SIST EN 60947-5-9:2008

Low-voltage switchgear and controlgear -- Part 5-9: Control circuit devices and switching elements - Flow rate switches

This part of IEC 60947 applies to flow rate switches that sense the rate of flow of a gas, a liquid or a granular solid. These switches change their output state if a pre-set value for the speed of flow is exceeded. These flow rate switches are self-contained, have semiconductor switching element(s) and are intended to be connected to circuits, the rated voltage of which does not exceed 250 V 50 Hz/60 Hz a.c. or 300 V d.c. This standard does not specify the additional measures that are necessary for flow rate switches used in conjunction with explosive sensing materials and/or in an explosive location. This standard is not intended to cover devices with analogue outputs. The object of this standard is to state for flow rate switches: - definitions; - classifications; - characteristics; - product information; - normal service, mounting and transport conditions; - constructional and performance requirements; - tests to verify rated characteristics.

Niederspannungsschaltgeräte -- Teil 5-9: Steuergeräte und Schaltelemente - Durchflussmengenschalter

Appareillage à basse tension -- Partie 5-9: Appareils et éléments de commutation pour circuit de commande - Détecteurs de débit

La présente partie de la CEI 60947 s'applique aux détecteurs de débit qui détectent la vitesse d'écoulement d'un gaz, d'un liquide ou de matière solide granulaire. Ces détecteurs changent l'état de leur sortie si une valeur préréglée du débit est dépassée. Ces détecteurs de débit sont des appareils complets, comprennent des éléments de commutation à semiconducteurs et sont destinés à être connectés à des circuits dont la tension nominale n'excède pas 250 V 50 Hz/60 Hz en courant alternatif ou 300 V en courant continu.

Nizkonapetostne stikalne in krmilne naprave - 5-9. del: Krmilne naprave in stikalni elementi - Stikala za hitrost pretoka (IEC 60947-5-9:2006)

General Information

• Status: Published
• Publication Date: 03-Jan-2008
• ICS: 29.130.20 - Low voltage switchgear and controlgear
• Technical Committee: SKA - Switchgear and control gear
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 11-Dec-2007
• Due Date: 15-Feb-2008
• Completion Date: 04-Jan-2008
• Directive: 2004/108/EU - DIRECTIVE 2004/108/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 15 December 2004 on the approximation of the laws of the Member States relating to electromagnetic compatibility and repealing Directive 89/336/EEC
• Directive: 2006/95/EC - Directive 2006/95/EC of the European Parliament and of the Council of 12 December 2006 on the harmonisation of the laws of Member States relating to electrical equipment designed for use within certain voltage limits (codified version)
• Directive: 2014/30/EU - Directive 2014/30/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to electromagnetic compatibility (recast)
• Directive: 2014/35/EU - Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits
• Directive: 73/23/EEC - Electrical equipment designed for use within certain voltage limits
• Directive: 89/336/EEC - Electromagnetic compatibility (EMC)
• Ref Project: EN 60947-5-9:2007 - Low-voltage switchgear and controlgear - Part 5-9: Control circuit devices and switching elements - Flow rate switches

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 60947-5-9:2008
01-februar-2008
Nizkonapetostne stikalne in krmilne naprave - 5-9. del: Krmilne naprave in stikalni
elementi - Stikala za hitrost pretoka (IEC 60947-5-9:2006)
Low-voltage switchgear and controlgear - Part 5-9: Control circuit devices and switching
elements - Flow rate switches (IEC 60947-5-9:2006)
Niederspannungsschaltgeräte - Teil 5-9: Steuergeräte und Schaltelemente -
Durchflussmengenschalter (IEC 60947-5-9:2006)
Appareillage à basse tension - Partie 5-9: Appareils et éléments de commutation pour
circuit de commande - Détecteurs de débit (IEC 60947-5-9:2006)
Ta slovenski standard je istoveten z: EN 60947-5-9:2007
ICS:
29.130.20 Nizkonapetostne stikalne in Low voltage switchgear and
krmilne naprave controlgear
SIST EN 60947-5-9:2008 en,fr
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------

