This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
2.2 Informative references .......................................................................................... 6 3 Terms and definitions .................................................................................................... 9 4 Identification of parts and application ............................................................................10
4.1 General ...............................................................................................................10 4.2 Procedure for parts ..............................................................................................11 4.3 Selection of symbols............................................................................................11 4.4 Size of symbols ...................................................................................................12 4.5 Use of color .........................................................................................................12
5 Graphic symbols ...........................................................................................................12 6 How to combine graphic symbols ..................................................................................52
6.1 General ...............................................................................................................52 6.2 Procedure to combine symbols ............................................................................53 6.3 Summary.............................................................................................................55
Annex A (informat ive) Examples of Grouping of Symbols ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ..57 A.1 Input voltage/power switch...................................................................................57 A.2 Use of remote receptacles and selector switches..................................................57 A.3 Weld start and stop push buttons .........................................................................58 A.4 Panel indicator lights ...........................................................................................58 A.5 Output (contactor) switch .....................................................................................59 A.6 Arc force control potentiometer . ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...59 A.7 Terminals and selector switch on AC/DC welder ...................................................60 A.8 Process switch (SMAW-GTAW-GMAW)................................................................60 A.9 Ignition switch on engine driven welder ................................................................61 A.10 Idle switch ...........................................................................................................61 A.11 Start/run switch ...................................................................................................62 A.12 Process selection for GMAW................................................................................62 A.13 Control potentiometers for GMAW........................................................................63 A.14 Switched settings for GMAW................................................................................63 A.15 Setting pulsing parameters using digital display....................................................64 A.16 Setting pulsed GMAW parameters with digital display ...........................................64 A.17
AC balance control with balanced position used for the SMAW process .. ... ... ... ... ..65
This publication provides manufacturers and users of arc welding and cutting equipment with asystem of graphic symbols that can be used and recognized throughout the arc welding andcutting industry. These graphic symbols communicate the required message independent of any
language, thus minimizing difficulties that could arise when equipment is used by operatorsspeaking different languages.
There are three major factors contributing to the need for graphic symbols: 1) large numbers of functionally illiterate people in the labor force; 2) large numbers of non-English speaking U.S.residents; and 3) the diversity of the global marketplace. In an effort to communicate with asmany people as possible, graphic symbols have been developed. This publication standardizesthose graphic symbols used on arc welding and cutting equipment, explains their direct meaning,and shows their proper use.
The work to develop graphic symbols that provide a clear and practical means of communicatingto operators of arc welding and cutting equipment the function and use of equipment controlsunique to the arc welding and cutting industry has been in progress for a number of decades.
In 1957, the International Organization for Standardization Technical Committee 44 (Welding)(ISO/TC 44) began work on the rating of manual arc welding equipment. This led to thepublication of ISO Recommendation R700.
In 1976, Subcommittee SC 4 (Arc Welding Equipment) of ISO/TC 44 proposed a revision of ISOR700 that incorporated graphic symbols for the identification of equipment control functions anddescription of welding processes.
In 1977, the NEMA Arc Welding Apparatus Graphic Symbols Committee, consisting of representatives of arc welding equ ipment manufacturers, was formed to review the ISO symbols.
In 1982, the first edition of NEMA Standards Publication EW 4 was published. In its preparation,the Committee also gave consideration to the work of other organizations such as theInternational Organization for Standardization (ISO), the American Welding Society (AWS), theSociety of Automotive Engineers (SAE), the American Society of Mechanical Engineers (ASME),as well as the symbols being used by U.S. and European welding and cutting equipmentmanufacturers. Many of the symbols were adopted directly from the work of these organizations,and credit was given to them in EW 4. As a result, the Committee proposed additional symbols for the identification and use of equipment controls that were captured in the first edition of NEMAEW 4. The first edition contained 92 of the most commonly used symbols for welding and cuttingproducts.
In 1984, Technical Committee ISO/TC 145 published ISO 7000 incorporating the graphic symbolsfrom R700 and a 1979 amendment that provided symbols for all kinds of equipment. In 1989, ISO7000 was revised and published.
In 1988, NEMA EW 4 was rescinded.
In 1994, a new version of EW 4 was published. As in the past, this edition gave a great deal of consideration to the work of other organizations, both national and international. Where symbolswere used directly from another source, credit was given to that document. This edition addedinformation on how to combine graphic symbols as well as additional and more current examples
of their use. This edition contained 185 symbols to accommodate more complex products andprocesses.
