PNW 69-176

SLOVENSKI STANDARD
SIST IEC 60255-3:1995
01-avgust-1995
Electrical relays - Part 3: Single input energizing quantity measuring relays with
dependent or independent time
Electrical relays - Part 3: Single input energizing quantity measuring relays with
dependent or independent time
Relais électriques - Troisième partie: Relais de mesure et dispositifs de protection à une
seule grandeur d'alimentation d'entrée à temps dépendant ou indépendant
Ta slovenski standard je istoveten z: IEC 60255-3
ICS:
29.120.70 Releji Relays
SIST IEC 60255-3:1995 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST IEC 60255-3:1995

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SIST IEC 60255-3:1995
NORME
CEI
INTERNATIONALE
IEC
255-3
INTERNATIONAL
Deuxième édition
STAN DARD
Second edition
1989-05
Relais électriques
Troisième partie:
Relais de mesure et dispositifs de protection
à une seule grandeur d'alimentation d'entrée
à temps dépendant ou indépendant
Electrical relays
Part 3:
Single input energizing quantity measuring relays
with dependent or independent time
© CEI 1989 Droits de reproduction réservés — Copyright - all rights reserved
Aucune partie de cette publication ne peut être reproduite ni No part of this publication may be reproduced or utilized
utilisée sous quelque forme que ce soit et par aucun procédé, in any form or by any means, electronic or mechanical,
électronique ou mécanique, y compris la photocopie et les including photocopying and microfilm, without permission
microfilms, sans l'accord écrit de l'éditeur. in writing from the publisher
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K
International Electrotechnical Commission PRICE CODE
IEC Me»spyHapopHae 3neerporexHH4ecKaa HoMHCCHri
• Pour prix, voir catalogue en vigueur
•
For price, see current catalogue

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SIST IEC 60255-3:1995
— 3 —
255 -3 0IEC
CONTENTS
Page
FOREWORD 5
PREFACE 5
SECTION 1 — GENERAL
Clause
1. Scope and object 7
2. Definitions 7
SECTION 2 — REQUIREMENTS
3. Standard values 9
13
4. Accuracy
17
5. Overshoot time
SECTION 3 — TEST METHODS
17
6. Accuracy tests
19 7. Test conditions for the measurement of overshoot

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SIST IEC 60255-3:1995
255-3 © IEC — 5 —
INTERNATIONAL ELECTROTECHNICAL COMMISSION
ELECTRICAL RELAYS
Single input energizing quantity measuring relays
Part 3:
with dependent or independent time
FOREWORD
The formal decisions or agreements of the I EC on technical matters, prepared by Technical Committees on which all the National
1)
Committees having a special interest therein are represented, express, as nearly as possible, an international consensus of opinion
on the subjects dealt with.
rnational use and they are accepted by the National Committees in that
2) They have the form of recommendations for inte
sense.
ational unification, the I EC expresses the wish that all National Committees should adopt the text of
3) In order to promote inte rn
the I EC recommendation for their national rules in so far as national conditions will permit. Any divergence between the I E C
recommendation and the corresponding national rules should, as far as possible, be clearly indicated in the latter.
PREFACE
This standard has been prepared by Sub-Committee 41B: Measuring relays and protection equipment,
of I EC Technical Committee No. 41: Electrical relays.
This second edition of I EC 255-3 replaces the first edition issued in 1971.
The text of this standard is based upon the following documents:
Report on Voting
Six Months' Rule
41B(CO)43 41B(CO)45
rt
Full information on the voting for the approval of this standard can be found in the Voting Repo
indicated in the above table.
The following IEC publications are quoted in this standard:
Publications Nos. 50: International Electrotechnical Vocabulary (IEV).
rt 6: Measuring relays with more than one input energizing quantity.
255-6 (1988): Electrical relays, Pa
255-8 (1978): Part 8: Thermal electrical relays.

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SIST IEC 60255-3:1995
255-3 © IEC — 7
ELECTRICAL RELAYS
Part 3: Single input energizing quantity measuring relays
with dependent or independent time
SECTION 1 - GENERAL
1.
Scope and object
This standard is applicable to electrical measuring relays and protection equipment having a
single input energizing quantity and where the operating time is independent or dependent on this
quantity.
The object of this standard is to state the particular requirements for these relays.
It excludes thermal electrical relays which are specified in I EC 255-8 (1978), first edition.
These requirements supplement those specified in higher level documents of the 255 series.
2.
Definitions
For definitions of general terms not defined in this standard, reference should be made to the
International Electrotechnical Vocabulary (I EC 50), or to higher level documents.
For the purpose of this standard the following definitions shall apply:
2.1
Theoretical curve of time/characteristic quantity (see Figure 1)
Graphical representation of relationship between the theoretical specified operating times and
the characteristic quantity.
2.2 Curves of maximum and minimum limits of the operating time (see Figure 1)
Curves of the limiting errors on either side of the theoretical time/characteristic quantity which
identify the maximum and minimum operating times corresponding to each value of the charac-
teristic quantity.
2.3 Setting value of the characteristic quantity (Gs) (see Figure 1)
The value of the input energizing quantity of the relay used as a reference for the definitions of the
characteristic of dependent time relays with decreasing function.
Note. — The term Gs replaces the concept of basic value GB which was previously used as a reference for defining the
characteristics. As this was defined as the value for which the relay was required not to operate, it caused difficulties
when considering the two types of relay described in 4.2.
2.4 Threshold value of the characteristic quantity (GT) (see Figure 1)
The lowest value of the input quantity for which the relay just operates.
Note. — There are two general forms of dependent time relay with decreasing time function:
when the threshold value lies between Gs and 1.3 X Gs (see Figure la);
a) GT
b) when the threshold value GT is coincident with Gs (see Figure lb).

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SIST IEC 60255-3:1995
— 9 —
255-3 ©IEC
2.5 Overshoot time
The overshoot time is the difference between the operating time of the relay at the specified value
of the input energizing quantity and the maximum duration of the value of input energizing
quantity which, when suddenly reduced to a specified value below the operating level, is insufficient
to cause operation.
SECTION 2 — REQUIREMENTS
3. Standard values
3.1 Standard values of dependent specified times
There are no standard values of dependent specified times. The relationship between operating
times and characteristic quantity can be expressed by means of a characteristic curve. The shape of
this curve shall be declared by the manufacturer by an equation or by graphical means.
For dependent time relays with decreasing function the most common characteristic curves
follow a law of the following form:
k
t—
G
GS a ) —1
where:
t = theoretical operating time (seconds)
k = constant characterizing the relay (seconds)
G = value of the characteristic quantity
Gs = setting value of the characteristic quantity (see 2.3)
a = index characterizing the algebraic function
Three classes of curves following the above general formula are as follows:
— type A for a 0.5
B for 0.5 — type
type C fora > 1.5
—
For relays whose operating time conforms to the above family the manufacturer shall declare the
and Gs. The following are preferred values of a and k:
values of a, k
TABLE 1
C
A B
13.5 80.0
k 0.14
a 0.02 1.0 2.0
3.2 Operative ranges of auxiliary energizing quantities
The limits of the operative range for each auxiliary energizing quantity shall be as specified in
National Standards or declared by the manufacturer.
3.3 Values of resetting and disengaging ratios
As specified in National Standards or declared by the manufacturer.

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SIST IEC 60255-3:1995
255-3 © IEC — 11 —
Standard reference conditions and test tolerances of influencing quantities and factors
3.4
Refer to t
...