EUROPEAN STANDARD
EN 60947-5-9

NORME EUROPÉENNE
November 2007
EUROPÄISCHE NORM

ICS 29.130.20


English version


Low-voltage switchgear and controlgear -
Part 5-9: Control circuit devices and switching elements -
Flow rate switches
(IEC 60947-5-9:2006)


Appareillage à basse tension -  Niederspannungsschaltgeräte -
Partie 5-9: Appareils et éléments Teil 5-9: Steuergeräte und
de commutation pour circuit Schaltelemente -
de commande - Durchflussmengenschalter
Détecteurs de débit (IEC 60947-5-9:2006)
(CEI 60947-5-9:2006)




This European Standard was approved by CENELEC on 2007-09-01. CENELEC members are bound to comply
with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard
the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on
application to the Central Secretariat or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other
language made by translation under the responsibility of a CENELEC member into its own language and notified
to the Central Secretariat has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Cyprus, the
Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Central Secretariat: rue de Stassart 35, B - 1050 Brussels


© 2007 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60947-5-9:2007 E

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EN 60947-5-9:2007 - 2 -
Foreword
The text of document 17B/1500/FDIS, future edition 1 of IEC 60947-5-9, prepared by SC 17B,
Low-voltage switchgear and controlgear, of IEC TC 17, Switchgear and controlgear, was submitted to the
IEC-CENELEC parallel vote and was approved by CENELEC as EN 60947-5-9 on 2007-09-01.
This standard is to be used in conjunction with EN 60947-1:2004 and EN 60947-5-2:1998.
The provisions of the general rules, EN 60947-1, are applicable to this part of EN 60947, where
specifically called for. General rules clauses and subclauses thus applicable, as well as tables, figures
and annexes are identified by a reference to IEC 60947-1, for example 1.2.3 or Annex A of IEC 60947-1.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2008-06-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2010-09-01
This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and covers essential requirements of
EC Directive EMC (2004/108/EC). See Annex ZZ.
Annexes ZA and ZZ have been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 60947-5-9:2007 was approved by CENELEC as a European
Standard without any modification.
__________

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- 3 - EN 60947-5-9:2007
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

NOTE  When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD
applies.

Publication Year Title EN/HD Year

1)
IEC 60446 1999 Basic and safety principles for man-machine EN 60446 1999
interface, marking and identification -
Identification of conductors by colours or
numerals


2)
IEC 60947-1 2004 Low-voltage switchgear and controlgear - EN 60947-1 2004
Part 1: General rules + corr. November 2004


IEC 60947-5-2 1997 Low-voltage switchgear and controlgear - EN 60947-5-2 1998
(mod) Part 5-2: Control circuit devices and switching
A1 1999 elements - Proximity switches A1 1999
A2 2003 A2 2004


IEC 61000-3-2 2005 Electromagnetic compatibility (EMC) - EN 61000-3-2 2006
Part 3-2: Limits - Limits for harmonic current
emissions (equipment input current ≤16 A per
phase)


IEC 61000-3-3 1994 Electromagnetic compatibility (EMC) - EN 61000-3-3 1995
 Part 3-3: Limits - Limitation of voltage + corr. July 1997
A1 2001 changes, voltage fluctuations and flicker in A1 2001
A2 2005 public low-voltage supply systems, for A2 2005
equipment with rated current ≤16 A per phase
and not subject to conditional connection


IEC 61000-4-2 1995 Electromagnetic compatibility (EMC) - EN 61000-4-2 1995
A1 1998 Part 4-2: Testing and measurement A1 1998
A2 2000 techniques - Electrostatic discharge immunity A2 2001
test


IEC 61000-4-3 2006 Electromagnetic compatibility (EMC) - EN 61000-4-3 2006
Part 4-3: Testing and measurement
techniques - Radiated, radio-frequency,
electromagnetic field immunity test


IEC 61000-4-4 2004 Electromagnetic compatibility (EMC) - EN 61000-4-4 2004
Part 4-4: Testing and measurement
techniques - Electrical fast transient/burst
immunity test



1)
EN 60446:1999 is superseded by EN 60446:2007, which is based on IEC 60446:2007.
2)
EN 60947-1:2004 is superseded by EN 60947-1:2007, which is based on IEC 60947-1:2007.

