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ANSI / IEEE C37.1-1987

definition, specification, and analysis of

systems used for supervisory control,

data acquisition, and automatic control

SHlW17

JuIy 6

987

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ANSI/IEEE C37.1-1987

C37.1-1979)

(Revision of ANSI/IEEE

An American National Standard

IEEE Standard Definition, Specification, and

Analysis of Systems Used for

Supervisory Control, Data Acquisition, and

Automatic Control

Sponsor

Substations Committee

of

the

IEEE Power Engineering Society

Secretariat

Institute of Electrical and Electronics Engineers

National Electrical Manufacturers Association

Approved March 22,1984

IEEE Standards Board

Approved December 2 ,1986

American National Standards Institute

o Copyright 1987

by

The Institute

of

Electrical and Electronics Engineers, Inc

345 East 47th Street, New York, NY

10017,

USA

No p a r t of th is pu b l icat ion may be reprodu ced in an y f o rm ,

in an electronic retrieval system or o therwise ,

wi th ou t th e p r io r wr i t t en permiss ion

of

the publisher.

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IEEE Standards documents are developed within the Technical Com-

mittees of the IEEE Societies and the Standards Coordinating Commit-

tees of the IEEE Standards Board. Members of the committees serve

voluntarily and without compensation. They are no t necessarily mem-

bers of the Institute. The standards developed within IEEE represent

a consensus of the broad expertise on the subject within the Institute

as well as those activities outside of IEEE which have expressed an in-

terest in participating in the development of the standard.

Use of an IEEE Standard is wholly voluntary. The existence of an

IEEE Standard does not imply that there are no other ways to pro-

duce, test, measure, purchase, market, or provide other goods and ser-

vices related to the scope of the IEEE Styndard. Furthermore, the view-

point expressed a t the time a standard is approved and issued is subject

to change brought about through developments in the state of the art

and comments received from users of the standard. Every IEEE Stan-

dard is subjected to review at least once every five years for revision

or reaffirmation. When a document is more than five years old, and has

not been reaffirmed, it is reasonable to conclude that its contents,

although still of some value, do not wholly reflect the present state of

the art. Users are cautioned to check to determine that they have the

latest edition of any IEEE Standard.

Comments for revision of IEEE Standards are welcome from any

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gestions for changes in documents should be in the form of a proposed

change of text, together with appropriate supporting comments.

Interpretat ions: Occasionally questions may arise regarding the mean-

ing of portions of standards as they relate t o specific applications. When

the need for interpretations is brought to the attention of IEEE, the

Institute will initiate action

to

prepare appropriate responses. Since

IEEE Standards represent a consensus of all concerned interests, it is

important to ensure that any interpretation has also received the con-

currence of a balance of interests. For this reason IEEE and the mem-

bers of its technical committees are not able to provide an instant re-

sponse

to

interpretation requests except in those cases where the mat ter

has previously received formal considerat ion.

Comments on standards and requests for interpretations should be ad-

dressed to:

Secretary, IEEE Standards Board

345 East 47th Street

New York, NY

10017

USA

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Foreword

(This Foreword is not a part of ANSUIEEE C37.1 1987 , IEEE Standard Definition, Specification, and Analysis of

Systems Used for Supervisory Contro l, Data Acquisition, and Automatic Control.)

This standard applies to systems used for monitoring, switching, and controlling electric apparatus

in unattended or attended substations, generating stations, and power utilization and conversion

facilities. It does not apply to equipment designed for the automatic protection of power system

apparatus o r for switching of communication circuits. The requirements of this standard are in addi-

tion t o those contained in standards relating to the individual devices.

This significantly revised standard was originally a section of ANSI C37.2-1970 which also con-

tained device function numbers. ANSI C37.2-1970 was revised into two standards: ANSI/IEEE

C37 .l-1979, Standard Definition, Specification, and Analysis of Manual, Automatic, and Super-

visory Station Control and Data Acquisition, and ANSI/IEEE C37.2-1979, Electrical Power System

Device Function Numbers. Previous editions were approved by the Standards Institute in 1962,

1956 , 1945, and 1937. The original work on this subject was done by the American Institute of

Electrical Engineers (now the Inst itute of Electrical and Electronics Engineers) and published in

1928 as AIEE No 26.

The standard applies to a rapidly changing technology. It is anticipated therefore that frequent

revision may be desirable. Electrical Power System Device Function Numbers on the other hand

have changed very little over the years. This revision, prepared by the Automatic and Supervisory

System Subcommittee of the IEEE Substat ion Committee, was

an

attempt to bring the standard up

to date and further broaden it s applicability with respect to control, supervisory, and telemetering,

for greater use in many industries.

IEEE Tutorial Course Text 81 EH0 1883-PWR1

is recommended for those not familiar with

Supervisory Control Systems.

The Standards Committee on Power Switchgear, C37, which reviewed and approved this standard,

had the following personnel at the time of approval:

C . L.

Wagner,

Chairman

John D. Hopkins,

Secretary

W. N.

Etothenbuhler,

Executive Vice-chairman o fHigh-Voltage Switchgear Standards

W.

E. Laubach,

Executive Vice-chairman

o f

Low -Vo ltage Switchgear Standards

S.

H. Telander,

Executive Vice-chairman

of IEC

Activ i t ies

Organization Represented Name of Representative

Association of Iron and Steel Engineers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J

M.

Tillman

Electric Light and Power Grou p.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D.0.

Craghead

R. L. Capra

K. D. Hendrix

R.

L.

Lindsey

J. P. Markey A l t )

D. . Weston

Institute of Electrical and Electronics Engineers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H. W. Mikulecky

M.

J

Beachy A l t )

G. Hanks

C. A. Mathews AZt)

E.

W.

Schmunk

C. A. Schwalbe

G. W.Walsh

C. E. Zanzie

A l t )

National Electrical Manufactu rers Association . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. A. Wilson

T. L. Fromm

R. A. McMaster

R . 0.

D.

Whitt

Tennessee Valley Authority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R. C. St. Clair

Testing Laboratory Grou p . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

L.

Frier

E.

J.

Huber

R.

W.

eelbach

A l t )

U S

Department

of

the Army.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

John S. Robertson

US Department of the Interior, Bureau of Reclamation

. . . . . . . . . . . . . . . . . . . . . . . . R. H. Auerbach

US Department of the Navy, Naval Facilities Engineering Command.

. . . . . . . . . . . . . . .

R. L. Clark

Western Area Power Authority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G. D. imey

This publication is available

from

the Institute of Electrical and Electronics Engineers Service Center,

445 Hoes

Lane, PO

Box

1331,

Piscataway, NJ

088551331.

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The membership of working group 77.1 of the Automatic and Supervisory Systems Subcommittee

which prepared this revised standard had the following personnel at the time this standard was sub-

mitted for approval:

Donald F. Koenig, Chairman

W. J. Ackerman R. Hayner A. Matthey

J.

D. Betz J. Holladay J. OHara

W.

R. Block D. E. Johannson D. G. Rishworth

G. Crask L. W. urtz, J r B. D. Russell

W. Frisbie K. P. Lau

J.

M. Thorson

D. J. Gaushell C. T. Lindeberg G. L. Unzicker

A. Haban M.

S.

Wadkins

The members of the IEEE Automatic and Supervisory Systems Subcommittees who reviewed and

approved this standard were as follows:

A. Matthey,

Chairman

W. J. Ackerman H. Hales C. T. Lindeberg

J. D. Betz D. . Johannson

J.

OHara

W. R. Block D. F. Koenig D. G. Rishworth

G. Crask L. W. Kurt z, Jr B. D. Russell

D. J. Gaushell K. P. Lau J. M. Thorson

A. Haban M. S.Wadkins

When the IEEE Standards Board approved this standard on March

22, 1984,

it had the following

membership:

James H. Beall,

Chairman

John E. May,

Vice Chairman

Sava I. Sherr, Secretary

J. J. Archambault

John T. Boettger

J . V. Bonucchi

Rene Castenschiold

Edward Chelotti

Edward J. &hen

Len S. Gxeyt

Donald C. Fleckenstein

Jay Forster

Daniel L. Goldberg

Donald N. Heirman

Irvin

N.

