EN 50156-1:2004

STANDARDElektrična oprema za peči in pomožno opremo – 1. del: Zahteve za zasnovo in inštalacijo napraveElectrical equipment for furnaces and ancillary equipment - Part 1: Requirements for application design and installation©
Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljenoReferenčna številkaSIST EN 50156-1:2006(en)ICS27.060.01

EUROPEAN STANDARD
EN 50156-1 NORME EUROPÉENNE EUROPÄISCHE NORM
October 2004 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
© 2004 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 50156-1:2004 E
ICS 27.060.01
English version
Electrical equipment for furnaces and ancillary equipment Part 1: Requirements for application design and installation
Equipements électriques d'installation
de chaudière Partie 1: Règles pour la conception,
pour l'application et l'installation
Elektrische Ausrüstung
von Feuerungsanlagen Teil 1: Bestimmungen für die Anwendungsplanung und Errichtung
This European Standard was approved by CENELEC on 2004-04-01. 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, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Foreword 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.
The text of the draft was submitted to the formal vote and was approved by CENELEC as EN 50156-1 on 2004-04-01. 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)
2005-04-01 - latest date by which the national standards
conflicting with the EN have to be withdrawn
(dow)
2007-04-01 The following further parts of this standard are under consideration: 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 type B standard (CEN/TC 114 terminology) is based on the IEC Standard 61508 Functional safety – Safety-related systems, Parts 1 to 7 as a basic safety standard. This standard shall serve as a basis for requirements on electrical equipment of boilers to be referenced in standards to be developed by CEN/TC 269. ________

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Contents
Introduction.5 1 Scope.7 2 Normative references.7 3 Definitions.9 4 General requirements.17 4.1 General considerations.17 4.2 Environmental requirements.18 4.3 Power supply.19 5 Incoming supply connections and devices for disconnecting and emergency stop.20 5.1 Incoming supply and equipment connections.20 5.2 Devices for disconnecting power supplies.22 5.3 Emergency stop.23 6 Protection against electric shock.24 6.1 Protection against direct contact.24 6.2 Protection against indirect contact.24 7 Environmental protection of the equipment.25 7.1 Protection against ingress of solid foreign bodies.25 7.2 Protection against water.25 8 Equipotential bonding.25 8.1 General.25 8.2 Equipotential bonding as a protective measure in case of indirect contact.25 8.3 Equipotential bonding for purpose of lightning protection.26 8.4 Functional equipotential bonding.26 9 Auxiliary circuits.26 9.1 Supply to auxiliary circuits.26 9.2 Voltage for auxiliary circuits.27 9.3 Connection to the protective conductor.28 9.4 Overcurrent protection of auxiliary circuits.28 9.5 Measures to prevent danger from short circuits to exposed conductive Parts or earth.29 9.6 Influence of capacitance and leakage resistance.29 10 Additional requirements for the application of protective system.30 10.1 General safety requirements.30 10.2 Concept and scope definition.33 10.3 Hazard and risk analysis.34 10.4 Safety requirements allocation.36 10.5 Design.37 10.6 Installation and commissioning.50 10.7 Safety validation.50

10.8 Operation and maintenance.53 10.9 Modification and retrofit.53 11 Electrical equipment.53 11.1 General requirements.53 11.2 Creepage distances and clearances.54 11.3 Motors.54 11.4 Transformers.54 11.5 Switching devices.55 11.6 Operator control devices.55 11.7 Immersion electrodes.55 11.8 Trace heating systems.55 12 Cables and cords.55 12.1 General requirements.55 12.2 Insulation.56 12.3 Current carrying capacity.56 12.4 Conductors of separate circuits.56 13 Warning signs and item designation.57 13.1 Name plates, markings and identifications plates.57 13.2 Warning signs.57 13.3 Functional identification.57 13.4 Marking of electrical equipment.57 13.5 Item designations.57 14 Technical documentation.58 14.1 Documentation describing functions and connections.58 14.2 Documents for type approved components.59 14.3 Documentation of the applications software.59 Annex A (informative)
Fault models of microelectronic components.60 Annex B (informative)
Configurations of programmable safety devices (PSD) with reference to
EN 61508.63 Annex C (informative)
Life cycle of programmable safety device of protective equipment.70 Annex D (informative)
Management of functional safety.71 Bibliography.72