---------------------- Page: 4 ----------------------

EN 60947-5-9:2007 - 4 -
Publication Year Title EN/HD Year
IEC 61000-4-6 2003 Electromagnetic compatibility (EMC) -
+ A1 2004 Part 4-6: Testing and measurement
+ A2 2006 techniques - Immunity to conducted EN 61000-4-6 2007
disturbances, induced by radio-frequency + corr. August 2007
fields


IEC 61000-4-8 1993 Electromagnetic compatibility (EMC) - EN 61000-4-8 1993
A1 2000 Part 4-8: Testing and measurement A1 2001
techniques - Power frequency magnetic field
immunity test


IEC 61000-4-11 2004 Electromagnetic compatibility (EMC) - EN 61000-4-11 2004
Part 4-11: Testing and measurement
techniques - Voltage dips, short interruptions
and voltage variations immunity tests


IEC 61000-4-13 2002 Electromagnetic compatibility (EMC) - EN 61000-4-13 2002
Part 4-13: Testing and measurement
techniques - Harmonics and interharmonics
including mains signalling at a.c. power port,
low frequency immunity tests


IEC 61140 2001 Protection against electric shock - Common EN 61140 2002
A1 (mod) 2004 aspects for installation and equipment A1 2006


IEC 61558-2-6 1997 Safety of power transformers, power supply EN 61558-2-6 1997
units and similar -
Part 2-6: Particular requirements for safety
isolating transformers for general use


CISPR 11 (mod) 2003 Industrial, scientific and medical (ISM)
+ A1 2004 radio-frequency equipment - Electromagnetic EN 55011 2007
disturbance characteristics - Limits and
methods of measurement

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- 5 - EN 60947-5-9:2007
Annex ZZ
(informative)

Coverage of Essential Requirements of EC Directives

This European Standard has been prepared under a mandate given to CENELEC by the European
Commission and the European Free Trade Association and within its scope the standard covers all
relevant essential requirements as given in Article 1 of Annex I of the EC Directive 2004/108/EC.

Compliance with this standard provides one means of conformity with the specified essential
requirements of the Directive concerned.

WARNING: Other requirements and other EC Directives may be applicable to the products falling within
the scope of this standard.

---------------------- Page: 6 ----------------------

NORME CEI
INTERNATIONALE
IEC



60947-5-9
INTERNATIONAL


Première édition
STANDARD

First edition

2006-12


Appareillage à basse tension –
Partie 5-9:
Appareils et éléments de commutation
pour circuit de commande –
Détecteurs de débit

Low-voltage switchgear and controlgear –
Part 5-9:
Control circuit devices and switching elements –
Flow rate switches
© IEC 2006 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 in any
utilisée sous quelque forme que ce soit et par aucun procédé, form or by any means, electronic or mechanical, including
électronique ou mécanique, y compris la photocopie et les photocopying and microfilm, without permission in writing from
microfilms, sans l'accord écrit de l'éditeur. the publisher.
International Electrotechnical Commission, 3, rue de Varembé, PO Box 131, CH-1211 Geneva 20, Switzerland
Telephone: [phone] Telefax: [phone] E-mail: [e-mail] Web: www.iec.ch
CODE PRIX
V
PRICE CODE
Commission Electrotechnique Internationale
International Electrotechnical Commission
МеждународнаяЭлектротехническаяКомиссия
Pour prix, voir catalogue en vigueur
For price, see current catalogue