Howell

Jack Kinn

Joseph L. Koepfinger;

Irving Kolodny

George Konomos

R. F. Lawrence

Donald

T.

Michael;

John

P.

Riganati

Frank L. Rose

Robert W. Seelbach

Jay A. Stewart

Clifford0. Swanson

W. B. Wilkens

Charles J. Wylie

Member emeritus

t Deceased

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Contents

SECTION

PAGE

1

Scope

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

2

.

References

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

7

3

.

Definitions

..............................................................

3

4

.

Functional Characteristics

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16

4.1 Typical Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

16

4.2 System Functional Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

5

.

Interfaces

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

22

5.1 Mechanical

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

22

5.2 Electrical Power and Grounding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

5.3 Data and Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

5.4 Communication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

6. Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

6.1 Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

6.2 Vibrationandshock

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32

6.4 Lightning Protection

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

33

6.5 Acoustic Interference Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

33

7

.

Characteristics

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

35

7.1 Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

7.2 Maintainability

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

35

7.3 Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

7.4 System Security . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

7.5 Expandability

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38

7.6 Changeability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

38

8. Marking

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

39

8.3

Warning

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

39

9

.

Tests and Inspections 39

Stages of Tests and Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Interface Tests and Inspections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

9.3 Environmental Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

9.4 Functional Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

System Performance Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Bum-In Tests (Optional)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

44

Availability Test (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44

Acceptance Test (Optional)

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

44

9.9 Documentation Verification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

1 0 Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

10.1 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

10.2 Installation

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

45

10.3 Operating Instructions and Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

10.4 Maintenance Instructions and Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

10.5 Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

5.5 ManIMachine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

6.3

SeismicEnvironment

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

32

6.6 Electromagnetic Interference (emi) and Electromagnetic Compatibility (emc)

. . . . . . .

33

8.1 Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

8.2 Nameplates

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

39

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

9.1

9.2

9.5

9.6

9.7

9.8

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FIGURES PAGE

Fig 1 Scada System Data/Control Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Fig 2 Master-Station Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Fig

3

Remote-Station Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Interface Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Data Communication Equipment

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27

Communication Channel

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27

Fig 7 Noise Criteria (NC) Curves for Speech Communication ........................... 34

Fig

8

Typical Surge Withstand Capability (SWC) Test Points

. . . . . . . . . . . . . . . . . . . . . . . . . . .

41

Fig 4 Manual. Automatic. and Supervisory Control Equipment

Fig 5 Signal Interfaces Between Equipment Governed by this Standard and

Fig 6 Signal Interfaces Between Equipment Governed by this Standard and

TABLES

Table

1

Table 2

Table 3

Table 4

Table 5

Table 6

Table 7

Table

8

Table 9

Table 10

Table 11

Analog Input Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Analog Output Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Digital Electronic Input Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Digital Electronic Output Signals

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

25

Digital Electromechanical Inputs (Status)

..................................

25

Digital Electromechanical Inputs (Accumulator) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Digital Electromechanical Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Operating Temperature and Humidity by Location . . . . . . . . . . . . . . . . . . . . . . . . . . .

31

Test Stages and Classes of Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

SystemInputScenario

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

43

Recommended Electrical Graphic Symbols and Meanings

. . . . . . . . . . . . . . . . . . . . . .

30

APPENDIX

Appendix A Master/Remote Station Interconnections ................................

47

Appendix B Bibliography

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

48

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A n Am er ican Nationa l S tandard

IEEE Standard Definition, Specification, and

Analysis of Systems Used for

Supervisory Control, Data Acquisition, and

Automatic Control

1. Scope

[ 2 ] ANSI X3.1-1976, American National Stan-

dard Synchronous Signaling Rates for Data

Transmission.

[

31 ANSI X3.4-1977, American National Stan-

This standard applies to, and provides the

basis for, the definition, specification, perfor-

mance analysis, and application of systems dard Code for Information Interchange.

used for supervisory control, data acquisition

or automatic control, or both: in attended or

unattended electric substations, including those

associated with generating stations, and power

[4] ANSI X3.5-1970, American National Stan-

dard Flowchart Symbols and Their Usage in

Information Processing.

utilization and conversion facilities.

[ 5 ] ANSI Y14.15-1966 (R 1973), American

National Standard Electrical and Electronics

his standard does not apply to electomech-

anical or static, protective-relaying equipment. Diagrams (Including Supplements ANSI

(See ANSI/IEEE C37.90-1978 (R 1982) [ l l ] 3

ANSI/IEEE C37.90.1-1974 (R 1979) [1 2] ,

Y14-15a-1970 and ANSI Y14.15b-1973).

ANSI/IEEE C37.91-1985

E131

, ANSI/IEEE [6 ] ANSI 224.21-1957 (R 197 1), American

C37.93-1976 [141, ANSI/IEEE C37.95-1973, National Standard Method for Measurement

(R 1980) [

151

, ANSI/IEEE C37.96-1976 Specifying the Characteristics of Pickups for

(R 1981) [161, and ANSI/IEEE C37.97-1979

(R 1984) [17].

Shock and Vibration.

[7] ANSI/EIA RS-310-C-1977 (R 1983),

Racks, Panels, and Associated Equipment.

2.

References

When the American National Standards

referred t o in this standard are superseded by a

revision approved by the American National

Standards Institute, the revision shall apply.

[ l ] ANSI X3 TR-1-1983, American National

Standard Dictionary for Information Proces-

sing.4

?Syst ems covered by this standard typically use co m-

puters in the master station and at times in the remote

stations. Such computers provide facilities for incorpo-

rating automatic control functions either by the sup-

plier or by the user after the system is installed.

3The numbers in brackets correspond to those of the

[8 ] ANSI/EIA RS-334-1968, Signal Quality at

Interface Between Data Processing Terminal

Equipment and Synchronous Data Communi-

cation Equipment for Serial Data Transmission.

[9 ] ANSI/EIA RS-404-1978, Start-Stop Signal

Quality Between Data Terminal Equipment

and Non-Synchronous Data Communication

Equipment.

[ l o ]

ANSI/IEEE C37.2-1979, IEEE Standard

Electrical Power System Device Function Num-

bers.

[111 ANSI/IEEE C37.90-1978 (R 198 2), IEEE

Standard Relays and Relay Systems Associated

with Electric Power Apparatus.

[12] ANSI/IEEE C37.90.1-1974 (R 1979),

eferences listed in Section 2 of thi; standard.

DeDartment. American National Standards Institute.

IEEE Guide for Surge Withstand Capability

4 . 4 publications are available from the Sales

14iO

Broadway, New York, NY

10018.

(SWC) Tests.

7

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ANSI/IEEE

C37.1-1987

DEFINITION, SPECIFICATION, AND ANALYSIS OF SYSTEMS USED FOR

[13] ANSI/IEEE C37.91.1985, IEEE Guide

for Protective Relay Applications to Power

Transformers.

[141 ANSI/IEEE C37.93-1976, IEEE Guide

for Protective Relay Applications of Audio

Tones over Telephone Channels.

[15] ANSI/IEEE C37.95-1973 (R 1980) , IEEE

Guide for Protective Relaying of Utility-Con-

sumer Interconnections.

[16] ANSI/IEEE C37.96-1976 (R 1981), IEEE

Guide for AC Motor Protection.

[17] ANSI/IEEE C37.97-1979 (R 1984), IEEE

Guide for Protective Relay Applications to

Power System Buses.

[

181 ANSI/IEEE C37.100-1981, IEEE Stan-

dard Definitions for Power Switchgear.

[19] ANSI/IEEE Std 91-1984, IEEE Standard

Graphic Symbols for Logic Functions.