Noting advancements in technology and equipment, changes in the global marketplace, andgreater need for harmonization with internationally used graphic symbols, a revision to EW 4
began in 2004 leading to the publication of this document.
This 2009 edition of EW 4 has three main enhancements. First, it adds symbols from Annex L of IEC 60974-1. Secondly, this revision uses an international style acceptable to NEMA draftingprinciples that harmonize with ISO/IEC documentation methods. Thirdly, where multiple symbolsfor the same control, function, or item exist, they are added and shown together to aid ease of use and clarity. As a result, this edition contains 217 symbols to address the expanded needs of users.
This publication will be reviewed periodically by the NEMA Arc Welding Section for the purpose of updating graphic symbols to reflect advancing technology or the latest graphic symbolapplications. Please address any comments or questions regarding this publication to:
Vice President, Technical ServicesNational Electrical Manufacturers Association1300 North 17th Street, Suite 1752Rosslyn, VA 22209
Comments from parties that have an interest in, or responsibility for, the purchase, application,use, and inspection of arc welding and cutting equipment were considered throughout the revisionof this publication, and led to a number of changes from the previous edition. When major changes to this publication are proposed, these parties will again have the opportunity toparticipate in NEMA committee proceedings in order to review and comment on the revision.
The artwork for the graphic symbols shown in this publication is stored in NEMA’s electronic files.
More information on downloading these files free of charge can be found on the EW 4 webpage athttp://www.nema.org/stds/ew4.cfm.
The information in this publication was considered technically sound by the consensus of personsengaged in the development and approval of the document at the time it was developed.Consensus does not necessarily mean that there is unanimous agreement among every person
participating in the development of this document.
NEMA standards and guideline publications, of which the document contained herein is one, aredeveloped through a voluntary consensus standards development process. This process bringstogether volunteers and/or seeks out the views of persons who have an interest in the topiccovered by this publication. While NEMA administers the process and establishes rules topromote fairness in the development of consensus, it does not write the document and it does notindependently test, evaluate or verify the accuracy or completeness of any information or thesoundness of any judgments contained in its standards and guideline publications.
NEMA disclaims liability for any personal injury, property or other damages of any naturewhatsoever, whether special, indirect, consequential or compensatory, directly or indirectlyresulting from the publication, use of, application, or reliance on this document. NEMA disclaimsand makes no guaranty or warranty, express or implied, as to the accuracy or completeness of any information published herein, and disclaims and makes no warranty that the information inthis document will fulfill any of your particular purposes or needs. NEMA does not undertake toguarantee the performance of any individual manufacturer’s or seller’s products or services byvirtue of this standard or guide.
In publishing and making this document available, NEMA is not undertaking to render professional or other services for or on behalf of any person or entity. Nor is NEMA undertakingto perform any duty owed by any person or entity to someone else. Anyone using this documentshould rely on his or her own independent judgment or, as appropriate, seek the advice of acompetent professional in determining the exercise of reasonable care in any givencircumstances. Information and other standards on the topic covered by this publication may beavailable from other sources, which the user may wish to consult for additional views or information not covered by this publication.
NEMA has no power, nor does it undertake to police or enforce compliance with the contents of this document. NEMA does not certify, test or inspect products, designs or installations for safetyor health purposes. Any certification or other statement of compliance with any health or safety– related information in this document shall not be attributable to NEMA and is solely theresponsibility of the certifier or maker of the statement.
This publication provides graphic symbols for arc welding and cutting equipment, including thosesymbols used to identify controls, indicators, connection points, operations, functions, commands,
and processes. This publication does not cover graphic symbols used to alert personnel of immediate or potential personal hazards in the use o f the equipment.
2 References
2.1 Normative references
Each publication listed below is directly referenced in subsequent clauses of this publication, andhas a corresponding footnote identifying the publisher and, where available, information on howto order the publication. It is recommended that the latest edition be requested when ordering astandard.
IEC 60027-1, Letter symbols to be used in electrical technology — Part 1: General1
IEC 60417-1, Graphical Symbols for use on equipment — Part 1: Overview and application2
IEC 60974-1, Arc welding equipment — Part 1: Welding power sources1
ISO 3767-1, Tractors, machinery for agriculture and forestry, powered lawn and garden equipment —Symbols for operator controls and other displays — Part 1: Common symbols3
ISO 7000, Graphical symbols for use on equipment — Index and synopsis2
ISO 17846, Welding and allied processes — Health and safety — Wordless precautionary labelsfor equipment and consumables used in arc welding and cutting
3
SAE International, Handbook4
2.2 Informative references
Each publication listed below has a corresponding footnote identifying the publisher and, whereavailable, information on how to order the publication. It is recommended that the latest edition berequested when ordering a standard.
