exchange medium needed for
the interchange of various types of fault, test, and simulation data. The rapid evolution and
implementation of digital devices for fault and transient data recording and testing in the
electric utility industry have generated the need for a standard format for the exchange of time
sequence data. These data are being used with various devices to enhance and automate the
analysis, testing, evaluation, and simulation of power systems and related protection schemes
during fault and disturbance conditions. Since each source of data may use a different
proprietary format, a common data format is necessary to facilitate the exchange of such data
between applications. This will facilitate the use of proprietary data in diverse applications and
allow users of one proprietary system to use digital data from other systems.
2 Normative references
TM
IEEE Std C37.118 -2005, IEEE Standard for Synchrophasors for Power Systems
TM
IEEE Std C37.232 -2007, IEEE Recommended Practice for Naming Time Sequence Data
Files
TM
IEEE Std 260.1 -1993, IEEE Standard Letter Symbols For Units of Measurement (SI Units,
Customary Inch-Pound Units)
TM
IEEE Std 280 -1985 (R1996), IEEE Standard Letter Symbols for Quantities Used in
Electrical Science and Electrical Engineering (DOD)
TM
IEEE Std 754 -2008, IEEE Standard for Floating Point Arithmetic
ISO 80000-1, Quantities and units – Part 1: General
3 Terms and definitions
For the purpose of this document the following terms and definitions apply:
3.1
critical data
any data that are necessary for reproduction of the sample data
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IEEE Std C37.111-2013
3.2
non-critical data
any data in the COMTRADE configuration file which are not absolutely necessary for
reproduction of the sample data, and some variables provided in the configuration file that
may not be relevant to a particular application
3.3
COMTRADE
Common Format for Transient Data Exchange
format of time sequence data generated by various sources for exchange purpose
Note 1 to entry: This note applies to the French language only.
3.4
electro-magnetic transient program
EMTP
programs that produce time sequence data by analyzing mathematical models of the power
system, unlike the devices that record actual power system events
Note 1 to entry: Electromagnetic transient simulation programs can provide many different test cases for a relay,
because of the use of the case with which the input conditions of the study can be changed.
Note 2 to entry: This note applies to the French language only.
3.5
skew
time difference between sampling of channels within the sample period of a record for an
analog-to-digital converter
EXAMPLE: In an eight-channel device with one analog-to-digital (A/D) converter without synchronized sample and
held running at a 1 ms sample rate, the first sample will be at the time represented by the timestamp; the sample
times for successive channels within each sample period could be up to 125 µs behind each other. In such cases
the skew for successive channels will be 0; 125; 250; 375 µs.; etc.
3.6
time sequence data
TSD
type of electronic data file where each data item in the file corresponds to an instant of time
that is identified by an explicit or implicit time tag, such as transient data records, event
sequences, and periodic data logs
Note 1 to entry: This note applies to the French language only.
4 File and data storage
4.1 Categories of files
4.1.1 General
Files stored on digital devices and media consist of bytes representing a combination of
alphabetic, numeric, symbol, punctuation, and other formatting characters. Depending on the
format, a byte, part of a byte, or more than one byte, may be represented by a letter, number,
or symbol (e.g., “A,” “3,” or “+”). There are three general classes of files used on computer
systems: executable files, text files, and data files. The use of the file determines the
category.
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– 10 – IEC 60255-24:2013
IEEE Std C37.111-2013
4.1.2 Executable files
Executable files contain a sequence of instructions suitable for processing by a computer.
Computer programs are stored as executable files (.EXE). COMTRADE does not define
executable files.
4.1.3 Text files
Text files imply data in human-readable form. A text file may be used for control of a computer
program if the format is rigidly specified. COMTRADE text files use the character
representation specified in ANSI X3.4-1986 [B1] .This is often called “ASCII format” or “text
(.TXT) format” by word processor programs. Characters from the Unicode UTF-8 Standard are
also allowed. Any occurrence of the terms ASCII or text in this document also inherently
implies Unicode UTF-8.