[

201 ANSI/IEEE Std 100-1984,IEEE Standard

Dictionary for Electrical and Electronics Terms.

[21]

ANSI/IEEE Std 200-1975, IEEE Stand-

ard Reference Designations for Electronics

Parts and Equipment.

[22 ANSI/IEEE Std 280-1985, IEEE Standard

Letter Symbols for Quantities Used in Elec-

trical Science and Electrical Engineering.

[23] ANSI/IEEE Std 315-1975, IEEE Standard

Graphic Symbols for Electrical and Electronics

Diagrams.

IEEE Recommended Practice for Seismic Qual-

ification of Class 1E Equipment for Nuclear

Power Generating Stations.

[25] ANSI/IEEE Std 422-1986, IEEE Guide

for t he Design and Installation of Cable Sys-

tems in Power Generating Stations.

[26] ANSI/NEMA ICs 6-1978, Enclosures for

Industrial Control and Systems.

[27] EIA EMC B1-1968, Introduction t o EMC

Designers Guide.

[24] ANSI/IEEE Std 344-1975 (R 1980) ,

5EIA publications are available from Electronic In-

dustries Association, 2001 Eye Street, NW, Washington,

DC

20006.

[28] EIA EMC B2-1968, EMC Specifications,

Standards and Bibiliography

.

[2 9] EIA EMC B3-1968, Testing and Measure-

ment Techniques for Electronic Equipment.

[30] EIA EMC B4-1965, Designers Guide on

Electromagnetic System Design of Electric

Equipment.

[311

EIA EMC B5-1964, Bonding of Electronic

Equipment.

[32] EIA EMC B6-1967, Grounding of Elec-

tronic Equipment.

[33] EIA EMC B7-1966, Enclosures of Elec-

tronic Equipment.

[34] EIA EMC B8-1965, Cabling of Electronic

Equipment.

[35] EIA EMC B9-1966, Filteringof Electronic

Equipment.

[36 ] EIA EMC B1 0- 19 67 , Electromagnetic

Susceptibility.

[37] EIA IE B12-1977, Application Notes on

Interconnection Between Interface Circuits

1969 (R 1981).

Using EIA RS-449-1980 and EIA RS-232C-

[381

EIA RS-232-C-1969 (R 1981) , Interface

Between Data Terminal Equipment Employing

Serial Binary Data Interchange.

[

391 EIA RS-363-1969, Standard for Specify-

ing Signal Quality for Transmitting and Receiv-

ing Data Processing Terminal Equipments

Using Serial Data Transmission at the Interface

with Non-Synchronous Data Communication

Equipment

.

[

401 EIA RS-422-A-1978, Electical Character-

istics of Balanced Voltage Digital Interface

Circuits.

[41]EIA RS-423-A-1978, Electrical Character-

istics of Unbalanced Voltage Digital Interface

Circuits.

[4 2] EIA RS-449-1977, General Purpose 37-

Position and 9-Position Interface for Data

Terminal Equipment and Data Circuit-Termi-

nating Equipment Employing Serial Binary

Data Interchange.

8

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SUPERVISORY CONTROL, DATA ACQUISITION, AND AUTOMATIC CONTROL

ANSIlIEEE

C37.1-1987

[43] IEC TC 65-1976, Safety Requirements

for Mains Operated and Related Apparatus for

Household and Similar General Use.6

[44] IEEE Std 525-1978, IEEE Guide for

Selection and Installation of Control and Low-

Voltage Cable Systems in

substation^.^

[45] MIL-HDBK 217D-1982, Reliability Pre-

diction of Electronic Equipment.8

[46] MIL-STD 471A-1973, Maintainability

Demonstration.

[47] MIL-STD 1472C-1981, Human Engineer-

ing Design Criteria for Military System Equip-

ment and Facilities.

[48 ] GAUSHELL, D. J., FRISBIE,

W.

L., and

KUCHEFSKI, M. H. Analysis

of

Analog Data

Dynamics

for

Supervisory Control and Data

Acquis i tion Sys tem , IEEE Paper 82

SM

304-4.

[49] LLOYD AND LIPOW.

Reliability, Man-

agement, Methods, and Mathematics.

Engle-

wood Cliffs, N J : Prentice-Hall, 1962.

3.

Definitions

The definitions of terms contained in this

standard, or in other American National Stan-

dards referred to in this standard, are not in-

tended to embrace all legitimate meanings of

the terms. They are applicable only to the sub-

ject treated in this American National Standard.

Supervisory control and data acquisition sys-

tems may use computers. For standard defini-

tion of computer terms refer to ANSI X3 TR-

1-1983 [ l ] .

6IEC publications are available from American

National Standards Institute, 14 30 Broadway, New

York, NY 10018.

IEEE publications are available from the Institute of

Electrical and Electronics Engineers Service Center, 445

Hoes

Lane, PO Box 1331, Piscataway, NJ 08855-1331.

*MIL publications are available from the Director,

US Navy Publications and Printing Service, Eastern

Division, 700 Robbins Avenue, Philadelphia, PA 191 11.

Definitions in this standard may also be listed

Definitions in ANSI/IEEE Std 100-1984 [201

are used whenever possible; however, sometimes

such definitions do not include the meaning

associated with the equipment governed by

this standard.

alarm condition. A predefined change in the

condition of equipment or the failure of equip-

ment to respond correctly. Indication may be

audible or visual, or both.

analog device. A device that operates with

variables represented by continuously mea-

sured quantities such as voltages, resistances,

rotations, and pressures.

in ANSI/IEEE C37.100-1981 [18].

analog-to-digital (a/d) conversion. Production

of a digital ou tput corresponding to the value

of an analog input quantity.

analog quantity.

A

continuous variable that is

typically digitized and represented as a scalar

value.

automatic. Pertaining to a process or device

that, under specified conditions, functions

without intervention by a human operator.

automatic circuit recloser. A self-controlled

device for automatically interrupting and

reclosing

an

alternating-current circuit, with

a predetermined sequence of opening and re-

closing followed by resetting, hold-closed, or

lockout operation.

automatic control. See: control, (1) utomatic.

automatic line sectionalizer. A self-contained

circuit-opening device that automatically opens

the main electrical circuit through it after sens-

ing and responding to a predetermined number

of successive main current impulses equal to o r

greater than a predetermined magnitude. It

opens while the main electrical circuit is de-

energized. It may also have provision to be

manually operated to interrupt loads.

automatic load throwover equipment (transfer

or switchover). An equipment that automatic-

ally transfers a load t o another source of power

when the original source to which it has been

connected fails, and tha t automatically restores

the load to the original source under desired

conditions.

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ANSI/IEEE

C37.1-1987

Modem One

DEFINITION, SPECIFICATION. AND ANALYSIS OF SYSTEMS USED FOR

Modem

Two

NOTE: The restoration of the load t o the preferred

source from the emergency source upon re-energization

of the preferred source after an outage may be

of

the

contin uous circuit restoration type or interrupted cir-

cuit restoration type.

(1)

quipment of the Nonpreferential Type.

Equipment tha t automatically restores the load

to the original source only when the other

source, t o which i t has been connected, fails.

(2)

Fixed Preferential Type.

Equipment in

which the original source always serves as the

preferred source and other source as the emer-

gency source. The automatic transfer equip-

ment will restore the load to the preferred

source upon its re-energization.

3 )

Selective Preferential Typ e.

Equipment in

which either source may serve as the preferred

or the emergency source of preselection as

desired, and which will restore the load to the

preferred source upon its re-energization.

(4)

Semiautomat ic Load Throwover Equip -

m e n t .

An equipment that automatically trans-

fers a load to another (emergency) source of

power when the original (preferred) source to

which it has been connected fails, but requires

manual restoration of the load to the original

source.

automatic reclosing equipment. Equipment

which initiates automatic closing of a switching

device under predetermined conditions without

operator intervention.

automatic opening (tripping). The opening of a

switching device under predetermined condi-

tions without operator intervention.

availability. The ratio of uptime and uptime

plus downtime.