ANSI/IEC 60974-1, Arc welding equipment — Part 1: Welding power sources5
——————— 1
Published by, and available from, the International Electrotechnical Commission, 3 rue de Varembé, Geneva 1120,Switzerland; website: www.iec.ch
2 IEC 60417 and ISO 7000 are published in a single volume, available from the International ElectrotechnicalCommission, 3 rue de Varembé, Geneva 1120, Switzerland; website: www.iec.ch
3 Published by, and available from, International Organization for Standardization (ISO), 1 rue de Varembé, Geneva1120, Switzerland; website: www.iso.org
4 Published by, and available from, SAE International, 400 Commonwealth Drive, Warrendale, PA 15906; website:www.sae.org; phone: 1-877-606-7323
5 Published by National Electrical Manufacturers Association and available from Global Engineering Documents;website: global.ihs.com; phone: 1-877-413-5184
ANSI Z129.1, American Nat ional Standard for Hazardous Industria l Chemicals — PrecautionaryLabeling7
ANSI Z535.1, Safety Color Code8
ANSI Z535.2, Environmental and Facility Safety Signs8
ANSI Z535.3, Criteria for Safety Symbols8
ANSI Z535.4, Product Safety Signs and Labels8
ANSI Z535.5, Safety Tags and Barricade Tapes (for Temporary Hazards)8
ANSI Z535.6, Product Safety Information in Product Manuals, Instructions, and Other CollateralMaterials
8
ASME Y14.5M, Dimensioning and Tolerancing9
AWS A3.0, Standard Welding Terms and Definitions6
CAN/CSA E60974-1-00 (R2005), Arc welding equipment — Part 1: Welding power sources10
CAN/CSA E60974-5-03, Arc welding equipment — Part 5: Wire Feeders10
CAN/CSA E60974-7-02 (R2007), Arc welding equipment — Part 7: Torches10
CSA C22.2 No. 60, Arc Welding Equipment10
DIN 30 600, Graphic Symbols (Bildzeichen Übersicht)11
FMC, Product Safety Sign and Label System12
——————— 6 Published by, and available from, American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126; website:
www.aws.org; phone: 1-800-443-9353
7 Available from American National Standards Institute, 11 West 42nd Street, New York, NY 10036; website:www.ansi.org; phone: 1-212-642-4980
8 Published by National Electrical Manufacturers Association and available through Global Engineering Documents;website: global.ihs.com; phone: 1-877-413-5184
9 Published, and available from, ASME International, Three Park Avenue, New York, NY 10016-5990; website:www.asme.org; phone: 1-800-843-2763
10 Published by, and available from, Canadian Standards Association, 5060 Spectrum Way, Mississauga, Ontario L4W5N6, Canada; website: www.csa.ca; phone: 1-800-463-6727
11 Published by Deutsche Institut für Normung and available from Beuth Verlag GmbH, Burggrafenstraße 6, 10787Berlin, Germany; website: www.beuth.de
12 Published by FMC Corporation, Corporate Technology Center, P.O. Box 580, Santa Clara, CA 95052
——————— 13 Published by John Wiley and Sons Inc. (last publication date: May 1984)
14 Published by John Wiley and Sons Inc. (last publication date: 1994)
15 Published by, and available from, International Electrotechnical Commission, 3 rue de Varembé, Geneva 1120,Switzerland; website: www.iec.ch
16 Published by, and available from, IEEE, 445 Hoes Lane, Piscataway, NJ 08854; website: www.ieee.org; phone: 1-800-701-4333
17 Published by, and available from, International Organization for Standardization (ISO), 1 rue de Varembé, Geneva1120, Switzerland; website: www.iso.org
18 Published by National Electrical Manufacturers Association and available through Global Engineering Documents;
website: global.ihs.com; phone: 1-877-413-5184
19 Published by, and available from, National Fire Protection Association, 1 Batterymarch Park, Quincy, MA 02169;website: www.nfpa.org; phone: 1-800-344-3555
20 Published by, and available from, Occupational Health & Safety Administration, U.S. Department of Labor; website:www.osha.gov; phone 1-800-321-6742
21 Published by Underwriters Laboratories and available from Comm 2000; website: www.comm-2000.com; phone: 1-800-853-3503
22 Draft developed by Underwriters Laboratories based on an Outline for Investigation, Subject 2201
23 Published by Westinghouse Electric Corporation, Gateway Center, Pittsburgh, PA 15222
NOTE The following terms have definitions unique to this publication. Other terms found in this publication, such asfor welding processes, are used as defined in AWS A3.0.
