Electrical equipment for furnaces and ancillary equipment - Part 1: Requirements for application design and installation

This European Standard applies to the application design and installation of electrical equipment, control
circuits and safety-related systems for furnaces which are operated with solid, liquid or gaseous fuels and
their ancillary equipment. It specifies requirements to meet the operating conditions of furnaces, to reduce
the hazards of combustion and to protect the heated systems from damage e.g. by overheating.
Such furnaces and the electrical equipment may be part by way of example of the following plant:
a) water heating systems;
b) steam boiler installations (steam and hot-water boilers) and heat recovery steam boilers;
NOTE 1 The requirements of this standard apply according to the electrical equipment of electrically heated steam
boilers.
NOTE 2 Seagoing vessels and offshore facilities are governed by International Maritime Law and as such are not
within the scope of this standard. These requirements may be used for such facilities.
c) warm air heaters;
d) hot-gas heaters;
e) heat exchanger systems;
f) combustion chambers of stationary turbines;
g) as long as no other standard is applicable for combined heat and power stations, we recommend the
use of the requirements of this standard;
h) This standard may also be used as reference for electrical equipment requirements for thermoprocessing
equipment.
The requirements in this standard are not applicable to electrical equipment for:
i) non-electrically heated appliances and burner control systems for household and similar purposes;
j) furnaces using technologies for the direct conversion of heat into electrical energy;
k) combustion chambers of non-stationary prime movers and turbines;
l) central oil supply systems for individual heating appliances;
m) furnaces using solid fuels for heating purposes for household use with a nominal thermal output up to
1 MW;
n) furnaces which are used to heat process fluids and gasses in chemical plant.
This European Standard may be used as a basis for the requirements placed on electrical equipment for
furnaces, which are excluded from its field of application.

Elektrische Ausrüstung von Feuerungsanlagen und zugehörige Einrichtungen - Teil 1: Bestimmungen für die Anwendungsplanung und Errichtung

Equipements électriques d'installation de chaudière - Partie 1: Règles pour la conception, pour l'application et l'installation

Električna oprema za peči in pomožno opremo - 1. del: Zahteve za zasnovo in vgradnjo

Ta evropski standard se uporablja za zasnovo in vgradnjo električne opreme, krmilnih tokokrogov in z varnostjo povezanih sistemov za peči, ki delujejo na trdna, tekoča ali plinasta goriva, ter njihove pomožne opreme. Določa zahteve za izpolnjevanje operativnih pogojev peči, zmanjšanje nevarnosti zgorevanja in varovanje gretih sistemov pred poškodbami, npr. zaradi pregrevanja.
Take peči in električna oprema so lahko del naslednjih obratov:
a) sistemov za gretje vode;
b) naprav s parnim kotlom (parni in toplovodni kotli) ter parnih kotlov z vračanjem toplote;
OPOMBA 1: Zahteve tega standarda se uporabljajo v skladu z električno opremo električno ogrevanih parnih kotlov.
OPOMBA 2: Pomorska plovila in opremo na odprtem morju ureja mednarodno pomorsko pravo, kot taka pa so zunaj področja uporabe tega standarda. Te zahteve se lahko uporabljajo za tako opremo.
c) grelnikov zraka;
d) plinskih grelnikov;
e) sistemov toplotnih prenosnikov;
f) zgorevalnikov nepremičnih turbin;
g) dokler se za postaje za soproizvodnjo toplote in električne energije ne uporabljajo drugi standardi, priporočamo uporabo zahtev v okviru tega standarda;
h) ta standard se lahko uporablja tudi kot sklicevanje za zahteve glede električne opreme za termopredelovalno opremo.
Zahteve v tem standardu se ne uporabljajo za električno opremo za:
i) neelektrično segrevane aparate ter sisteme s samodejnim nadzorom gorilnikov za gospodinjske in podobne namene;
j) peči, ki uporabljajo tehnologije za neposredno pretvorbo toplote v električno energijo;
k) zgorevalnike premičnih lokomotiv in turbin;
l) centralne sisteme za dobavo olja za posamezne ogrevalne naprave;
m) peči, ki uporabljajo trdna goriva za ogrevanje za gospodinjsko uporabo z nazivnim toplotnim izhodom do 1 MW;
n) peči, ki se uporabljajo za segrevanje procesnih tekočin in plinov v kemičnem obratu.
Ta evropski standard se lahko uporablja kot podlaga za zahteve glede električne opreme za peči, ki so zunaj njegovega polja uporabe.

