IEC TR 62711:2011

Mnemonics and designations of symbols for measuring relays, instruments and related device

IEC/TR 62711:2011(E) provides recommendations for consistent use of mnemonics and qualifying symbols to be applied to symbols representing devices used in systems for monitoring, protection, switching, and controlling of apparatus in electrical substations, generating stations, power utilization and conversion facilities, and equipment designed for automatic protection of power systems. The recommendations are intended for designers, manufacturers and engineers of such systems.

General Information

• Status: Published
• Publication Date: 11-Oct-2011
• ICS: 01 - GENERALITIES. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION
• ICS: 01.080.40 - Graphical symbols for use on electrical and electronics engineering drawings, diagrams, charts and in relevant technical product documentation
• ICS: 29.200 - Rectifiers. Convertors. Stabilized power supply
• Technical Committee: TC 3 - Documentation, graphical symbols and representations of technical information
• Current Stage: PPUB - Publication issued
• Start Date: 12-Oct-2011
• Completion Date: 31-Dec-2011

Overview

IEC TR 62711:2011 - "Mnemonics and designations of symbols for measuring relays, instruments and related device" is a Technical Report from the IEC that provides recommendations for the consistent use of mnemonics and qualifying symbols applied to graphical representations of measuring relays and measuring instruments. It targets devices used in monitoring, protection, switching and control of apparatus in electrical substations, generating stations, power conversion facilities and automatic protection equipment for power systems.

This report is advisory (technical report) and complements the graphical symbol rules of IEC 60617 and the design guidance in ISO/IEC 81714-1.

Key topics and requirements

• Purpose: standardize mnemonics and designations so symbols are consistent and unambiguous across drawings and documentation.
• Symbol usage:
  • Use the general measuring-relay symbol (IEC 60617‑S00327) and combine it with appropriate supplementary/qualifying symbols.
  • Use the general measuring-instrument symbols (IEC 60617‑S00910 / S00911 / S00912) and replace the asterisk with the relevant letter/graphical designation.
• Mnemonics tables: comprehensive tables (Tables 1–19) list permitted prefixes, suffixes, general, current, voltage, frequency, impedance, power, phase and other designations for relays and instruments.
  • Example prefix/suffix mnemonics (from the report): O (over), U (under), B (band); suffixes B (balance), V (with voltage restraint).
  • Examples of relay designations: D (directional), Df (differential), RDf (ratio/percentage differential), G (ground relay).
• Normative references and alignment: links to IEC 60617, IEC 60909 (designation variables), and ISO/IEC 81714‑1 are provided for correct symbol construction and application notes.

Practical applications and users

Who uses IEC TR 62711:

• Substation and protection engineers
• Power system designers and schematics authors
• Relay and instrument manufacturers
• Technical authors preparing wiring diagrams, single-line diagrams and maintenance documentation

Practical benefits:

• Improves clarity and interoperability of protection & control diagrams.
• Reduces ambiguity in procurement, testing and maintenance documents.
• Helps manufacturers label devices and front-panel instruments consistently for global projects.

Related standards

• IEC 60617 - Graphical symbols for diagrams (primary symbol source)
• ISO/IEC 81714‑1 - Design of graphical symbols for product documentation
• IEC 60909, IEC 60050 - referenced for designation variables and terminology

Keywords: IEC TR 62711:2011, mnemonics, designations, measuring relays, measuring instruments, symbols, IEC 60617, electrical substations, protection diagrams.

Standards Content (Sample)

IEC/TR 62711 ®
Edition 1.0 2011-10
TECHNICAL
REPORT
Mnemonics and designations of symbols for measuring relays, instruments and
related device
IEC/TR 62711:2011(E)
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IEC/TR 62711 ®
Edition 1.0 2011-10
TECHNICAL
REPORT
Mnemonics and designations of symbols for measuring relays, instruments and
related device
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
T
ICS 01.080.40; 29.200 ISBN 978-2-88912-691-0

– 2 – TR 62711  IEC:2011(E)
CONTENTS
FOREWORD . 3
1 Scope . 5
2 Normative references . 6
3 Terms and definitions . 6
4 Measuring relay symbols . 6
5 Measuring instruments . 6
6 Mnemonics and designations for measuring relays and instruments . 7
6.1 Overview . 7
6.2 Measuring relays . 7
6.3 Power system measuring instruments. 17
Bibliography . 24

Figure 1 – The general symbol for a measuring relay in IEC 60617 . 5
Figure 2 – The general symbols for a measuring instrument in IEC 60617 . 5