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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; – ease and economy of maintenance. The operating conditions of the furnace, the hazards of combustion and the safety of heated systems are considered. A protective 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 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 explosive mixture of fuel and air, and also to avoid damage of the heated systems (see 3.25). The rating of necessary safety integrity levels is based on standard EN 61508-1. The requirements for protective system(s) for boilers have been coordinated with CEN/TC 269. 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 protective system(s). The following further parts of this Standard are under consideration: Part 2: Requirements for design, development and type approval of safety-relevant equipment Part 3: Requirements for plant-specific tests of safety-relevant equipment

Figure 1 – Example of the functionality of a furnace with ancillary equipment, heated systems and relationship to control system and protective equipment.

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1 Scope This standard applies to the application design and installation of electrical equipment, control circuits and protective 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 of the following plants for example: 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 it is recommended to use the requirements of this standard h) This standard may also be used as reference for electrical equipment requirements for thermo-processing equipment. NOTE 3 The requirements of this standard are applicable in all cases where an equipment specific standard does not specify a requirement. 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 purpose; 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 standard may be used as a basis for the requirements placed on electrical equipment for furnaces which are excluded from its field of application. 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. EN 267:1999, Forced draught oil burners – Definitions, requirements, testing, marking EN 298:1993, Automatic gas burner control systems for gas burners and gas burning appliances with or without fans EN 50265-1:1998, Common test methods for cables under fire conditions – Test for resistance to vertical flame propagation for a single insulated conductor or cable – Part 1: Apparatus

EN 55011:1998, Industrial, scientific and medical (ISM) radio-frequency equipment – Radio disturbance characteristics – Limits and methods of measurement (CISPR 11:1997, modified) A1:1999 (CISPR 11:1997/A1:1999) A2:2002 (CISPR 11:1997/A2:2002) EN 55022:1998, Information technology equipment – Radio disturbance characteristics – Limits and methods of measurement (CISPR 22:1997, modified) A1:2000 (CISPR 22:1997/A1:2000) A2:2003 (CISPR 22:1997/A2:2002) EN 60034-1:1998, Rotating electrical machines – Part 1: Rating and performance (IEC 60034- 1:1996, modified) A1:1998 (IEC 60034- 1:1996/A1:1997) A2:1999 (IEC 60034-1:1996/A2:1999) EN 60204-1:1997, Safety of machinery – Electrical equipment of machines – Part 1: General requirements (IEC 60204-1:1997) EN 60309-1:1999, Plugs, socket-outlets and couplers for industrial purposes – Part 1: General requirements (IEC 60309-1:1999) EN 60445:2000, Basic and safety principles for man-machine interface, marking and
identification – Identification of equipment terminals and of terminations of certain
designated conductors, including general rules for an alphanumeric system (IEC 60445:1999) EN 60519-1:1993, Safety in electroheat installations; Part 1: general requirements (IEC 60519-1:1984) EN 60529:1991, Degrees of protection provided by enclosures (IP code) (IEC 60529:1989) EN 60617 series, Graphical symbols for diagrams (IEC 60617 series) EN 60654-3:1997, Operating conditions for industrial-process measurement and control equipment –
Part 3: Mechanical influences (IEC 60654-3:1983) EN 60664-1:2003, Insulation coordination for equipment within low-voltage systems – Part 1: Principles, requirements and tests (IEC 60664-1:1992 + A1:2000 + A2:2002) EN 60947-2:1989, Low-voltage switch gear and control gear – Part 2: Circuit-breakers (IEC 60947-2:1995) A1:1997 A2:2001 EN 60947-3:1990, Low-voltage switch gear and control gear – Part 3: Switches, disconnectors, switch-disconnectors and fuse-combination units (IEC 60947-3:1999, mod.). A1:2001 EN 60947-4-1:2001, Low-voltage switchgear and controlgear – Part 4-1: Contactors and motor starters – Electromechanical contactors and motor-starters (IEC 60947-4-1:2000) EN 60947-5
series, Low-voltage switchgear and controlgear (IEC 60947-5 series) EN 61000-4
series, Electromagnetic compatibility (EMC) (IEC 61000-4 series) EN 61082
series, Preparation of documents used in electrotechnology (IEC 61082 series) EN 61131-3:2003, Programmable controllers – Part 3: Programming languages (IEC 61131-3:2003) EN 61140:2002: Protection against electric shock – Common aspects for installation and equipment (IEC 61140:2001)