General Information

Status
Published
Public Enquiry End Date
24-Jul-2012
Publication Date
12-Aug-2015
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
27-Jul-2015
Due Date
01-Oct-2015
Completion Date
13-Aug-2015

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SLOVENSKI STANDARD
SIST EN 50156-1:2015
01-september-2015
1DGRPHãþD
SIST EN 50156-1:2006
(OHNWULþQDRSUHPD]DSHþLLQSRPRåQRRSUHPRGHO=DKWHYH]D]DVQRYRLQ
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Electrical equipment for furnaces and ancillary equipment - Part 1: Requirements for

application design and installation

Elektrische Ausrüstung von Feuerungsanlagen und zugehörige Einrichtungen - Teil 1:

Bestimmungen für die Anwendungsplanung und Errichtung
Equipements électriques d'installation de chaudière - Partie 1: Règles pour la
conception, pour l'application et l'installation
Ta slovenski standard je istoveten z: EN 50156-1:2015
ICS:
27.060.01 Gorilniki in grelniki vode na Burners and boilers in
splošno general
SIST EN 50156-1:2015 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 50156-1:2015
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SIST EN 50156-1:2015
EUROPEAN STANDARD EN 50156-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2015
ICS 27.060.01 Supersedes EN 50156-1:2004
English Version
Electrical equipment for furnaces and ancillary equipment - Part
1: Requirements for application design and installation

Equipements électriques d'installation de chaudière - Partie Elektrische Ausrüstung von Feuerungsanlagen und

1: Règles pour la conception, pour l'application et zugehörige Einrichtungen - Teil 1: Bestimmungen für die

l'installation Anwendungsplanung und Errichtung

This European Standard was approved by CENELEC on 2015-01-26. 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 CEN-CENELEC

Management Centre 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 CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2015 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 50156-1:2015 E
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SIST EN 50156-1:2015
EN 50156-1:2015 (E)
Contents

European foreword ................................................................................................................. 6

Introduction ............................................................................................................................ 7

1 Scope .............................................................................................................................. 9

2 Normative references ..................................................................................................... 10

3 Terms and definitions ..................................................................................................... 11

4 General requirements .................................................................................................... 19

4.1 General considerations ......................................................................................... 19

4.2 Environmental requirements ................................................................................. 20

4.2.1 General ..................................................................................................... 20

4.2.2 Environmental and operating conditions .................................................... 20

4.2.3 Electromagnetic compatibility .................................................................... 20

4.2.4 Ambient temperature ................................................................................. 21

4.2.5 Humidity .................................................................................................... 21

4.2.6 Contamination ........................................................................................... 22

4.2.7 Vibration and shock................................................................................... 22

4.2.8 Equipment used in flammable atmospheres .............................................. 22

4.3 Power supply ........................................................................................................ 22

4.3.1 General ..................................................................................................... 22

4.3.2 Power stations .......................................................................................... 22

5 Incoming supply connections and devices for disconnecting and emergency stop .......... 22

5.1 Incoming supply and equipment connections ........................................................ 22

5.1.1 Types of connection .................................................................................. 22

5.1.2 Terminations ............................................................................................. 23

5.2 Devices for disconnecting power supplies ............................................................. 24

5.2.1 General ..................................................................................................... 24

5.2.2 Disconnecting switch ................................................................................. 25

5.2.3 Excluded circuits ....................................................................................... 25

5.3 Emergency stop .................................................................................................... 26

5.3.1 General ..................................................................................................... 26

5.3.2 Emergency stop device for furnaces in heating installations ...................... 26

5.3.3 Emergency stop device for other furnaces, e.g. steam boilers ................... 26

5.3.4 Application as isolating switch ................................................................... 26

6 Protection against electric shock .................................................................................... 26

6.1 Protection against direct contact ........................................................................... 26

6.2 Protection against indirect contact ........................................................................ 27

7 Environmental protection of the equipment..................................................................... 27

7.1 Protection against ingress of solid foreign bodies.................................................. 27

7.2 Protection against water ....................................................................................... 27

8 Equipotential bonding .................................................................................................... 27

8.1 General ................................................................................................................. 27