Se e :

7 . 3 , Availability.)

backup. Provision for

an

alternate means of

operation if the primary system is not available.

backup, degraded. A backup capability that

does not perform all of the functions of the

primary system.

baud. The term

baud

defines the signaling

speed, that is, keying rate of the modem.

The signaling speed in baud is equal to the

reciprocal of the shortest element duration in

seconds to be transmitted.

For example, in the following table, th e sig-

naling speed is calculated from the signaling

element duration. In addition, the distinction

between bit rate and baud for two different

types of modems is illustrated.

Signaling

element

duration

Signaling

speed

0.833

ms

1200 Bd

Information

transmitted

per element 1bit

duration

Bit rate 1200 bits

per second

2 bits

2400 bits

per second

The bit rate and baud are not synonymous

and shall not be interchanged in usage. Prefer-

red usage is bit rate, with baud used only when

the details of a communication modem or

channel are specified.

bit.

(1)

east significant. In an

n

bit binary word

its contribution is

(0

or 1) oward the maxi-

mum word value of (2 -1).

2)

most significant. In an

n

bit binary word

its contribution is

(0

or 1 imes 2'

-I))

toward

the maximum word value of (2 -1).

bit rate. The number of bits transferred in a

given time interval. Bits per second is a measure

of the rate at which bits are transmitted.

buffer (buffer storage).

(1)A device in which data are stored tempo-

rarily, in the course of transmission from one

point to another; used to compensate for a dif-

ference

in

the flow of data, or time of occur-

rence of events, when transmitting data from

one device to another.

(2 ) An isolating circuit used to prevent a

driven circuit from influencing a driving circuit.

bum in. A period, usually prior to on-line oper-

ation, during which equipment is continuously

energized for the purpose of forcing infant

mortality failures.

calibration. Adjustment of a device so that the

output is within a specific range for particular

values of t he input.

cathode ray tube (crt). A display device in

which controlled electron beams are used to

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present alphanumeric or graphical data on an

electroluminescent screen.

channel load factor.

See : 5.4.4

channel, scada. The communication path be-

tween master and remote stations.

See:

Sec-

tion

4,

ig

1.)

checkback message. The response from the

re-

ceiving end to the initiating end of a coded

signal or message.

(1)

artial.

Message from the initiating end is

mirrored by the receiving end back to the

initiating end to verify error-free transmission

of the message.

2)

Comple te .

Message from the initiating

end is interpreted by the receiving end. A new

message is sent to the initiating end to verify

error-free transmission and proper interpreta-

tion of the message.

See : 7.4,

ystem Security.)

common equipment. That complement of

either the master or remote station supervisory

equipment that interfaces with the intercon-

necting channel and is otherwise basic to the

operation of the supervisory system, but is

exclusive of those elements that are peculiar

to and required for the particular applications

and uses of the equipment.

console. That component of the system which

provides facilities for control and observation

of the system. Examples include operators

console, maintenance console.

See :

panel,

control

)

contention.

An

operational condition on a data

communication channel in which no station is

-designated a master station. In contention,

each station on the channel shall monitor the

signals on the channel and wait for a quiescent

condition before initiating a bid for circuit con-

trol.

control. The execution of a system change by

manual means, remote means, automatic

means, or partially automatic means.

(1) utomatic. An arrangement of electrical

controls that provides for switching or control-

ling, or both, of equipment in an automatic

sequence and under predetermined conditions.

(2) closed loop. A type of automatic control

in which control actions are based on signals

fed back from the controlled equipment or sys-

11

ANSI/IEEE

C37.1-1987

tem. For example, remote stations can manage

local voltage conditions by control of load tap

changers and volt amperes reactive

(VAR)

con-

trol compensation equipment.

(3)open loop. A form of control without

feedback.

4)

anual. Control in which the system or

main device, whether direct or power-aided in

operation, is directly controlled by an attend-

ant.

5 )

partial automatic. Control which is a

combination of manual and automatic control.

For example, to cause a voltage reduction the

local automatic load tap changing closed-loop

control may be biased by way of a supervisory

control command.

(6)

remote. Control of a device from a distant

point.

data. Any representation of a digital or analog

quantity to which meaning has been assigned.

data acquisition. The collection of data .

data acquisition system. A centralized system

which receives data from one or more remote

points. A telemetering system. Data may be

transported by either analog or digital tele-

metering.

See ;

teleme ering )

data rate. The rate at which a data path (for

example, channel) carries data, measured in

bits per second (b/s).

data logging. The recording of selected data on

suitable media.

dead band. The range through which an input

can be varied without initiating response.

device (electrical equipment).

An

operating

element such as a relay, contactor, circuit

breaker, switch, valve, or governor used to per-

form a given function in the operation of elec-

trical equipment.

digital quantity. A variable represented by a

number of discrete units.

digital-to-analog (d/a) coversion. Production

of an analog signal whose magnitude is propor-

tional t o the value of a digital input .

disable. A command or condition which pro-

hibits some specific event from proceeding.

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ANSI/IEEE

C37.1-1987

DEFINITION, SPECIFICATION, AND ANALYSIS O F SYSTEMS USED

FO R

display, graphic. A hardware device (crt,

plasma panel, arrays of lamps, or light emitting

diodes) used to present pictorial information.

distributed processing. A design in which all

dat a is not processed in one processor. Multiple

processors in the master station or in the re-

mote stations, or both, share the functions.

downtime. The time during which a device or

system is not capable of meeting performance

requirements.

echo.

A

communication technique assuring

that a word received at the termination point

in a system is the same as the word originally

transmitted. The received word is retransmitted

to the sending device and matched to ensure

that the original message was received properly.

electromagnetic compatibility (emc). A mea-

sure of equipment tolerance to external elec-

tromagnetic fields.

electromagnetic interference (emi). A measure

of electromagnetic radiation from equipment.

enable. A command or condition which permits

some specific event to proceed.

engineering units. A unit of measure for use by

operatinglmaintenance personnel usually pro -

vided by scaling the input quantity for display

(meter, stripchart, or crt).

expandability. The capability of a system to be

increased in capacity

or

provided with addi-

tional functions.

See :

7.5.)

event.

A

discrete change of state (status) of a

system or device.

failure. An event that may limit the capability

of an equipment or system to perform its

function(s).

(1)

Critical. Causes a false or undesired opera-

tion of apparatus under control.

2)

Major.

Loss

of control or apparatus which

does not involve a false operation.

3)

Minor.

Loss of data relative to power flow

or equipment status.

failure distribution. The manner in which fail-

ures occur as a function of time; generally ex-

pressed in the form of a curve with the abscissa

being time.

failures. (1) nfant mortality. A characteristic

pattern of failure, sometimes experienced with

new equipment which may contain marginal

components, wherein the number of failures

per unit of time decrease rapidly as the number

of operating hours increase. A burn-in period

may be utilized t o age (or mature) an equip-

ment to reduce the number of marginal com-

ponents.

(2)

random. The pattern of failures for equip-

ment that has passed out of its infant mortality

period and has not reached the wear-out phase

of its operating lifetime. The reliability of an

equipment in this period may be computed by

the equation

where

R

= e-ht

X =

failure rate

t

=

time period of interest

(3) wear out. The pattern of failures experi-

enced when equipment reaches its period of

deterioration. Wear-out failure profiles may be

approximated by a Gaussian (bell curve) dis-

tribution centered on the nominal life of the

equipment.

firmware. Hardware used for the nonvolatile

storage of instructions or data that can be read

only by the computer. Stored information is

not alterable by any computer program.

See :

station, remote.)

function check. A check of master and remote

station equipment by exercising a predefined

component or capability.

(1)

nalog.

Monitor a reference quantity

(2)

Control . Control and indication from a

control-check relay

3) Scan. Accomplished when control func-

tion check has been performed with all remotes

4) oll.