---------------------- Page: 7 ----------------------

60947-5-9 © IEC:2006 – 3 –
CONTENTS
FOREWORD.7

1 General.11
1.1 Scope and object.11
1.2 Normative references.11
2 Terms and definitions .13
2.1 Basic definitions .15
2.2 Characteristics of a flow rate switch .17
2.3 Delay times.19
3 Classification.19
3.1 General.19
3.2 Classification according to sensing means .21
3.3 Classification according to the construction form .21
3.4 Classification according to the switching element function.21
3.5 Classification according to the type of output.21
3.6 Classification according to the method of connection.21
4 Characteristics.21
4.1 Summary of characteristics.21
4.2 Operating conditions .21
4.3 Rated and limiting values for the flow rate switch .23
4.4 Utilization categories for the switching element .27
5 Product information .27
5.1 Nature of information.27
5.2 Marking.27
5.3 Instruction for installation, operation and maintenance .29
6 Normal service, mounting and transport conditions.29
6.1 Normal service conditions .29
6.2 Conditions during transport and storage .31
6.3 Mounting.31
6.4 Indicating means.31
7 Constructional and performance requirements.31
7.1 Constructional requirements.31
7.2 Performance requirements .35
7.3 Shock and vibration.47
8 Tests.47
8.1 Kinds of tests.49
8.2 Compliance with constructional requirements .49
8.3 Performance.49
8.4 Verification of set point and delay times .63
8.5 Verification of the electromagnetic compatibility .65
8.6 Test results and test report.69

---------------------- Page: 8 ----------------------

60947-5-9 © IEC:2006 – 5 –

Figure 1 – Relationship between operating points of a flow rate switch .23
Figure 2 – Relationship between U and U .23
e B
Figure 3 – Test circuit for the verification of time delay before availability .55
Figure 4 – Signal output across load in Figure 3 .55
Figure 5 – Test circuit for the verification of minimum operational current OFF-state
current, voltage drop and independent snap action .57
Figure 6 – Short-circuit testing .63
Figure 7 – Testing set point and delay times .65

Table 1 – Classification of flow rate switches .19
Table 2 – Acceptance criteria.43
Table 3 – Immunity tests.45

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60947-5-9 © IEC:2006 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 5-9: Control circuit devices and switching elements –
Flow rate switches


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with an IEC Publication.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60947-5-9 has been prepared by subcommittee 17B: Low-voltage
switchgear and controlgear, of IEC technical committee 17: Switchgear and controlgear.
The text of this standard is based on the following documents:
FDIS Report on voting
17B/1500/FDIS 17B/1525/RVD

Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.

---------------------- Page: 10 ----------------------

60947-5-9 © IEC:2006 – 9 –
This International Standard should be used in conjunction with IEC 60947-1 and
IEC 60947-5-2.
The provisions of the general rules, IEC 60947-1, are applicable to this standard, where
specifically called for. General rules clauses and subclauses thus applicable, as well as
tables, figures and annexes are identified by a reference to IEC 60947-1, for example 1.2.3 or
Annex A of IEC 60947-1.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts in the IEC 60947 series, under the general title Low-voltage switchgear and
controlgear, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

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60947-5-9 © IEC:2006 – 11 –
LOW-VOLTAGE SWITCHGEAR AND CONTROLGEAR –

Part 5-9: Control circuit devices and switching elements –
Flow rate switches



1 General
1.1 Scope and object
This part of IEC 60947 applies to flow rate switches that sense the rate of flow of a gas, a
liquid or a granular solid. These switches change their output state if a pre-set value for the
speed of flow is exceeded.
These flow rate switches are self-contained, have semiconductor switching element(s) and
are intended to be connected to circuits, the rated voltage of which does not exceed 250 V
50 Hz/60 Hz a.c. or 300 V d.c.
This standard does not specify the additional measures that are necessary for flow rate
switches used in conjunction with explosive sensing materials and/or in an explosive location.
This standard is not intended to cover devices with analogue outputs.
The object of this standard is to state for flow rate switches:
– definitions;
– classifications;
– characteristics;
– product information;
– normal service, mounting and transport conditions;
– constructional and performance requirements;
– tests to verify rated characteristics.
1.2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60446:1999, Basic and safety principles for man-machine interface, marking and
identification – Identification of conductors by colours or numerals
IEC 60947-1:2004, Low-voltage switchgear and controlgear – Part 1: General rules
IEC 60947-5-2:1997, Low-voltage switchgear and controlgear – Part 5-2: Control circuit
devices and switching elements – Proximity switches
Amendment 1 (1999)
Amendment 2 (2003)

---------------------- Page: 12 ----------------------

60947-5-9 © IEC:2006 – 13 –
IEC 61000-3-2:2005, Electromagnetic compatibility (EMC) – Part 3-2: Limits – Limits for
harmonic current emissions (equipment input current ≤ 16 A per phase)
IEC 61000-3-3:1994, Electromagnetic compatibility (EMC) – Part 3-3: Limits – Limitation of
voltage changes, voltage fluctuations and flicker in public low-voltage supply systems for
equipment with rated current ≤ 16 A per phase and not subject to conditional connection