COMTRADE defines one freeform ASCII text file intended for strictly human interpretation, the
header file. COMTRADE also defines three files in which the format is rigidly controlled and
which are both human- and computer-readable—the configuration file, the information file, and
the ASCII form of the data file.
Most word processors can save text files in two or more formats. The text format contains only
the characters actually typed, including punctuation and standard formatting characters such
as carriage return/line feed. Other formats contain special characters, specific to the particular
word processor being used. The text format shall be used for the text files in a COMTRADE
record to eliminate word processor-specific characters or codes. Programs intended to read
COMTRADE files only require use of the typed characters that most word processor programs
can read or print.
If no command exists in the word processor to save the file in this format, an alternative
method is to use the print functions to print the text to disk to create the file.
4.1.4 Data files
Data files may contain numeric data, text data, or both. The data may be stored in either
binary or ASCII format. Fields within ASCII format data files use defined text separated by
commas, or some other common delimiter. As such, they are both human- and machine-
readable. Most word processors cannot format, read, or write data files in binary form.
However, many spreadsheet and data processing programs can read binary data files, if the
format is known. Binary numbers must be processed by application-specific software to be
easily interpreted by humans. COMTRADE defines one binary file, the binary form of the data
file. Binary data are generally used when large amounts of data are to be stored because this
uses less storage space (e.g., three bytes of binary data can represent numbers from 0 to
16 777 215 whereas three bytes of ASCII data can only represent numbers from 0 to 999).
ASCII numbers have the advantage of being interpreted by humans and by standard computer
hardware and software.
4.2 Critical/non-critical data
Some of the data in the configuration file are not absolutely necessary for reproduction of the
sample data, and some variables provided in the configuration file may not be relevant to a
particular application. Such data is described as non-critical and may be omitted. However,
the position normally occupied by such variables shall be maintained in order to maintain the
integrity of the file. If data are described as non-critical in any clause of this standard, the
position may be left empty and the corresponding data separator retained following the
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This is a reference to the Bibliography.
Published by IEC under license from IEEE. © 2013 IEEE. All rights reserved.

IEEE Std C37.111-2013
preceding data separator with no intervening characters or spaces. Any data that are
necessary for reproduction of the sample data are termed critical. If such data are missing,
the file may be unusable.
4.3 Data representation
4.3.1 General
Data are stored in files as series of binary digits or bits. Each bit can be either a 1 or a 0. The
bits are organized in groups of eight bits called bytes. When a computer reads the data in a
file, it reads the data as a series of bytes.
4.3.2 Binary data
The eight bits in a byte can be organized in 256 different combinations. They can be used,
therefore, to represent the numbers from 0 to 255. If larger numbers are needed, several
bytes can be used to represent a single number. For example, 2 bytes (16 bits) can represent
the numbers from 0 to 65 535. When the bytes are interpreted in this fashion, they are known
as binary data. Several different formats are in common use for storage of numeric data in
binary form. This standard supports three of these formats. The supported formats are 16 and
32 bit integer numbers defined according to the two’s complement system (hereinafter,
referred to as “binary” and “binary32” data respectively), and 32 bit real numbers defined
TM
according to the IEEE Std 754 -2008 (hereinafter, referred to as float32 data). The float32
data type format is intentionally listed in this binary data subclause for convenience even
though the format is not a straight binary count.
4.3.3 ASCII data
As an alternative to a byte representing the numbers 0 to 255, a byte can be used to
represent 256 different symbols. ASCII is a standard code of symbols that match 128 of the
combinations of eight binary bits. For example, the byte 01000001 represents an uppercase
“A” while 01100001 represents a lowercase “a.” With 128 different combinations, it is possible
to represent all of the keys on the keyboard plus many other special symbols. The remainder
of the 256 combinations available from an eight-bit format are used for drawing and other
special characters. To represent a number in ASCII format requires one byte for each digit of
the number. For example, 4 bytes are needed to represent the number 9 999 in ASCII format.