Accomplished when analog function

is performed with all remotes

(5)

Logging. Accomplished when results of

the control function check are logged

hard copy. A permanent record of information

in readable form for human use, for example,

reports, listings, displays, logs, and charts.

hardwired. The implementation of processing

steps within a device by way of the placement

of conductors between components within the

device. The processing steps are not alterable

except by modifying the conducting paths

between components.

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SUPERVISORY CONTROL, DATA ACQUISITION, A ND AUTOMATIC CONTROL

ANSI/IEEE

C37.1-1987

indication.

A

light or other signal (audio or

visual) provided by the man/machine interface

that signifies a particular condit ion.

inhibit. To prevent a specific event from oc-

curring.

log. A printed record of data.

master terminal unit

(MTU).

Refers to the

master station of a supervisory control system

See: station, master).

mean time between failure

(MTBF).

The time

interval (hours) that may be expected between

failures of an operating equipment.

mean time to repair

(MTTR).

The time interval

(hours) that may be expected to return a failed

equipment t o proper operation.

modem. A MOdulator/DEModulator device

which converts serial binary digital data to and

from the signal form appropriate for the respec-

tive communication channel.

multiplexer. (1)A device that allows the inter-

leaving of two or more signals to a single line or

terminal.

( 2 ) A device for selecting one of a number of

inputs and switching its information to the out-

put.

offset.

A

predetermined value modifying the

actual value

so

as to improve the integrity of the

system, for example, the use of a

4

mA signal

to represent zero in a 4 mA to 20 mA system.

panel, control. An assembly of man machine

interface devices. See: 5.5.)

point equipment (poin t). Elements of a super-

visory system, exclusive of the basic common

equipment, which are peculiar to and required

for the performance of a discrete supervisory

function. (See: supervisory control functions.)

(1) larm Point . Station (remote or master,

or both) equipment(s) that inputs a signal to

the alarm function.

(2)

Accumulator Point . Station (remote or

master, or both) equipment(s) that accepts a

pulsing digital input signal to accumulate a

total of pulse counts.

3)Analog Point . Station (remote or master,

or both) equipment(s) that inputs

an

analog

quantity to the analog function.

(4 )

Control Point. Station (remote or master,

or both) equipment(s) that operates to perform

the control function.

5 )

ndicat ion Status)Point .

Station (remote

or master, or both) equipment(s) that accepts a

digital input signal for the function of indica-

tion.

(6)

Sequence

of

Events Point .

Station (re-

mote or master, or both) equipment(s) that

accepts a digital input signal to perform the

function of registering sequence of events.

(7)

Telemetering S election Point . Station (re-

mote or master, or both) equipment(s) for the

selective connection of telemetering transmit-

ting equipment to appropriate telemetering re-

ceiving equipment over an interconnect ing

communication channel. This type of point is

more commonly used in electromechanical or

stand-alone type of supervisory control.

8 )

pare Point. Point equipment that is not

being utilized but is fully wired and equipped.

(9) Wired Poin t.

Point for which all common

equipment, wiring, and space are provided.

To

activate the point requires only the addition of

plug-in hardware.

(10)

Space O nly Point .

Point for which cabi-

net space only is provided for future addition

or wiring and other necessary plug-in equip-

ment.

NOTE: A point may serve for one

or

more

of

the pur-

poses described above, for example, when a supervisory

system is used for combined control and supervision of

remotely operated equipment, a point for supervisory

control and point for supervisory indication may be

combined into a single control and indication point.

polling (data request). The process by which a

data acquisition system selectively requests

data from one or more of its remote terminals.

A remote terminal may be requested to re-

spond with all, or a selected portion

of,

the

data available.

primary.

An

equipment or subsystem which

normally contributes to system operation. See:

backup.

programmable equipment.

A

remote or master

station having one or more of its operations

specified by a program contained in a memory

device.

protocol.

A

strict procedure required to initiate

and maintain communication.

quantization error. The amount that the digital

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ANSI/IEEE

C37.1-1987


quantity differs from the analog quantity.

Se e :

analog-to-digital (a/d) conversion.)

quiescent supervisory system.

See:

supervisory

system, quiescent.)

refresh rate. The number of times in each

second that the information displayed on a

nonpermanent display, for example, a crt, is

rewritten or re-energized.

relay, interposing. A device which enables the

energy in a high-power circuit t o be switched

by a low-power control signal.

remote terminal unit (RTU). Refers to a re-

mote station equipment of a supervisory sys-

tem. See: station, remote.)

repeatability. The measure of agreement among

multiple readings of an output for the same

value of input, made under the same operating

conditions, approaching from the same direc-

tion, using full-range traverses.

reproducibility. The measure of agreement

among multiple readings of the output for the

same value of input, made under the same

operating conditions, approaching from either

direction, using full-range traverses.

resolution. The least value of the measured

quanti ty which can be distinguished.

scan (interrogation). The process by which a

data acquisition system interrogates remote

stations of points for data.

scan cycle. The time in seconds required to ob-

tain a collection of data (for example, all data

from one remote, all data from all remotes, and

all data of a particular type from all remotes).

serial communication.

A

method of transmitting

information between devices by sending all

bits serially over a single communication chan-

nel.

station, automatic.

A

station that operates in

automatic control mode.

NOTE: An automatic station may go in and out of

operation in response to predetermined voltage, load,

time, or other conditions, or in response to a remote

o r

locally manually operated control device.

station check (supervisory check, status up-

date). The automatic selection, in a definite

order, of all the supervisory

alarm

and indi-

cation points associated with one remote

station or all remote stations of a system, and

the transmission of all the indications to the

master station.

station identification.

A

sequence of signal

elements used to identify a station.

station.

1)

master (of a supervisory system).

The entire complement of devices, functional

modules, and assemblies which are electrically

interconnected to effect the master station

supervisory functions. The equipment includes

the interface with the communication channel

but does not include the interconnecting chan-

nel.

During communication with one or more

remote stations the master station is the supe-

rior in t he communication hierarchy.

(2)remote (of a supervisory system). The

entire complement of devices, functional

modules, and assemblies which are electrically

interconnected

to

effect the remote station

supervisory functions. The equipment includes

the interface with the communication channel

but does not include the interconnecting chan-

nel.

During communication with a master station

the remote station is the subordinate in the

communication hierarchy.

NOTES: Examples of station equipments include

(1) Hardwi red .

Station supervisory equipment which

is comprised entirely o f wired-logic elements.

2 )

Firm ware.

Station supervisory equipment which

uses hardware logic programmed routines in a manner

similar to a computer. The routines can only be modi-

fied by physically exchanging logic memory elements.

3 )

Programmable.

Station supervisory equipment

which uses software routines.

3) semiautomatic.

A

station that requires

both automatic and manual modes to main-

tain the required character of service.

4)

ubmaster. A station that can perform

as

a master station on one message transaction

and as a remote station on another message

transaction.

sta,tus. Information describing a logical state of

a point or equipment.

supervisory control. An arragement for operator

control and supervision of remotely located

apparatus using multiplexing techniques over a

relatively small number of interconnecting

channels.

supervisory control data acquisition system.

A

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ANSI/IEEE

C37.1-1987

system operating with coded signals over com-

munication channels so as to provide controI

of remote equipment (using typically one

communication channel per remote station).

The supervisory system may be combined with

a data acquisition system, by adding the use of

coded signals over communication channels to

acquire information about the status of the re-

mote equipment for display or for recording

functions.

supervisory control functions. Equipment gov-

erned by this standard comprise one or more of

the following functions:

(1)Alarm Func t ion. The capability of a su-

pervisory system to accomplish a predefined

action in response to an alarm condition. See:

alarm condition.)

(2) Analog Function. The capability of a su-

pervisory system to accept , record or display,

or do all of these, an analog quantity as pre-

sented by a transducer or external device. The

transducer may or may not be a part of the

supervisory control system.