Amendment 1 (2001)
Amendment 2 (2005)
IEC 61000-4-2:1995, Electromagnetic compatibility (EMC) – Part 4-2: Testing and
measurement techniques – Electrostatic discharge immunity test
Amendment 1 (1998)
Amendment 2 (2000)
IEC 61000-4-3:2006, Electromagnetic compatibility (EMC) – Part 4-3: Testing and
measurement techniques – Radiated, radio-frequency, electromagnetic field immunity test
IEC 61000-4-4:2004, Electromagnetic compatibility (EMC) – Part 4-4: Testing and
measurement techniques – Electrical fast transient/burst immunity test
IEC 61000-4-6:2003, Electromagnetic compatibility (EMC) – Part 4-6: Testing and
measurement techniques – Immunity to conducted disturbances, induced by radio-frequency
fields
Amendment 1 (2004)
Amendment 2 (2006)
IEC 61000-4-8:1993, Electromagnetic compatibility (EMC) – Part 4-8: Testing and
measurement techniques – Power frequency magnetic field immunity test
Amendment 1 (2000)
IEC 61000-4-11:2004, Electromagnetic compatibility (EMC) – Part 4-11: Testing and
measurement techniques – Voltage dips, short interruptions and voltage variations immunity
tests
IEC 61000-4-13:2002, Electromagnetic compatibility (EMC) – Part 4-13: Testing and
measurement techniques – Harmonics and interharmonics including mains signalling at a.c.
power port, low-frequency immunity tests
IEC 61140:2001, Protection against electric shock – Common aspects for installation and
equipment
Amendment 1 (2004)
IEC 61558-2-6, Safety of power transformers, power supply units and similar – Part 2:
Particular requirements for safety isolating transformers for general use
CISPR 11:2003, Industrial, scientific and medical (ISM) radio-frequency equipment –
Electromagnetic disturbance characteristics – Limits and methods of measurement
Amendment 1 (2004)
2 Terms and definitions
For the purposes of this document, the relevant definitions given in Clause 2 of IEC 60947-1
and Clause 2 of IEC 60947-5-2 apply with the following additional definitions.

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60947-5-9 © IEC:2006 – 15 –
Alphabetical index of definitions
Reference
A
Active zone. 2.2.1
Adjuster (for a flow rate switch). 2.2.4

F
Flow direction . 2.1.6
Flow rate sensor . 2.1.2
Flow rate switch. 2.1.1

H
Homogenization zone. 2.1.7
Hysteresis (H). 2.2.8

M
Maximum temperature gradient. 2.2.9
Medium. 2.1.4

R
Reference medium. 2.1.5
Repeat accuracy (R). 2.2.7

S
Semiconductor switching element . 2.1.3
Sensing range . 2.2.6
Sensor tip . 2.2.2
Set point (s). 2.2.5
s
Submersion depth. 2.2.3

T
Time delay before availability (t). 2.3.3
v
Turn-off time . 2.3.2
Turn-on time . 2.3.1

2.1 Basic definitions
2.1.1
flow rate switch
device consisting of a flow rate sensor and a switching element which, in accordance with an
increasing or decreasing flow of a defined medium (flow medium), changes the output signal
at a predetermined value

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60947-5-9 © IEC:2006 – 17 –
2.1.2
flow rate sensor
transducer which detects the rate of flow of a medium in an active area
2.1.3
semiconductor switching element
element designed to switch the current in an electric circuit by controlling conductivity of a
semiconductor
2.1.4
medium
gaseous, liquid, or fine granular solid, or a combination thereof
2.1.5
reference medium
medium with which measurements according to this standard are made
2.1.6
flow direction
direction from which the medium flows towards the sensor
2.1.7
homogenization zone
zone in front of and behind the sensor with undisturbed flow necessary to homogenize the
flow of the medium in order to obtain correct measurement results
2.2 Characteristics of a flow rate switch
2.2.1
active zone
zone in
...