3.1connection pointplace such as output terminal or receptacle where electrical connections are made (can bemechanical, water, or gas connections)
3.2controldevice whose movement causes changes in equipment operation or status such as rheostats,potentiometers, or switches
3.3downslopetime during which process parameters change from one welding or cutting value to a second
lower value
3.4functionaction that a control causes to happen or not to happen by adjusting the control
3.5graphic symbolpictogramgraphical symbolpictorialpicture used to replace or supplement one or more written words in order to transmit a messageor to represent an object, concept, or function
3.6indicator device that shows or indicates something such as water level or temperature level
3.7inputinput power requirements of equipment including volts, amps, phase, and hertz (frequency)
3.8memorycapability of the equipment, usually microprocessor-based, to store one or more parameters for
recall at a later time
3.9modevolt-ampere curve type of operation such as CC (constant current, drooper) or CV (constantvoltage, flat)
3.10outputrated output of the equipment at a specific load, and usually expressed in amperes and volts at aspecific duty cycle
3.11plasma arc gougingplasma arc cutting process variation that uses a constricted arc and removes the molten metalwith a high velocity jet of ionized gas issuing from the constricting orifice to form a bevel or groove
3.12programsingle program selected in a multi-program device, usually found on microprocessor-controlledtype of equipment
3.13sequence
various parts of a process cycle such as preflow, initial, weld, crater, final, and postflow
3.14sloperising or falling areas of a process cycle
3.15sourceplace, document, or group from which the symbol element(s) were taken or originated
3.16unit of measurement
unit used to describe a quantityEXAMPLE For current as the quantity, ampere is the unit of measurement.
3.17upslopetime during which the process parameters change from one welding or cutting value to a secondhigher value
4 Identification of parts and application
4.1 General
The symbols are normally placed on equipment to instruct as to its use and operation. In addition,there may be warnings or limits as to use of some controls. In some cases, symbols may be usedto identify the complete package or subassemblies.
The user of equipment can determine the meaning of symbols by referring to Clause 5. Symbolsmay be accompanied by words and phrases until such time that universal recognition is achieved.Words or phrases, to be used in addition to the symbols, are to be selected by the manufacturer (see Annex A for typical examples). The process of selecting symbols for a particular applicationis simplified by the procedure in 4.2.
The following steps should be taken for parts needing identification that can be expressed withsymbols:
a) list all existing parts and group similar parts together in tabular form; for example: switches,receptacles, and terminals;
b) list the exact function of each part, for example:
1) switch – to control input power;
2) rheostat – to control welding current;
3) lamp – to indicate low oil pressure when lit;
4) terminal – to identify the work lead connection point;
c) list the direction of movement and result of such movement associated with the part; for example:
1) rotate clockwise to increase;
2) push up for ON; down for OFF;3) pull out to STOP;
d) list the command associated with the part; for example: do not switch while welding
e) list the quantity and unit of measurement related to the part; for example:
1) 0-10 dial, in seconds;
2) 0-10 dial, no meaning to graduations;
f) list all items (words or phrases) that are not physical parts, but for which symbols are to beselected; for example: water, high frequency, positive polarity;
g) review the preceding steps to ensure that all physical parts have some distinguishingdescription that clearly states, in an understandable manner, exactly what is to berepresented by graphic symbols; it is important that the language description be clear before
attempting to select symbols.
4.3 Selection of symbols
A symbol may exist that exactly transmits the requirements worked out in the preceding sections.However, it is usually necessary to use a building block approach and use combinations of symbols as required.
Refer to Tables 2 and 3 which list the function keyword or phrase columns and correspondinggraphic symbol number. Select symbols by looking at both the symbol and the function, keywordor phrase columns. List the symbol numbers opposite the parts and items listed from theprocedure described in 4.2. Use this composite list as a guide for preparing the artwork for labelsor screening process. Consistent positioning of each symbol around the device promotes overall
readability.
Alternative methods of applying symbols are shown in the examples in Annex A. Select themethod that best identifies the control or component, how it is to be used, and what is indicated,as needed for the application.
For the application of the symbols it may be necessary either to reduce or to enlarge the originalto a suitable size. In the case of symbols composed of several graphic elements, or whenreducing to minimum height, check that clear identification is still possible and legibility isadequate.