(3) Control Function. The capability of a su-

pervisory system to selectively perform man-

ual or automatic, or both, operation (singularly

or in selected groups) of external devices. Con-

trol may be either analog (magnitude or dura-

tion) or digital.

4) ndicat ion Status ) Func t ion. The capa-

bility of a supervisory system to accept, record,

or display, or d o all of these, the status of a

device. The status of a device may be derived

from one or more inputs giving two or more

states of indication.

(a)

Two -State Indicat ion.

Only one of the

two possible positions of the supervised device

is displayed at one time. Such display may be

derived from a single set of contacts.

(b) Three-State Indication. One in which

the transitional state or security indication as

well as the terminal positions of the supervised

device is displayed. Such a display is derived

from at least two sets of initiating contacts.

(c) Multistate Indication. Only one of the

predefined states (transi tional or discrete, or

both) is indicated at a time. Such a display is

derived from multiple inputs.

(d)

Indication with Memory.

An indication

function with the additional capability of stor-

ing single or multiple change(s) of status that

occur between scans.

5 )

Accumulator Func t ion. The capability of

a supervisory system to accept and totalize

digital pulses and make them available for dis-

play or recording, or both.

(6)

Sequence

of

Events Fun c t ion. The capa-

bility of a supervisory system to recognize each

predefined event, associate a time of occurrence

with each event, and present the event data in

order of occurrence of the events.

supervisory system. All control indicating and

associated with telemetering equipment at the

master station and all of the complementary

devices at the remote station, or stations.

(1) ontinuous update. A system in which

the remote station continuously updates indi-

cation and telemetering to the master station

regardless of action taken by the master station.

The remote station may interrupt the continu-

ous data updating to perform a control opera-

tion.

(2)polling. A system in which the master

interrogates each remote to ascertain if there

has been a change since the last interrogation.

Upon detection of a change the master may

request data immediately.

(3)quiescent. A system which is normally

alert but inactive and transmits information

only when a change in indication occurs at the

remote station or when a command operation

is initiated at the master station.

4)

canning. A system in which the master

controls all information exchange. The normal

state is usually one of repetitive communication

with the remote stations.

system time.

A

coordinated value of time main-

tained a t stations throughout the power system.

tag. A visual indication, usually a t the master

station, to indicate that a device has been

cleared for field maintenance/construction

purposes and is not available for control or

data acquisition.

telemetering. (1 Transmission of measurable

quantities using telecommunication techniques.

(a ) Current-Type Telemeter. A telemeter

that employs the magnitude of a single current

as the translating means.

(b) Frequen cy-npe Telemeter. A telemeter

that employs the frequency of a periodically

recurring electric signal

as

the translatingmeans.

(c ) Pulse-Type Telemeter. A telemeter that

employs characteristics of intermittent electric

signals, other than their frequency, as the trans-

lating means.

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ANSIlIEEE

C37.1-1987

DEFINITION, SPECIFICATION, AND ANALYSIS

OF

SYSTEMS USED

FOR

(d ) Ratio-Type Telemeter. A telemeter that

employs the relative phase position between, or

the magnitude relation between, two or more

electrical quantit ies as the translating means.

NOTE: Examples

of

ratio-type telemeters include ac or

dc position matching systems.

(e) Voltage-Type Telemeter. A telemeter

that employs the magnitude of a single voltage

as the translating means.

(2) analog. Telemetering in which some char-

acteristic of the transmitter signal

is

propor-

tional t o the quantity being measured.

(3) digital. Telemetering in which a numerical

representation is generated and transmitted; the

number being representative of the quantity

being measured.

terminal. (1)A point in a system or communi-

cation network at which data can either enter

or leave.

(2) An

input/output device capable of trans-

mitting entries to and obtaining output from

the system of which i t is a part, for example,

cathode ray tube (crt) terminal.

test. (1) ertified design. A test performed on a

production model specimen of a generic type of

equipment to establish a specific performance

parameter of that genre of equipment. The

condition and results of the test are described

in a document that

is

signed and attested to by

the testing engineer and other appropriate,

responsible individuals.

(2)

data

(a) The recorded results of test.

(b ) A set of data developed specifically to

test the adequacy of a computer run or system.

They may be actual data taken from previous

operations or artificial data created for this

purpose.

3)point. A predefined location within equip-

ment or routines at which a known result

should be present if the equipment or routine

is operating properly.

time.

(1)

esponse. The time between initiating

some operat ion and obtaining results.

(2)

settling. Time required by channel or ter-

minal equipment t o reach an acceptable opera-

ting condition.

timer, watchdog. A form of interval timer which

is used t o detect a possible malfunction.

transaction. That sequence of messages between

master and remote stations required to perform

a specific function (for example, acquire spe-

cific data or control a selected device).

troubleshoot. Action taken by operating or

maintenance personnel, or both, to isolate a

malfunctioned component of a system. Actions

may be supported by printed procedures, diag-

nostic circuits, test points, and diagnostic rou-

tines.

update. The process of modifying or reestablish-

ing data with more recent information.

uptime. The time during which a device or sys-

tem is capable of meeting performance require-

ments.

4.

Functional Characteristics

The equipment governed by this standard

may be arranged in various configurations and

be required

to

perform some or all of the func-

tions identified in this section.

Typically, equipment governed by this stan-

dard compose a system with at least one master

station and one (typically several) remote

sta-

tion. Figure

1

illustrates the data and control

flow from field sensors and actuators to and

from an operator by way of a master station

and remote-station system.

4.1

Typical Diagrams. Diagrams of typical

equipment and configurations of equipment

governed by this standard are illustrated within

this section.

The media between the stations could be any

suitable communication channel or channels.

The communication protocol typically used

requires a master station to initiate message

transactions.

For brevity, t he terms master and remote de-

note master station and remote station.

The functional components of a master sta-

tion are illustrated in Fig

2.

A dual computer

station is illustrated, however, a single computer

master station may be adequate for some appli-

cations. The functional components of aremote

station are illustrated in Fig

3.

Various inter-

connections of master and remote stations are

illustrated in Appendix A.

The computer system illustrated in Fig

2

as a

single box typically includes mass memory and

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SUPERVISORY CONTROL, DAT A ACQUISITION. AND AUTOMATIC CONTROL

-

M

M

ANSI/IEEE

C37.1-1987

r

R E M O T E

-

T A T I O N-

PULSE

C O U N T E R

P O I N T S

B I N A R Y

D A T A

P O I N T S

D A T A D I S PL A Y S

I N D I C A T I O N

r

C O N T R O L A N D

I N D I C A T I O N

D E V I C E S

~

D A

C O N V E R T E R

I

1

I

N D C A T I O N

P O I N T S

S T A T I O N C H E CK

TR IP-CLOSE

L O W E R R A I S E

CLOSE-OPEN

S T O P -S T A R T

4

r

A N A L O G D A T A

C O U N T E D D A T A

B I N A R Y D A T A

L A R M S A N D

L

T A T U S

I N D I C A T I O N S 1

IP l

P O I N T S

Fig

1

Scada System Data/Control Flow

C O M P U T E R

S U B S Y S T E M

C O M P U T E R C O M P U T E R

S Y S T E M

C O M M U N I C A T I O N S

I N T E R F A C E

A N A L O G R E C O R D E RS

D I G I T A L D I S P L A Y S

I

I LRTUUNCTIONS

I i

Fig 2

Master-Station Block Diagram

various peripherals. It is common practice to interface remote station communication chan-

switch the complete computer system in the

nels to the primary computer system. The

event of a peripherial or computer failure rather man/machine subsystem is that equipment

than attempt to reconfigure a system by switch- used to present information to the operator(s)

ing peripherials. The communication interface and to accept inputs from the operator@).

subsystem of Fig

2

is that equipment used to

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ANSI/IEEE

C37.1-1987

INTERFACE

I

I

1

DEFINITION, SPECIFICATION, A ND ANALYSIS OF SYSTEMS USED FOR

I

I

I

I

I

I LOGIC

I

COMMON

( 1 ) STATUS AND ALA RM PULSE

INPUTS INPUTS FROM

( 2 )

SWITCH POSITIONS ACCUM ULATO R'

F R O M M A N U A L E N T R Y (W A T T H O UR

PANELS METERS, ETC)

I

*

I POWER

OWER

SUPPLY

TRANSDUCERS RELAYS

D/A CONVER

I

TERS, ETC

I

I

I POINT INPUTiOUTPUT LOGIC

(1 CONTACT OUTPUTS

TO CIRCUIT BREAKERS,

ANA LOG OUTPUTS DISCONNECT SWITCHES, ETC

TO SETPOINT ( 2 ) CONTACT OUTPUTS

CONTROLLERS TO DIG ITAL SETPOINT

CONTROLLERS

Fig

3

Remote-Station Block Diagram

4.2

System Functional Characteristics. This

section provides guidance for helping both sup-

pliers and users define the functional capabili-

ties that may be required in a system. Not all

of the capabilities discussed below are required

in every system. When a function or capability

is

not required, tha t fact shall be noted.