8.2 Equipotential bonding as a protective measure in case of indirect contact ............. 27

8.3 Equipotential bonding for the purpose of lightning protection ................................ 28

8.4 Functional equipotential bonding ........................................................................... 28

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SIST EN 50156-1:2015
EN 50156-1:2015 (E)

9 Auxiliary circuits ............................................................................................................. 29

9.1 Supply to auxiliary circuits .................................................................................... 29

9.1.1 Supply from 3-phase or a.c. systems ......................................................... 29

9.1.2 Supply from d.c. mains .............................................................................. 29

9.1.3 Auxiliary circuits connected between the line conductors .......................... 30

9.2 Voltage for auxiliary circuits .................................................................................. 30

9.2.1 Operating voltage of auxiliary circuits ........................................................ 30

9.2.2 Preferred nominal voltages ....................................................................... 30

9.3 Connection to the protective conductor ................................................................. 30

9.4 Overcurrent protection of auxiliary circuits ............................................................ 30

9.4.1 Rating of overcurrent protective devices ................................................... 30

9.4.2 Overcurrent protection of auxiliary circuits connected to the protective

conductor .................................................................................................. 31

9.4.3 Overcurrent protection of auxiliary circuit with the middle conductor

connected to the protective conductor ....................................................... 31

9.4.4 Overcurrent protection of auxiliary circuits with no electrical connection to

the protective conductor ............................................................................ 31

9.4.5 Overcurrent protection of control system supply transformers ................... 31

9.4.6 Rating and setting of overcurrent protection .............................................. 31

9.5 Measures to prevent danger from short circuits to exposed conductive parts or

earth ..................................................................................................................... 31

9.6 Influence of capacitance and leakage resistance .................................................. 32

10 Additional requirements for the application of a safety-related system ............................ 32

10.1 General safety requirements ................................................................................. 32

10.1.1 Safety lifecycle requirements for a safety-related system .......................... 32

10.1.2 Planning .................................................................................................... 34

10.2 Concept and scope definition ................................................................................ 37

10.3 Hazard and risk analysis ....................................................................................... 38

10.4 Safety requirements allocation .............................................................................. 39

10.5 Design .................................................................................................................. 40

10.5.1 General requirements................................................................................ 40

10.5.2 Design of the safety-related system .......................................................... 41

10.5.3 Measures to avoid faults ........................................................................... 46

10.5.4 Consideration of times .............................................................................. 47

10.5.5 Hardware design ....................................................................................... 47

10.5.6 Plant specific application software............................................................. 52

10.6 Installation and commissioning ............................................................................. 55

10.7 Safety validation ................................................................................................... 55

10.7.1 System integration of hardware and software ............................................ 55

10.7.2 Fault assessment for the system integration of hardware and software ..... 56

10.7.3 Type approval ........................................................................................... 57

10.7.4 Plant-specific test ...................................................................................... 57

10.8 Operation and maintenance .................................................................................. 57

10.9 Modification and retrofit ........................................................................................ 58

10.9.1 General ..................................................................................................... 58

10.9.2 Measures against unauthorised changes or overriding .............................. 58

11 Electrical equipment ....................................................................................................... 59

11.1 General requirements ........................................................................................... 59

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SIST EN 50156-1:2015
EN 50156-1:2015 (E)

11.2 Creepage distances and clearances ...................................................................... 59

11.3 Motors .................................................................................................................. 59

11.4 Transformers ........................................................................................................ 59

11.5 Switching devices ................................................................................................. 60

11.6 Operator control devices ....................................................................................... 60

11.7 Immersion electrodes ............................................................................................ 60

11.8 Trace heating systems .......................................................................................... 60

12 Cables and cords ........................................................................................................... 60

12.1 General requirements ........................................................................................... 60

12.2 Insulation .............................................................................................................. 61

12.3 Current-carrying capacity ...................................................................................... 61

12.4 Conductors of separate circuits ............................................................................. 61

13 Warning signs and item designation ............................................................................... 62

13.1 Warning signs ....................................................................................................... 62

13.2 Functional identification ........................................................................................ 62

13.3 Item designations .................................................................................................. 62

14 Technical documentation ............................................................................................... 62

14.1 General ................................................................................................................. 62