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EN 61346-1:1996, Industrial systems, installations and equipment and industrial products – Structuring principles and reference designations – Part 1: Basic rules (IEC 61346-1:1996) EN 61508
series, Functional safety of electrical/electronic/programmable electronic safety-related systems (IEC 61508-1 series) EN 61558-1:1997, Safety of power transformers, power supply units and similar - Part 1: General requirements and tests (IEC 61558-1:1997, mod.) EN 61810-1:1998, Electromechanical non-specified time all-or-nothing relays – Part 1: General requirements (IEC 61810-1:1998) HD 384.4 series, Electrical installations of buildings – Part 4: Protection for safety (IEC 60364-4 series) HD 384.4.41 S2:1996, Electrical installations of buildings – Part 4: Protection for safety – Chapter 41: Protection against electric shock (IEC 60364-4-41:1992) HD 384.5.54 S1:1988, Electrical installations of buildings - Part 5: selection and erection of electrical
equipment; chapter 54: earthing arrangements and protective conductors (IEC 60364-5-54:1980) HD 472 S1:1989, Nominal voltages for low voltage public electricity supply systems (IEC 60038:1983). A1:1995 IEC 60050-191:1990, International Electrotechnical Vocabulary - Chapter 191: Dependability and quality of service IEC 60050-826:1982, International Electrotechnical Vocabulary - Chapter 826: Electrical installations of buildings IEC 60092-101:1994, Electrical installations in ships – Part 101: Definitions and general requirements. A1:1995 IEC 60417 database, Graphical symbols for use on equipment (IEC 60417 series) IEC 60536-2:1992, Classification of electrical and electronic equipment with regard to protection against electric shock – Part 2: Guide to requirements for protection against electric shock ISO 3864:1984, Safety colours and safety signs ISO 7000:1989, Graphical symbols for use on equipment; index and synopsis ISO 9000:2000, Quality management and quality assurance – Vocabulary 3 Definitions For the purposes of this standard the following definitions apply. 3.1 actuating element a component which produces changes in other electrical circuits or volume flows (e.g. fuel, air) as a result of the effect of changes in signal 3.2 auxiliary circuit an electrical circuit for ancillary functions, e.g. control circuits (command initiation, interlocking operation), signalling and measuring circuits

3.3 certificate of conformity declarations that the equipment is in accordance with relevant standard (see 10.7.3) NOTE In some legislation these declarations are only accepted from independent assessors depending on the required safety integrity level. 3.4 component a constituent part of the electrical equipment, usually specified by function, but used in various applications. Examples include resistors, capacitors, transistors, integrated circuits, printed-circuit boards NOTE A component is the smallest element a circuit can be subdivided into. If a component has to be broken down it loses its physical characteristics and/or does not conform to specifications. 3.5 components proven in operation components which have been applied in numerous and varied applications with acceptable low rates of failures. This shall be validated e. g. according EN 61508 3.6 continuous operation operation can be maintained for longer then 24 h without interruption 3.7 control circuit an electrical circuit used for the operational control and the protection of the furnace and of the power circuits 3.8 control device a device connected into the control circuit and used for controlling the operation of the furnace. For example, a manually operated switch, a limit transducer, or a valve 3.9 current limiting limiting of electric current to a predetermined maximum value for the defined operation by means of a suitable arrangement of components in the circuit 3.10 diagnostic Coverage (DC) the fraction of all hardware faults, which are detected by the online diagnostics embedded in the safety-related system NOTE To determine the DC a fault model should be used which is sufficient for the concerned technology. 3.11 diverse programs (software) programs or program sections which represent different solutions to an identical task which were either written (independently) by various persons or take different approaches to problems from the outset to achieve the same result (design diversity) 3.12 electrical equipment equipment for furnaces includes all electrical equipment for the fields of application mentioned in Clause 1 3.13 emergency stop device a manually operated switch which can be used to shut down the furnace and its associated equipment in the event of danger. The emergency stop device shall prevent fuel flow and electrical preheating