Each generic function is addressed in a sub-

section that follows in terms

of

the minimum

features or characteristics that should be ad-

dressed to adequately define the function.

Definition of the system functions is a joint

responsibility of the user and supplier . The sub-

paragraphs that follow provide a checklist that

will help ensure adequate communication be-

tween the user and supplier of equipment

governed by this standard.

When the feature or characteristic is fixed by

the design of the equipment the burden of defi-

nition rests on the supplier (for example, num-

ber of inputs/ou tputs per card). However,

variable features (for example, scaling resistors,

switch settings, firmware, and software) should

be jointly defined by the user and the supplier.

4.2.1 Communication Management. The capa-

bilities to manage communication between the

master station and the remote station shall be

well defined. The topics to be defined include

(1)

Message protocol

(2 ) Number of channels

(3) Bit rate

4)

rror detection techniques

5)

Channel switching

(6)

Number of remotes per channel

( 7 )

Number of retries each at tempt

(8)

Number of attempts per hour

(9) Time out value(s)

(10)

Communication error reporting

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ANSI/IEEE

C37 . 1 - 1 9 8 7

(11)Channel quality monitoring (normal and

(12)

Loop-back provisions

4.2.2

Data Acquisition. (See

5.3).

When data

acquisition is a function to be performed, the

characteristics for each data type shall be

defined. Ranges of data input, scale factors,

rates, and accuracy shall be defined for

backup)

(1)

Analog inputs

(2)

Indication inputs-single bit

(3)

Indication inputs-multibit

(4)

Indication inputs-with memory

5 )

Accumulator inputs

(6)

Sequence of events inputs

The data acquisition capability for each data

type shall be defined in terms of the following

characteristics.

Scan Groups.

How many scan groups, size of

group, inputs in each group.

Scan Cyc le .

Each group (seconds to complete

an

acquisition from all remotes).

NOTE: The communication hardware related perform-

ance capabilities used in the calculation of scan cycle

shall

be

defined.

4.2.2.1 Remote- Station Data Acquisition.

When the remote station locally acquires data

between master-station data requests, the

capacity (total inputs) and rate of acquisition

(inputs per second) for field data interfaced to

remote-station equipment shall be defined for

each of the above data types.

The modularity (for example, number of in-

puts per card) of each data type shall also be

specified.

4.2.2.2

Master-Station Data Acquisition.

The capacity (total inputs) and rate of acquisi-

tion (inputs per second) for local or remote-

station data interfaced to master-station

equipment shall be defined for all applicable

data types.

4.2.3

Data Processing. Data processing capa-

bilities shall be defined for each equipment and

data type. Systems with report-by-exception

functions shall have the capability to report all

data for initialization and periodic update

purposes.

4.2.3.1

Analog Data Processing. Analog

change detection may be a function included

as

an alternative to processing every input on

every scan. Analog change detection is accom-

plished by testing to see if the new value for

each input is within N digital counts (for exam-

ple, dead band) of the last stored value for that

input. The new value shall replace the last stored

value only if the dead band was exceeded and

then the input will be further processed

as

de-

fined below. When the analog change detection

function is included, the following characteris-

tics shall be defined:

(1)Location of processing, remote or master,

or both

(2)

Range of N- remo te or master, or both

(3)

Applicability of N-re mote, card, or point

4) echnique for changing value of N

When the analog change detection is imple-

mented

in the remote stat ion,

its output may

be used by an analog data report-by-exception

function to save communication of unchanged

data from the remote station to the master

station. When the analog data report-by-excep-

tion function is included the following charac-

teristics shall be defined.

(1)Percent of analog changes per scan that

results in the channel load associated with

reporting all analog points from the remote

terminal unit (RTU).

(2)

Description of logic in the master station

that can be used to select between using the

Analog Data Report-by-Exception function or

the Report All Analog Data Functions when

acquiring analog data from each remote station.

Filtering of analog data may be provided to

smooth such data before it is used by other

functions. When this function is included, de-

fine the equation used and the time delay

introduced by the filtering.

Analog data conversion to engineering units

is typically required before analog data

is

used

by the operator, other software, or printed in

an alarm message. The mathematical equa-

tion(s) used to convert analog values repre-

sented

by

digital counts into the corresponding

engineering units shall be defined. Specific

attention shall be given to sensor and trans-

ducer scale factors that may be provided by the

user.

Scaling of analog inputs should give adequate

consideration to off-normal operation of the

power system (for example, over voltage,

emergency load limits).

Techniques that are used to

(1)Detect an open input to an analog chan-

2) Identify reasonable values, or

(3) Automatically calibrate an analog chan-

nel, or a combination of these three shall be

defined.

nel, or

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ANSI/IEEE

C37 . 1 -1987 DEFINITION, SPEC

Analog data limit checking is typically in-

cluded to determine if other downstream func-

tions such as alarm management or further pro-

cessing

is

required. The number of high or low

limits accommodated and associated dead-band

processing, shall be defined. Specific attention

shall be given to the procedure for user speci-

fication and revision of limit and dead-band

values.

4.2.3.2

Indication Data Processing. Indica-

tion input change detection may be a function

included as an alternative to processing every

input on every scan. Indication input change

detection is performed by testing to see if the

current indication is the same as the last stored

indication for that input. Changed indications

shall replace the last stored value and the point

or group of inputs shall be routed for other

downstream functions such as indication data

report by exception, or alarm management, or

both.

When the Indication Input Change Detection

function is included, the following characteris-


(1)Location of processing (remote or master)

(2)

Quanti ty of da ta reported when a single

(3)Minimum signal duration

When the indication input change detection

function is implemented in

the remote

station,

its output may be used by an indication data

report-byexc ept ion function to save communi-

cation of unchanged data from the remote

station to the master station. When the indica-

tion data repor t-byexception function is in-

cluded, the following characteristics shall be

defined:

(1)Percent of indication point changes per

scan that results in the channel load associated

with reporting all indication points from the

remote.

(2)

Description of logic in the master or re-

mote station tha t can be used to select between

using the indication data report-by-exception

or t he report all indication data function when

acquiring indication data from each remote.

Indication with memory may be a function

implemented in th e remote. When this function

is

included, define the number of status changes

accommodated, and legal bit combinations

supported by the design.

Define the sta tus data processing options sup-

ported. Particular attention shall be given to

input changes

'IFICATION, AND ANALYSIS OF SYSTEMS USED

FOR

input validity processing and to the interface

between the supervisory control function and

the status data processing function.

4.2.3.3

Accumulator Data Processing. When

pulse accumulation and pulse accumulator data

processing is included the following character-

istics shall be defined:

(1)

nput circuit

(2

or

3

connections)

(2)

Sources of freeze command (internal/

3)

Ranges of values (remote and master

4)

ominal and maximum counting rates

5 )

Source of memory power

external)

station)

4.2.3.4

Sequence of Events (SOE) Data.