Recommended minimum symbol size is 1/4 inch (6.3 mm) square. It will be necessary to usesound judgment when size reduction is done. Show the proposed size to a typical targetaudience, and carefully check their responses. Consider available light, user distance, andpossible operating conditions as factors during size selection also. Always retain adequate linethickness for reproduction process and user visibility.
4.5 Use of color
In general, the graphic form of a symbol reproduced in black on white or white on black should besufficient for its identification. However, there may be cases in which the meaning of the symbolmay depend on the application of one or more colors. In these cases the relevant colors are
normally specified in the standard regulating or advising that specific area of concern. For thepurposes of this standard and these symbols, adequate contrast between symbol and backgroundis most important. As long as the symbol is clearly delineated and fully legible, actual color selection is not mandatory. Be aware that certain colors, such as red, orange, and yellow, aredesignated safety alerting colors according to ANSI Z535. If necessary for legibility when reducedin size, the symbol may be filled.
5 Graphic symbols
The symbols shown in Table 1 are for use on arc welding and cutting apparatus, except for therating plate; see IEC 60974-1 for symbols used on rating plates. Table 1 presents the symbolsalong with its reference number; function, keyword or phrase, application and source.
NOTE 1 The symbols shown in Table 1 may differ slightly in terms of shading from those shown in the sourcedocument. Table 1 contains all symbols found in Annex L of IEC 60974-1 except those symbols that differ only slightlyfrom symbols from other sources.
NOTE 2 Some functions, keywords, or phrases in Table 1 show more than one symbol. The order in which the symbolsappear imply no order of importance or preference. It is assumed that the user will determine his own importance or preference according to factors such as intended product use and product certification requirements.
Table 2 provides an alphabetical listing by function, keyword or phrase with correspondingsymbol numbers. Table 3 provides a numerical listing by symbol number with correspondingfunction, keyword or phrase.
207 UNLOCKEDSignifies an unlockedfunction or control
IEC 60417-1-5570
SAE
208 LOCKEDSignifies a lockedfunction or control
IEC 60417-1-5569
SAE
aExplanation of source acronyms:
ANSI American National Standards Inst ituteIEC International Electrotechnical CommissionISO International Organization for StandardizationNEMA National Electrical Manufacturers AssociationSAE Society of Automotive Engineers
There can be up to three numbers following the acronym of a source, e.g., IEC 60417-1-5110. The first number represents the number of the standard, the second number represents the part of the standard, and the third number represents the symbol number listed in a table of symbols or the clause/annex of the standard in which the symbolappears. If a standard does not have more than one part, e.g., ISO 7000, there will be no second number. Similarly, if a source has no numerical designation, e.g., SAE Handbook, there will be no first number ― and, for that matter, nosecond number as well.
CLASS II EQUIPMENT ............................................................................................. 41
CLOCK, TIME SWITCH ............................................................................................ 131
COLD JOG (INCH) AWAY FROM WORKPIECE......................................................... 171
COLD JOG (INCH) TOWARD WORKPIECE .............................................................. 170
CONSTANT CURRENT ............................................................................................ 94
CONSTANT VOLTAGE OR CONSTANT POTENTIAL ................................................ 95CONTINUOUS WELDING ......................................................................................... 90a,b
GAS INPUT.............................................................................................................. 52
GAS METAL ARC WELDING (GMAW) ...................................................................... 78a,b
GAS METAL ARC WELDING (GMAW) GUN .............................................................. 103a,b
GAS OUTPUT .......................................................................................................... 53
GAS POSTFLOW ..................................................................................................... 156GAS POSTFLOW ..................................................................................................... 157
GAS SUPPLY........................................................................................................... 42
GAS TUNGSTEN ARC WELDING (GTAW) TORCH ................................................... 107a,b
GAS TUNGSTEN ARC WELDING (GTAW)/TUNGSTEN INERT GAS (TIG)WELDING ................................................................................................................
81a,b
GAS TYPE ............................................................................................................... 43
PERCENT ................................................................................................................ 132PERCENT ON TIME ................................................................................................. 134
PILOT ARC STARTING ............................................................................................ 165
SUITABLE FOR WELDING IN AN ENVIRONMENT WITH INCREASED RISK OFELECTRIC SHOCK...................................................................................................
40
TEMPERATURE INDICATION .................................................................................. 123
Follow the instructions in Clause 5 to determine what part is being described and how to select
an existing symbol for it if one exists. Always try to use the standard symbols in Table 1 exactlyas they are presented. If they do not satisfy the need, then develop a combination or compositesymbol using standard symbols as described in 6.2.