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3.14 external diagnostic (ED) measures to detect failures, particularly passive failures, where additional devices, which do not form part of the programmable controller or one of its channels, are used to test the function of particular sections or the entire programmable controller. The external diagnostic may be performed by another channel in the case of a multi-channel configuration 3.15 external influences influences from the environment which could bring about a failure or malfunction of the function NOTE The following are examples of external influences on electrical systems: a) Power failure and return of power, over voltage and under voltage, short-power interruptions (< 0,5 s). b) Electromagnetic and electrical disturbances, such as inductive or capacitive interference or leakage currents through resistive connections. c) For microelectronic components, ionising radiation as well as UV radiation for EPROMs. 3.16 failure (F) the termination of the ability of an item to perform required function (191-04-01 of IEC 60050-191:1990) NOTE 1
After failure, the item has a fault. NOTE 2
„Failure“ is an event, as distinguished from „fault“ which is a state. NOTE 3
This concept as defined does not apply to items consisting of software only. 3.17 failure mechanism physical or chemical process which causes an assembly to fail. It may also define how the assembly fails, e.g. fail to safety. In doing so it may be possible to detect a failure tendency direction 3.18 fault the state of an item characterised by inability to perform a required function, excluding the inability during preventative maintenance or other planned actions, or due to lack of external resources e.g. loss of power supplied (see Figures 2 and 3). NOTE A fault is often the result of a failure of the item itself, but may exist without prior failure (191-05-01 of IEC 60050-191:1990).

fault hardware fault
(system. or random) software fault
(allways systematic) Other software fault software fault, which causes shut down or malfunction
Figure 2 – Kinds of faults (related to the equipment 1) to be considered)
systematic fault fault caused by environment random fault fault syst. HW fault syst. SW fault EMC climatic other influences (e.g. mechan., chem.) HW failure, permanent sporadic HW faults (malfunction)
Figure 3 – Causes of faults (related to the equipment 1) to be considered) 3.19 fault exclusion exclusion of a theoretically possible fault whose occurrence, in the light of practical experience, or under the given physical conditions is so unlikely, that it needs not to be taken into account ——————— 1) equipment to be considered could be: – component – device – module – plant component