Table 1 – Measuring relays – Prefix . 7
Table 2 – Measuring relays – Suffix . 7
Table 3 – Measuring relays – General . 8
Table 4 – Measuring relays – Current . 9
Table 5 – Measuring relays – Voltage . 10
Table 6 – Measuring relays – Frequency . 10
Table 7 – Measuring relays – Impedance . 11
Table 8 – Measuring relays – Power . 11
Table 9 – Measuring relays – Phase . 12
Table 10 – Measuring relays – Other quantities . 12
Table 11 – Measuring relays – Other fault phenomenon. 12
Table 12 – Measuring relays – Pilot wire relay . 13
Table 13 – Measuring relays – Carrier pilot relay . 13
Table 14 – Measuring relays – Microwave relay . 14
Table 15 – Measuring relays – Calculation type . 14
Table 16 – Measuring relays – Apparatus protection and control . 14
Table 17 – Measuring relays – Other type . 15
Table 18 – Measuring relays – Power system control . 17
Table 19 – Measuring instruments – Power system measuring instruments . 18

TR 62711  IEC:2011(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MNEMONICS AND DESIGNATIONS OF SYMBOLS FOR MEASURING
RELAYS, INSTRUMENTS AND RELATED DEVICE

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
The main task of IEC technical committees is to prepare International Standards. However, a
technical committee may propose the publication of a technical report when it has collected data
of a different kind from that which is normally published as an International Standard, for
example "state of the art".
IEC 62711, which is a technical report, was prepared by IEC technical committee 3: Information
structures, documentation and graphical symbols.
The text of this technical report is based on the following documents:
Enquiry draft Report on voting
3/1029A/DTR 3/1041/RVC
Full information on the voting for the approval of this technical report can be found in the report
on voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

– 4 – TR 62711  IEC:2011(E)
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this standard may be issued at a later date.

TR 62711  IEC:2011(E) – 5 –
MNEMONICS AND DESIGNATIONS OF SYMBOLS FOR MEASURING
RELAYS, INSTRUMENTS AND RELATED DEVICE

1 Scope
This Technical Report provides recommendations for consistent use of mnemonics and
qualifying symbols to be applied to symbols representing devices used in systems for monitoring,
protection, switching, and controlling of apparatus in electrical substations, generating stations,
power utilization and conversion facilities, and equipment designed for automatic protection of
power systems. The recommendations are intended for designers, manufacturers and
engineers of such systems.
For symbols of measuring relay and measuring instrument, it is intended to serve two purposes,
namely:
– Give a review of standardized designations (as defined in this report);
– Limit the range of possible variants (after final standardization and introduction in
IEC 60617).
Symbols for measuring relays are symbols in which the functional behaviour of an element,
mostly because of its complexity, is described by qualifying symbols e.g. IEC 60617-S00328
(2001-07), IEC 60617-S00337 (2001-07), particularly by referring to supporting documentation;
the relevant rules and explanations are to be found in IEC 60617 in the application notes
associated with the symbols, e.g. IEC 60617-S00327 (2001-07) (A00091 through A00094).
IEC 60617-S00327 (2001-07):
Measuring relay
Figure 1 – The general symbol for a measuring relay in IEC 60617
Symbols for indicating, recording or integrating instruments are symbols in which the functional
behaviour of an element is fully described by standardized means. The relevant rules and
explanations are to be found in IEC 60617 in the application notes associated with the symbols
IEC 60617-S00910 (2001-07), IEC 60617-S00911 (2001-07) and IEC 60617-S00912 (A00144
through A00147).
IEC 60617-S00910 (2001-07): IEC 60617-S00911 (2001-07): IEC 60617-S00912 (2001-07):
Indicating instrument Recording instrument Integrating instrument

Figure 2 – The general symbols for a measuring instrument in IEC 60617

– 6 – TR 62711  IEC:2011(E)
2 Normative references
The following referenced documents are indispensable for the application of this document. For
dated references, only the edition cited applies. For undated references, the latest edition of the
referenced document (including any amendments) applies.
IEC 60617, Graphical symbols for diagrams
ISO/IEC 81714-1, Design of graphical symbols for use in the technical documentation of
products – Part 1: Basic rules
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
protection relay
measuring relay which, either solely or in combination with other relays, is a constituent of a
protection equipment
[IEC 60050-448:1995, 448-11-02]
4 Measuring relay symbols
Power systems are extremely complicated electrical networks that are geographically spread
over very large areas. The power systems are so complex that a complete conventional diagram
showing all the connections is impractical. There is some concise way of communicating the
basic arrangement of power system components. This is done by using diagrams with
universally accepted symbols in IEC 60617.
When measuring relay symbols are required, pick the general symbol IEC 60617-S00327
(2001-07) (see Figure 1), and then combine it with one or more appropriate supplementary
symbols.
Some devices, especially newer devices, may not have universally accepted symbols. These
devices could be represented in a number of ways, usually a matter of personal choice. In such
instances, the symbol is usually accompanied by a verbal description.
When an appropriate symbol does not exist, either the general symbol IEC 60617-S00327
(2001-07) should be applied, or a symbol may be constructed following the rules of IEC 60617
and ISO/IEC 81714-1.
5 Measuring instruments
When measuring instrument symbols are required, pick the general symbols from among
IEC 60617-S00910 (2001-07), IEC 60617-S00911 (2001-07) and IEC 60617-S00912 (2001-07)
according to the function, that is, indicating, recording and integrating (see Figure 1). Then the
asterisk within the symbol is replaced with the letter symbol or the graphical symbol.
The replacing symbol is related to the information displayed by the instrument regardless of the
means used to obtain the information.