A combination or composite symbol is one that is made up of one or more symbols. Compositesymbols are useful when standard symbols do not provide enough information to communicatethe desired information. There are some composite symbols that are listed in Clause 5. Thesesymbols are used often and should be used in new applications whenever possible. Theexamples in 6.2 show how to develop composite symbols when a new symbol is required.
The procedure to combine symbols is shown by way of the example below.
EXAMPLE 1 Assume a symbol is needed to explain that a given receptacle is used for connecting a Remote Amperage Control to the power source. First , li st the connec tion to be exp lained in ful l and then break into par ts, as
follows:REMOTE AMPERAGE CONTROL
Key words: Remote, Amperage Control
Use the standard symbol for each key word from Table 1, i.e., symbols 1 and 68.
Amperage (Control ):
Remote:
Combine the standard symbols to produce the composite.
Remote Amperage Control (Connection Point or Function):
The example above shows a composite symbol being formed from two standard symbols. Thefollowing examples are of a composite symbol formed from three standard symbols.
EXAMPLE 2 Remote Amperage and Voltage Control
Key Words: Remote, Amperage Control, Voltage Control
Apply the standard symbol from Tabl e 1 for each key word, i.e., symbol s 1 , 2 and 68.
Remote:
Amperage (Control ):
Voltage (Control):
Combine the symbols to form the composite symbol.
Remote Amperage and Voltage Control (Connection Point or Function):
EXAMPLE 3 High Frequency SwitchKey Words: High Frequency, Switch (with ON and OFF positions)
The examples that follow use the same basic principles as in the above examples, but usedifferent symbols for different purposes.
EXAMPLE 4 This grouping of symbols shows Initial Current and Weld Current for use with controls for separatefunctions during parts of a weld cycle. To create the symbol for Initial Current, use symbols 1 and 133 from Table 1 andproceed as follows.
Amperage (un its o f measure for current) :
Process Cycle:
The two combined symbols along with a thickened portion of the process cycle mean Initial Current, shown as follows:
The Initial Current segment of the process cycle symbol is approximately 3 to 4 times as thick as the other segments toshow clearly the portion being emphasized. The symbol for Weld Current is created in the same way as shown below.
Amperage:
Weld Process Cycle.
The two combined symbols along with a thickened portion of the Process Cycle mean Weld Current, shown as follows:
OR
This example also used symbols 1 and 133 from Table 1. The exact location of "A" in relation to the thickened portioncan be moved slightly to accommodate nameplate space as shown. The emphasized portion again is appropriatelythickened to indicate clearly the selected segment of the process cycle.
EXAMPLE 5 This grouping shows Peak (High) Pulse Time and Background (Low) Pulse Current for use withpulsing controls. Using symbols 6 and 135 from Table 1, proceed as follows to create the symbol for Peak (High) PulseTime.
The two combined symbols along with a thickened portion of the pulse mean Peak (High) Pulse Time, shown as follows:
The top segment of the pulse symbol is widened to approximately 3 to 4 times the thickness of the other segments to
show clearly the portion being emphasized.
EXAMPLE 6 The symbol for Background (Low) Pulse Current is created in the same way as in the example above.
Amperage:
Pulse:
The two symbols along with a thickened portion of the pulse mean Background (Low) Pulse Current, shown as follows:
This example uses symbols number 1 and 135 from Table 1. The emphasized portion again is appropriately widened toindicate clearly the selected segment of the pulse.
The example below follows the same method used in the previous examples, but for a differentpurpose.
EXAMPLE 7 This example shows Fast Pulse Frequency for use on the positions of a pulse time range switch. Tocreate the proper symbol, proceed as follows.
Pulse (Pulsing), symbol 135:
Slow Pulse:
By suitably modifying symbol 135 from Table 1, the two symbols above now represent fast and slow pulsing. Notice theconsistent line weights, heights, and total length of both symbols. Use this procedure and apply these considerationswhen creating new symbols.
The two symbols work well when used as Fast Pulse and Slow Pulse positions of a Pulse Tune Range Switch, shownas follows:
6.3 Summary
Creating composite symbols is not difficult. It requires only simple care and precision. Alwaysproceed according to the standard method shown in the example in 6.2 using the followingguidelines:
a) write down the name for the connection or control;
b) identify the keywords;
c) find the standard symbol in Table 1 for each keyword;