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3.20 fault tolerance time the fault tolerance time is the time between the occurrence of an unsafe condition (caused by the process itself or due to equipment failure) and the point when the process changes into critical operation, which would result in an hazardous event in the absence of any protective systems 3.21 flame monitoring device or unit a safety device which is triggered by the presence or absence of flame and gives an appropriate signal to the protective equipment 3.22 function test the complete test of an individual safety-related function. This includes testing, whether the protective system (sensors, protective equipment and actuating elements) is acting correctly when a process parameter is changed to ensure correct operation of the safety-related function NOTE Function tests of the complete safety-related functions may be carried out by overlapping partial tests. 3.23 furnace a structure within which heat is generated to a controlled temperature by combustion of fuel NOTE The English term „furnace“ includes structures within which heat is generated by electricity and other forms of energy. This standard also applies to the electrical equipment of electrically heated or heat recovery steam boilers. 3.24 furnace and ancillary equipment this includes all the equipment for the burning of fuels, for example equipment for the storage, preparation and transport of fuels, combustion air supply2), cleaning and removal of flue gas and exhausts and relevant closed-loop and open-loop control and monitoring equipment 3.25 heated system the equipment which absorbs the heat generated in the furnaces, e.g. economiser, evaporator, and superheater of a steam boiler, heat exchanger, gas turbine 3.26 immersion electrode an immersion electrode is a limit transducer for fluid level monitoring 3.27 limiter a transducer which, on reaching a defined limit value (e.g. pressure, temperature, flow, level), interrupts the energy supply and remains in that state until manually reset NOTE Resetting of the limiter can be done either manually or by use of a tool. The resetting is only possible once the performance quantity has been restored to within its operating limits. This function of locking can be achieved mechanically on the equipment or by means of an electrical circuit. 3.28 limit sensor a transducer which, on reaching a defined limit value, outputs a signal and/or cuts out and only reverses the output signal in the event of a specific change in the performance quantity (e.g. pressure, temperature, flow, level). Limit sensors are used for signalling or for triggering control processes ——————— 2) Also applies to gas turbines containing oxygen within its exhaust gas.

3.29 main circuit the electrical circuit which supplies the electrical energy to equipment for the generation, conversion, distribution, switching and consumption of electrical energy 3.30 malfunction (M) a transient fault 3.31 management of faults all measures which ensure that when a fault occurs the system remains in a safe state or that a safe state is achieved 3.32 non-opening of contact elements a fault which prevents the opening of contacts of relays or other switching devices e.g. contact welding, sticking of the magnet armature, etc. 3.33 program analysis (PA) all measures used in the context of theoretical checking to reveal software errors 3.34 programmable controller a device with binary logic elements which responds to control devices and initiates a specific programmed sequence 3.35 programmable safety device (PSD) a programmable component within the protective equipment 3.36 proof of correctness (POC) verification that the safety related program functions have been fulfilled 3.37 protective bonding circuit the protective conductors and conductive parts used to protect against the consequences of earth faults 3.38 protective conductor a conductor required by some measures for protection against electric shock for electrically connecting any of the following parts: – exposed conductive parts; – extraneous conductive parts; – main earthing terminal. (826-04-05 of IEC 60050-826:1982) 3.39 protective equipment safety-related control and switching equipment which receives signals from sensors, limiters and other monitoring devices. Its purpose is to switch actuating elements according to the specified safety function NOTE Protective equipment may consist of a completely hard-wired device or it may be a programmable safety device incorporating electronics and a programming facility. In hard-wired equipment, the signals from all modules are generated and processed by individual connections. In programmable safety devices signals are processed by means of programs (software) stored in memories.

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3.40 protective system all equipment, units and safety related circuits whose main purpose is the protection of personnel, property or the environment. The protective system includes all the components required to carry out the safety function, for example sensors which monitor safety related parameters (e.g. flame monitoring), interruption device for the flow of fuel, ventilation of the body of the furnace and protection of the heated system (e.g. monitoring the water level of steam boilers). Typically a protective system consists of sensors, logic solving protective equipment and actuating elements (see Figure 4). If this is achieved by multi-channel systems, then all channels and monitoring devices used for safety purposes are included within the protective system
sensor (3.28) protective equipment actuating element safety devices (3.41) protective system
Figure 4 – Definition and components of a protective system 3.41 safety device any device which is used to carry out safety-related functions, either on its own or as a part of a protective system (e.g. sensors, limiters, flame monitors, burner control devices according EN 298, logic system, actuating elements, fuel shut down valves etc.) 3.42 safety integrity level (SIL) the probability of a safety-related system satisfactorily performing the required safety functions under all the stated conditions within a stated period of time. There are 4 possible discrete levels for specifying the safety integrity requirements of the safety function to be allocated to the safety related systems. Safety integrity level 4 has the highest level of safety integrity; safety integrity level 1 has the lowest 3.43 safety related circuit an electrical control circuit used for the protection of personnel, property and environment. For example, safety circuits, which prevent or interrupt the flow of fuel, either directly or indirectly 3.44 safety time the safety time of a furnace is the time taken (lower part of Figure 13) from the occurrence of an unsafe operating condition (for example, flame interrupt during normal operation) to the point at which closure of the shut off valve or the final element is initiated 3.45 self diagnostic (SD) measures to detect failures where additional programs in the programmable safety device (PSD) are used to test the function of specific components (e.g. ROM) or functional modules (e.g. I/O modules) which belong to the programmable controller or to one of its channels