14.2 Documentation describing functions and connections ........................................... 63

14.2.1 General ..................................................................................................... 63

14.2.2 Documentation describing functions .......................................................... 63

14.2.3 Documentation describing connections ..................................................... 63

14.2.4 Documentation describing the process ...................................................... 63

14.2.5 Documentation of the risk assessment ...................................................... 63

14.3 Documents for type approved components ............................................................ 64

14.4 Documentation of the application software ............................................................ 64

Annex A (informative) Configurations of programmable safety devices (PSD) with reference

to EN 61508 ................................................................................................................... 65

A.1 Configuration 1oo1 ......................................................................................................... 66

A.2 Configuration 1oo1D ...................................................................................................... 66

A.3 Configuration 1oo2 ......................................................................................................... 67

A.4 Configuration 1oo2D ...................................................................................................... 68

A.5 Configuration 2oo3 ......................................................................................................... 69

A.6 Configuration 2oo3D ...................................................................................................... 70

Annex B (informative) Lifecycle of programmable safety device ............................................ 72

Annex C (informative) Management of functional safety ....................................................... 73

Annex D (informative) Examples of determining the safety integrity level SIL using the risk

graph method ................................................................................................................. 74

D.1 General .......................................................................................................................... 74

D.2 Risk parameter C (Consequences of the hazardous event) ............................................ 74

D.3 Risk parameter F (Frequence and duration of the time spent in the hazard area) ........... 74

D.4 Risk parameter P (Possibility of preventing the hazardous event) .................................. 74

D.5 Risk parameter W (Likelihood of occurrence of the hazardous event) ............................. 74

Bibliography ......................................................................................................................... 76

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SIST EN 50156-1:2015
EN 50156-1:2015 (E)

Figure 1 – Example of the functionality of a furnace with ancillary equipment, heated

systems and relationship to control system and safety related system ............................. 8

Figure 2 – Types of faults to be considered .......................................................................... 14

Figure 3 – Causes of faults to be considered ........................................................................ 14

Figure 4 – Definition and components of a safety-related system ......................................... 17

Figure 5 – Software .............................................................................................................. 18

Figure 6 – Example of power supply, switching, isolating devices and other electrical

components of a furnace ................................................................................................ 24

Figure 7 – Supply from two d.c. sources ............................................................................... 29

Figure 8 – Safety lifecycle model for application, design and installation of a safety-related

system (Clause 10) ....................................................................................................... 33

Figure 9 – Rating of safety integrity levels for furnaces ........................................................ 39

Figure 10 – Choice of design principals ................................................................................ 41

Figure 11 – Fault assessment for the hard-wired section of a safety-related system ............. 42

Figure 12 – Proof of safety against failures and malfunctions of the programmable safety

device of the safety-related system ................................................................................ 43

Figure 13 – Proof of safety of software ................................................................................. 44

Figure 14 – Consideration of fault tolerance time and safety time for furnaces ..................... 47

Figure 15 – Examples for wiring of fuel shut down with hardware diversity of the

disconnecting devices .................................................................................................... 48

Figure 16 – Example for wiring of fuel shut down with diverse functionality of the

disconnecting devices .................................................................................................... 49

Figure A.1 - Explanation of symbols ..................................................................................... 65

Figure A.2 ............................................................................................................................ 66

Figure A.3 ............................................................................................................................ 67

Figure A.4 ............................................................................................................................ 68

Figure A.5 ............................................................................................................................ 69

Figure A.6 ............................................................................................................................ 70

Figure A.7 ............................................................................................................................ 71

Figure B.1 ............................................................................................................................ 72

Table 1 – Consideration of different field equipment (sensors and actuating elements)

configurations if subsystems or devices are used based on product standards without

data in accordance with EN 61508 or only based on the fault assessment in accordance

on the Figures 11, 12 or 13 ............................................................................................ 45

Table 2 – Allocation of fault exclusions to safety integrity levels ........................................... 50

Table A.1 ............................................................................................................................. 66

Table A.2 ............................................................................................................................. 67

Table A.3 ............................................................................................................................. 68

Table A.4 ............................................................................................................................. 69

Table A.5 ............................................................................................................................. 70

Table A.6 ............................................................................................................................. 71

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SIST EN 50156-1:2015
EN 50156-1:2015 (E)
European foreword

This document (EN 50156-1:2015) has been prepared by CLC/BTTF 132-2 “Revision of EN 50156 “Electrical

equipment for furnaces and ancillary equipment” in cooperation with the National Committee DKE/K 232.