TR 62711  IEC:2011(E) – 7 –
6 Mnemonics and designations for measuring relays and instruments
6.1 Overview
Where in Tables 1 to 19 below the letter “M” is shown in the second column, this means that the
designation concerned may be used in measuring relay symbols. A letter “I” in the second
column means that the designation concerned may be in indicating instrument symbols. A letter
“R” in the second column means that the designation concerned may be in recording instrument
symbols. A letter “G” in the second column means that the designation concerned may be in
integrating instrument symbols. In these tables, the English descriptions appear in the fourth
column, because in many cases designations are derived from terms in English.
6.2 Measuring relays
Tables 1 to 18 present the mnemonics and designations for measuring relays.
Table 1 – Measuring relays – Prefix
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
O - over Actuating when the characteristic quantity is
higher than the setting value.

IEC 60617-S0
0108(2001-07)
U - under Actuating when the characteristic quantity is
lower than the setting value.
IEC 60617-S0
0109(2001-07)
B - band Actuating when the characteristic quantity is
either higher than a given high setting or lower
than a given low setting.
IEC 60617-S0
0110(2001-07)
R - reverse Actuating when the characteristic quantity is N/A
contrary or opposite to what has been
mentioned.
H - high or high speed Actuating at high speed or other high level of a N/A
measured value or indicating signal.

Table 2 – Measuring relays – Suffix
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
B - balance Relay which operates by comparing the N/A
magnitudes of two similar input quantities.
NOTE The balance may be affected by
counteracting electromagnetic forces on a
common armature, or by counteracting
magnetomotive forces in a common magnetic
circuit, or by similar means, such as springs,
levers, etc.
V - with voltage restraint Method of restraining the operation of a relay by N/A
means of a voltage input which opposes the
typical response of the relay to other inputs.
NOTE With regard to suffixes, designation variables as described in IEC 60909-0 and IEC 60909-3 may be used
as a suffix.
– 8 – TR 62711  IEC:2011(E)
Table 3 – Measuring relays – General
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
D M Directional relay Relay that responds to the relative phase
position of a current with respect to another
current or voltage reference.
NOTE the above definition which applies
IEC 60617-S0
basically to a single phase directional relay may
be extended to cover a polyphase directional
(2001-07)
relay.
Df M Differential relay Measuring relay having two windings so
connected in different parts of a circuit that the
relay will operate if the difference between the
currents in the two circuits exceeds a specified

value.
IEC 60617-S0
(IEC 60050-811:1991, 811-31-16)
(2001-07)
RDf M Ratio (Percentage) Differential relay which functions when the
Differential relay difference between two quantities of the same
nature exceeds a fixed ratio (percentage) of the
smaller quantity.
IEC 60617-S0
0332(2001-07)
G M Ground relay, Earth Relay which operates when a failure of
fault relay insulation to earth is detected in the equipment
or circuits protected.
(IEC 60050-811:1991, 811-31-15)
IEC 60617-S0
0200(2001-07)
DG M Directional Ground Directional relay used primarily to detect N/A
relay single-phase-to-ground faults, but also
sensitive to double-phase-to-ground faults.
NOTE This type of relay is usually operated
from the zero-sequence components of voltage
and current, but is sometimes operated from
negative-sequence quantities.
DfG M Differential Ground Differential relay used primarily to detect N/A
relay internal ground faults of generators.
S M Short circuit relay Device that operates with no intentional time N/A
delay when the current exceeds a preset value.
SG M Selecting Ground relay Measuring relay that, by comparing the N/A
magnitudes of the zero sequence currents in
two parallel lines, will identify a line having
ground fault.
SS M Selecting Short-circuit Measuring relay that, by comparing the N/A
relay magnitudes of the currents in two parallel lines,
will identify a line having a short- circuit fault.
DS M Directional Directional relay used primarily to detect N/A
Short-circuit relay short-circuit faults.
TT M Transfer Trip relay Form of remote trip in which a communication N/A
channel is used to transmit a trip signal from the
relay location to a remote location.