3.46 software (SW) software includes programs, parameters and data. The software is made up of application software and system software (see Figure 5)
software application software system software 3) Compiler/Interpreter plant specific SW 2) (individual programmed) Standardised modules 1) (only parameter changed) Test SW (for diagnostics) functional SW operating system
NOTES: 1) Type approval according to Part 2 of this Standard, test of correctness of parameter setting (application related) according to Part 3 of this Standard. 2) Application related approval according to Part 3 of this Standard. 3) Type approval according to Part 2 of this Standard. Figure 5 – Software 3.47 software faults discrepancies between program functions performed in the program and the specified program functions
(see also Figures 3 and 4) NOTE All software errors are systematic errors. 3.48 software modules proven in operation software modules which have been used, without any change for at least 100 000 operation hours. It should have been applied in numerous and varied applications with no safety related software faults having been detected 3.49 software test (T) measures to reveal software errors where the input interfaces of the program modules or the entire program is supplied with input data records and program execution and results (output data) are captured and compared with those obtained on the basis of the specification or program analysis 3.50 systematic hardware faults faults in the equipment under consideration caused by inadequate specifications or errors in design, manufacturing, installation or maintenance 3.51 type approval examination by a third party (accredited) that a duly identified product, process or service is in conformity with a specific standard and/or the specified requirements

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3.52 validation confirmation by examination and provision of objective evidence, that the particular requirements for a specific intended use are fulfilled (ISO 9000) NOTE In the context of this European Standard, validation means the process of demonstrating that the protective system under consideration, and after installation, meets in all respects the safety requirements specification for that protective system. Therefore, for example, Software Validation means confirming by examination and provision of objective evidence that the software satisfies the Software Safety Requirements Specification. 3.53 verification confirmation by examination and provision of objective evidence that the specified requirements have been fulfilled (ISO 9000) NOTE 1 In the context of this European Standard, verification means the process of demonstrating for each phase of the relevant Safety Lifecycle (see Figure 8) by analysis and/or tests, that, for the specific inputs, the deliverables meet in all respects the Objectives and Requirements set for the specific phase. NOTE 2 Examples of verification activities would include: - Reviews on deliverables (documents from all phases of the Safety Lifecycle) to ensure compliance with the Objectives and Requirements of the phase taking into account the specific inputs to that phase. - Design reviews. - Tests performed on the designed products to ensure that they perform according to their specification. - Integration tests performed where different parts of a system are put together in a step by step manner and by the performance of environmental tests to ensure that all the parts work together in the specified manner. 4 General requirements 4.1 General considerations The relevant European Standards for electrical equipment apply to the installation of the electrical part of furnaces. Clause 2 lists appropriate standards and other technical codes. Risks associated with the hazards relevant to the electrical equipment shall be assessed as part of the overall requirements for assessment of the furnace or boiler plant. This risk assessment shall be carried out for each individual situation. The risk assessment includes the following elements for which the standard gives guidance: a) hazard identification, b) determine the probability of all hazards, c) evaluate the risk(s), and d) consider measures for risk reduction. This will determine the acceptable level of risk and the necessary protective measures for persons who can be exposed to the hazards of the furnace and the system heated by it (e.g. steam boiler). Hazards can include but are not limited to the following: – electrical shock or electrical fire resulting from failures or faults in the electrical equipment; – malfunctioning of the furnace resulting from failures or faults in control circuits (or components and devices associated with these circuits); – malfunctioning of the furnace resulting from disturbances or disruptions in external power sources as well as failures or faults in the power circuits; – electrical disturbances (e.g. electromagnetic, electrostatic, radio disturbance) either from outside the electrical equipment or internally generated; – stored energy (either electrical or mechanical);