When the bytes are interpreted in this fashion, they are known as ASCII data.
4.4 Data field delimiters and lengths
4.4.1 General
Data fields within a file or within a subset of data in a file shall be separated from the other
data fields so that they may be extracted for reading or manipulation. For instance, written
text uses a space as a word delimiter. Computer files use a variety of delimiters. In the binary
form of COMTRADE data files, the only delimiter is a strict definition of the length and position
of each data variable, and a byte count of the position within the file is necessary to determine
the limit of any data entry. On the other hand, the ASCII files defined by COMTRADE use the
comma and the carriage return/line feed as data separators. This permits the use of variable
field lengths, but means that these characters cannot be used within any data entry. Leading
spaces or zeroes are allowed in ASCII numeric fields provided the permitted maximum
character count is not exceeded.
4.4.2 Carriage return/line feed delimiter
COMTRADE uses the symbol to represent a data separator terminating a set of
data. The delimiter is the combination of two ASCII formatting characters:
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– 12 – IEC 60255-24:2013
IEEE Std C37.111-2013
CR = carriage return takes the cursor or insertion point back to the beginning of the current
line and is identified by the hexadecimal value 0D.
LF = line feed moves the cursor or insertion point to a new line below the current line and is
identified by the hexadecimal value 0A.
The symbols “<” and “>” surrounding the CR/LF are used to delineate the delimiter from the
neighbouring text within this standard and are not part of the delimiter.
Historically, operating systems use LF to indicate a new line but not all of them do. Others
may use a variety of other characters for indicating new lines. It is important to note that in
COMTRADE is defined as a separator and not as a new line indicator because the
main intent is to exchange transient data between users and across operating systems.
4.4.3 Comma delimiter
The comma is used as a delimiter for data entries within the COMTRADE configuration
(.CFG), information (.INF), ASCII format data (.DAT), and combined format data (.CFF) files.
4.4.4 Field lengths
Field lengths are specified for many alphabetic or numeric variables in the COMTRADE
standard. These limitations were specified to simplify reading lines of data containing many
variables. For integer numeric variables, the maximum field length is one character longer
than required to hold the maximum value for that field. This extra character space is allowed
for a leading minus for signed numbers and to allow the application of simple programming
techniques that automatically print the leading space, even for unsigned numbers.
4.5 Floating point notation for ASCII data
Real numbers may be stored in several ways. Numbers of limited range can be entered as a
numeric string of ASCII characters with a decimal point. For larger or smaller numbers, any
reasonable limit on string length leads to a loss of resolution. In such cases, it is desirable to
store the number in a format allowing use of a representation of the significant digits
(mantissa) and a multiplier (exponent) format. Spreadsheets and other mathematical
programs often use floating point notation to represent such numbers. COMTRADE allows the
use of floating point notation (Kreyszig [B6]) to represent real numbers in the .CFG and .DAT
files. The terms exponential notation or scientific notation are sometimes used for this form
and interpretations of the form vary. Since programs designed to read COMTRADE files must
be able to recognize and interpret numbers represented in this format, one single format is
defined here. The numbers shall be interpreted and displayed as follows.
A signed floating point value consists of an optional sign (+ or –) and a series of decimal
digits containing an optional decimal point, followed by an optional exponent field that
contains the character “e” or “E” followed by an optionally signed (+ or –) integer exponent.
) or 300. Correct
The exponent is a factor of base 10, so 3E2 means 3 multiplied by 100 (10
interpretation of negative numbers and negative exponents requires the inclusion of the
negative sign. For positive numbers or exponents the sign is optional and is assumed positive
if absent.
The format shall be written as:
[±]d[d][.]d[d][d][d][E[±]d[d][d]]
where
– Square brackets surround any optional item.
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IEEE Std C37.111-2013
– “d” represents any numeral between 0 and 9.
– At least one numeral must appear in the field.
– If the decimal point appears, at least one numeral shall appear to the left and right.
– The character “e” or “E” represents “ex
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