TR 62711  IEC:2011(E) – 9 –
Table 4 – Measuring relays – Current
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
C M Current relay Actuating when the current quantity is equal to N/A
a setting value.
BC M Band Current relay Current relay with maximum and minimum
setting.
IEC 60617-S0
0345(2001-07)
CB M Current Balance relay Balance relay that operates by comparing the N/A
magnitudes of two current inputs.
OC M Over Current relay Measuring relay which operates when the value N/A
of the current exceeds the setting (operating
value) of the relay.
(IEC 60050-811:1991, 811-31-12)
DCG M Direct Current Ground Device that functions when the d.c. input N/A
relay current exceeds a predetermined value, and in
which the input current and operating time are
inversely related through a substantial portion
of the performance range.
OCG M Over Current Ground Device that functions when the net (phasor N/A
relay sum) current flowing in the phase and neutral
conductors or the total current flowing in the
normal neutral to ground connection exceeds a
predetermined value.
OCV M Over Current relay with Overcurrent relay which is used primarily to N/A
Voltage restraint protect a generator. The function of the voltage
is to prevent or moderate over current operation
until the generator voltage is reduced by a fault.
DOC M Directional Over Relay consisting of an overcurrent unit and a N/A
Current relay directional unit combined to operate jointly.
UC M Under Current relay Relay that operates when the current is less N/A
than a predetermined value.
RC M Reverse Current relay Relay that operates on a current flow in a
direct-current circuit in a direction opposite to a
predetermined reference direction.

IEC 60617-S0
0339(2001-07)
CL M Current Limiting relay Relay specifying a range of currents between N/A
the threshold current and the rated interrupting
current within which current limitation occurs.

– 10 – TR 62711  IEC:2011(E)
Table 5 – Measuring relays – Voltage
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
V M Voltage relay Relay that responds to voltage. N/A
VB M Voltage Balance relay Balance relay which operates by comparing the N/A
magnitudes of two voltage inputs.
OV M Over Voltage relay Measuring relay which operates when the value N/A
of the current exceeds the setting (operating
value) of the relay.
(IEC 60050-811:1991, 811-31-13)
UV M Under Voltage relay Measuring relay which operates when the value
of the voltage is equal to or less than the setting
(operating value) of the relay.

IEC 60617-S0
0344(2001-07)
OVG M Over Voltage Ground Relay that operates when its input zero N/A
relay sequence voltage exceeds a predetermined
value.
VDf M Voltage Differential Measuring relay which intended to protect N/A
relay grounded-wye shunt capacitor banks.
SOG M Selective Over voltage Relay that determines the fault feeders of the N/A
Ground relay high impedance ground fault by shedding the
feeders of the bus in predetermined order.
It operates when the zero sequence voltage of
the bus exceeds the specific value for a specific
time.
UVC M Under Voltage relay Undervoltage relay whose setting (operating) N/A
with Current value is varied by the magnitude of the current.
compensation
Table 6 – Measuring relays – Frequency
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
F M Frequency relay Relay that responds to the frequency of an N/A
alternating electrical input quantity.
Of M Over frequency relay Relay that responds to the frequency of an N/A
electrical quantity, operating when the
frequency or rate of change of frequency
exceeds a predetermined value.
Uf M Under frequency relay Relay that responds to the frequency of an N/A
electrical quantity, operating when the
frequency or rate of change of frequency is less
than a predetermined value.
TR 62711  IEC:2011(E) – 11 –
Table 7 – Measuring relays – Impedance
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
Z M Distance relay; Relay that functions when the circuit
Impedance relay admittance, impedance or reactance increases
or decreases beyond a predetermined value.

IEC 60617-S0
0346(2001-07)
DZ M Directional Distance Relay consisting of a distance unit and a (S00346)
relay directional unit combined to operate jointly.
DGZ M Directional Ground Relay consisting of a ground distance unit and a (S00346)
distance relay directional unit combined to operate jointly.
OM M Offset Mho relay Distance relay for which the inherent operating (S00346)
characteristic on an R-X diagram is a circle
which passes through the origin.
NOTE The operating characteristics may be
described by the equation Z = K·cos(θ–α) where
K and α are constants and θ is the phase angle
by which the input voltage leads the input
current.
CZ M Continuous curve Distance relay in which the operating time is in (S00346)
distance-time relay proportion to the impedance.

Table 8 – Measuring relays – Power
MNEMONICS M/I/ GRAPHICAL
NAMES DESCRIPTIONS
DESIGNATION R/G SYMBOLS
P M Power relay Relay that responds to a suitable product of N/A
voltage and current in an electric circuit.
Q M Reactive power relay Power relay that responds to reactive power. N/A
RP M Reverse Power relay Device that operates on a predetermined value N/A
of power flow in a given direction such as
reverse power flow resulting from the motoring
of a generator upon loss of its prime mover.
UP M Under Power relay Relay that functions when the
...