The following dates are fixed:
• latest date by which this document has to be (dop) 2016-01-26
implemented at national level by publication of
an identical national standard or by
endorsement
• latest date by which the national standards (dow) 2018-01-26
conflicting with this document have to
be withdrawn
This document supersedes EN 50156-1:2004.

EN 50156-1:2015 includes the following significant technical changes with respect to EN 50156-1:2004:

• harmonization of the definitions to the new version of EN 61508;
• check and updating of the normative references;
• elimination of all normative references to the machinery directive 2006/42/EC;

• alignment to the requirements for safety related system to EN 12952 and EN 12953;

• modifications in Clause 10.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such patent rights.

This standard covers the Principle Elements of the Safety Objectives for Electrical Equipment Designed for

Use within Certain Voltage Limits (LVD - 2006/95/EC).

Requirements of this standard covers the essential safety requirements for limiting devices in the scope of

this standard which are safety accessories in the sense of pressure equipment directive 97/23/EG, which are

classified in the category II and higher.

This standard is the first part of a series of European standards which specify the requirements for

equipment of safety functions for furnaces, especially safety related system to protect personnel, the furnace

with ancillary equipment against hazards related to heat generation, the heated system and to operate

reliably during normal conditions, and abnormal conditions which can be foreseen.

This European Standard has been prepared by the German National Committee with the participation of

experts of other National Committees on the basis of CLC/BT(DE/NOT)140. It is divided into 3 parts under

the generic title “Electrical equipment for furnaces and ancillary equipment”:
• Part 1: Requirements for application design and installation;

• Part 2: Requirements for design, development and type approval of safety-relevant equipment;

• Part 3: Requirements for plant-specific tests of safety-relevant equipment.
This European Standard is based on the EN 61508:2010 “Functional safety of

electrical/electronic/programmable electronic safety-related systems”, Parts 1 to 7 as a basic safety

standard.
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SIST EN 50156-1:2015
EN 50156-1:2015 (E)
Introduction

This part of the European Standard EN 50156 specifies the requirements and recommendations for the

application design and installation of electrical and control equipment for furnaces and ancillary equipment

and for the systems heated by the thermal energy released in the furnace to ensure:

• safety of personnel, property and the environment;
• consistency of proper function.

The operating conditions of the furnace, the hazards of combustion and the safety of heated systems are

considered.
A safety-related system consisting of safety devices for:
• monitoring of flames and other safety conditions of the firing;
• interrupting the flow of fuel to the furnace;
• ventilating the body of the furnace and the flue gas ducts;

• monitoring of the safety condition of the heated systems (e.g. water level limiter in steam boilers);

may be necessary to ensure proper ignition and combustion of fuel and to avoid the development, existence

and/or ignition of an explosive mixture of fuel and air, and also to avoid damage to the heated systems (see

3.25).
The rating of necessary safety integrity levels is based on EN 61508-1.

Figure 1 is provided as an aid to understanding the relationship between the various elements of furnaces

and their ancillary equipment, the heated systems, the control system and the safety-related systems.

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SIST EN 50156-1:2015
EN 50156-1:2015 (E)

Figure 1 – Example of the functionality of a furnace with ancillary equipment, heated systems and

relationship to control system and safety related system
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SIST EN 50156-1:2015
EN 50156-1:2015 (E)
1 Scope

This European Standard applies to the application design and installation of electrical equipment, control

circuits and safety-related systems for furnaces which are operated with solid, liquid or gaseous fuels and

their ancillary equipment. It specifies requirements to meet the operating conditions of furnaces, to reduce

the hazards of combustion and to protect the heated systems from damage e.g. by overheating.

Such furnaces and the electrical equipment may be part by way of example of the following plant:

a) water heating systems;

b) steam boiler installations (steam and hot-water boilers) and heat recovery steam boilers;

NOTE 1 The requirements of this standard apply according to the electrical equipment of electrically heated steam

boilers.

NOTE 2 Seagoing vessels and offshore facilities are governed by International Maritime Law and as such are not

within the scope of this standard. These requirements may be used for such facilities.

c) warm air heaters;
d) hot-gas heaters;
e) heat exchanger systems;
f) combustion chambers of stationary turbines;

g) as long as no other standard is applicable for combined heat and power stations, we recommend the

use of the requirements of this standard;
h) This standard may also be used as reference for electric
...

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