– burns or heat stress or damage or malfunction of parts of the electrical equipment caused by extreme temperatures of parts of the plant or in their vicinity; – operation outside the design limits of the furnace and its associated equipment; – incorrect combustion conditions resulting in an explosion in the furnace, the fuel or flue gas paths; – incorrect operating condition resulting in damage to the heated system (e.g. explosion of a steam boiler caused by water level below minimum); – not ventilated furnaces in standby mode in case of a sudden ignition. A combination of measures are necessary at the stages of design, installation and operation for protection against the hazards of the furnace and its electrical equipment. 4.2 Environmental requirements The electrical equipment shall be selected and mounted so that it withstands the potential electrical, chemical and mechanical stresses at its place of use as well as external influences e.g. environmental stresses. 4.2.1 Environmental and operating conditions The electrical equipment shall be suitable for use in the environmental and operating conditions as specified below. An agreement is required between supplier and user, if the environmental and operating conditions are outside those specified below. 4.2.2 Electromagnetic compatibility 4.2.2.1 Electromagnetic compatibility – Emission requirements The electrical interference generated by the equipment itself shall not exceed levels specified in the relevant equipment standard and other standards with electromagnetic compatibility (EMC). For permissible limits and methods of measurement of radio interference characteristics see EN 55011 or EN 55022 depending on the application. 4.2.2.2 Electromagnetic compatibility -– Immunity requirements Test instrumentation, test set-up and test procedure shall be in accordance with the relevant parts of EN 61000-4 series. The severity levels being at least level 3 and the performance criteria as specified below. The equipment under test (EUT) shall be operated at rated voltage unless otherwise specified. The Equipment shall be tested during stand-by, running and lock-out condition. NOTE Higher EMC levels may be selected depending on the environment in which the equipment is used. In these cases the appropriate levels should be used. The levels as mentioned in the EN 61000-4 series are preferred. Whenever the levels are not defined in the EN 61000-4 standard they should be pre-defined between manufacturer and test house. 4.2.2.3 Performance criteria – Safety related functions:
When tested in accordance with 4.2.2.2, safety relevant functions shall remain operational in accordance with the manufacturer’s specifications. Furthermore, the equipment shall not reset when tested in lock-out condition. – Non safety relevant aspects:
Non safety relevant functions should meet the requirements as intended under the EMC-Directive. Therefore the performance criteria of these functions shall be in accordance with the manufacturer´s specifications. These specifications shall be predefined. 4.2.3 Ambient temperature Electrical equipment shall be capable of operating correctly under the ambient temperature prevailing at the place of use.

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Normally the following ambient temperatures shall be considered: – Electrical installation rooms: Electrical equipment shall be capable of operating correctly in ambient temperatures between +5 °C and +35 °C; – Plant environment (e.g. boiler house): Electrical Equipment shall be capable of operating correctly in ambient temperatures between +0 °C and +55 °C; – Outdoor installation: Electrical equipment shall be capable of operating correctly in ambient temperatures between –25 °C and +40 °C. Electrical equipment shall be so designed that it withstands temperatures from –25 °C to +70 °C during transport and storage. If other temperatures than those specified above are expected at the place of use (e.g. upper level boiler area) electrical equipment shall be so designed that it is capable of operating correctly under these conditions. The operating temperature range shall be indicated. If the equipment is designed to be cooled while in use, the permissible coolant temperatures should be indicated on the type plate. 4.2.4 Operating under on-board conditions Electrical equipment shall be selected to ensure that it works correctly in on-board conditions making an allowance for an ambient temperature of at least 45 °C and a possible tilt of 22,5 °(45 ° for a sh
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