When a sequence of events data acquistion ca-

pability is included the following characteris-


(1)Time resolution (at and between remotes)

(2)

Method of system time synchronization

3) Time accuracy between any two remote

4) umber of

SOE

inputs

5 ) Size of buffers (number of SOE messages

which can be stored)

(6)

Time (Minimum/Maximum) between suc-

cessive change of an input

(7 ) Method of indicating tha t SOE data is

available

(8) Data filter time constant (for example,

contact de-bounce)

(9)

Data time skew (introduced by de-bounce

filters)

4.2.3.5

Computed Data Points. When the

capability of computing data or results (that

are not directly measured) is included the fol-

lowing characteristics shall be defined:

stations

(1)Location (remote or master)

(2)Equations supported

(3)

Resulting data types (numeric or logical,

or both)

4) ownstream functions (for example,

limit checking)

4.2.3.6 Alarm Management. When the capa-

bility to manage and report alarm conditions is

included the following characteristics shall be

defined:

(1)Conditions reported as alarms

(2)Methods of acknowledgement (single or

3)Methods of highlighting reports (flash,

4)

nformation in alarm messages

5 )

Hierarchy of alarms (priority level)

groups )

tone, etc)

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SUPERVISORY CONTROL, DATA ACQUISITION, AN D AUTOMATIC CONTROL

ANSI/IEEE

C37.1-1987

(6)

Size of alarm queue(s)

(7)

Queue management (for example, time

(8)

Alarm limit@)

4.2.4 Supervisory Control Characteristics

Se e : 5.3) . When the capability to remotely

control external apparatus is provided, the

characteristics of such a control capability shall

be defined.

Definition of characteristics common to all

control interfaces shall include

(1)Control sequence description

(2)Type

of

checkback message (partial or

complete)

(3) Security of control sequences

4)mmediate operate controls

(5) Broadcast controls

ordered)

4.2.4.1 Apparatus Control with Relay In-

terface. Control using a relay output shall be

described as follows:

(1) Dwell time of relay contacts

(2)

Number of relays that can be simultane-

ously energized in each type of remote

3)Processing actions (for example, logging,

and alarm suppression)

4.2.4.2 Apparatus Control with Setpoint

Interface. Control using a setpoint out put shall

be defined for

(1)Resolution of setpoint value

(2) Duration of outpu t value

(3) Processing actions (for example, limit

check, equation, and alarms)

4.2.4.3 Apparatus Control with Electronic

Interface. Control using a solid-state interface

shall be described as follows:

(1)

Timing diagram of signals

(2 ) Interface communication protocol

3) Processing actions associated with control

4.2.5 Automatic Control. When the capability

to automatically control external apparatus is

provided the characteristics of such control

capabilities shall be defined

1) ocation of automatic control logic (re-

mote or master)

(2) Control equation@)

3)

Frequency of execution

4) ield alterable control criteria

(5) Associated logging or alarming

4.2.6 Operator Interface Characteristics. The

capability to support data or control interfaces

to operating or maintenance personnel at either

the master or remote station shall be described.

4.2.6.1 Control of Equipment Functions.

When operator controllable functions are in-

cluded the applicable characteristics shall be

defined:

(1)

Control outpu t interfaces

(a) Enable/disable

(b ) Tagging (types and uses)

(c) Local/remote

2) Control of data acquisition

(a) Enable/disable scan (inputs o r stations)

(b ) Enable/disable processing

(c) Manual entry of data

(d ) Change scan frequency by group

(e) Assign/reassign data to a group

3) Control of data processing

(a) Setting date and time

(b) Setting input change limits

(c) Defining formats

(d) Defining conversiondata

(e) Defining operator override values

4)

ontrol of alarm processing

(a) Enable/disable individual alarms

(b) Enterledit alarm limits

(c) Enter/edit alarm dead-band

(d) Edit alarm to operator assignment

(e) Acknowledge alarms (individual/page)

(f) Silence audible alarm

(g) Inhibit alarms

(h) Override invalid alarms

5)

Control of function checks

(a) Enable/disable

(b ) Change frequency

(a) Enable/disable

(b) Modify criteria

(c) Add/delete control functions

(d) Reset to reference level or position

(6)Control of automatic control functions

4.2.6.2 CRT Display Capabilities. When

crt formats are supported the applicable char-

acteristics shall be defined

(1)Generation of display formats

(a) Format definition capabilities

(b ) Symbols supported

(c) Memory per format

(d ) Use of colors

(e ) Use of special features (flash, inverse

(f) Control level of detail

(2)

Standard formats

(a) Index formats

(b) System formats

(c) Communication channel format

(d ) Summary of inhibited alarms

video, etc)

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ANSI/IEEE

C37.1-1987


(e) Input point profile formats

( f ) Alarmsummary

(h) Station notes format

(3) Control of crt and cursor

(a ) Cursor operation

(b) Selection of formats

(c) Response time

(d) Update cycle (from data base)

(e) Paging of multipage formats

4.2.6.3

Digital and Analog Displays. When

such display devices are supported theapplic-

able characteristics shall be defined

(a) Numeric range with decimal

(b) Update frequency

(c) Maximum number supported

(a) Ranges

(b) Update frequency

(c) Maximum number supported

4.2.6.4

Hardcopy Devices. When support of

hardcopy devices is required such as loggers,

strip chart recorders, and crt video-copiers

the applicable characteristics shall be defined

as

follows:

(g) Tag summary

(1)Digital displays

(2) Analog displays

(1)Device assignments

(a) Initial

(b ) Automatic re-assignment

(c ) Manual re-assignment

(2)

Generation of log formats

(a) On-line/batch capabilities

(b) Symbols supported

(c) Spooling capabilities

(a) Standard formats

(b) Time for response

(a) Standard events (for example, operator

and actions)

(b) System events (for example, computer

failover and communication failure)

4.2.7

Computer Backup and Switchover.

When primary and backup facilities are provided

the applicable characteristics shall be defined as

follows:

(3)

Demand logs

4) ogged activities

(1)

Data base backup

(a) Data residency (bulk or main memory)

(b ) Frequency of update (by data type)

(c) Other uses of backup facilities

(a) Method of failure detection

(b) Response time for detection

(2)

Failure monitoring

(3)

Switchover

(a) Method of switchover

(b ) Time required for switchover

(c) Operator interface response following

(d ) Operator actions following switchover

4.2.8

History Data. When a capability for

history data acquisition, archiving and retrieval

is provided, the appropriate characteristics

shall be defined as follows:

switch over

(1)

Number of history files supported

(2)

Data quantities per file

3) Data intervals per file

4) umber of data intervals per file

(5)

Method of file management

(6)Method of data archiving

( 7 )

Method of data retrieval

5.

Interfaces

The equipment governed by this standard

shall have interfaces as described in this section.

The interfaces described consist of those illus-

trated in Fig 4.

Fig 4

Manual, Automatic, and Supervisory

Control Equipment Interface Block Diagram

POWER SOURCE

AN0 GROUNDING

INTERFACES

(REFER TO SECTION 5 2)

I

AUTOMATIC

CONTROL

EOUIPMENT

I

ATA AN0 CONTRX

INTERFACES

(REFER TO SECTION

531

5.1

Mechanical

5.1.1

Enclosures. Equipment located

in

an

outdoor environment shall utilize enclosures

which satisfy t he requirements defined for the

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specified environment by ANSI/IEEE ICs

6-

1978 [26] .

Equipment which is housed in a building or

other suitable enclosure in which it is protected

from the weather shall utilize enclosures meet-

ing the requirements of ANSI/EIA RS-310-C-

1977

(R

1983) [7].

5.1.2

Special Requirements. The location of

access doors, enclosure mounting requirements,

cooling requirements, terminal-block type and

location, cable entry locations, and special

cabling and connector requirements should be

specified for individual applications.

When required, electromagnetic shielding

characteristics of en

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